Previous month:
January 2006
Next month:
March 2006

Mild Thang, You Make My Heart Sing...But Midweek Singing to be Replaced By Weekend Stinging!

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 [email protected].  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 (New!):  We're living life on the mild side across New England for the next couple of days!  Southwest winds have ushered in plenty of mild air, so our steady snowmelt continues across the region today as patches of morning black ice melt off and a blend of sunshine and clouds helps to push temperatures into the 40's for most of New England - even nearing 50 in the City of Boston!  With these mild temperatures and plenty of snow still lingering around our major metropolitan areas of Southern New England, some poor drainage areas of these big cities will see some large puddles today, so you may want to consider grabbing the waterproof boots if you know your office is in one of these puddle-prone areas!  Far northern Maine is closer to bitter cold air locked in Canada, and will only top out around freezing today with periods of light snow accumulating up to an inch.  Overnight Wednesday night, a bit of additional moisture moves into New England near the surface, and this is likely to result in scattered areas of fog and black ice.  Thursday will be another mild and dry day for most of New England, though snow will develop Thursday afternoon and evening across Northern Maine, where snow will fall heavily at times into Friday.  Elsewhere, clouds thicken Friday with downpours, possible thunder, and potentially damaging winds swinging through most of New England Friday afternoon and evening associated with a cold front.  Behind this front, arctic air spills in for the weekend with frigid temperatures and a stinging wind.  Our next possibility of widespread snow comes toward the middle of next week.  -Matt

General Weather Summary:  The amazing range in temperature straddling the Canadian border that we examined in yesterday's discussion continues to strengthen as it drops slowly southward for our Wednesday.  Bitter arctic air was settling into the Northern Plains, and temperatures from St. Louis northward to the north shore of Lake Superior ranged from 47 degrees to -33 degrees, respectively - some 80 degrees difference!  This kind of a tremendous difference in temperature often can serve as a breeding ground for strong storms, and one of these storms will crank up to our west over the next few days, eventually kicking up the winds across New England and yanking down the bitterly cold arctic air that sits north of the border.

In the meantime, however, New England is spending some time living on the "mild side" of life!  Early morning patches of black ice continue to give way to growing puddles through the day Wednesday as our snowpack continues to shrivel in the mild temperatures.  Those of you who work in the major metropolitan areas of Southern New England and usually find big puddles near your office building in poor drainage areas of the cities may want to bring the waterproof footwear today!  Winds will be active from the southwest again Wednesday, though the mild nature of the air will not allow these winds to create much of a brisk feel - most of us will agree the day feels downright mild!  With more moist air slowly moving in through the day Wednesday and into Wednesday night, use caution during the overnight period as areas of fog and more widespread black ice is likely to develop on our New England roadways.

Those of you who read regularly have been ready for this brief pattern change - really more of a weather pattern "reshuffling," whereby mild air returns for a few days before we jump right back into a cold and likely stormy pattern.  This overall pattern reshuffling comes as the jet stream winds aloft - the fast river of air high in the sky that steers our storms and acts as a thermostat for the atmosphere, separating cold air to the north from warm air to the south - reconfigure briefly.  These jet stream winds flow in a wave-pattern across the globe, with ridges (bumps) and troughs (dips).  The Eastern U.S. has been in a trough of late, which means New England has fallen on the cold side of these atmospheric winds - and we've felt the results!  As the jet stream shifts northward and rises directly over New England for the middle and end of the week, we shift to the milder side of life.  With very few strong disturbances for the jet stream to steer our way, the weather will be fairly tranquil for midweek.

Thursday, a stronger storm system will begin taking shape along the clash between cold and warm air, and will move through the Central Rockies and Midwestern U.S.  Ahead of this storm, a reinforcing shot of warmth and moisture will stream northward, at the same time cold air oozes southward from Eastern Canada.  The result will be precipitation developing along the Canadian border again Thursday evening into Thursday night, and where enough cold air is in place across Aroostook County, ME, snow will pile up several inches Thursday night into Friday!  There is still some question as to how far north warmth reaches early on Friday, and a brief change to sleet or rain is possible in these northern expanses of Maine, but most of what falls will be as snow, and we're likely to see amounts nearing a foot in Northern parts of the County. 

By Friday, the approaching storm center will bring periods of rain for all of New England, especially during the afternoon, along with gusty winds and one last mild day before a cold front sweeps through.  This front may bring a few Friday afternoon thunderstorms with it as it pushes through New England, and bitterly cold arctic air will come rushing in behind this front.  The surge of new air may be so strong, that wind gusts exceed 60 mph, and this would mean a widespread damaging wind event for much of New England Friday late afternoon and evening...but we'll continue to monitor this threat and fine tune the forecast with regard to this threat as necessary.  In addition to the possibility of rapid freezing of standing water Friday night (dependent upon how much rain falls on Friday), this surge of arctic air will set up a truly frigid weekend for the Northeast, with highs only in the teens for Southern New England Saturday and Sunday, and in the single digits across the north!  Winds should be quite gusty on both days, but especially on Saturday, with wind chill values in the single digits south and around or below zero north!

Remember that the mild air this week is truly just a reshuffling of the atmospheric pattern, which means that this bitter blast of arctic air - in my estimation - is a return to reality, and a return to a cold, wintry and at times stormy pattern that will persist until the end of the month, when another brief turn toward mild weather may surface again.  In the meantime, there will be a couple of chances for storm - strong indications have been persistent for a storm sometime around next Tuesday, though with a storm track to our south, a snowstorm looks to be in the cards for the Mid-Atlantic, while here in New England we'll be watching this storm carefully, as the northern shield of snow may bring accumulating snow our way, and in addition, the storm will strengthen and turn north parallel to the coast at some point, and how close it hugs the coast will be another factor we'll watch carefully.  Chances for snow will continue later next week, as well, so there will be plenty to watch.

Have a great Wednesday!

