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February 2006

Gradually a Bit Wamer and a Bit Less Windy...Plowable Snow for Many on Thursday...Cold Returns for Weekend Before Another Potential Storm Next Week

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net

Matt's Quick Weather Synopsis:  Another day of chilly sunshine across most of New England as a storm system parked well to our northeast continues to spin in place while gradually weakening.  The result will be continued busy winds, though less intense than Monday, with gusts to 25-30 mph, teaming up with continued cold temperatures for a nippy feel.  Most areas will enjoy sunshine, though most of Maine will be in and out of clouds as we were yesterday, with these clouds spinning southward from the aforementioned storm in Eastern Canada.  A fast-moving but moisture starved disturbance will eject southward out of Canada Tuesday night, bringing variable cloud cover south, and mountain flurries north.  Another quiet day is in store for New England on Wednesday, as we'll be sandwiched between Tuesday night's departing disturbance, and a much stronger storm moving east across the Midwest.  This approaching storm comes from roots in the Pacific Ocean, and has dumped several inches of rain and several feet of snow on the West Coast over the last two days.  This moisture-laden and energetic storm will cross New England on Thursday, with snow developing Wednesday night after midnight, and continuing into Thursday.  At this point, a widespread plowable snow (3" or greater) appears likely in many areas by the time the storm winds down, with a band of higher amounts possible, especially through interior locales (see map below).  There is also the possibility of lesser amounts farther south in New England, where enough mild air may nose in to mix with or change to sleet and rain for a time.  By Friday, northerly breezes behind the departing storm will bring in one installment of cooler air, and another arctic surge appears en route for the weekend.  Have a great Fat Tuesday!  -Matt

Early Thoughts on Thursday Snow (check in for updates, though...still some time to go on this one):

Accums_neweng_1

Weather Summary coming later, as usual.

General Weather Summary:  With a stalled and gradually weakening storm loadged northeast of New England, winds will continue to be active from the west-northwest on Tuesday, and cold air will remain locked in place.  While the gradually weakening state of this storm will mean slightly less wind than Monday with gusts to 25 or 30 mph rather than 35 mph, and slightly warmer temperatures nearing 30 in a few communities, a chill will certainly still be felt for all who spend an extended period of time outdoors. Northwest winds extend upward, deep into the atmosphere above us, and this means that any disturbances to affect New England - for now - will be dropping south out of Canada.  A morning analysis shows one of these energetic disturbances "upstream" to our northwest, ready to dive over New England Tuesday night as it becomes caught in the fast flow from the northwest.  Because it's originating in Canada, this disturbance is moisture-starved, and will bring little more than passing clouds and mountain snow showers as it moves overhead Tuesday night.

With one disturbance moving away from us, and the next still hundreds of miles to our west, Wednesday will bring much lighter winds and a continued gradual moderation in temperatures.  Meanwhile, several inches of rain and several feet of snow have been falling the past two days along the Pacific Coast and mountains of the Western United States.  Heavy rains have fallen in Los Angeles with this storm, and residents of Phoenix, Arizona, will be turned skyward in search of the first raindrops in 132 days on Tuesday as a strong Pacific storm system barrels its way inland.  This moisture-laden system will eject a piece of energy eastward across the U.S., and the associated surface storm center will move through New England on Thursday. 

As with this past weekend's disturbance, the exact track of the storm will make a large difference regarding where the heaviest precipitation falls.  Regardless, as warmer and more moist air surges north in association with this approaching storm and collides with our cold airmass, snow is likely to develop for many areas after midnight Wednesday night.  Given the surge of warmth and moisture associated with this system of Pacific Ocean origins, it's likely to snow heavily at times in many areas late Wednesday night through Thursday morning.  Though some variation is still possible, the most likely scenario takes a strengthening storm center into Southeast New York State by Thursday morning, then shifts energy to a new storm center that will take shape immediately south of Cape Cod.  At the surface, this means winds will blow from the southeast in advance of the approaching storm, which will slowly bring warmer air in from the Atlantic Ocean.  Eventually, if enough warm air comes into play, a mix or change to sleet or rain would be possible in far Southern New England, though right now I wouldn't count on a widespread mix or changeover.  Unlike the last storm, fluffy snow will be confined mainly to Northern New England, while the remainder of us will see a heavier, wetter snowfall. - and this also will cut back on amounts.  I've posted a map of my initial thoughts in the Synopsis above, but keep in mind a few things:  1) Storm track still is subject to change, which would bodily shift the corridor of highest amounts, though I don't see a significant shift in track as likely at this point, and 2) The amount of warm air that moves in will be critical to snowfall amounts.  Areas of Southern NH, Southern VT, and Northern MA stand the best chance of seeing the combination of somewhat fluffier snow with plentiful moisture, and these are the areas most at risk for either side of a 6" snowfall, but there is still plenty of time to fine tune this.

After our Thursday snow, cold northerly winds take hold behind the departing and strengthening storm, and these winds will usher in cold and dry air - helpful in bringing the sun out for Friday, but also likely to hold daytime high temperatures in the upper 20's to around 30 for most areas.  By Saturday, a stronger northerly flow will set in behind a reinforcing cold front, and the result will likely be weather equally cold to the beginning of this week, in place just in time for the weekend.

Looking farther out in time, the weather pattern continues to indicate potential strong storm development in the early to middle part of next week, as a strong storm south of Alaska - over the Aleutian Islands - breaks down this weekend and ejects east and across the nation.  At the same time, the stalled storm to our northeast that's been keeping a northwest flow of wind relaxes, and this would allow the new energetic storm to move to the East Coast, where it would be likely to develop into a more potent system - chock full of wind and likely to spell at least a week-long temporary end to deep cold here in the Northeast, which would mean milder weather after the storm...from roughly March 8 to March 14.  Thereafter, early signs are that at least somewhat colder than normal weather may return for a time.

Have a great Tuesday!

Technical Discussion:  Probably not today with lots going on here at the station, but I'm reposting below what I posted late yesterday afternoon, in case you missed it due to the late post.

Matt

Matt's Technical Meteorological Discussion:  Reposted from Monday, February 27 at 3:20 PM

Warm advection clouds across ME/NH/parts of NE MA today are the result of warm air wrapped all the way around the north side of storm circulation to our northeast and another burst of these is possible later Tuesday as polar vortex throws warmer air southward aloft.  A strange reality, I know, but this is what happens when you get a wound up storm bombing northeast of NewEng during a strong Greenland block and developing strong negative NAO.

I'm going to broadbrush the short-term in favor of focusing on the medium range and longer range forecasts today...and the broad strokes paint an eastward moving shortwave moving over NewEng Mon Ngt and bringing snow showers with it - esp Nrn MA point N - with a dusting of accum possible given a couple of hundreths that output on esp SUNYSB MM5 and WRF.

Good mixing Tuesday will team with downslope flow and sunshine for at least most of the day away from warm advection clouds from the north to bring temps into the 20's most areas Central and South.  Wed features a westward retrogression of the polar vortex and this is an important shift as it dictates where the storm currently slamming the west coast with copious amounts of rain and snow will be steered.

In fact, using this pattern shift, we could determine that the NAM solution for the track of Thursday's shortwave - our first stopping point in the medium range - was initially likely much too far north as it took the shortwave over Central and Northern NewEng, but the new 12Z position is more in line with the remainder of the operational models and likely more on target.  There are a few things to keep in mind with this shortwave:  1) It is the composite of northern and southern stream energy, but really is a reincarnation of the storm over the West Coast Monday afternoon, which splits north and south and then comes together again over the Western Great Lakes, 2) When the new merged vorticity maximum moves through the northeast on Thu, remember its origin - it has come from moisture-laden beginnings bringing rain from SEA to LAX on Monday, and feet of snow to the CA mountains, 3) It is cresting a thermal ridge of tremendous warmth - some 20 to 25 C at 850 mb over the Central and Southern Plains, and this sets up a tremendous baroclinic zone with the cold air shoved south of the polar vortex, 4) The surface low will be strengthening as it moves in a path that...according to progged 500 mb and 700 mb flow...should take it immediately south of NewEng as it races E.

Once again this leaves us with a storm that we wonder whether it will be able to generate a closed circulation and add ocean moisture, but this time it's not nearly as important to do this as it was with the weekend system.  Remember that in this discussion you and I considered the importance of this ocean inflow for the past weekend storm, and we knew that where an easterly flow could establish, the higher snowfall and QPF would be, and that was likely to set up on the northern side of the circulation.  We needed that moisture this weekend to offset what was otherwise a bone-dry atmosphere.  Though the air is dry currently, by Thursday the situation will be quite different, as this storm comes of Pacific origin - carrying its own moisture.  For snow lovers, that's a good thing because indications right now are somewhat iffy on whether it could get its act together quickly enough to incorporate Atlantic moisture, largely owing to its very fast progression eastward.  Nonetheless, this system of moist origins will carry a southerly llvl jet east into NewEng late Wed Ngt into Thu, and this will again result in a band of snow, heavy at times, into Thu across most of Southern and Central NewEng, and likely spreading into Nrn NewEng as well, esp given lingering trough and SE sfc flow in place.  Remember that with this past weekend's event, there was a fairly well-defined southern cutoff to the plowable snowfall amounts - that is the nature of a system that is relying heavily upon a surge of warmth and moisture colliding with a cold airmass - south of the collision there will be a sharp drop in precip amounts.  This will be the case again with the upcoming storm, but indications are that most areas should end up under this enhanced baroclinicity.  So, once again a shot of plowable snows appears en route for NewEng late Wed Ngt into Thu.

Thereafter, with northwest flow the weather may quiet down for a few days, but this is likely to only be the calm before the storm that will break the back of the deep cold for a time, if not for the rest of winter.  Consistent indications for several days have been coming back for a few things to happen around March 6-7.  The first is that the polar vortex lets go of Eastern Canada and shifts north and northeast, diminishing the confluent flow that has kept disturbances moving so quickly across us.  The second is that...in response to this shift and a weakening of the Greenland Block, the NAO approaches neutral.  Historically, when we see the NAO shift from strongly negative to near-neutral or slightly positive, this can signal a large storm development near the Northeastern US.  Add to this the fact that a strong Pacific shortwave will be traversing the country - the leftover heart of the Aleutian low spinning south of Alaska today - into a less confluent flow over the Northeastern US but still confluent enough over Nova Scotia to hold cold high pressure to our NE, and we have a recipe for a strong storm.  Additionally, the operational models continue to key in on this time period for storm development, which can add further confidence to a forecast of a large storm in this time period.  Behind the storm, it does appear heights rise dramatically, which tells me two things: 1) The storm will likely be a strong one, as this is evidence of the amount of warmth and moisture available to it from the southern stream and the resultant baroclinicity, and 2) This strong storm will lead the northeast into a spring-like pattern for what is likely to be at least a week, taking us to around March 13-14.  Thereafter, while the deep cold will be exhausted, cold locked in Siberia that will have been cut off from migrating eastward (truly it's this bridge to Siberian cold that's been feeding our current cold streak) will be able to slide east into Western and Central Canada again, and renewed cold appears possible sometime after March 14, though not as deep and not for as long a period, it still will be watched carefully as baroclinicity would be a big factor at that point, owing to a significantly higher sun angle.

Needless to say, plenty watch for one and all.  That's all for today.

Matt


Gradually a Bit Wamer and a Bit Less Windy...Plowable Snow for Many on Thursday...Cold Returns for Weekend Before Another Potential Storm Next Week

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net

Matt's Quick Weather Synopsis:  Another day of chilly sunshine across most of New England as a storm system parked well to our northeast continues to spin in place while gradually weakening.  The result will be continued busy winds, though less intense than Monday, with gusts to 25-30 mph, teaming up with continued cold temperatures for a nippy feel.  Most areas will enjoy sunshine, though most of Maine will be in and out of clouds as we were yesterday, with these clouds spinning southward from the aforementioned storm in Eastern Canada.  A fast-moving but moisture starved disturbance will eject southward out of Canada Tuesday night, bringing variable cloud cover south, and mountain flurries north.  Another quiet day is in store for New England on Wednesday, as we'll be sandwiched between Tuesday night's departing disturbance, and a much stronger storm moving east across the Midwest.  This approaching storm comes from roots in the Pacific Ocean, and has dumped several inches of rain and several feet of snow on the West Coast over the last two days.  This moisture-laden and energetic storm will cross New England on Thursday, with snow developing Wednesday night after midnight, and continuing into Thursday.  At this point, a widespread plowable snow (3" or greater) appears likely in many areas by the time the storm winds down, with a band of higher amounts possible, especially through interior locales (see map below).  There is also the possibility of lesser amounts farther south in New England, where enough mild air may nose in to mix with or change to sleet and rain for a time.  By Friday, northerly breezes behind the departing storm will bring in one installment of cooler air, and another arctic surge appears en route for the weekend.  Have a great Fat Tuesday!  -Matt

Early Thoughts on Thursday Snow (check in for updates, though...still some time to go on this one):

Accums_neweng_1

Weather Summary coming later, as usual.

General Weather Summary:  With a stalled and gradually weakening storm loadged northeast of New England, winds will continue to be active from the west-northwest on Tuesday, and cold air will remain locked in place.  While the gradually weakening state of this storm will mean slightly less wind than Monday with gusts to 25 or 30 mph rather than 35 mph, and slightly warmer temperatures nearing 30 in a few communities, a chill will certainly still be felt for all who spend an extended period of time outdoors. Northwest winds extend upward, deep into the atmosphere above us, and this means that any disturbances to affect New England - for now - will be dropping south out of Canada.  A morning analysis shows one of these energetic disturbances "upstream" to our northwest, ready to dive over New England Tuesday night as it becomes caught in the fast flow from the northwest.  Because it's originating in Canada, this disturbance is moisture-starved, and will bring little more than passing clouds and mountain snow showers as it moves overhead Tuesday night.