Matt

Matt's Technical Meteorological Discussion:  Updated Wednesday, February 15 at 1:30 PM

Short term remains fairly straight-forward.  Both NAM and GFS were overdoing the inversion over CT southwest thru NJ significantly in the last couple of runs and I basically ignored this forecast of a strong low level inversion in my forecasts for today.  Actual temperatures as of this writing are running about 15 degrees higher than operational model forecast, so thankfully this was the way to go today.  Will it be the right correction to make tomorrow as well?  A bit trickier given that increasing moisture overnight and slackening winds will allow fog and black ice to develop in many areas, and with an inversion in place (formed due to cold snowpack) it is certainly a concern that we may not mix out on Thursday, but at this point I think we have to remember that we're dealing with a sun angle that's now equivalent to October sunshine, and this shallow moisture should not even build up more than a couple thousand feet, so any low level cloud deck should burn off Thu AM.  Thereafter, not much has changed from the technical details laid out here yesterday for vorticity lobe moving across Northern NewEng border and the lift that increases in advance of main shortwave, though there has been a definite northward trend in the baroclinic zone in response to warm advection ahead of the shortwave trough.  So now the challenge for Aroostook County becomes just how long we can hold onto snow, and how much precip we crank out - with the NAM putting most of the precip into Canada and the GFS/GGEM holding the rain snow line through Central Aroostook County.  At this point, I still would like to buy the colder scenario given the tremendous weight of such deep cold to the north, though I have to admit that with actual highs running above what was expected through most of NewEng today, that tells me to step very carefully for this Northern ME situation.  Will stick with the colder scenario for now and re-evaluate Thu.

Elsewhere, Fri forecast has seen some subtle changes in how everything comes together, with the low deepening sooner than previously anticipated, which means the period of greatest intensification occurs farther west.  This hasn't changed much from our perspective here in NewEng, except perhaps creating a bit less of a fall/rise couplet along the front when it swings thru.  Nonetheless, strong subsidence is still progged immediately behind the frontal boundary and I winds are still progged to be between 60 and 90 knots 850-500 mb, so the threat for a damaging wind event continues later Fri.  I still haven't opted to go too far off on this on-air or in the general weather summary above because I want to make sure there are no other trends or changing signals here before really putting folks on guard.

I've made no changes to the weekend temperature forecast for most spots to be in the teens both days, which still is quite clearly frigid.  I think guidance is much too heavily weighted by climo and while there will be a downsloping component to the winds, this air is brutally cold and has produced a large area of daytime highs below zero as it's been building in Southern and Central Canada - now being evidenced in the International Falls, MN, areas.  Next northern stream shortwave swings thru on Sat and carries a reinforcing arctic front with it, which will bring intense squalls to the mountains Sat afternoon, and a chance elsewhere Sat eve tho downslope flow will fight this potential.  Regardless, this backs up yesterday's idea of colder temps on Sunday than on Sat.

Next Tuesday's storm continues to look promising for the Northern Mid-Atlantic and is looking ever more promising for New England to pick up accumulating snow.  Ensemble trends show a clear northward drift in the precip probability fields, and more importantly, there's been a shift in some of the Ensemble members and occasional operational runs of varying models (depends on the cycle) to shift the omega block east of Greenland just slightly more westward.  Additionally, signs are for a piece of Mexican warmth to break off late this week and travel east along the Gulf Coast this weekend, making its way off the Eastern Seaboard by Monday and Tuesday, which certainly would help pump up a shortwave ridge east of the coast, helping to steer this Tuesday storm farther north.  Once again, as with our blizzard when we examined it several days in advance, we can make the argument that the flow aloft is too confluent across the Eastern half of the US, but really a closer inspection yields confluent flow until the East Coast, then a switch to diffluence over the immediate Eastern states.  This, combined with the thermal structure and ridge placement near Greenland, have me still believing in the potential of a sizeable storm going from flat juicy wave to potential coastal storm capable of a big dumping for next Tue.

Time will tell, but you and I will be watching closely.  That's all for today.

Matt


Brief Warmup Poised to Move Into New England...Arctic Chill and Winter Pattern to Return This Weekend After Strong Friday Winds

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 [email protected].  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 (New!):  Weak upper level disturbances moving over New England will bring more clouds than sun to Northern New England today with a few mountain snow showers, while the rest of us enjoy a blend of sun and clouds.  While temperatures will rise above freezing through most of New England, an active southwest wind will bring breezy and therefore brisk day.  Overnight Tuesday night, expect a nearby weak storm system moving through Southern Canada to bring a period of light snow with a couple of inches of accumulation in the Northern third of Maine.  Southwest winds continue to blow on Wednesday, ushering in mild air for one and all, with temperatures climbing into the 40's under a pleasant blend of sun and clouds.  Look for a repeat on Thursday before a stronger storm sweeps wind-driven rains and embedded thunder through New England Friday afternoon.  This storm will yank a chunk of bitter arctic air into New England for the weekend - with high temperatures only in the teens in Southern New England, and in the single digits across the North Country!  -Matt

General Weather Summary:  A tremendous difference in temperature can be found in the morning surface analysis from the Northern Tier of the United States where temperatures are starting some 20-25 degrees, to the Southern Tier of Canada where Tuesday has dawned with temperatures some 20-25 degrees BELOW ZERO!  Yikes!  This well of arctic air will remain locked in Canada for the time-being, as the jet stream winds aloft - the fast river of air that steers our storms and acts as a thermostat for the atmosphere, separating northern cold from southern warmth - will lift to the Canadian border.  This pattern change and sharp temperature difference along the Canadian border means two things for New England:  1) Warmer air will move in as we transition closer to that southern side of the thermostatic jet stream, and 2) Frequent disturbances will move across the far reaches of Northern New England, bringing periodic showers of snow and rain to the Canadian border.

As the warmer air takes aim on New England and is on the move northward, southwest winds will continue to increase in intensity on Tuesday - gradually ushering in this new airmass.  While multiple weak upper level disturbances caught in the jet stream winds aloft will keep more clouds than sun - and even a few mountain flurries - in place across Northern New England, the remainder of our six-state region will enjoy a brisk blend of sun and clouds for most of the day Tuesday, with dry air in place through most of the atmosphere and a few high altitude cirrus clouds streaming overhead from time to time.  The active southwest wind, though gradually bringing in a milder airmass, will add a bit of a chill to the air and those with outdoor plans may want to bring the hat and gloves along.

Yet another disturbance will move across the Canadian border Tuesday night, bringing a period of light snow to Northern Maine, where a couple of fresh inches of snow will fall by Wednesday morning.  The rest of New England will remain quiet with passing clouds and low temperatures once again dropping just far enough below freezing for areas of black ice where daytime melted snow refreezes, especially on walkways and secondary roadways.