With one disturbance moving away from us, and the next still hundreds of miles to our west, Wednesday will bring much lighter winds and a continued gradual moderation in temperatures.  Meanwhile, several inches of rain and several feet of snow have been falling the past two days along the Pacific Coast and mountains of the Western United States.  Heavy rains have fallen in Los Angeles with this storm, and residents of Phoenix, Arizona, will be turned skyward in search of the first raindrops in 132 days on Tuesday as a strong Pacific storm system barrels its way inland.  This moisture-laden system will eject a piece of energy eastward across the U.S., and the associated surface storm center will move through New England on Thursday. 

As with this past weekend's disturbance, the exact track of the storm will make a large difference regarding where the heaviest precipitation falls.  Regardless, as warmer and more moist air surges north in association with this approaching storm and collides with our cold airmass, snow is likely to develop for many areas after midnight Wednesday night.  Given the surge of warmth and moisture associated with this system of Pacific Ocean origins, it's likely to snow heavily at times in many areas late Wednesday night through Thursday morning.  Though some variation is still possible, the most likely scenario takes a strengthening storm center into Southeast New York State by Thursday morning, then shifts energy to a new storm center that will take shape immediately south of Cape Cod.  At the surface, this means winds will blow from the southeast in advance of the approaching storm, which will slowly bring warmer air in from the Atlantic Ocean.  Eventually, if enough warm air comes into play, a mix or change to sleet or rain would be possible in far Southern New England, though right now I wouldn't count on a widespread mix or changeover.  Unlike the last storm, fluffy snow will be confined mainly to Northern New England, while the remainder of us will see a heavier, wetter snowfall. - and this also will cut back on amounts.  I've posted a map of my initial thoughts in the Synopsis above, but keep in mind a few things:  1) Storm track still is subject to change, which would bodily shift the corridor of highest amounts, though I don't see a significant shift in track as likely at this point, and 2) The amount of warm air that moves in will be critical to snowfall amounts.  Areas of Southern NH, Southern VT, and Northern MA stand the best chance of seeing the combination of somewhat fluffier snow with plentiful moisture, and these are the areas most at risk for either side of a 6" snowfall, but there is still plenty of time to fine tune this.

After our Thursday snow, cold northerly winds take hold behind the departing and strengthening storm, and these winds will usher in cold and dry air - helpful in bringing the sun out for Friday, but also likely to hold daytime high temperatures in the upper 20's to around 30 for most areas.  By Saturday, a stronger northerly flow will set in behind a reinforcing cold front, and the result will likely be weather equally cold to the beginning of this week, in place just in time for the weekend.

Looking farther out in time, the weather pattern continues to indicate potential strong storm development in the early to middle part of next week, as a strong storm south of Alaska - over the Aleutian Islands - breaks down this weekend and ejects east and across the nation.  At the same time, the stalled storm to our northeast that's been keeping a northwest flow of wind relaxes, and this would allow the new energetic storm to move to the East Coast, where it would be likely to develop into a more potent system - chock full of wind and likely to spell at least a week-long temporary end to deep cold here in the Northeast, which would mean milder weather after the storm...from roughly March 8 to March 14.  Thereafter, early signs are that at least somewhat colder than normal weather may return for a time.

Have a great Tuesday!

Technical Discussion:  Probably not today with lots going on here at the station, but I'm reposting below what I posted late yesterday afternoon, in case you missed it due to the late post.

Matt

Matt's Technical Meteorological Discussion:  Reposted from Monday, February 27 at 3:20 PM

Warm advection clouds across ME/NH/parts of NE MA today are the result of warm air wrapped all the way around the north side of storm circulation to our northeast and another burst of these is possible later Tuesday as polar vortex throws warmer air southward aloft.  A strange reality, I know, but this is what happens when you get a wound up storm bombing northeast of NewEng during a strong Greenland block and developing strong negative NAO.

I'm going to broadbrush the short-term in favor of focusing on the medium range and longer range forecasts today...and the broad strokes paint an eastward moving shortwave moving over NewEng Mon Ngt and bringing snow showers with it - esp Nrn MA point N - with a dusting of accum possible given a couple of hundreths that output on esp SUNYSB MM5 and WRF.

Good mixing Tuesday will team with downslope flow and sunshine for at least most of the day away from warm advection clouds from the north to bring temps into the 20's most areas Central and South.  Wed features a westward retrogression of the polar vortex and this is an important shift as it dictates where the storm currently slamming the west coast with copious amounts of rain and snow will be steered.

In fact, using this pattern shift, we could determine that the NAM solution for the track of Thursday's shortwave - our first stopping point in the medium range - was initially likely much too far north as it took the shortwave over Central and Northern NewEng, but the new 12Z position is more in line with the remainder of the operational models and likely more on target.  There are a few things to keep in mind with this shortwave:  1) It is the composite of northern and southern stream energy, but really is a reincarnation of the storm over the West Coast Monday afternoon, which splits north and south and then comes together again over the Western Great Lakes, 2) When the new merged vorticity maximum moves through the northeast on Thu, remember its origin - it has come from moisture-laden beginnings bringing rain from SEA to LAX on Monday, and feet of snow to the CA mountains, 3) It is cresting a thermal ridge of tremendous warmth - some 20 to 25 C at 850 mb over the Central and Southern Plains, and this sets up a tremendous baroclinic zone with the cold air shoved south of the polar vortex, 4) The surface low will be strengthening as it moves in a path that...according to progged 500 mb and 700 mb flow...should take it immediately south of NewEng as it races E.

Once again this leaves us with a storm that we wonder whether it will be able to generate a closed circulation and add ocean moisture, but this time it's not nearly as important to do this as it was with the weekend system.  Remember that in this discussion you and I considered the importance of this ocean inflow for the past weekend storm, and we knew that where an easterly flow could establish, the higher snowfall and QPF would be, and that was likely to set up on the northern side of the circulation.  We needed that moisture this weekend to offset what was otherwise a bone-dry atmosphere.  Though the air is dry currently, by Thursday the situation will be quite different, as this storm comes of Pacific origin - carrying its own moisture.  For snow lovers, that's a good thing because indications right now are somewhat iffy on whether it could get its act together quickly enough to incorporate Atlantic moisture, largely owing to its very fast progression eastward.  Nonetheless, this system of moist origins will carry a southerly llvl jet east into NewEng late Wed Ngt into Thu, and this will again result in a band of snow, heavy at times, into Thu across most of Southern and Central NewEng, and likely spreading into Nrn NewEng as well, esp given lingering trough and SE sfc flow in place.  Remember that with this past weekend's event, there was a fairly well-defined southern cutoff to the plowable snowfall amounts - that is the nature of a system that is relying heavily upon a surge of warmth and moisture colliding with a cold airmass - south of the collision there will be a sharp drop in precip amounts.  This will be the case again with the upcoming storm, but indications are that most areas should end up under this enhanced baroclinicity.  So, once again a shot of plowable snows appears en route for NewEng late Wed Ngt into Thu.

Thereafter, with northwest flow the weather may quiet down for a few days, but this is likely to only be the calm before the storm that will break the back of the deep cold for a time, if not for the rest of winter.  Consistent indications for several days have been coming back for a few things to happen around March 6-7.  The first is that the polar vortex lets go of Eastern Canada and shifts north and northeast, diminishing the confluent flow that has kept disturbances moving so quickly across us.  The second is that...in response to this shift and a weakening of the Greenland Block, the NAO approaches neutral.  Historically, when we see the NAO shift from strongly negative to near-neutral or slightly positive, this can signal a large storm development near the Northeastern US.  Add to this the fact that a strong Pacific shortwave will be traversing the country - the leftover heart of the Aleutian low spinning south of Alaska today - into a less confluent flow over the Northeastern US but still confluent enough over Nova Scotia to hold cold high pressure to our NE, and we have a recipe for a strong storm.  Additionally, the operational models continue to key in on this time period for storm development, which can add further confidence to a forecast of a large storm in this time period.  Behind the storm, it does appear heights rise dramatically, which tells me two things: 1) The storm will likely be a strong one, as this is evidence of the amount of warmth and moisture available to it from the southern stream and the resultant baroclinicity, and 2) This strong storm will lead the northeast into a spring-like pattern for what is likely to be at least a week, taking us to around March 13-14.  Thereafter, while the deep cold will be exhausted, cold locked in Siberia that will have been cut off from migrating eastward (truly it's this bridge to Siberian cold that's been feeding our current cold streak) will be able to slide east into Western and Central Canada again, and renewed cold appears possible sometime after March 14, though not as deep and not for as long a period, it still will be watched carefully as baroclinicity would be a big factor at that point, owing to a significantly higher sun angle.

Needless to say, plenty watch for one and all.  That's all for today.

Matt


Quiet But Cold To Start the Week...

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net

Matt's Quick Weather Synopsis:  Monday morning has brought a chill to all of New England, with many areas starting the day within 10 degrees of zero, and an active wind providing additional chill.  Though the cold arctic air is also dry air, and will bring sunshine to most areas to start the new work week, a few clouds sliding south out of Canada will blot out the sun from time to time on a line from the Mount Washington Valley of New Hampshire to Portland, ME, points northeast.  Otherwise, don't let the sunshine fool you!  With winds gusting to 35 mph and frigid temperatures in place, wind chill values will hover in the single digits north and teens south at even the warmest time of the day.  Monday night, a fast moving upper level disturbance slides through New England, providing widespread snow showers for a fresh dusting through particularly interior New England by early Tuesday morning.  This system scoots east quickly on Tuesday morning, however, keeping breezy and chilly, but bright weather in place.  Another weak disturbance may deliver a few more flurries Tuesday night, then once again sunshine returns for Wednesday.  A more potent storm center moving east from the Western U.S. will cross New England on Thursday, bringing widespread snow and perhaps a mix with rain in extreme southern New England.  Behind this storm, fresh winds will usher in another shot of chill for Friday...keeping the entirety of this week a cold a wintry feeling one for us all!  Have a wonderful Monday.  -Matt

General Weather Summary:  After receiving amounts of snow varying from a dusting to a foot of accumulation this weekend across New England, a quieter weather pattern takes hold for the start of our new workweek.  Incidentally, I receive lots of inquiries for snow amounts from folks after storms have passed, and for those of you who are interested, the National Weather Service issues all of their snow spotter reports, completely free of charge anytime snow amounts are greater than 2".  If you find their network dense enough, there's no need to pay for this data elsewhere:  http://www.erh.noaa.gov/box/pns.shtml is the address.  I'll add this to my mattnoyes.net web page soon, too.  In the meantime, the weather may be quiet, but quiet won't equate to comfortable as cold arctic air has a firm grip on New England and will team up with an active wind to bring very chilly conditions through Tuesday.

While most of New England can enjoy sunshine between disturbances today, satellite imagery shows an area of clouds drooping southward through Maine and northeastern New Hampshire, and trying to slide farther south along the eastern New England coastline.  These clouds are actually the result of warmer air aloft - that's right, warmer air coming from the north - as storms to our east have become so tightly wound that the counter-clockwise flow of air around them has carried warmer and more moist air all the way around the north side of the storms and back around the back of them.  The clash of this warmer and more moist air with our dry, arctic air, is causing for the clouds.  In most areas under this shield of renegade clouds, sunshine will still be able to break through, and the rest of New England will enjoy blend of golden sunshine.  "Enjoy" may be a rather tame word to use, however, given that temperatures will hold in the teens across Northern New England and in the lower to middle twenties through Southern New England with winds from the west-northwest gusting to 35 mph, creating wind chill values ("feels like" temperatures) in the teens region-wide!

A fast moving, energetic disturbance located across the Central Great Lakes Monday morning will swing overhead through New England overnight Monday night.  This disturbance will bring with it scattered snow showers and flurries, and many residents of interior New England - especially north of the Massachusetts Turnpike - may awaken to a fresh and very light dusting of snow Tuesday morning, with a thicker coating of fluff possible in the higher terrain of Northern New England.  Breezes will remain active Monday night, keeping wind chill values below zero in many communities.

While Tuesday may dawn with lingering clouds and perhaps even a lingering flurry in some areas, sunshine will return along with another day of brisk west-northwest winds, gusting to 25-30 mph at times.  With arctic air slow to let go of New England, temperatures will only climb about 4 or 5 degrees higher than they did on Monday, even with the help of plenty of sunshine.  Expect a virtual repeat Tuesday night into Wednesday - that is, flurries Tuesday night with a fast moving upper level disturbance, followed by sunny but brisk conditions Wednesday, though winds are likely to subside a bit.

Meanwhile, rains and several feet of snow will be falling up and down the West Coast Monday - even raining in Los Angeles - as a strong Pacific storm system barrels its way inland.  This moisture-laden system will eject a piece of energy eastward across the U.S., and the associated surface storm center will move into New England on Thursday.  As with this past weekend's disturbance, the exact track of the storm will make a large difference regarding where the heaviest precipitation falls.  Regardless, as warmer and more moist air surges north in association with this approaching storm, snow is likely to develop for many areas on Thursday.  If enough warm air comes into play, a mix or change to rain would be possible in especially far Southern New England, though right now I wouldn't count on a widespread mix or changeover.

Cold air sticks around through the first 7-10 days of March, as the atmospheric pattern features something special in the world of meteorology...a "Greenland Block."  This is the term meteorologists use to describe a large and stationary area of high pressure that builds across Greenland - well to our east - and because high pressure is generally a fair-weather center, it blocks storms from moving quickly across the North Atlantic.  The result is to keep storms curling north when they move just east of the Canadian Maritimes, and with counter-clockwise flow of air around storms, this keeps an average northerly wind blowing into New England for quite some time.  The result of a pattern like this is for cold conditions to persist, with storms reaching their maximum intensity to our east, rather than over us, but that's not to say storms can't still affect New England - stronger disturbances can occasionally strengthen further as they move overhead and this can produce widespread snows.  A few chances of disturbed weather will remain while this "Greenland Block" holds.