Those of you who read regularly will probably remember that over a week ago you and I began eyeing this brief pattern change together - really more of a weather pattern "reshuffling," whereby mild air returns for a few days before we jump right back into a cold and likely stormy pattern.  We've arrived upon that pattern change, and beginning Wednesday this important shift in the weather pattern will make itself evident.  The jet stream winds aloft flow in a wave-pattern across the globe, with ridges (bumps) and troughs (dips).  The Eastern U.S. has been in a trough of late, which means New England has fallen on the cold side of these atmospheric winds - and we've felt the results!  As the jet stream shifts northward and rises directly over New England for the middle and end of the week, we shift to the milder side of life.  With very few strong disturbances for the jet stream to steer our way, the weather will be fairly tranquil for midweek.

Thursday, a stronger storm system will begin taking shape along the clash between cold and warm air along the Northern Tier of the Central and Western United States, and moving through the Central Rockies and Midwestern U.S.  Ahead of this storm, a reinforcing shot of warmth and moisture will stream northward, at the same time cold air oozes southward from Eastern Canada.  The result will be precipitation developing along the Canadian border again Thursday evening into Thursday night, and if enough cold air is in place, some limited accumulating snow would be possible.  By Friday, the approaching storm center will bring periods of rain for all of New England, especially during the afternoon, along with gusty winds and one last mild day before a cold front sweeps through.  This front is likely to bring a few Friday afternoon thunderstorms with it as it pushes through New England, and bitterly cold arctic air will come rushing in behind this front.  In addition to the possibility of rapid freezing of standing water Friday night (dependent upon how much rain falls on Friday), this will set up a truly frigid weekend for the Northeast, with highs only in the teens for Southern New England Saturday and Sunday, and in the single digits across the north!

Remember that the mild air this week is truly just a reshuffling of the atmospheric pattern, which means that this bitter blast of arctic air - in my estimation - is a return to reality, and a return to a cold, wintry and at times stormy pattern that will persist until the end of the month, when another brief turn toward mild weather may surface again.  In the meantime, there will be a couple of chances for storm - strong indications have been persistent for a storm sometime around next Tuesday, though with a storm track to our south, a snowstorm looks to be in the cards for the Mid-Atlantic, while here in New England we'll be watching this storm carefully, as the northern shield of snow may bring accumulating snow our way, and in addition, the storm will strengthen and turn north parallel to the coast at some point, and how close it hugs the coast will be another factor we'll watch carefully.  Chances for snow will continue later next week, as well, so there will be plenty to watch.

Enjoy your Valentine's Day!

Matt

Matt's Technical Meteorological Discussion:  Updated Tuesday, February 14 at 1:35 PM

Short term forecast is fairly straight-forward.  It's a baroclinically charged atmosphere in place along the Canadian border with a 50 degree temp difference over about 350 miles centered along and just north of the US/Canadian border.  This will become important in the forecast for Northern Maine, and will be worth paying attention to for the remainder of Northern NewEng in the short range, and for the rest of NewEng by the upcoming weekend.

Multiple weak shortwaves are prompting snow showers and continuous light snow from the northern Greens east through the Mountains of ME and Northern ME.  This ribbon of clouds and broken precip extends westward thousands of miles, just south of the baroclinic zone, then curling SW across the Rockies and tapping moisture from the SW US upper low, which is in turn feeding off a Pacific flow.  Overall, a rather remarkable train of moisture and energy not phasing with the Northern Stream, but instead trickling into it.  In fact, the lack of phasing is what keeps the next few days dry, though a strong vorticity maximum dropping into the Pacific Northwest this afternoon has plans to change that by the end of the week.

But before we become too deeply entrenched in talk of the pattern and its repercussions in the medium and long range, let's briefly address the short-term first.  Snow showers and heavier squalls in Northern and Central ME are the most intense snow in NewEng today - convective creatures working off the aforementioned baroclinicity and shortwaves rippling through the fast flow.  I expect another shortwave to interact with this baroclinic zone overnight, and as it moves east the area of snow associated with it moving thru MI will propogate east into Northern ME with a couple of fresh inches of snow.  Elsewhere, passing clouds will be the rule overnight with lows similar to or perhaps just slightly above last night's.

Mild flow continues Wed and wtih rising heights and SW surface flow, warming is evident thru all levels.  Even with fresh snowpack, this warmth should boost temps into middle/upper 40's wtih good mixing and sunshine thru cirrus.  Xpct areas of fog and more widespread black ice where we drop below freezing Wed Ngt.  Continued mild flow Thu with a bit more in the way of clouds for most of NewEng as a couple of vorticity lobes race thru - the first to our north associated with the active northern stream will nudge a cold front southward from Canada and bring into to the Canadian border, while the second lobe of energy moves east well in advance of the Intermountain trof and moves thru Thu eve and night under modest warm and moist advection and associated isentropic lift.  Now comes the part where folks along the Canadian border, and especially those of you reading from Northern Maine, will want to pay especially close attention, though let's go through the scenario for all.

Remember how intense the baroclinic zone sitting over the Canadian border is, and will continue to be this week.  As the trof over the Rockies ejects east, dynamic forcing increases Thu Ngt into Fri along and near this baroclinic zone.  After the passage of the Thu Ngt vorticity lobe, the frontal boundary will be draped along the Canadian border and then across Central Maine.  Due to the very tight thermal zone, air should be cold enough along and immediately north of the boundary for snow, and lots of it given the isentropic lift that will result as warm advection lifts north ahead of the main upper level vorticity maximum.  The result will be a period of extended accumulating snow Thursday night thru Fri for Central and Northern ME, with very heavy snow likely to fall during the day Fri.  Great agreement on at least an inch of melted QPF in most of Northern ME - esp north of Dexter, ME, so a major snowstorm seems to be in the making for the Northern half of the state.

Elsewhere, let's review the facts of the Friday event:  Strong vorticity maximum produces rapidly deepening surface low pressure center as it interacts with tremendously strong baroclinicity and strengthens from 1002 mb at 12z Fri to 991 mb by 00Z Sat.  Well defined low-level wind shift to occur along cold front, extremely tight baroclinic zone to get wrapped into storm, strong lift ahead of front and strong subsidence behind it likely brings strong pressure fall/rise couplet, and winds are as follows: 500 mb 80-100 kts, 700 mb 60-80 kts, 850 mb 60-80 kts.  All of these factors add up for what should be a widespread synoptic damaging wind event, brief shot of heavy downpours for Central and Southern NewEng while the North Country sees aforementioned snow far north, and rain changing to snow elsewhere across Northern New Eng.  Southern NewEng will be vulnerable to elevated convection, as well, and while there are signals of a shallow surface inversion through parts of NewEng, some areas may erode inversion enough for damaging convection ahead of the synoptic wind event.