Have a wonderful Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Monday, February 27 at 3:20 PM

Warm advection clouds across ME/NH/parts of NE MA today are the result of warm air wrapped all the way around the north side of storm circulation to our northeast and another burst of these is possible later Tuesday as polar vortex throws warmer air southward aloft.  A strange reality, I know, but this is what happens when you get a wound up storm bombing northeast of NewEng during a strong Greenland block and developing strong negative NAO.

I'm going to broadbrush the short-term in favor of focusing on the medium range and longer range forecasts today...and the broad strokes paint an eastward moving shortwave moving over NewEng Mon Ngt and bringing snow showers with it - esp Nrn MA point N - with a dusting of accum possible given a couple of hundreths that output on esp SUNYSB MM5 and WRF.

Good mixing Tuesday will team with downslope flow and sunshine for at least most of the day away from warm advection clouds from the north to bring temps into the 20's most areas Central and South.  Wed features a westward retrogression of the polar vortex and this is an important shift as it dictates where the storm currently slamming the west coast with copious amounts of rain and snow will be steered.

In fact, using this pattern shift, we could determine that the NAM solution for the track of Thursday's shortwave - our first stopping point in the medium range - was initially likely much too far north as it took the shortwave over Central and Northern NewEng, but the new 12Z position is more in line with the remainder of the operational models and likely more on target.  There are a few things to keep in mind with this shortwave:  1) It is the composite of northern and southern stream energy, but really is a reincarnation of the storm over the West Coast Monday afternoon, which splits north and south and then comes together again over the Western Great Lakes, 2) When the new merged vorticity maximum moves through the northeast on Thu, remember its origin - it has come from moisture-laden beginnings bringing rain from SEA to LAX on Monday, and feet of snow to the CA mountains, 3) It is cresting a thermal ridge of tremendous warmth - some 20 to 25 C at 850 mb over the Central and Southern Plains, and this sets up a tremendous baroclinic zone with the cold air shoved south of the polar vortex, 4) The surface low will be strengthening as it moves in a path that...according to progged 500 mb and 700 mb flow...should take it immediately south of NewEng as it races E.

Once again this leaves us with a storm that we wonder whether it will be able to generate a closed circulation and add ocean moisture, but this time it's not nearly as important to do this as it was with the weekend system.  Remember that in this discussion you and I considered the importance of this ocean inflow for the past weekend storm, and we knew that where an easterly flow could establish, the higher snowfall and QPF would be, and that was likely to set up on the northern side of the circulation.  We needed that moisture this weekend to offset what was otherwise a bone-dry atmosphere.  Though the air is dry currently, by Thursday the situation will be quite different, as this storm comes of Pacific origin - carrying its own moisture.  For snow lovers, that's a good thing because indications right now are somewhat iffy on whether it could get its act together quickly enough to incorporate Atlantic moisture, largely owing to its very fast progression eastward.  Nonetheless, this system of moist origins will carry a southerly llvl jet east into NewEng late Wed Ngt into Thu, and this will again result in a band of snow, heavy at times, into Thu across most of Southern and Central NewEng, and likely spreading into Nrn NewEng as well, esp given lingering trough and SE sfc flow in place.  Remember that with this past weekend's event, there was a fairly well-defined southern cutoff to the plowable snowfall amounts - that is the nature of a system that is relying heavily upon a surge of warmth and moisture colliding with a cold airmass - south of the collision there will be a sharp drop in precip amounts.  This will be the case again with the upcoming storm, but indications are that most areas should end up under this enhanced baroclinicity.  So, once again a shot of plowable snows appears en route for NewEng late Wed Ngt into Thu.

Thereafter, with northwest flow the weather may quiet down for a few days, but this is likely to only be the calm before the storm that will break the back of the deep cold for a time, if not for the rest of winter.  Consistent indications for several days have been coming back for a few things to happen around March 6-7.  The first is that the polar vortex lets go of Eastern Canada and shifts north and northeast, diminishing the confluent flow that has kept disturbances moving so quickly across us.  The second is that...in response to this shift and a weakening of the Greenland Block, the NAO approaches neutral.  Historically, when we see the NAO shift from strongly negative to near-neutral or slightly positive, this can signal a large storm development near the Northeastern US.  Add to this the fact that a strong Pacific shortwave will be traversing the country - the leftover heart of the Aleutian low spinning south of Alaska today - into a less confluent flow over the Northeastern US but still confluent enough over Nova Scotia to hold cold high pressure to our NE, and we have a recipe for a strong storm.  Additionally, the operational models continue to key in on this time period for storm development, which can add further confidence to a forecast of a large storm in this time period.  Behind the storm, it does appear heights rise dramatically, which tells me two things: 1) The storm will likely be a strong one, as this is evidence of the amount of warmth and moisture available to it from the southern stream and the resultant baroclinicity, and 2) This strong storm will lead the northeast into a spring-like pattern for what is likely to be at least a week, taking us to around March 13-14.  Thereafter, while the deep cold will be exhausted, cold locked in Siberia that will have been cut off from migrating eastward (truly it's this bridge to Siberian cold that's been feeding our current cold streak) will be able to slide east into Western and Central Canada again, and renewed cold appears possible sometime after March 14, though not as deep and not for as long a period, it still will be watched carefully as baroclinicity would be a big factor at that point, owing to a significantly higher sun angle.

Needless to say, plenty watch for one and all.  That's all for today.

Matt


Quiet But Cold To Start the Week...

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net

Matt's Quick Weather Synopsis:  Monday morning has brought a chill to all of New England, with many areas starting the day within 10 degrees of zero, and an active wind providing additional chill.  Though the cold arctic air is also dry air, and will bring sunshine to most areas to start the new work week, a few clouds sliding south out of Canada will blot out the sun from time to time on a line from the Mount Washington Valley of New Hampshire to Portland, ME, points northeast.  Otherwise, don't let the sunshine fool you!  With winds gusting to 35 mph and frigid temperatures in place, wind chill values will hover in the single digits north and teens south at even the warmest time of the day.  Monday night, a fast moving upper level disturbance slides through New England, providing widespread snow showers for a fresh dusting through particularly interior New England by early Tuesday morning.  This system scoots east quickly on Tuesday morning, however, keeping breezy and chilly, but bright weather in place.  Another weak disturbance may deliver a few more flurries Tuesday night, then once again sunshine returns for Wednesday.  A more potent storm center moving east from the Western U.S. will cross New England on Thursday, bringing widespread snow and perhaps a mix with rain in extreme southern New England.  Behind this storm, fresh winds will usher in another shot of chill for Friday...keeping the entirety of this week a cold a wintry feeling one for us all!  Have a wonderful Monday.  -Matt

General Weather Summary:  After receiving amounts of snow varying from a dusting to a foot of accumulation this weekend across New England, a quieter weather pattern takes hold for the start of our new workweek.  Incidentally, I receive lots of inquiries for snow amounts from folks after storms have passed, and for those of you who are interested, the National Weather Service issues all of their snow spotter reports, completely free of charge anytime snow amounts are greater than 2".  If you find their network dense enough, there's no need to pay for this data elsewhere:  http://www.erh.noaa.gov/box/pns.shtml is the address.  I'll add this to my mattnoyes.net web page soon, too.  In the meantime, the weather may be quiet, but quiet won't equate to comfortable as cold arctic air has a firm grip on New England and will team up with an active wind to bring very chilly conditions through Tuesday.

While most of New England can enjoy sunshine between disturbances today, satellite imagery shows an area of clouds drooping southward through Maine and northeastern New Hampshire, and trying to slide farther south along the eastern New England coastline.  These clouds are actually the result of warmer air aloft - that's right, warmer air coming from the north - as storms to our east have become so tightly wound that the counter-clockwise flow of air around them has carried warmer and more moist air all the way around the north side of the storms and back around the back of them.  The clash of this warmer and more moist air with our dry, arctic air, is causing for the clouds.  In most areas under this shield of renegade clouds, sunshine will still be able to break through, and the rest of New England will enjoy blend of golden sunshine.  "Enjoy" may be a rather tame word to use, however, given that temperatures will hold in the teens across Northern New England and in the lower to middle twenties through Southern New England with winds from the west-northwest gusting to 35 mph, creating wind chill values ("feels like" temperatures) in the teens region-wide!

A fast moving, energetic disturbance located across the Central Great Lakes Monday morning will swing overhead through New England overnight Monday night.  This disturbance will bring with it scattered snow showers and flurries, and many residents of interior New England - especially north of the Massachusetts Turnpike - may awaken to a fresh and very light dusting of snow Tuesday morning, with a thicker coating of fluff possible in the higher terrain of Northern New England.  Breezes will remain active Monday night, keeping wind chill values below zero in many communities.

While Tuesday may dawn with lingering clouds and perhaps even a lingering flurry in some areas, sunshine will return along with another day of brisk west-northwest winds, gusting to 25-30 mph at times.  With arctic air slow to let go of New England, temperatures will only climb about 4 or 5 degrees higher than they did on Monday, even with the help of plenty of sunshine.  Expect a virtual repeat Tuesday night into Wednesday - that is, flurries Tuesday night with a fast moving upper level disturbance, followed by sunny but brisk conditions Wednesday, though winds are likely to subside a bit.

Meanwhile, rains and several feet of snow will be falling up and down the West Coast Monday - even raining in Los Angeles - as a strong Pacific storm system barrels its way inland.  This moisture-laden system will eject a piece of energy eastward across the U.S., and the associated surface storm center will move into New England on Thursday.  As with this past weekend's disturbance, the exact track of the storm will make a large difference regarding where the heaviest precipitation falls.  Regardless, as warmer and more moist air surges north in association with this approaching storm, snow is likely to develop for many areas on Thursday.  If enough warm air comes into play, a mix or change to rain would be possible in especially far Southern New England, though right now I wouldn't count on a widespread mix or changeover.

Cold air sticks around through the first 7-10 days of March, as the atmospheric pattern features something special in the world of meteorology...a "Greenland Block."  This is the term meteorologists use to describe a large and stationary area of high pressure that builds across Greenland - well to our east - and because high pressure is generally a fair-weather center, it blocks storms from moving quickly across the North Atlantic.  The result is to keep storms curling north when they move just east of the Canadian Maritimes, and with counter-clockwise flow of air around storms, this keeps an average northerly wind blowing into New England for quite some time.  The result of a pattern like this is for cold conditions to persist, with storms reaching their maximum intensity to our east, rather than over us, but that's not to say storms can't still affect New England - stronger disturbances can occasionally strengthen further as they move overhead and this can produce widespread snows.  A few chances of disturbed weather will remain while this "Greenland Block" holds.

Have a wonderful Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Monday, February 27 at 3:20 PM

Warm advection clouds across ME/NH/parts of NE MA today are the result of warm air wrapped all the way around the north side of storm circulation to our northeast and another burst of these is possible later Tuesday as polar vortex throws warmer air southward aloft.  A strange reality, I know, but this is what happens when you get a wound up storm bombing northeast of NewEng during a strong Greenland block and developing strong negative NAO.

I'm going to broadbrush the short-term in favor of focusing on the medium range and longer range forecasts today...and the broad strokes paint an eastward moving shortwave moving over NewEng Mon Ngt and bringing snow showers with it - esp Nrn MA point N - with a dusting of accum possible given a couple of hundreths that output on esp SUNYSB MM5 and WRF.

Good mixing Tuesday will team with downslope flow and sunshine for at least most of the day away from warm advection clouds from the north to bring temps into the 20's most areas Central and South.  Wed features a westward retrogression of the polar vortex and this is an important shift as it dictates where the storm currently slamming the west coast with copious amounts of rain and snow will be steered.

In fact, using this pattern shift, we could determine that the NAM solution for the track of Thursday's shortwave - our first stopping point in the medium range - was initially likely much too far north as it took the shortwave over Central and Northern NewEng, but the new 12Z position is more in line with the remainder of the operational models and likely more on target.  There are a few things to keep in mind with this shortwave:  1) It is the composite of northern and southern stream energy, but really is a reincarnation of the storm over the West Coast Monday afternoon, which splits north and south and then comes together again over the Western Great Lakes, 2) When the new merged vorticity maximum moves through the northeast on Thu, remember its origin - it has come from moisture-laden beginnings bringing rain from SEA to LAX on Monday, and feet of snow to the CA mountains, 3) It is cresting a thermal ridge of tremendous warmth - some 20 to 25 C at 850 mb over the Central and Southern Plains, and this sets up a tremendous baroclinic zone with the cold air shoved south of the polar vortex, 4) The surface low will be strengthening as it moves in a path that...according to progged 500 mb and 700 mb flow...should take it immediately south of NewEng as it races E.

Once again this leaves us with a storm that we wonder whether it will be able to generate a closed circulation and add ocean moisture, but this time it's not nearly as important to do this as it was with the weekend system.  Remember that in this discussion you and I considered the importance of this ocean inflow for the past weekend storm, and we knew that where an easterly flow could establish, the higher snowfall and QPF would be, and that was likely to set up on the northern side of the circulation.  We needed that moisture this weekend to offset what was otherwise a bone-dry atmosphere.  Though the air is dry currently, by Thursday the situation will be quite different, as this storm comes of Pacific origin - carrying its own moisture.  For snow lovers, that's a good thing because indications right now are somewhat iffy on whether it could get its act together quickly enough to incorporate Atlantic moisture, largely owing to its very fast progression eastward.  Nonetheless, this system of moist origins will carry a southerly llvl jet east into NewEng late Wed Ngt into Thu, and this will again result in a band of snow, heavy at times, into Thu across most of Southern and Central NewEng, and likely spreading into Nrn NewEng as well, esp given lingering trough and SE sfc flow in place.  Remember that with this past weekend's event, there was a fairly well-defined southern cutoff to the plowable snowfall amounts - that is the nature of a system that is relying heavily upon a surge of warmth and moisture colliding with a cold airmass - south of the collision there will be a sharp drop in precip amounts.  This will be the case again with the upcoming storm, but indications are that most areas should end up under this enhanced baroclinicity.  So, once again a shot of plowable snows appears en route for NewEng late Wed Ngt into Thu.

Thereafter, with northwest flow the weather may quiet down for a few days, but this is likely to only be the calm before the storm that will break the back of the deep cold for a time, if not for the rest of winter.  Consistent indications for several days have been coming back for a few things to happen around March 6-7.  The first is that the polar vortex lets go of Eastern Canada and shifts north and northeast, diminishing the confluent flow that has kept disturbances moving so quickly across us.  The second is that...in response to this shift and a weakening of the Greenland Block, the NAO approaches neutral.  Historically, when we see the NAO shift from strongly negative to near-neutral or slightly positive, this can signal a large storm development near the Northeastern US.  Add to this the fact that a strong Pacific shortwave will be traversing the country - the leftover heart of the Aleutian low spinning south of Alaska today - into a less confluent flow over the Northeastern US but still confluent enough over Nova Scotia to hold cold high pressure to our NE, and we have a recipe for a strong storm.  Additionally, the operational models continue to key in on this time period for storm development, which can add further confidence to a forecast of a large storm in this time period.  Behind the storm, it does appear heights rise dramatically, which tells me two things: 1) The storm will likely be a strong one, as this is evidence of the amount of warmth and moisture available to it from the southern stream and the resultant baroclinicity, and 2) This strong storm will lead the northeast into a spring-like pattern for what is likely to be at least a week, taking us to around March 13-14.  Thereafter, while the deep cold will be exhausted, cold locked in Siberia that will have been cut off from migrating eastward (truly it's this bridge to Siberian cold that's been feeding our current cold streak) will be able to slide east into Western and Central Canada again, and renewed cold appears possible sometime after March 14, though not as deep and not for as long a period, it still will be watched carefully as baroclinicity would be a big factor at that point, owing to a significantly higher sun angle.

Needless to say, plenty watch for one and all.  That's all for today.

Matt


Storm Remains on Track...Plowable Snow En Route...Blustery and Cold Sunday Awaits

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net

Matt's Quick Weather Synopsis: 

SATURDAY UPDATE:  Just a quick update to let you know I'm here and checking in...and I think the forecast will fall within about an inch of the numbers on the map posted below from yesterday (Friday) morning.  There are likely to be a few 6" amounts coming back, and up to 7 or 8 in the higher terrain of the 5+ area, but average amounts should still fall very close to what's been posted.  Enjoy the storm...nice to have it be big enough to see the snow, but small enough that I can enjoy it from home...a rare treat for a broadcast meteorologist!  Be sure to check out Joe Joyce with his coverage on NECN if you can!

Friday's Post:  Areas of black ice on roadways greet commuters of secondary roads and exit/entrance ramps to some highways Friday morning as scattered showers of rain and snow Thursday afternoon and night have left plenty of moisture in some spots.  Heavier snow squalls are moving east through Maine, where they will set up shop in Eastern Coastal Maine through Friday afternoon, delivering 3"-4" of snow in this area.  Elsewhere, mountain snow squalls will float through Northern and Western New England today while the remainder of New England finds a very gusty northwest wind bringing in enough dry air for plenty of sunshine and just a few scattered flurries.  Wind gusts may reach 55 mph Friday afternoon in some communities around New England and this means isolated damage to trees, tree limbs and power lines are possible - nothing like last Friday's damaging winds that gusted to 70-80 mph, but isolated damage is possible today nonetheless.  Expect winds to subside Friday night under mostly clear skies and a cold night.  A storm located over the Northern Plains Friday morning will move over New England later Saturday, blotting out any early morning sunshine behind increasing clouds, with light snow developing either side of 2 PM across New England and becoming heavier around 5 PM and lasting until around midnight with plowable snow for many (see accumulation maps below).  After snow ends late Saturday night, expect a drier, brighter, but cold and blustery day on Sunday as an arctic airmass pours into New England.  Cold air will remain in place on Monday, though another approaching storm will thicken the clouds and allow for snow to develop late and at night.  I'm expecting the cold and wintry feel to continue through next week!  -Matt

Accumulation Map for Saturday/Saturday Night Snow:

Accums_neweng

General Weather Summary:  After heavy snow and rain squalls for some communities later Thursday into predawn Friday, black ice found on secondary roadways, walkways, and exit/entrance ramps to some highways will melt away after making for a few Friday morning slick spots.  Exceptions will continue to be found in Eastern Maine where a weak area of low pressure will keep snow squalls falling through the day for 3"-4" of accumulation in Coastal Washington and Hancock Counties, and in the mountains of Northern and Western New England where scattered snow showers and squalls will continue to blow through.  Otherwise, expect a very gusty northwest wind to usher in cold and dry air for most of New England, bringing out plenty of sunshine amidst just a few isolated flurries, but also bringing wind gusts to 55 mph for some communities, which will be sufficient to cause isolated damage to trees, tree limbs and power lines.  It's important to note that while the wind will be capable of causing damage, blowing light objects around and pushing your car around a bit on the road, they will be nothing like the prolonged and intense damaging wind event of one week ago today.

Today's busy winds come as New England is sandwiched between a departing area of low pressure to our northwest and a bubble of high pressure building in from the west.  With a very fast flow in the atmosphere, this high pressure, fair weather center will build in quickly overnight Friday night and winds will subside with clearing skies for most areas as it does.  This combination of lighter wind and clearing skies will allow temperatures to drop into the single digits north and teens south Friday night.

Saturday likely dawns with some limited sunshine ahead of a fast-moving storm center traversing the nation and taking aim on New England.  Though the storm came ashore from the Pacific in the Pacific northwest on Thursday and was located over the Northern Plains Friday morning, it will be racing east and already spreading clouds into New England Saturday morning.  By mid-afternoon Saturday - likely sometime around 2-3 PM - light snow will begin falling in many parts of New England, becoming steadier and heavier by 5 PM.  This snow will not come down for very long thanks to the fast winds aloft pushing the storm through quickly, but will come down heavily at times Saturday evening and the first part of Saturday night, with widespread accumulations of 4"-5" by midnight Saturday night (see accumulation maps above), with local amounts to half a foot and lesser amounts to the north and south of the heaviest band of precipitation.  The snowfall accumulation forecast you see on my map is the result of two factors to be considered:  1) The shape of the snowfall pattern is defined by the rapid increase of warmth and moisture moving in from southwest to northeast in the south winds ahead of the counter-clockwise storm circulation, and 2) The amounts are based on somewhere around or just over 1/4" of melted precipitation in most areas in the heart of the precipitation band, but cold temperatures aloft will allow for a fluffy snow, so snow will pile up quickly and easily.

Again dictated by the fast jet stream winds aloft in the atmosphere, this storm will keep on truckin' and snow will end around midnight in most areas.  Winds will once again become quite active from the northwest and north behind this storm, and those winds will tap a well of cold Canadian arctic air that will come screaming in on Sunday, holding temperatures in the lower 20's through Southern New England and teens for Central and Northern areas.  With a biting wind, wind chill values will feel a good 8-12 degrees colder than the actual highs!  A few flurries and snow showers will still be possible in the mountains, though most of New England is likely to stay mainly dry.

Cold air sticks around into Monday and beyond, as the atmospheric pattern features something special in the world of meteorology...a developing "Greenland Block."  This is the term meteorologists use to describe a large and stationary area of high pressure that builds across Greenland - well to our east - and because high pressure is generally a fair-weather center, it blocks storms from moving quickly across the North Atlantic.  The result is to keep storms curling north when they move just east of the Canadian Maritimes, and with counter-clockwise flow of air around storms, this keeps an average northerly wind blowing into New England for quite some time.  The result of a pattern like this is for cold conditions to persist, with storms reaching their maximum intensity to our east, rather than over us, but that's not to say storms can't still affect New England - just like what's happening this weekend, stronger disturbances can occasionally strengthen further as they move overhead and this can produce widespread snows.  A similar situation may be in the cards for Monday night, then several chances of disturbed weather will remain while this "Greenland Block" holds.

Enjoy your weekend - I'll be back with you on Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Friday, February 24 at 10:20 AM

Upslope snow squalls will continue in the Green Mountains in cold advection upslope flow today, and Champlain Valley is also reaping the benefits of a WNW flow until wind veers more to the NW later today.  Amounts in the higher terrain will near 10" in the Central and Northern Greens where the squalls stay put, a few inches of accumulation elsewhere up the spine of the Greens and away from the higher summits.  Squalls moving across the Maine Turnpike Fri AM are the result of a vorticity maximum and associated weak developing surface wave which, as of this writing, is moving SE across Penobscot Bay.  Once this circulation hits the waters of the Gulf of ME, agreement among the guidance is for stationary/slow moving band of snow squalls to set up over or near Coastal Washington and Hancock Counties and with QPF nearing .25" (perhaps a bit overdone, and the chance it will miss and set up over the ocean) I've gone with a few inches possible in immediate coastal locales in this area.  Elsewhere in NewEng, mixing to about 880 mb by the end of the day and this will tap an increasing cold llvl jet screaming around the base of the vort max moving N of NewEng and evident on morning satellite imagery.  This jet streak extends low enough to encounter our well mixed layer with about 50-55 kts of NW flow, and damaging wind gusts to 55 mph will be possible in some areas.  Nothing like the event of exactly one week ago today, but capable of isolated damage and disruption.

Subsidence between shortwaves and associated with splitting high pressure cell means clearing skies Fri Ngt with diminishing winds as surface ridge axis shifts over NewEng and this will set us up for decent radiational cooling with single digits in the north and teens south, and of course will ensure - as if we needed it - that temperatures region-wide will be plenty cold enough for snow with the next system on Saturday.

As for this system, it's been much talked about here for a few days, and perhaps the most remarkable part is the lack of change in the guidance from one cycle to the next.  Of course, that's to be expected in this pattern - a well-defined fast flow that features strongest cyclogenesis to our east.  A few storms earlier this year I remarked here how we were in the most difficult part of the pattern to accurately forecast - just ahead of the mean trof positon.  Now, being just behind it, we will find differences in the guidance usually only pertaining to timing, and that has been the case this time around, but I still think we're on target for the faster Saturday afternoon timing laid out yesterday, and at this point it looks like clouds race in Sat AM ahead of what is still very impressive speed convergence ahead of llvl jet punching north and northwest into NewEng during the day.  This teams up with intense cyclonic vorticity advection ahead of 30-35 unit vorticity maximum that dives SE across Central and Southern NewEng Sat afternoon and eve.  As mentioned yesterday, I truly believe it's the combination of this strong CVA, coupled with what's going on especially in the lower levels of the atmosphere that will drive the evolution of this storm.  Somewhat of a center jump appears to be in the cards for the surface low with this fast moving vort, but the shortwave is strong enough as it comes through that dynamic forcing will make this center jump a help rather than a hindrance when it comes to snow production, as it will enhance low level easterly flow ahead of the center of the vort max, and therefore enhance available moisture thanks to Atlantic inflow.  QPF is well agreed upon for the broad swath of over .25" among virtually all guidance, with center of the band closer to .40".  Temps aloft are actually a bit too cold for ideal ratios, so somewhere around 15:1 looks reasonable.  What's scary is that this keeps snowfall amounts right where you and I them two days ago in this discussion at about 4"-6" in a large swath of NewEng.  Given the limited area of .40" QPF amounts in only the heart of the band, I've opted to go 4-5" in my broadcasts for this area, with obvious orographic enhancement in the appropriate areas.  Also important to note that SE flow will mean a shadow effect for parts of West-Central NH, and for parts of the Northeast Kingdom of VT - I've tried to indicate that on the maps.  Even though I'm still expecting bursts of heavy snow in the heart of the isentropic lift Sat eve, especially during passage of the vort, there's absolutely no question that this is a fast moving system, and snow will not last longer than from about noon (west) and 2 PM (east) to around midnight most areas.  So, considering the short duration, these snowfall amounts become even more impressive.

After the storm departs around midnight Sat Ngt (perhaps eastern areas with snow lingering longer thanks to marine airmass contrasting with incoming arctic air, which has a tendency to wring moisture out as snowflakes), arctic airmass still expected to unload on NewEng with 850 temps dropping to -18 C Sunday and NNW wind direction - one of the coldest for NewEng.  Fighting the build of surface cold will be the fact that high pressure stays put to our east, so this cold truly has to build down from aloft, but there's enough of it to get 925 mb temps -12 to -13 C Sunday, and equally cold if not a tad colder Monday as the flow tries to turn SW but has to wait for weak shortwave ridge axis to pass, and once that SW flow does come in, clouds increase quickly.

This leads us into our next shortwave with potential, which is slated for Mon Ngt.  Again, timing on this may end up speeding up a bit, and NAM is already indicating that in its new 12Z run.  And while I'll acknowledge this shortwave has potential, I'm not willing to bite too hard on it yet, as steering flow is very much a NW flow with mean trof position shifting E of NewEng as polar vortex effective shifts to a position NE of ME.  This, in conjunction with the strong building Greenland block position and an NAO that will tank over the coming week and really for the first 7-10 days of March, will keep the storm breeding ground east of us, so it's going to take strong shortwaves, AND some flattening of the flow east of us - usually in response to shortwave ridging ahead of the disturbances - to get these systems to amplify.  So, for now, we'll keep an eye on the Monday/Monday night vorticity maximum and see how it evolves.  The one behind it may have more potential for midweek.  Regardless, a good meteorologist will stay on guard at all times in the aforementioned pattern, as it won't take much to organize something nearby, and it's also important to note that when the NAO finally does switch from strongly negative to neutral or even positive - which is somewhere around the 7th or 8th of March - research suggests major precipitation producing storms are often found with such NAO signal shifts, especially coming out of a pattern like the one we're in now.  Food for thought.