Behind this front cold air streams in Fri Ngt for what may be a flash freeze event, tho I'm not sold on this yet given the limited QPF that - at least right now - seems to be in the cards for Central and Southern NewEng.  In other words, I want to make sure the rainfall won't simply dry up in the fast and drying winds before enuf cold air streams in.  Arctic air builds in Fri Ngt and good agreement on cold being in place both Sat and Sun.  While Sat high temps will only be in the teens south and singles north, I think Sun probably is even colder!  Even tho the core of 850 cold is departing, there's no mechanism for surface warm advection and Sat night will be below zero almost all locales (perhaps singles Southern NewEng thanks to active downsloping wind...TBD) so you're not going to have much to build from on Sat.

Beyond this, I've been eyeing a potential major storm for Tue Feb 21 timeframe for quite some time now, but have had no opportunity to set it in writing in this discussion due to time crunches each day.  Even today I'm running thin on time for in-depth discussion, but the short version is:  with strong upper low that pushes thru this weekend ready to retreat back toward the north pole, new energy ejects from the polar vortex and is caught in fast northerly flow aloft over West-Central Canada Saturday into Sunday.  With a ridge in place over Mexico and extending into the SW US, and a broad Eastern Pacific trough, this will prohibit troffing over the Rockies and the result will instead be a relatively flat W to E flow over the Intermountain Region as this next strong vort max arrives.  With the strong and cold surface high moving off the ECoast during this period, this allows broadscale warm advection to return ahead of the incoming shortwave, allowing it to intensify as it moves E.  This has long appeared to have its sights set on the Northern Mid-Atlantic for a sizeable snow event in the Ensemble Guidance, but there are two reasons to watch it here:  1) The potential for the northern part of the snow shield, but more importantly, 2) A tremendous block building just E of Greenland.  This will mean the storm HAS to turn northward after moving off the coast - the key and the challenge will be determining how close to the coast it makes that turn.

I'm out of time for today - make it a great Valentine's Day.

Matt


Chill As Storm Departs, Brief Mild Spell To Move In

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  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. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is [email protected].  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  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 (New!):  Plenty of cold air has been left in the wake of Sunday's storm, and with an active west wind, our workweek certainly begins on a chilly note!  Abundant sunshine for the first half of the day will give way to increasing cloud cover Monday afternoon for one and all with a few flurries possible, but especially in the mountains of Northern and Western New England where snow showers will develop Monday afternoon and persist through Monday night with a couple of fresh inches of snow in the Northern Green Mountains and the higher terrain of the Whites.  Elsewhere, mostly cloudy skies Monday night will give way to breaking sunshine Tuesday, with active southwest breezes transporting milder air into New England.  By Wednesday, we'll be downright mild under mostly sunny skies.  By the end of the week, a strong disturbance approaching New England will produce a swath of rain or snow (most likely snow) across Northern New England later Thursday, then a chance of rain and thunderstorms with windy conditions for all on Friday.  The passage of a cold front Friday afternoon, however, will bring much colder air - another arctic blast - for next weekend.  -Matt

Weather Summary coming later this morning.

General Weather Summary:  With Southern New England's blizzard departing, a shot of modified arctic air has poured into New England.  While this dry and cold air has allowed for plenty of Monday Morning sunshine, a series of weak upper level disturbances racing east out of the Great Lakes will bring building clouds - first to the mountains and evenually to most of New England - by the end of the day.  Some of these clouds will grow large and heavy enough for snow showers to fall, especially in the mountains of Northern and Western New England, though flurries are a possibility for one and all.  With an active wind from the west, wind chill values will bring "feels like" temperatures about 8-10 degrees colder than the thermometer will actually be reading.

With a continued stream of weak upper level disturbances racing overhead Monday night, snow showers will continue in the higher terrain of the Green and White Mountains, with around an inch expected, though amounts of 3" will be found in the summits of the Northern Greens.  Elsewhere, expect plenty of clouds and perhaps a few flurries, with light surface winds gradually shifting to a southwest direction.

Southwest winds will increase in intensity on Tuesday - a sure sign that milder air is poised to move into New England.  Any lingering morning cloud cover should quickly give way to a cool blend of sun and clouds for most of the day Tuesday, with dry air moving in through most of the atmosphere and a few high altitude cirrus clouds moving overhead late in the day.

The remainder of the week will feature an important shift in the weather pattern that will be temporary, but will have a large effect on this week's weather.  The expected shift comes in the jet stream winds aloft - the fast river of air high in the sky that steers our storms and acts as a thermostat for the atmosphere, separating cold air to the north of the jet stream from warmer air to the south.  This corridor of fast wind flows in a wave-pattern across the globe, with ridges (bumps) and troughs (dips).  The Eastern U.S. has been in a trough of late, which means New England has fallen on the cold side of this thermostat - and we've felt the results!  Later this week, the jet stream winds that have been flowing south of us for the past couple of weeks will shift northward and eventually rise directly over New England.  This means New England shifts from squarely on the cold side of the jet stream, to the milder side of life, and we'll feel the results by Wednesday.  With very few strong disturbances for the jet stream to steer our way, the weather will be fairly tranquil for midweek.

Thursday, a stronger storm system will begin taking shape along the clash between cold and warm air, set up through the Central Rockies and Midwestern U.S.  Ahead of this storm, a reinforcing shot of warmth and moisture will stream northward, at the same time cold air oozes southward from Eastern Canada.  The result will be precipitation developing across Northern New England Thursday evening into Thursday night, and if enough cold air is place, accumulating snow would be possible and the North Country could make up for lost ground from this weekend's storm miss across the North.  By Friday, the approaching storm center will bring periods of rain for all of New England, along with gusty winds and one last mild day before a cold front sweeps through, ushering in arctic air for next weekend.

Have a great day!

Technical Discussion:  None today as I try to catch up from the hundreds of emails from Sunday.

Matt


Blizzard Underway...Live Coverage Through The Day on NECN...