Enjoy your weekend and good luck with your snow forecasts!

Matt


Storm Remains on Track...Plowable Snow En Route...Blustery and Cold Sunday Awaits

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net

Matt's Quick Weather Synopsis: 

SATURDAY UPDATE:  Just a quick update to let you know I'm here and checking in...and I think the forecast will fall within about an inch of the numbers on the map posted below from yesterday (Friday) morning.  There are likely to be a few 6" amounts coming back, and up to 7 or 8 in the higher terrain of the 5+ area, but average amounts should still fall very close to what's been posted.  Enjoy the storm...nice to have it be big enough to see the snow, but small enough that I can enjoy it from home...a rare treat for a broadcast meteorologist!  Be sure to check out Joe Joyce with his coverage on NECN if you can!

Friday's Post:  Areas of black ice on roadways greet commuters of secondary roads and exit/entrance ramps to some highways Friday morning as scattered showers of rain and snow Thursday afternoon and night have left plenty of moisture in some spots.  Heavier snow squalls are moving east through Maine, where they will set up shop in Eastern Coastal Maine through Friday afternoon, delivering 3"-4" of snow in this area.  Elsewhere, mountain snow squalls will float through Northern and Western New England today while the remainder of New England finds a very gusty northwest wind bringing in enough dry air for plenty of sunshine and just a few scattered flurries.  Wind gusts may reach 55 mph Friday afternoon in some communities around New England and this means isolated damage to trees, tree limbs and power lines are possible - nothing like last Friday's damaging winds that gusted to 70-80 mph, but isolated damage is possible today nonetheless.  Expect winds to subside Friday night under mostly clear skies and a cold night.  A storm located over the Northern Plains Friday morning will move over New England later Saturday, blotting out any early morning sunshine behind increasing clouds, with light snow developing either side of 2 PM across New England and becoming heavier around 5 PM and lasting until around midnight with plowable snow for many (see accumulation maps below).  After snow ends late Saturday night, expect a drier, brighter, but cold and blustery day on Sunday as an arctic airmass pours into New England.  Cold air will remain in place on Monday, though another approaching storm will thicken the clouds and allow for snow to develop late and at night.  I'm expecting the cold and wintry feel to continue through next week!  -Matt

Accumulation Map for Saturday/Saturday Night Snow:

Accums_neweng

General Weather Summary:  After heavy snow and rain squalls for some communities later Thursday into predawn Friday, black ice found on secondary roadways, walkways, and exit/entrance ramps to some highways will melt away after making for a few Friday morning slick spots.  Exceptions will continue to be found in Eastern Maine where a weak area of low pressure will keep snow squalls falling through the day for 3"-4" of accumulation in Coastal Washington and Hancock Counties, and in the mountains of Northern and Western New England where scattered snow showers and squalls will continue to blow through.  Otherwise, expect a very gusty northwest wind to usher in cold and dry air for most of New England, bringing out plenty of sunshine amidst just a few isolated flurries, but also bringing wind gusts to 55 mph for some communities, which will be sufficient to cause isolated damage to trees, tree limbs and power lines.  It's important to note that while the wind will be capable of causing damage, blowing light objects around and pushing your car around a bit on the road, they will be nothing like the prolonged and intense damaging wind event of one week ago today.

Today's busy winds come as New England is sandwiched between a departing area of low pressure to our northwest and a bubble of high pressure building in from the west.  With a very fast flow in the atmosphere, this high pressure, fair weather center will build in quickly overnight Friday night and winds will subside with clearing skies for most areas as it does.  This combination of lighter wind and clearing skies will allow temperatures to drop into the single digits north and teens south Friday night.

Saturday likely dawns with some limited sunshine ahead of a fast-moving storm center traversing the nation and taking aim on New England.  Though the storm came ashore from the Pacific in the Pacific northwest on Thursday and was located over the Northern Plains Friday morning, it will be racing east and already spreading clouds into New England Saturday morning.  By mid-afternoon Saturday - likely sometime around 2-3 PM - light snow will begin falling in many parts of New England, becoming steadier and heavier by 5 PM.  This snow will not come down for very long thanks to the fast winds aloft pushing the storm through quickly, but will come down heavily at times Saturday evening and the first part of Saturday night, with widespread accumulations of 4"-5" by midnight Saturday night (see accumulation maps above), with local amounts to half a foot and lesser amounts to the north and south of the heaviest band of precipitation.  The snowfall accumulation forecast you see on my map is the result of two factors to be considered:  1) The shape of the snowfall pattern is defined by the rapid increase of warmth and moisture moving in from southwest to northeast in the south winds ahead of the counter-clockwise storm circulation, and 2) The amounts are based on somewhere around or just over 1/4" of melted precipitation in most areas in the heart of the precipitation band, but cold temperatures aloft will allow for a fluffy snow, so snow will pile up quickly and easily.

Again dictated by the fast jet stream winds aloft in the atmosphere, this storm will keep on truckin' and snow will end around midnight in most areas.  Winds will once again become quite active from the northwest and north behind this storm, and those winds will tap a well of cold Canadian arctic air that will come screaming in on Sunday, holding temperatures in the lower 20's through Southern New England and teens for Central and Northern areas.  With a biting wind, wind chill values will feel a good 8-12 degrees colder than the actual highs!  A few flurries and snow showers will still be possible in the mountains, though most of New England is likely to stay mainly dry.

Cold air sticks around into Monday and beyond, as the atmospheric pattern features something special in the world of meteorology...a developing "Greenland Block."  This is the term meteorologists use to describe a large and stationary area of high pressure that builds across Greenland - well to our east - and because high pressure is generally a fair-weather center, it blocks storms from moving quickly across the North Atlantic.  The result is to keep storms curling north when they move just east of the Canadian Maritimes, and with counter-clockwise flow of air around storms, this keeps an average northerly wind blowing into New England for quite some time.  The result of a pattern like this is for cold conditions to persist, with storms reaching their maximum intensity to our east, rather than over us, but that's not to say storms can't still affect New England - just like what's happening this weekend, stronger disturbances can occasionally strengthen further as they move overhead and this can produce widespread snows.  A similar situation may be in the cards for Monday night, then several chances of disturbed weather will remain while this "Greenland Block" holds.

Enjoy your weekend - I'll be back with you on Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Friday, February 24 at 10:20 AM

Upslope snow squalls will continue in the Green Mountains in cold advection upslope flow today, and Champlain Valley is also reaping the benefits of a WNW flow until wind veers more to the NW later today.  Amounts in the higher terrain will near 10" in the Central and Northern Greens where the squalls stay put, a few inches of accumulation elsewhere up the spine of the Greens and away from the higher summits.  Squalls moving across the Maine Turnpike Fri AM are the result of a vorticity maximum and associated weak developing surface wave which, as of this writing, is moving SE across Penobscot Bay.  Once this circulation hits the waters of the Gulf of ME, agreement among the guidance is for stationary/slow moving band of snow squalls to set up over or near Coastal Washington and Hancock Counties and with QPF nearing .25" (perhaps a bit overdone, and the chance it will miss and set up over the ocean) I've gone with a few inches possible in immediate coastal locales in this area.  Elsewhere in NewEng, mixing to about 880 mb by the end of the day and this will tap an increasing cold llvl jet screaming around the base of the vort max moving N of NewEng and evident on morning satellite imagery.  This jet streak extends low enough to encounter our well mixed layer with about 50-55 kts of NW flow, and damaging wind gusts to 55 mph will be possible in some areas.  Nothing like the event of exactly one week ago today, but capable of isolated damage and disruption.

Subsidence between shortwaves and associated with splitting high pressure cell means clearing skies Fri Ngt with diminishing winds as surface ridge axis shifts over NewEng and this will set us up for decent radiational cooling with single digits in the north and teens south, and of course will ensure - as if we needed it - that temperatures region-wide will be plenty cold enough for snow with the next system on Saturday.

As for this system, it's been much talked about here for a few days, and perhaps the most remarkable part is the lack of change in the guidance from one cycle to the next.  Of course, that's to be expected in this pattern - a well-defined fast flow that features strongest cyclogenesis to our east.  A few storms earlier this year I remarked here how we were in the most difficult part of the pattern to accurately forecast - just ahead of the mean trof positon.  Now, being just behind it, we will find differences in the guidance usually only pertaining to timing, and that has been the case this time around, but I still think we're on target for the faster Saturday afternoon timing laid out yesterday, and at this point it looks like clouds race in Sat AM ahead of what is still very impressive speed convergence ahead of llvl jet punching north and northwest into NewEng during the day.  This teams up with intense cyclonic vorticity advection ahead of 30-35 unit vorticity maximum that dives SE across Central and Southern NewEng Sat afternoon and eve.  As mentioned yesterday, I truly believe it's the combination of this strong CVA, coupled with what's going on especially in the lower levels of the atmosphere that will drive the evolution of this storm.  Somewhat of a center jump appears to be in the cards for the surface low with this fast moving vort, but the shortwave is strong enough as it comes through that dynamic forcing will make this center jump a help rather than a hindrance when it comes to snow production, as it will enhance low level easterly flow ahead of the center of the vort max, and therefore enhance available moisture thanks to Atlantic inflow.  QPF is well agreed upon for the broad swath of over .25" among virtually all guidance, with center of the band closer to .40".  Temps aloft are actually a bit too cold for ideal ratios, so somewhere around 15:1 looks reasonable.  What's scary is that this keeps snowfall amounts right where you and I them two days ago in this discussion at about 4"-6" in a large swath of NewEng.  Given the limited area of .40" QPF amounts in only the heart of the band, I've opted to go 4-5" in my broadcasts for this area, with obvious orographic enhancement in the appropriate areas.  Also important to note that SE flow will mean a shadow effect for parts of West-Central NH, and for parts of the Northeast Kingdom of VT - I've tried to indicate that on the maps.  Even though I'm still expecting bursts of heavy snow in the heart of the isentropic lift Sat eve, especially during passage of the vort, there's absolutely no question that this is a fast moving system, and snow will not last longer than from about noon (west) and 2 PM (east) to around midnight most areas.  So, considering the short duration, these snowfall amounts become even more impressive.

After the storm departs around midnight Sat Ngt (perhaps eastern areas with snow lingering longer thanks to marine airmass contrasting with incoming arctic air, which has a tendency to wring moisture out as snowflakes), arctic airmass still expected to unload on NewEng with 850 temps dropping to -18 C Sunday and NNW wind direction - one of the coldest for NewEng.  Fighting the build of surface cold will be the fact that high pressure stays put to our east, so this cold truly has to build down from aloft, but there's enough of it to get 925 mb temps -12 to -13 C Sunday, and equally cold if not a tad colder Monday as the flow tries to turn SW but has to wait for weak shortwave ridge axis to pass, and once that SW flow does come in, clouds increase quickly.

This leads us into our next shortwave with potential, which is slated for Mon Ngt.  Again, timing on this may end up speeding up a bit, and NAM is already indicating that in its new 12Z run.  And while I'll acknowledge this shortwave has potential, I'm not willing to bite too hard on it yet, as steering flow is very much a NW flow with mean trof position shifting E of NewEng as polar vortex effective shifts to a position NE of ME.  This, in conjunction with the strong building Greenland block position and an NAO that will tank over the coming week and really for the first 7-10 days of March, will keep the storm breeding ground east of us, so it's going to take strong shortwaves, AND some flattening of the flow east of us - usually in response to shortwave ridging ahead of the disturbances - to get these systems to amplify.  So, for now, we'll keep an eye on the Monday/Monday night vorticity maximum and see how it evolves.  The one behind it may have more potential for midweek.  Regardless, a good meteorologist will stay on guard at all times in the aforementioned pattern, as it won't take much to organize something nearby, and it's also important to note that when the NAO finally does switch from strongly negative to neutral or even positive - which is somewhere around the 7th or 8th of March - research suggests major precipitation producing storms are often found with such NAO signal shifts, especially coming out of a pattern like the one we're in now.  Food for thought.

Enjoy your weekend and good luck with your snow forecasts!

Matt


Isolated Wind Damage Friday...Plowable Snow for Many on Saturday...Blustery and Cold Sunday in Store

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net 

Matt's Quick Weather Synopsis:  Areas of black ice on roadways greet commuters of secondary roads and exit/entrance ramps to some highways Friday morning as scattered showers of rain and snow Thursday afternoon and night have left plenty of moisture in some spots.  Heavier snow squalls are moving east through Maine, where they will set up shop in Eastern Coastal Maine through Friday afternoon, delivering 3"-4" of snow in this area.  Elsewhere, mountain snow squalls will float through Northern and Western New England today while the remainder of New England finds a very gusty northwest wind bringing in enough dry air for plenty of sunshine and just a few scattered flurries.  Wind gusts may reach 55 mph Friday afternoon in some communities around New England and this means isolated damage to trees, tree limbs and power lines are possible - nothing like last Friday's damaging winds that gusted to 70-80 mph, but isolated damage is possible today nonetheless.  Expect winds to subside Friday night under mostly clear skies and a cold night.  A storm located over the Northern Plains Friday morning will move over New England later Saturday, blotting out any early morning sunshine behind increasing clouds, with light snow developing either side of 2 PM across New England and becoming heavier around 5 PM and lasting until around midnight with plowable snow for many (see accumulation maps below).  After snow ends late Saturday night, expect a drier, brighter, but cold and blustery day on Sunday as an arctic airmass pours into New England.  Cold air will remain in place on Monday, though another approaching storm will thicken the clouds and allow for snow to develop late and at night.  I'm expecting the cold and wintry feel to continue through next week!  -Matt

Accumulation Map for Saturday/Saturday Night Snow:

Accums_neweng

General Weather Summary:  After heavy snow and rain squalls for some communities later Thursday into predawn Friday, black ice found on secondary roadways, walkways, and exit/entrance ramps to some highways will melt away after making for a few Friday morning slick spots.  Exceptions will continue to be found in Eastern Maine where a weak area of low pressure will keep snow squalls falling through the day for 3"-4" of accumulation in Coastal Washington and Hancock Counties, and in the mountains of Northern and Western New England where scattered snow showers and squalls will continue to blow through.  Otherwise, expect a very gusty northwest wind to usher in cold and dry air for most of New England, bringing out plenty of sunshine amidst just a few isolated flurries, but also bringing wind gusts to 55 mph for some communities, which will be sufficient to cause isolated damage to trees, tree limbs and power lines.  It's important to note that while the wind will be capable of causing damage, blowing light objects around and pushing your car around a bit on the road, they will be nothing like the prolonged and intense damaging wind event of one week ago today.

Today's busy winds come as New England is sandwiched between a departing area of low pressure to our northwest and a bubble of high pressure building in from the west.  With a very fast flow in the atmosphere, this high pressure, fair weather center will build in quickly overnight Friday night and winds will subside with clearing skies for most areas as it does.  This combination of lighter wind and clearing skies will allow temperatures to drop into the single digits north and teens south Friday night.

Saturday likely dawns with some limited sunshine ahead of a fast-moving storm center traversing the nation and taking aim on New England.  Though the storm came ashore from the Pacific in the Pacific northwest on Thursday and was located over the Northern Plains Friday morning, it will be racing east and already spreading clouds into New England Saturday morning.  By mid-afternoon Saturday - likely sometime around 2-3 PM - light snow will begin falling in many parts of New England, becoming steadier and heavier by 5 PM.  This snow will not come down for very long thanks to the fast winds aloft pushing the storm through quickly, but will come down heavily at times Saturday evening and the first part of Saturday night, with widespread accumulations of 4"-5" by midnight Saturday night (see accumulation maps above), with local amounts to half a foot and lesser amounts to the north and south of the heaviest band of precipitation.  The snowfall accumulation forecast you see on my map is the result of two factors to be considered:  1) The shape of the snowfall pattern is defined by the rapid increase of warmth and moisture moving in from southwest to northeast in the south winds ahead of the counter-clockwise storm circulation, and 2) The amounts are based on somewhere around or just over 1/4" of melted precipitation in most areas in the heart of the precipitation band, but cold temperatures aloft will allow for a fluffy snow, so snow will pile up quickly and easily.

Again dictated by the fast jet stream winds aloft in the atmosphere, this storm will keep on truckin' and snow will end around midnight in most areas.  Winds will once again become quite active from the northwest and north behind this storm, and those winds will tap a well of cold Canadian arctic air that will come screaming in on Sunday, holding temperatures in the lower 20's through Southern New England and teens for Central and Northern areas.  With a biting wind, wind chill values will feel a good 8-12 degrees colder than the actual highs!  A few flurries and snow showers will still be possible in the mountains, though most of New England is likely to stay mainly dry.

Cold air sticks around into Monday and beyond, as the atmospheric pattern features something special in the world of meteorology...a developing "Greenland Block."  This is the term meteorologists use to describe a large and stationary area of high pressure that builds across Greenland - well to our east - and because high pressure is generally a fair-weather center, it blocks storms from moving quickly across the North Atlantic.  The result is to keep storms curling north when they move just east of the Canadian Maritimes, and with counter-clockwise flow of air around storms, this keeps an average northerly wind blowing into New England for quite some time.  The result of a pattern like this is for cold conditions to persist, with storms reaching their maximum intensity to our east, rather than over us, but that's not to say storms can't still affect New England - just like what's happening this weekend, stronger disturbances can occasionally strengthen further as they move overhead and this can produce widespread snows.  A similar situation may be in the cards for Monday night, then several chances of disturbed weather will remain while this "Greenland Block" holds.

Enjoy your weekend - I'll be back with you on Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Friday, February 24 at 10:20 AM

Upslope snow squalls will continue in the Green Mountains in cold advection upslope flow today, and Champlain Valley is also reaping the benefits of a WNW flow until wind veers more to the NW later today.  Amounts in the higher terrain will near 10" in the Central and Northern Greens where the squalls stay put, a few inches of accumulation elsewhere up the spine of the Greens and away from the higher summits.  Squalls moving across the Maine Turnpike Fri AM are the result of a vorticity maximum and associated weak developing surface wave which, as of this writing, is moving SE across Penobscot Bay.  Once this circulation hits the waters of the Gulf of ME, agreement among the guidance is for stationary/slow moving band of snow squalls to set up over or near Coastal Washington and Hancock Counties and with QPF nearing .25" (perhaps a bit overdone, and the chance it will miss and set up over the ocean) I've gone with a few inches possible in immediate coastal locales in this area.  Elsewhere in NewEng, mixing to about 880 mb by the end of the day and this will tap an increasing cold llvl jet screaming around the base of the vort max moving N of NewEng and evident on morning satellite imagery.  This jet streak extends low enough to encounter our well mixed layer with about 50-55 kts of NW flow, and damaging wind gusts to 55 mph will be possible in some areas.  Nothing like the event of exactly one week ago today, but capable of isolated damage and disruption.

Subsidence between shortwaves and associated with splitting high pressure cell means clearing skies Fri Ngt with diminishing winds as surface ridge axis shifts over NewEng and this will set us up for decent radiational cooling with single digits in the north and teens south, and of course will ensure - as if we needed it - that temperatures region-wide will be plenty cold enough for snow with the next system on Saturday.

As for this system, it's been much talked about here for a few days, and perhaps the most remarkable part is the lack of change in the guidance from one cycle to the next.  Of course, that's to be expected in this pattern - a well-defined fast flow that features strongest cyclogenesis to our east.  A few storms earlier this year I remarked here how we were in the most difficult part of the pattern to accurately forecast - just ahead of the mean trof positon.  Now, being just behind it, we will find differences in the guidance usually only pertaining to timing, and that has been the case this time around, but I still think we're on target for the faster Saturday afternoon timing laid out yesterday, and at this point it looks like clouds race in Sat AM ahead of what is still very impressive speed convergence ahead of llvl jet punching north and northwest into NewEng during the day.  This teams up with intense cyclonic vorticity advection ahead of 30-35 unit vorticity maximum that dives SE across Central and Southern NewEng Sat afternoon and eve.  As mentioned yesterday, I truly believe it's the combination of this strong CVA, coupled with what's going on especially in the lower levels of the atmosphere that will drive the evolution of this storm.  Somewhat of a center jump appears to be in the cards for the surface low with this fast moving vort, but the shortwave is strong enough as it comes through that dynamic forcing will make this center jump a help rather than a hindrance when it comes to snow production, as it will enhance low level easterly flow ahead of the center of the vort max, and therefore enhance available moisture thanks to Atlantic inflow.  QPF is well agreed upon for the broad swath of over .25" among virtually all guidance, with center of the band closer to .40".  Temps aloft are actually a bit too cold for ideal ratios, so somewhere around 15:1 looks reasonable.  What's scary is that this keeps snowfall amounts right where you and I them two days ago in this discussion at about 4"-6" in a large swath of NewEng.  Given the limited area of .40" QPF amounts in only the heart of the band, I've opted to go 4-5" in my broadcasts for this area, with obvious orographic enhancement in the appropriate areas.  Also important to note that SE flow will mean a shadow effect for parts of West-Central NH, and for parts of the Northeast Kingdom of VT - I've tried to indicate that on the maps.  Even though I'm still expecting bursts of heavy snow in the heart of the isentropic lift Sat eve, especially during passage of the vort, there's absolutely no question that this is a fast moving system, and snow will not last longer than from about noon (west) and 2 PM (east) to around midnight most areas.  So, considering the short duration, these snowfall amounts become even more impressive.

After the storm departs around midnight Sat Ngt (perhaps eastern areas with snow lingering longer thanks to marine airmass contrasting with incoming arctic air, which has a tendency to wring moisture out as snowflakes), arctic airmass still expected to unload on NewEng with 850 temps dropping to -18 C Sunday and NNW wind direction - one of the coldest for NewEng.  Fighting the build of surface cold will be the fact that high pressure stays put to our east, so this cold truly has to build down from aloft, but there's enough of it to get 925 mb temps -12 to -13 C Sunday, and equally cold if not a tad colder Monday as the flow tries to turn SW but has to wait for weak shortwave ridge axis to pass, and once that SW flow does come in, clouds increase quickly.

This leads us into our next shortwave with potential, which is slated for Mon Ngt.  Again, timing on this may end up speeding up a bit, and NAM is already indicating that in its new 12Z run.  And while I'll acknowledge this shortwave has potential, I'm not willing to bite too hard on it yet, as steering flow is very much a NW flow with mean trof position shifting E of NewEng as polar vortex effective shifts to a position NE of ME.  This, in conjunction with the strong building Greenland block position and an NAO that will tank over the coming week and really for the first 7-10 days of March, will keep the storm breeding ground east of us, so it's going to take strong shortwaves, AND some flattening of the flow east of us - usually in response to shortwave ridging ahead of the disturbances - to get these systems to amplify.  So, for now, we'll keep an eye on the Monday/Monday night vorticity maximum and see how it evolves.  The one behind it may have more potential for midweek.  Regardless, a good meteorologist will stay on guard at all times in the aforementioned pattern, as it won't take much to organize something nearby, and it's also important to note that when the NAO finally does switch from strongly negative to neutral or even positive - which is somewhere around the 7th or 8th of March - research suggests major precipitation producing storms are often found with such NAO signal shifts, especially coming out of a pattern like the one we're in now.  Food for thought.

Enjoy your weekend and good luck with your snow forecasts!

Matt


Isolated Wind Damage Friday...Plowable Snow for Many on Saturday...Blustery and Cold Sunday in Store

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net 

Matt's Quick Weather Synopsis:  Areas of black ice on roadways greet commuters of secondary roads and exit/entrance ramps to some highways Friday morning as scattered showers of rain and snow Thursday afternoon and night have left plenty of moisture in some spots.  Heavier snow squalls are moving east through Maine, where they will set up shop in Eastern Coastal Maine through Friday afternoon, delivering 3"-4" of snow in this area.  Elsewhere, mountain snow squalls will float through Northern and Western New England today while the remainder of New England finds a very gusty northwest wind bringing in enough dry air for plenty of sunshine and just a few scattered flurries.  Wind gusts may reach 55 mph Friday afternoon in some communities around New England and this means isolated damage to trees, tree limbs and power lines are possible - nothing like last Friday's damaging winds that gusted to 70-80 mph, but isolated damage is possible today nonetheless.  Expect winds to subside Friday night under mostly clear skies and a cold night.  A storm located over the Northern Plains Friday morning will move over New England later Saturday, blotting out any early morning sunshine behind increasing clouds, with light snow developing either side of 2 PM across New England and becoming heavier around 5 PM and lasting until around midnight with plowable snow for many (see accumulation maps below).  After snow ends late Saturday night, expect a drier, brighter, but cold and blustery day on Sunday as an arctic airmass pours into New England.  Cold air will remain in place on Monday, though another approaching storm will thicken the clouds and allow for snow to develop late and at night.  I'm expecting the cold and wintry feel to continue through next week!  -Matt

Accumulation Map for Saturday/Saturday Night Snow:

Accums_neweng

General Weather Summary:  After heavy snow and rain squalls for some communities later Thursday into predawn Friday, black ice found on secondary roadways, walkways, and exit/entrance ramps to some highways will melt away after making for a few Friday morning slick spots.  Exceptions will continue to be found in Eastern Maine where a weak area of low pressure will keep snow squalls falling through the day for 3"-4" of accumulation in Coastal Washington and Hancock Counties, and in the mountains of Northern and Western New England where scattered snow showers and squalls will continue to blow through.  Otherwise, expect a very gusty northwest wind to usher in cold and dry air for most of New England, bringing out plenty of sunshine amidst just a few isolated flurries, but also bringing wind gusts to 55 mph for some communities, which will be sufficient to cause isolated damage to trees, tree limbs and power lines.  It's important to note that while the wind will be capable of causing damage, blowing light objects around and pushing your car around a bit on the road, they will be nothing like the prolonged and intense damaging wind event of one week ago today.

Today's busy winds come as New England is sandwiched between a departing area of low pressure to our northwest and a bubble of high pressure building in from the west.  With a very fast flow in the atmosphere, this high pressure, fair weather center will build in quickly overnight Friday night and winds will subside with clearing skies for most areas as it does.  This combination of lighter wind and clearing skies will allow temperatures to drop into the single digits north and teens south Friday night.

Saturday likely dawns with some limited sunshine ahead of a fast-moving storm center traversing the nation and taking aim on New England.  Though the storm came ashore from the Pacific in the Pacific northwest on Thursday and was located over the Northern Plains Friday morning, it will be racing east and already spreading clouds into New England Saturday morning.  By mid-afternoon Saturday - likely sometime around 2-3 PM - light snow will begin falling in many parts of New England, becoming steadier and heavier by 5 PM.  This snow will not come down for very long thanks to the fast winds aloft pushing the storm through quickly, but will come down heavily at times Saturday evening and the first part of Saturday night, with widespread accumulations of 4"-5" by midnight Saturday night (see accumulation maps above), with local amounts to half a foot and lesser amounts to the north and south of the heaviest band of precipitation.  The snowfall accumulation forecast you see on my map is the result of two factors to be considered:  1) The shape of the snowfall pattern is defined by the rapid increase of warmth and moisture moving in from southwest to northeast in the south winds ahead of the counter-clockwise storm circulation, and 2) The amounts are based on somewhere around or just over 1/4" of melted precipitation in most areas in the heart of the precipitation band, but cold temperatures aloft will allow for a fluffy snow, so snow will pile up quickly and easily.