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  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. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is [email protected].  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  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 (New!):  Dangerous blizzard continues through parts of New England.  For complete summary on this page, scroll down to yesterday's discussion.  I'm posting accumulation maps below, but otherwise all of my attention will of course be devoted to continuous live NECN coverage.  Please feel free to email observations to me personally at [email protected], or to our weather team at [email protected], and reference homepage www.mattnoyes.net for radar imagery.  See you on the TV, and see you back here with a complete update Monday.  -Matt

Accums_sne_5 Accums_nne_1 Accums_me_2


Quiet Saturday...Later-Arriving Blizzard Still En Route...Some Snow Amounts Will Fall Either Side of Two Feet

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  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. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is [email protected].  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  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 (New!):  More sunshine greeted most of New England Saturday morning than I initially expected, but you won't find me complaining!  Friday night's snow showers did drop a dusting of snow in many locations but the associated clouds evaporated very quickly after the disturbance passed through.  Saturday's sunshine will fade behind increasing clouds through the day in Southern New England as clouds move north ahead of our approaching blizzard.  Saturday night, snow moves north associated with a rapidly strengthening storm that moves southeast of Nantucket during the day on Sunday.  The result is snow developing from around 11 PM (at the south coast) onward from south to north Saturday night, then becoming heavy at times from the predawn hours of Sunday morning into Sunday afternoon.  Winds will gust frequently over 35 mph along the coastal plain of Eastern MA and the South Coast of New England, as well as the Worcester Hills, and combined with heavy snow, this will cause blizzard conditions with visibility near zero, especially after during the first half of Sunday an possibly lasting into Sunday afternoon.  Scattered power outages may result in these areas and travel will be treacherous.  Waves will build 15-20 feet offshore, and minor coastal flooding is possible at the time of high tide just before midday Sunday.  Snow lingers into Sunday afternoon with windy and cold conditons - highs only in the upper teens, and windchill values in the single digits.  Monday looks breezy and cool with a quick moving disturbance racing eastward, bringing a period of mostly light snow Monday night into Tuesday morning.  Warmer air moves in for midweek before the winter pattern resumes toward the end of next week.  -Matt

The following accumulation Maps are from yesterday, and still look valid, though if I were making them today, I'd feel comfortable putting a few areas of 1-2 feet on there.  As explained in the full summary below, I wouldn't be surprised to find some two foot amounts coming back from Northern RI to SE MA, and some amounts either side of 18" farther north thru parts of Eastern MA and through CT.  Blizzard Condition Details are in the final map:

Accums_sne_4 Accums_nne Accums_me_1 Matt_threats

General Weather Summary:  The pattern you and I have been watching together in these discussions the past few weeks is finally cranking out the first of what will likely be several winter storms over the next four weeks.  A month of record national warmth in January - some 8.5 degrees above normal (see end of this Summary for details) - has left an abundance of available energy in the atmosphere across the nation.  As cold air piles southward out of Canada creating a clash in airmasses across the country, the natural way for the atmosphere to find equilibrium is to disperse this energy in the form of storms.  We've seen these storms all winter long - though many with rain, and other with snow that melted quickly, each storm has been quite vigorous and has brought plenty of wind.  This time, enough cold air is in place that we'll wring out snow across New England.

Friday night's snow showers left a dusting of snow in some areas, but the clouds associated with the disturbance that produced them have evaporated quickly leaving most of New England with a sunny start to our Saturday.  By and large the first half of our weekend will begin fairly quiet, though a shield of clouds across parts of Southern New England will continue to move north.  With a developing east wind due to clockwise airflow around a center of cold high pressure over Maine Saturday morning, a few ocean effect snow showers are possible by evening in Eastern Massachusetts, though these would not amount to anything appreciable aside from a few snowflakes.  Meanwhile, to our south, an area of low pressure will be strengthening along the mid-Atlantic coastline as a moist Gulf Coast storm and strong northern stream energy center combine their most volatile characteristics to create a moisture-loaded, energetic, and therefore rapidly strengthening storm along the East Coast.

Aloft, the jet stream pattern - the fast corridor of wind aloft that steers our storms and acts as a thermostat for the atmosphere, separating cold air to the north from warm to the south - will be orienting from south to north up the Eastern Seaboard.  These fast jet stream winds will pick up the developing storm and carry it north-northeast, eventually taking the storm just southeast of Nantucket Island, MA, during the day on Sunday.

Well in advance of the approaching storm, warmth and moisture will be thrust northward, colliding with our arctic airmass in place across New England and resulting in snow.  The timing of the approaching snow has been delayed slightly from my thinking yesterday, as the components coming together have taken just a bit longer to come together.  Still, this snow will develop either side of 11 PM  across Southern Connecticut, Rhode Island and Cape Cod.  Soon after, expect the snow to march northward across the remainder of Southern New England and eventually becoming steadier and noteably heavier around dawn Sunday.  Sunday morning into early afternoon, snow will fall heavily at times as the center of low pressure moves northeast toward New England.  This strengthening area of low pressure - like so many others this year - will create plenty of wind, and this wind will combine with the heavy snowfall rates of 2"-4" per hour at times to create blinding conditions amidst frequent wind gusts over 35 mph, especially through Sunday morning, and especially likely from the Connecticut coastal plain, all the way through the coastal plain of Massachusetts (which includes most areas within 25 miles of the coastline), along with the hilly terrain of Northern Connecticut and Central Massachusets.  The New Hampshire and Southern Maine coastlines also may reach blizzard conditions for a brief time, though perhaps not quite long enough to qualify officially.  The combination of visibility below .25 miles and frequent gusts above 35 mph meets the criteria for a blizzard, and for this reason the National Weather Service has posted a Blizzard Watch for the South Coast of Connecticut, the hills of Connecticut and the coastal plain of Massachusetts for Saturday night through most of Sunday.

For the areas that fall into blizzard conditions, the typical threats associated with a blizzard apply, though it certainly is a help to one and all that this storm will be charging through on a weekend, when a relatively small number of people have critical need to be out and about.  Nonetheless, some of you will have to reach your destinations and it's important to understand that travel will be treacherous and life-threatening Sunday predawn into early Sunday afternoon.  If you absolutely must travel in the blizzard areas, be sure to have a winter survival kit in your vehicle, containing a shovel, warm clothes, a blanket, water and small food items should you become stranded.  Power outages are likely to occur for at least some communities.  Total snowfall amounts are posted above, and though they are the same maps I created yesterday, it appears at this point as though they remain valid.  The most questionable area of accumulations in the forecast will be on the northwest fringe of the precipitation shield, where uncertainty exists over how far northwest the heavy snow progresses.  While I do expect less precipitation to fall in places like South-Central NH through Southern VT, I also expect it to be a fluffy snow with nearly 20 to 1 ratio which will boost the amount of measurable snow that falls.  In Southern New England, I'm fully expecting to find localized amounts totaling two feet from interior Southeastern MA to Northern RI and then running southeast across Cape Cod.  This will be dependent upon where the heaviest bands of precipitation setup, but the clash between the cold and arctic airmass and the modified ocean air streaming in off of the Atlantic will setup a coastal front that will help to focus localized bands of snow on the cool side of this boundary.  I also wouldn't be surprised to find localized higher amounts farther north through Eastern MA along this coastal front from the Metro West area of the 95 corridor west of Boston, though Central Essex County, MA, where slightly less moisture will fall but this enhancement may still produce widespread amounts either side of 16" with some communities around 20" of snow.  Amounts like this are also likely to be found in the higher terrain of Connecticut, where ample moisture will meet with cold arctic air for plenty of fluffy snow.  There is certainly a marine threat with this storm, as well, and given the likelihood of storm force gusts and seas of 15-20 feet, mariners should plan on staying in port from Saturday evening through Sunday.  As for coastal flooding, the delay in the storm's timing means an onshore flow is now likely to still persist Sunday morning to midday - for the 11 AM high tide - and the threat of coastal flooding is now present for all east and northeast facing shorelines two hours either side of this tide.  Preparations should be made for minor to perhaps moderate coastal flooding in these areas, and along Western Long Island Sound at high tide late Saturday night.

The next upper level disturbance swings through Monday night, bringing nighttime light snow to much of New England after a partly sunny and breezy day.  Lingering early morning light snow on Tuesday should give way to clearing skies and breezy conditions. 

Obviously there's plenty to keep an eye on over the next several days, but for those of you who enjoy looking farther into the future, there are some signs coming back on how the rest of February may play out.  Though I think we've shifted into what will - on average - be a wintry pattern through the end of the month, some atmospheric reshuffling appears to be in the cards around and just after Valentine's Day.  As mentioned above, while we're currently in the heart of cold Canadian air, and this cold air extends west into the Northern Plains, heat is building under a strengthening high pressure center in the Western United States.  Strong signs are for this high pressure center to grow very large and very warm over the next several days, and though we deal with a storm threat Saturday night into Sunday, this will mean that our replenishing supply of cold air will be temporarily cut off, since we've been feeding our cold in from Alaska.  While this is likely to result in 3-4 days of somewhat warmer weather - at or somewhat above normal temperatures for this time of the year - next week, I don't think it's the end of winter, or of the new wintry pattern by any stretch.  I continue to foresee a pattern shift allowing cold air to return once this Western high pressure ridge has reached its peak next week, and with an active subtropical jet stream nearby, multiple opportunities for cold and moist systems will exist in the new pattern.  It's obviously not a comfortable feeling to make a prediction of a return to cold and multiple chances for snow, then see even a brief return of warmth, but indications of this being only a brief stint with milder air are fairly strong, so I remain confident that winter turns back on at the end of the month.

Updates will follow through the weekend.

Details on January Warmth:  The nation checked in with an average temperature of 39.5 degrees for the month of January - the warmest January ever recorded with regard to national average.  The previous record was 37.3 degrees set in 1953.  Over 75% of the nation was "much above normal", which has only happened twice in history - once in March of 1910, and the other time in November of 1999.  This remarkable warmth marks an abundance of energy available in the atmosphere as we enter a new, colder, stormier pattern.

Matt

Matt's Technical Meteorological Discussion:  Updated Saturday, February 11 at 10:10 AM

I suppose it's odd to be coming up on such a major storm and not have much to say from a technical perspective, but I think things are playing out close to what you and I have been expecting for the past several days, and most of my time can probably be better spent catering to the public need for information right now.  That being said, I'll add a few thoughts here, and then touch up yesterday's very late post of the technical discussion in case you didn't catch it since it took me until 4:45 to get it out:

Models continue to waver with regard to the northwest extent of the QPF field, but the regional Canadian (RGEM) looks like one of the most reasonable solutions given the thoughts about storm track you and I examined in this discussion yesterday (again, see below if you missed it).  Max QPF is likely to come up to 1.25"-1.50" over SE MA and while I expect a 10:1 ratio on Cape Cod, likely to be closer to an 18:1 ratio at Providence.  There will be a coastal front in between, and where the higher QPF bisects this coastal front, expect precipitation enhancement to produce locally higher precip amounts.  On the cold side of the front in the higher ratios, it becomes easy to envision amounts either side of two feet in favored areas.  Coastal front should expand northward, extending through the Metro West area along the 95 corridor west of Boston, then thru Central Essex County, MA and then curl NNE just inland from the NH Seacoast.  There areas, too, will see enhanced QPF greater than progged by guidance, and with around .90" QPF here, and a ratio of about 18:1 here, as well, widespread amounts either side of 16" of snow with localized amounts of up to 20" or even a bit higher along the coastal front will be possible in Essex County...then decreasing a bit into SE NH but still some localized 18" amounts likely to show up.

Blizzard conditions seem attainable in the following locations:  Coastal plain of Southern CT, Hills of Central and Northern CT, Hills of Central MA, Coastal Plain of MA, and probably just barely qualifying on the Coastal Plain of Rockingham County, NH, also.

Ageostrophic flow into the center of the strengthening low will allow winds to turn from NE to NNE Sunday late morning, and though this may help to mitigate the coastal flood threat, obviously the delay in storm passage means an increased risk for coastal flooding at east and northeast facing shorelines on Sunday 11 AM high tide...and for tonight in Western Long Island Sound locations.

Everything else seems to be progressing as you and I have expected through these discussions over the past several days...I'll leave the final determining factor on storm track that I posted later yesterday below if you missed it - it was this investigating that truly eased my concerns amidst fluctuating models.  All in all...no reason not to stay the course and enjoy the show.

Excerpts from yesterday's technical discussion:

***********************************

There's no question the synoptics are featuring a slowing trend among the guidance.  A large part of this is due to the strongly confluent flow at 700 and 500 mb just east of NewEng, and while confluent flow is necessary to lock in cold air, this strong and this close has been a concern all week long with this storm that it's not going to allow the moisture to spread northward.  Admittedly, this is still a bit of a concern for me, but there comes a point when we have to examine the storm and decide which features will dominate its evolution.  As mentioned yesterday, the baroclinicity and low level dynamics are impressive enough that surface cyclogenesis should overpower the progressive tendency of this flow, though if someone told me to find where the forecast might bust, certainly this close confluent flow would be the way to do it.  Nonetheless, there is a decided midlevel wind shift that moves northward to the South Coast of NewEng by 00Z as the northern stream 850 mb trough pulls out, and the snow shield should follow this directional convergence zone.