Again dictated by the fast jet stream winds aloft in the atmosphere, this storm will keep on truckin' and snow will end around midnight in most areas.  Winds will once again become quite active from the northwest and north behind this storm, and those winds will tap a well of cold Canadian arctic air that will come screaming in on Sunday, holding temperatures in the lower 20's through Southern New England and teens for Central and Northern areas.  With a biting wind, wind chill values will feel a good 8-12 degrees colder than the actual highs!  A few flurries and snow showers will still be possible in the mountains, though most of New England is likely to stay mainly dry.

Cold air sticks around into Monday and beyond, as the atmospheric pattern features something special in the world of meteorology...a developing "Greenland Block."  This is the term meteorologists use to describe a large and stationary area of high pressure that builds across Greenland - well to our east - and because high pressure is generally a fair-weather center, it blocks storms from moving quickly across the North Atlantic.  The result is to keep storms curling north when they move just east of the Canadian Maritimes, and with counter-clockwise flow of air around storms, this keeps an average northerly wind blowing into New England for quite some time.  The result of a pattern like this is for cold conditions to persist, with storms reaching their maximum intensity to our east, rather than over us, but that's not to say storms can't still affect New England - just like what's happening this weekend, stronger disturbances can occasionally strengthen further as they move overhead and this can produce widespread snows.  A similar situation may be in the cards for Monday night, then several chances of disturbed weather will remain while this "Greenland Block" holds.

Enjoy your weekend - I'll be back with you on Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Friday, February 24 at 10:20 AM

Upslope snow squalls will continue in the Green Mountains in cold advection upslope flow today, and Champlain Valley is also reaping the benefits of a WNW flow until wind veers more to the NW later today.  Amounts in the higher terrain will near 10" in the Central and Northern Greens where the squalls stay put, a few inches of accumulation elsewhere up the spine of the Greens and away from the higher summits.  Squalls moving across the Maine Turnpike Fri AM are the result of a vorticity maximum and associated weak developing surface wave which, as of this writing, is moving SE across Penobscot Bay.  Once this circulation hits the waters of the Gulf of ME, agreement among the guidance is for stationary/slow moving band of snow squalls to set up over or near Coastal Washington and Hancock Counties and with QPF nearing .25" (perhaps a bit overdone, and the chance it will miss and set up over the ocean) I've gone with a few inches possible in immediate coastal locales in this area.  Elsewhere in NewEng, mixing to about 880 mb by the end of the day and this will tap an increasing cold llvl jet screaming around the base of the vort max moving N of NewEng and evident on morning satellite imagery.  This jet streak extends low enough to encounter our well mixed layer with about 50-55 kts of NW flow, and damaging wind gusts to 55 mph will be possible in some areas.  Nothing like the event of exactly one week ago today, but capable of isolated damage and disruption.

Subsidence between shortwaves and associated with splitting high pressure cell means clearing skies Fri Ngt with diminishing winds as surface ridge axis shifts over NewEng and this will set us up for decent radiational cooling with single digits in the north and teens south, and of course will ensure - as if we needed it - that temperatures region-wide will be plenty cold enough for snow with the next system on Saturday.

As for this system, it's been much talked about here for a few days, and perhaps the most remarkable part is the lack of change in the guidance from one cycle to the next.  Of course, that's to be expected in this pattern - a well-defined fast flow that features strongest cyclogenesis to our east.  A few storms earlier this year I remarked here how we were in the most difficult part of the pattern to accurately forecast - just ahead of the mean trof positon.  Now, being just behind it, we will find differences in the guidance usually only pertaining to timing, and that has been the case this time around, but I still think we're on target for the faster Saturday afternoon timing laid out yesterday, and at this point it looks like clouds race in Sat AM ahead of what is still very impressive speed convergence ahead of llvl jet punching north and northwest into NewEng during the day.  This teams up with intense cyclonic vorticity advection ahead of 30-35 unit vorticity maximum that dives SE across Central and Southern NewEng Sat afternoon and eve.  As mentioned yesterday, I truly believe it's the combination of this strong CVA, coupled with what's going on especially in the lower levels of the atmosphere that will drive the evolution of this storm.  Somewhat of a center jump appears to be in the cards for the surface low with this fast moving vort, but the shortwave is strong enough as it comes through that dynamic forcing will make this center jump a help rather than a hindrance when it comes to snow production, as it will enhance low level easterly flow ahead of the center of the vort max, and therefore enhance available moisture thanks to Atlantic inflow.  QPF is well agreed upon for the broad swath of over .25" among virtually all guidance, with center of the band closer to .40".  Temps aloft are actually a bit too cold for ideal ratios, so somewhere around 15:1 looks reasonable.  What's scary is that this keeps snowfall amounts right where you and I them two days ago in this discussion at about 4"-6" in a large swath of NewEng.  Given the limited area of .40" QPF amounts in only the heart of the band, I've opted to go 4-5" in my broadcasts for this area, with obvious orographic enhancement in the appropriate areas.  Also important to note that SE flow will mean a shadow effect for parts of West-Central NH, and for parts of the Northeast Kingdom of VT - I've tried to indicate that on the maps.  Even though I'm still expecting bursts of heavy snow in the heart of the isentropic lift Sat eve, especially during passage of the vort, there's absolutely no question that this is a fast moving system, and snow will not last longer than from about noon (west) and 2 PM (east) to around midnight most areas.  So, considering the short duration, these snowfall amounts become even more impressive.

After the storm departs around midnight Sat Ngt (perhaps eastern areas with snow lingering longer thanks to marine airmass contrasting with incoming arctic air, which has a tendency to wring moisture out as snowflakes), arctic airmass still expected to unload on NewEng with 850 temps dropping to -18 C Sunday and NNW wind direction - one of the coldest for NewEng.  Fighting the build of surface cold will be the fact that high pressure stays put to our east, so this cold truly has to build down from aloft, but there's enough of it to get 925 mb temps -12 to -13 C Sunday, and equally cold if not a tad colder Monday as the flow tries to turn SW but has to wait for weak shortwave ridge axis to pass, and once that SW flow does come in, clouds increase quickly.

This leads us into our next shortwave with potential, which is slated for Mon Ngt.  Again, timing on this may end up speeding up a bit, and NAM is already indicating that in its new 12Z run.  And while I'll acknowledge this shortwave has potential, I'm not willing to bite too hard on it yet, as steering flow is very much a NW flow with mean trof position shifting E of NewEng as polar vortex effective shifts to a position NE of ME.  This, in conjunction with the strong building Greenland block position and an NAO that will tank over the coming week and really for the first 7-10 days of March, will keep the storm breeding ground east of us, so it's going to take strong shortwaves, AND some flattening of the flow east of us - usually in response to shortwave ridging ahead of the disturbances - to get these systems to amplify.  So, for now, we'll keep an eye on the Monday/Monday night vorticity maximum and see how it evolves.  The one behind it may have more potential for midweek.  Regardless, a good meteorologist will stay on guard at all times in the aforementioned pattern, as it won't take much to organize something nearby, and it's also important to note that when the NAO finally does switch from strongly negative to neutral or even positive - which is somewhere around the 7th or 8th of March - research suggests major precipitation producing storms are often found with such NAO signal shifts, especially coming out of a pattern like the one we're in now.  Food for thought.

Enjoy your weekend and good luck with your snow forecasts!

Matt


Emerging Snow Squalls to Pose Travel Hazards Thursday...Plowable Snow For Some Saturday Night

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net

Matt's Quick Weather Synopsis:  A strong upper level disturbance will cross New England today, and will push a weak disturbance, called a "trough", through at ground level.  This trough, in conjunction with the approaching disturbance, will continue to spark showers of snow and rain across New England today, under mostly cloudy skies.  With high temperatures approaching 40 degrees in Southern New England, and in the middle 30's north, some rain showers will certainly mix in, but the concern is that temperatures will fall just enough around the time of evening commute in Southern New England - and will be cold enough through the day across hilly terrain and VT, NH and ME - that roads may become slippery and covered with snow and ice in some communities.  A key to understanding today's forecast is the realization that *localized bands* of heavier precipitation will cause the problems - not all communities will be hit hard - but you can monitor where these areas of rain and snow are today via radar imagery on my main page, www.mattnoyes.net.  Overnight, snow and rain showers will end between 9 PM (most areas) and midnight (eastern ME), but with partial clearing and light winds, black ice will become a problem in many communities.  Another disturbance raises chances for snow squalls just in time for the morning commute on Friday, then a blustery day with scattered snow showers between breaks of sunshine.  Saturday dawns with limited sunshine, but clouds thicken and snow is likely by late Saturday afternoon, lasting through Saturday night.  This won't be a blockbuster storm, but a few inches and therefore a plowable snow does appear likely.  Behind this storm, bitter winds usher in very cold air for both Sunday and Monday, with a blend of sun and clouds interspersed with occasional flurries.  Take it easy!  -Matt

General Weather Summary:  The overall weather pattern has been consistent this week - keeping the northern (polar) and southern (subtropical) jet streams separate - thereby keeping the significant cold and energy separate from southern moisture.  These streams have been phasing to our east, across the Western Atlantic, and that's where larger storm centers have been taking shape.  Thursday, the merger of northern energy and southern moisture will occur closer to New England, at the same time a strong northern stream disturbance drops across the six-state region. 

This combination of factors will serve to produce plenty of clouds for all areas, with morning mountain snow squalls expanding in areal coverage to envelope most of New England by Thursday afternoon.  With a light wind but limited daytime heating through the clouds, temperatures will still be able to climb to around 40 degrees in Southern New England and this will be warm enough for a mix of rain and snow showers, or even just rain in some locales as precipitation blossoms later Thursday.  With cold air aloft, however, hilly terrain across Southern New England will likely find mainly snow showers, and as the afternoon progresses, this cold air will allow for a change to snow squalls for most valleys and the coastal plain, as well.  Road crews will need to be on standby across Southern New England today as a result, because while bursts of snow will be found in *localized* heavy bands, communities under these bands of snow late this afternoon and this evening will see a quick ice/snow coating on roadways as temperatures fall to near freezing.  Farther north in New England, most of Vermont, New Hampshire and Maine will be cold enough for mostly snow, and therefore a few inches of accumulation are possible in only a few hours in some of these heavier squalls Thursday afternoon and evening.  By 9 or 10 PM Thursday evening, after what will obviously be a difficult commute for some areas, snow squalls will diminish and skies will partially clear - though this will be delayed until around midnight in Central and Eastern Maine as the disturbance sparking these squalls moves east across New England.  For more on how this disturbance is coming together...an explanation of the "Norlun Trough" that will set up across New England today...please refer to yesterday's summary (found in the archives at left, and found below today's post).

Friday will dawn wtih widespread black ice after clearing skies allow temperatures to drop into the 20s through most of New England by Friday morning, and leftover moisture on New England roadways freezes.  On top of this black ice, it appears as though at least some communities will find a fresh coating of snow coming through Friday morning - right around the time of the morning drive - as yet another disturbance moves through and sparks a new round of snow showers and squalls for some communities of both Northern and Southern New England.  For a few unlucky souls, we certainly may see back-to-back aggravating commutes.  The passage of this Friday morning disturbance marks the leading edge to a new installment of cold air, and blustery conditions will prevail with emerging breaks of sunshine amidst leftover flurries for most of us, and lingering heavier squalls in the Northern Mountains.

This weekend, with multiple energetic disturbances still dropping in from the north, and moisture beginning to finally ride northward to meet the energy, we will be very close to phasing the streams over or near New England.  It continues to appear as though later Saturday, energy slides through quickly, passing through Saturday night and then ushering in cold air as the storm strengthens once passing to our east.  The end result should be as follows:  Saturday morning sunshine fades behind thickening clouds in advance of the approaching storm.  Snow will develop later Saturday afternoon as moisture and warmth aloft is ushered northward in the south winds ahead of this counter-clockwise circulation, and snow will become heavier Saturday night.  As the storm circulation moves over New England, a big part of the forecast hinges on how strong the storm center becomes.  If it strengthens quickly enough - and I think it will - an east wind will develop through the lower few thousand feet of the atmosphere and this will mean we tap moisture from the Atlantic Ocean.  My expectation is for relatively light snow late Saturday afternoon to find embedded bursts of heavier snow Saturday evening, then an overnight gasp of steady snow as this easterly wind develops at the very same time the storm gets ready to pull away.  This means a short-duration event that will be winding down Sunday morning, with a few inches that falls in most of at least Central and Southern New England (Northern New England likely to get into some of this, too) but areas that see this ocean influence may come closer to 4"-6" of snow.  It's still early to pinpoint whether those higher amounts fall - but likely somewhere between Northeast MA and the Central Coast of ME - certainly in eastern New England.

Behind this storm, cold and blustery conditions come pouring in on Sunday with scattered snow showers between sun and clouds, and a reinforcing shot of cold air with possible snow squalls swings through on Monday.  Don't be expecting the cold air to go very far!  Indications are we'll remain chilly through next week.

Have a wonderful Thursday.

Matt

Matt's Technical Meteorological Discussion:  Updated Thursday, February 23 at 2:45 PM

Today's convective activity is firing nicely as of this writing and visibility to 1/2 mile in snow has already been reported under numerous locales in the northern band and also in HFD under the southern activity.  Details on today's event were laid out here yesterday and I won't bother to rehash - suffice to say the bridging of convection between northern energy/front and southern moist inflow has begun and will continue, bringing heavy squalls of rain and snow to Southern NewEng, and of snow to areas N of the MA State line and in the hills of Southern NewEng as well.  Of course, the challenges won't stop there - while surface wet bulb temps have risen above zero in most of Southern NewEng, still well below zero just off ground level and this will allow snow to make it to ground level.  Dynamic cooling is likely to bring some of this colder and drier air toward the surface and heavier convective bursts will feature changeover to snow even in the valleys and coastal plain during the afternoon.  Approaching sunset, the combo of this factor and waning diurnal heating will help road surfaces to cool enough for snow and ice to accumulate in some areas, which is the reason for concern on roadways of both northern and southern NewEng Thu afternoon and evening.  Snowwfall rates of 2" per hour will be found in the White Mountains, Mountains of Maine, and perhaps in the Berkshires.  Anywhere from Berkshires to hilly terrain of MA to MA/NH border points north will be susceptible to a few inches of snow in just a few hours in the more intense convective bands and bursts.

Overnight, skies will clear in area of subsidence and wedge of dry air between shortwaves as next vorticity maximum shoots east from current position over MI and across the Great Lakes into NewEng by morning.  In the interim, widespread black ice will result thanks to light winds, high ambient RH in the boundary layer, and widespread precip of various forms during the day leaving plenty of moisture on the roadways.  Next shortwave will be driving a cold front with it as it charges thru Fri AM, and the trof moving thru NewEng will also whip southward, providing multiple lines of convergence for what will likely be another round of snow squalls for Fri AM commute.  Once this shortwave whips thru, expect strong subsidence combined with downslope flow to bring the sun out most areas, tho upslope areas will capitalize on cold air aloft and associated instability to keep squalls going thru most of the day.

Two trends for Sat system: faster and farther N.  The farther north trend is the one that should be a bit concerning for snow lovers across Southern NewEng - I'd say we're still guaranteed to get the snow in here, but it's going to mean any easterly flow on the north side of the low level circulation is mostly going to be focused along the Maine coastline and into Northern New England.  But while this news may bring some frowns to Southern New England snow lovers, it brings smiles to the faces of Northerners, who are undoubtedly leaning forward into your monitors right now, waiting for more info!  Here's the deal:  As the northern stream shortwave races east on Saturday, the reason I'm so confident we'll see a shield of snow moving into New England from the south is owing to the intense speed convergence and isentropic lift associated with strong warm and moist advection at 850 mb ahead of the circulation.  With a faster eastward progression of the low, this convergence and warm/moist advection spreads into far SW NewEng as soon as Sat morning, then overspreads the remainder of NewEng during the day Sat, and snow is certain to develop with this southerly thrust of air.  The downside to this is that while it can snow exceptionally hard in situations like these, it will also even further shorten the duration of an already short-lived event.  The result is likely to be a burst of about 6 hours of steady and at times heavy snow for Southern NewEng on Saturday, then the areas to see extended snowfall will be found where easterly or southeasterly flow can set up on the north side of especially the 850 mb circulation.  In fact, given the baroclinicity, the low level jet max, and the available ocean moisture, I'm a big believer that this event will be strongly driven by what unfolds in the low levels, and this means a burst of warm advection snow to start for everyone, then lingering snow where easterly flow establishes.  Ratios will likely be somewhere around 16:1 as an early rough estimate, but I'll dig into this a bit more tomorrow.

Still looks like real cold stuff in store for Sun and reinforcing arctic front with wave possible Monday.  NAO stays negative and cold air looks to stay locked in with trough over Northeastern US and Greenland block developing.  While this keeps in the cold, it still leaves us on the fence for storms, favoring a continued storm maximization to our east, but close enough that we'll be watching each strong shortwave like a hawk.

Enjoy your day.

Matt


Emerging Snow Squalls to Pose Travel Hazards Thursday...Plowable Snow For Some Saturday Night

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. My email is contact@mattnoyes.net.  This blog is for you, so I hope you enjoy it!  -Matt Noyes

For latest radar imagery, to check for watches and warnings, and for links to sites in the world of weather, feel free to click over to my website: www.mattnoyes.net

Matt's Quick Weather Synopsis:  A strong upper level disturbance will cross New England today, and will push a weak disturbance, called a "trough", through at ground level.  This trough, in conjunction with the approaching disturbance, will continue to spark showers of snow and rain across New England today, under mostly cloudy skies.  With high temperatures approaching 40 degrees in Southern New England, and in the middle 30's north, some rain showers will certainly mix in, but the concern is that temperatures will fall just enough around the time of evening commute in Southern New England - and will be cold enough through the day across hilly terrain and VT, NH and ME - that roads may become slippery and covered with snow and ice in some communities.  A key to understanding today's forecast is the realization that *localized bands* of heavier precipitation will cause the problems - not all communities will be hit hard - but you can monitor where these areas of rain and snow are today via radar imagery on my main page, www.mattnoyes.net.  Overnight, snow and rain showers will end between 9 PM (most areas) and midnight (eastern ME), but with partial clearing and light winds, black ice will become a problem in many communities.  Another disturbance raises chances for snow squalls just in time for the morning commute on Friday, then a blustery day with scattered snow showers between breaks of sunshine.  Saturday dawns with limited sunshine, but clouds thicken and snow is likely by late Saturday afternoon, lasting through Saturday night.  This won't be a blockbuster storm, but a few inches and therefore a plowable snow does appear likely.  Behind this storm, bitter winds usher in very cold air for both Sunday and Monday, with a blend of sun and clouds interspersed with occasional flurries.  Take it easy!  -Matt

General Weather Summary:  The overall weather pattern has been consistent this week - keeping the northern (polar) and southern (subtropical) jet streams separate - thereby keeping the significant cold and energy separate from southern moisture.  These streams have been phasing to our east, across the Western Atlantic, and that's where larger storm centers have been taking shape.  Thursday, the merger of northern energy and southern moisture will occur closer to New England, at the same time a strong northern stream disturbance drops across the six-state region. 

This combination of factors will serve to produce plenty of clouds for all areas, with morning mountain snow squalls expanding in areal coverage to envelope most of New England by Thursday afternoon.  With a light wind but limited daytime heating through the clouds, temperatures will still be able to climb to around 40 degrees in Southern New England and this will be warm enough for a mix of rain and snow showers, or even just rain in some locales as precipitation blossoms later Thursday.  With cold air aloft, however, hilly terrain across Southern New England will likely find mainly snow showers, and as the afternoon progresses, this cold air will allow for a change to snow squalls for most valleys and the coastal plain, as well.  Road crews will need to be on standby across Southern New England today as a result, because while bursts of snow will be found in *localized* heavy bands, communities under these bands of snow late this afternoon and this evening will see a quick ice/snow coating on roadways as temperatures fall to near freezing.  Farther north in New England, most of Vermont, New Hampshire and Maine will be cold enough for mostly snow, and therefore a few inches of accumulation are possible in only a few hours in some of these heavier squalls Thursday afternoon and evening.  By 9 or 10 PM Thursday evening, after what will obviously be a difficult commute for some areas, snow squalls will diminish and skies will partially clear - though this will be delayed until around midnight in Central and Eastern Maine as the disturbance sparking these squalls moves east across New England.  For more on how this disturbance is coming together...an explanation of the "Norlun Trough" that will set up across New England today...please refer to yesterday's summary (found in the archives at left, and found below today's post).

Friday will dawn wtih widespread black ice after clearing skies allow temperatures to drop into the 20s through most of New England by Friday morning, and leftover moisture on New England roadways freezes.  On top of this black ice, it appears as though at least some communities will find a fresh coating of snow coming through Friday morning - right around the time of the morning drive - as yet another disturbance moves through and sparks a new round of snow showers and squalls for some communities of both Northern and Southern New England.  For a few unlucky souls, we certainly may see back-to-back aggravating commutes.  The passage of this Friday morning disturbance marks the leading edge to a new installment of cold air, and blustery conditions will prevail with emerging breaks of sunshine amidst leftover flurries for most of us, and lingering heavier squalls in the Northern Mountains.

This weekend, with multiple energetic disturbances still dropping in from the north, and moisture beginning to finally ride northward to meet the energy, we will be very close to phasing the streams over or near New England.  It continues to appear as though later Saturday, energy slides through quickly, passing through Saturday night and then ushering in cold air as the storm strengthens once passing to our east.  The end result should be as follows:  Saturday morning sunshine fades behind thickening clouds in advance of the approaching storm.  Snow will develop later Saturday afternoon as moisture and warmth aloft is ushered northward in the south winds ahead of this counter-clockwise circulation, and snow will become heavier Saturday night.  As the storm circulation moves over New England, a big part of the forecast hinges on how strong the storm center becomes.  If it strengthens quickly enough - and I think it will - an east wind will develop through the lower few thousand feet of the atmosphere and this will mean we tap moisture from the Atlantic Ocean.  My expectation is for relatively light snow late Saturday afternoon to find embedded bursts of heavier snow Saturday evening, then an overnight gasp of steady snow as this easterly wind develops at the very same time the storm gets ready to pull away.  This means a short-duration event that will be winding down Sunday morning, with a few inches that falls in most of at least Central and Southern New England (Northern New England likely to get into some of this, too) but areas that see this ocean influence may come closer to 4"-6" of snow.  It's still early to pinpoint whether those higher amounts fall - but likely somewhere between Northeast MA and the Central Coast of ME - certainly in eastern New England.

Behind this storm, cold and blustery conditions come pouring in on Sunday with scattered snow showers between sun and clouds, and a reinforcing shot of cold air with possible snow squalls swings through on Monday.  Don't be expecting the cold air to go very far!  Indications are we'll remain chilly through next week.

Have a wonderful Thursday.

Matt

Matt's Technical Meteorological Discussion:  Updated Thursday, February 23 at 2:45 PM

Today's convective activity is firing nicely as of this writing and visibility to 1/2 mile in snow has already been reported under numerous locales in the northern band and also in HFD under the southern activity.  Details on today's event were laid out here yesterday and I won't bother to rehash - suffice to say the bridging of convection between northern energy/front and southern moist inflow has begun and will continue, bringing heavy squalls of rain and snow to Southern NewEng, and of snow to areas N of the MA State line and in the hills of Southern NewEng as well.  Of course, the challenges won't stop there - while surface wet bulb temps have risen above zero in most of Southern NewEng, still well below zero just off ground level and this will allow snow to make it to ground level.  Dynamic cooling is likely to bring some of this colder and drier air toward the surface and heavier convective bursts will feature changeover to snow even in the valleys and coastal plain during the afternoon.  Approaching sunset, the combo of this factor and waning diurnal heating will help road surfaces to cool enough for snow and ice to accumulate in some areas, which is the reason for concern on roadways of both northern and southern NewEng Thu afternoon and evening.  Snowwfall rates of 2" per hour will be found in the White Mountains, Mountains of Maine, and perhaps in the Berkshires.  Anywhere from Berkshires to hilly terrain of MA to MA/NH border points north will be susceptible to a few inches of snow in just a few hours in the more intense convective bands and bursts.

Overnight, skies will clear in area of subsidence and wedge of dry air between shortwaves as next vorticity maximum shoots east from current position over MI and across the Great Lakes into NewEng by morning.  In the interim, widespread black ice will result thanks to light winds, high ambient RH in the boundary layer, and widespread precip of various forms during the day leaving plenty of moisture on the roadways.  Next shortwave will be driving a cold front with it as it charges thru Fri AM, and the trof moving thru NewEng will also whip southward, providing multiple lines of convergence for what will likely be another round of snow squalls for Fri AM commute.  Once this shortwave whips thru, expect strong subsidence combined with downslope flow to bring the sun out most areas, tho upslope areas will capitalize on cold air aloft and associated instability to keep squalls going thru most of the day.

Two trends for Sat system: faster and farther N.  The farther north trend is the one that should be a bit concerning for snow lovers across Southern NewEng - I'd say we're still guaranteed to get the snow in here, but it's going to mean any easterly flow on the north side of the low level circulation is mostly going to be focused along the Maine coastline and into Northern New England.  But while this news may bring some frowns to Southern New England snow lovers, it brings smiles to the faces of Northerners, who are undoubtedly leaning forward into your monitors right now, waiting for more info!  Here's the deal:  As the northern stream shortwave races east on Saturday, the reason I'm so confident we'll see a shield of snow moving into New England from the south is owing to the intense speed convergence and isentropic lift associated with strong warm and moist advection at 850 mb ahead of the circulation.  With a faster eastward progression of the low, this convergence and warm/moist advection spreads into far SW NewEng as soon as Sat morning, then overspreads the remainder of NewEng during the day Sat, and snow is certain to develop with this southerly thrust of air.  The downside to this is that while it can snow exceptionally hard in situations like these, it will also even further shorten the duration of an already short-lived event.  The result is likely to be a burst of about 6 hours of steady and at times heavy snow for Southern NewEng on Saturday, then the areas to see extended snowfall will be found where easterly or southeasterly flow can set up on the north side of especially the 850 mb circulation.  In fact, given the baroclinicity, the low level jet max, and the available ocean moisture, I'm a big believer that this event will be strongly driven by what unfolds in the low levels, and this means a burst of warm advection snow to start for everyone, then lingering snow where easterly flow establishes.  Ratios will likely be somewhere around 16:1 as an early rough estimate, but I'll dig into this a bit more tomorrow.

Still looks like real cold stuff in store for Sun and reinforcing arctic front with wave possible Monday.  NAO stays negative and cold air looks to stay locked in with trough over Northeastern US and Greenland block developing.  While this keeps in the cold, it still leaves us on the fence for storms, favoring a continued storm maximization to our east, but close enough that we'll be watching each strong shortwave like a hawk.

Enjoy your day.

Matt