Theta-e progs at all levels show a direct tap from the Gulf of Mexico up a warm SW wind conveyor belt feeding off the Eastern Seaboard.  This is a huge reason to support the idea of dynamics and baroclinicity taking center stage, not to mention the cold core aloft that's rotating east with the upper low across the OH Valley, the relatively warm ocean temperatures sitting offshore, and an airmass that is DRY extending all the way down the Eastern Seaboard.  Amazing that...even as the storm moves east across the Gulf Coast...dewpoints are still in the teens and 20's all the way down the Eastern Seaboard.  Lots of 50's/20's in the Carolinas - yikes!  This should stand out to many meteorologically inclined folks as further evidence of how well entrenched the land airmass truly is - and remember that those temperatures are going to plummet on the cold northwest side of the storm as the column saturates.

So how does this play into the evolution of our storm?  First and foremost, it guarantees we'll be setting up a land/ocean contrast once the storm winds up along the Carolina coastline.  Second, this should serve to increase the baroclinicity present along the coastline.  Now, with the models beginning to sway from run to run after great agreement in the 00Z cycle last night, meteorologists are having heart attacks throughout NewEng.  Of course, those of you who read often know how much I hate a flip-flopping forecast, so what we need to do in order to avoid such a forecast is find something worth hanging our hat on.  We've already agreed together in this discussion that baroclinicity is going to be a key player, so let's think in terms of airmasses.  My absolute favorite airmass indicator is theta-e, or equivalent potential temperature.  A fancy term, but basically a measure of both warmth and moisture in an airmass.  Theta-e values are quite high across the Gulf Coast, and moderately high SE of Florida - indicating lots of warmth and moisture.  Normally this would be a "no kidding, Noyes" comment...of course there's warmth and moisture there.  But the important key is that it is MUCH warmer and MUCH more moist air than the exceptionally dry and soon to be cool air all up and down the Eastern Seaboard.  Additionally, buoy 44001 east of the Carolinas is reporting a water temperature of 66.2 F this afternoon with an air temp of 52 F, and 44004 which is 200 mi E of Cape May, NJ, has a water temp of 57.7 and an air temp of 42.1.  The thing to focus on here is not the air temp, but water temps.  Warmth surging north out of the Gulf and Bahamas is going to thrive over 66 degree water temps, and should be able to boost air temps well into the 60's even over the 57.7 degree water.  Remember, this isn't model data we're looking at, this is real data - far more important in this situation.  But now we can incorporate model data, and a model such as the WRF is doing a fantastic job, in my estimation, of carrying this high Theta-E air up over the Western Atlantic ahead of the storm track for no only tons of available warmth and moisture, but also a tremendous increase in baroclinicity between the Eastern Seaboard dry and soon to be evaporatively cooled air, and the downright tropical airmass that will be advecting northward off the coastline.  So the key as we come into New England territory is to nail down this gradient of airmasses - the battle zone that will serve as the storm path.  Then don't forget to add the retreating but very evident arctic boundary into the equation.  This arctic boundary is likely going to play a more important role regarding coastal front development and heavy snow banding during the storm as it retreats across the interior, but I think the important point to make with regard to storm track here is that the natural baroclinic zone is farther north than even the GFS would indicate from its forecasted surface low track, meaning I think even the 12Z GFS is probably too far south.  Again, the confluent flow aloft so close to us can make us nervous, but if we're going to agree that the extreme baroclinicity is going to be the dominant force here, than we need to follow through on that theory by finding real data, not model data, to hang our hat on.  I think we've done that above.

I will spare you from the rest of the details on this storm regarding things like timing, duration and intensity, for the most part, because these are factors that I think...once we get through the hard part of not worrying so much about forecast track, like we've done above...become rather self-evident as we examine the guidance products.  I will say that I see enough warm advection and cyclonic vorticity advection both in the lower and midlevels for 2"-4" per hour snows in eastern Southern NewEng during the heart of the storm, and that the most intense period certainly appears to be centered on early Sun AM.

******************************

Have a great Saturday.

Matt


Time To Prepare..."Saturday Late-Night Special" to Bring Blizzard Conditions for Some Into Sunday

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  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. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is [email protected].  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  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 (New!):  A blizzard is en route to parts of Southern New England for Saturday night into Sunday morning, but quiet weather prevails for our Friday.  Sunshine gives way to increasing clouds late in the day, and arctic air in association with a bubble of Canadian high pressure just north of the border holds temperatures in the teens north and twenties south, with a breeze adding a bit of an extra chill to the air.  Thickening clouds Friday night lead to a period of light snow that may drop a fresh dusting of snow, especially in Southern New England, associated with an upper level disturbance moving overhead and not associated with the major weekend storm.  Most of Saturday will be quiet - while bands of light snow may come streaming in from the ocean to Eastern MA throughout the day, these should not affect plans through the daylight hours.  Saturday night, snow moves north associated with a rapidly strengthening storm that moves southeast of Nantucket early Sunday morning.  The result is snow developing from sundown (at the south coast) onward and from south to north Saturday evening, then becoming heavy at times Saturday night into Sunday morning, especially after midnight.  Winds will gust frequently over 35 mph along the coastal plain of Eastern MA and the South Coast of New England, as well as the Worcester Hills, and combined with heavy snow, this will cause blizzard conditions with visibility near zero, especially after 11 PM Saturday night, lasting into Sunday morning.  Scattered power outages may result in these areas and travel will be treacherous.  Waves will build 15-20 feet offshore, but limited if any coastal flooding is expected.  They key to this forecast will hinge upon how far north and west the heavy snow penetrates into New England - a track farther south will result in a change to the accumulation forecasts on the north side of the precipitation.  Snow winds down late Sunday morning, then windy and cold with partial clearing late.  Monday looks breezy and cool with a quick moving disturbance racing eastward, bringing a period of snow Monday night into Tuesday morning.  Warmer air moves in for midweek before the winter pattern resumes toward the end of next week.  -Matt

Accumulation Maps and Blizzard Condition Details:

Accums_sne_4 Accums_nne Accums_me_1 Matt_threats

General Weather Summary:  The pattern you and I have been watching together in these discussions the past few weeks is finally cranking out the first of what will likely be several winter storms over the next four weeks.  A month of record national warmth in January - some 8.5 degrees above normal (see end of this Summary for details) - has left an abundance of available energy in the atmosphere across the nation.  As cold air piles southward out of Canada creating a clash in airmasses across the country, the natural way for the atmosphere to find equilibrium is to disperse this energy in the form of storms.  We've seen these storms all winter long - though many with rain, and other with snow that melted quickly, each storm has been quite vigorous and has brought plenty of wind.  This time, enough cold air is in place that we'll wring out snow across New England.

But a complete weather discussion takes this one step at a time, starting with our Friday.  Sunshine abound Friday morning will continue to give way to increasing clouds moving in from the west.  Arctic air is in place throughout New England, and northwest winds pushing against the Northern Green Mountains have allowed some light snow to continue in these locales.  Elsewhere, winds will swing around from the west-northwest, and breezes will add an extra chill to already cold temperatures expected to top off in the teens north and 20's south.  Increasing clouds through the day come in advance of an upper level energy center, racing east out of the Great Lakes and having nothing to do with the upcoming weekend spectacle.  With this disturbance, light snow will fall in parts of Southern New England overnight Friday night, just north of an arctic cold front that settled south of New England Thursday night, and will serve as the boundary for a clash in airmasses as slightly warmer and more moist air attempts to rebound from the south, ahead of the incoming disturbance.  Only a dusting of snow is expected in most areas overnight Friday night.

While some of this light snow may linger into Saturday morning, by and large the first half of our weekend will begin fairly quiet.  Mostly cloudy skies will prevail through the day, and with a developing east wind due to clockwise airflow around a center of cold high pressure over Maine Saturday morning, ocean effect snow showers are possible in Eastern Massachusetts later Saturday afternoon.  These should be fairly light in nature, and will not affect preparations that are being made for our incoming storm.  Meanwhile, to our south, an area of low pressure will be strengthening along the mid-Atlantic coastline.  The players in storm development are a strong energy center dropping across the Northern Plains Friday Morning, and a moist storm moving east across Texas.  After bringing heavy rains to the Lower Mississippi River Valley and the Gulf Coast, these two storms will merge and combine their most volatile characteristics to create a moisture-loaded, energetic, and therefore rapidly strengthening storm along the East Coast.

Aloft, the jet stream pattern - the fast corridor of wind aloft that steers our storms and acts as a thermostat for the atmosphere, separating cold air to the north from warm to the south - will be orienting from south to north up the Eastern Seaboard.  These fast jet stream winds will pick up the developing storm and carry it north-northeast, eventually taking the storm over Nantucket Island, MA, early Sunday Morning.

Well in advance of the approaching storm, warmth and moisture will be thrust northward, colliding with our arctic airmass in place across New England and resulting in snow.  This snow will develop from late afternoon through sunset across Southern Connecticut, Rhode Island and Cape Cod.  After sunset, expect the snow to march northward across the remainder of Southern New England, though it may take until after midnight to reach the New Hampshire border.  Saturday night through Sunday morning, snow will fall heavily at times as the center of low pressure moves northeast toward New England.  This strengthening area of low pressure - like so many others this year - will create plenty of wind, and this wind will combine with the heavy snowfall rates of 2"-4" per hour at times to create blinding conditions amidst frequent wind gusts over 35 mph, especially after midnight Saturday night, especially likely from Connecticut east through Southeastern MA.  This combination of visibility below .25 miles and frequent gusts above 35 mph meets the criteria for a blizzard, and for this reason the National Weather Service has posted a Blizzard Watch for the South Coast of Connecticut for Saturday night into Sunday morning.  Farther north and west, through the coastal plain of Massachusetts, Southeast NH, and the higher terrain of the Worcester Hills, this potential is highly dependent upon whether the heavy snow band can rotate far enough north and west late Saturday night and Sunday morning.

For the areas that fall into blizzard conditions, the typical threats associated with a blizzard apply, though it certainly is a help to one and all that this storm will be charging through on a weekend, when a relatively small number of people have critical need to be out and about.  Nonetheless, travel will be treacherous through Saturday Night and into Sunday morning.  If you absolutely must travel in the blizzard areas, be sure to have a winter survival kit in your vehicle, containing a shovel, warm clothes, a blanket, water and small food items should you become stranded.  Power outages are likely to occur for at least some communities.  Total snowfall amounts will be posted in the accumulation maps with this discussion shortly, but expect over a foot for parts of Southern New England, and I wouldn't be surprised to find localized higher amounts, especially considering that there is also likely to be a coastal front that develops - the collision between modified ocean air, and arctic air through the interior.  Where this coastal front sets up - sometimes just miles inland from the coast - localized enhancement of snow will occur and some amounts may be exceptionally higher.  There is certainly a marine threat with this storm, as well, and given the likelihood of storm force gusts and seas of 15-20 feet, mariners should plan on staying in port from Saturday afternoon through Sunday.  As for coastal flooding, there is the potential for minor coastal flooding in Western Long Island Sound at high tide late Saturday night, otherwise the combination of an astronomically lower tide and a wind that won't kick until right around the time of high tide should limit the threat elsewhere.  If winds still are out of the northeast Sunday morning, some splashover and minor coastal flooding will be possible in Eastern Massachusetts and Southeast NH.

Snow most likely snow lingers in the morning regardless of which storm scenario plays out, and as the storm draws east of New England and intensifies, winds will be gusty and cold air will spill into New England.  The next upper level disturbance swings through on Monday, bringing a chance of snow showers later in the afternoon. 

Obviously there's plenty to keep an eye on over the next several days, but for those of you who enjoy looking farther into the future, there are some signs coming back on how the rest of February may play out.  Though I think we've shifted into what will - on average - be a wintry pattern through the end of the month, some atmospheric reshuffling appears to be in the cards around and just after Valentine's Day.  As mentioned above, while we're currently in the heart of cold Canadian air, and this cold air extends west into the Northern Plains, heat is building under a strengthening high pressure center in the Western United States.  Strong signs are for this high pressure center to grow very large and very warm over the next several days, and though we deal with a storm threat Saturday night into Sunday, this will mean that our replenishing supply of cold air will be temporarily cut off, since we've been feeding our cold in from Alaska.  While this is likely to result in 3-4 days of somewhat warmer weather - at or somewhat above normal temperatures for this time of the year - next week, I don't think it's the end of winter, or of the new wintry pattern by any stretch.  I continue to foresee a pattern shift allowing cold air to return once this Western high pressure ridge has reached its peak next week, and with an active subtropical jet stream nearby, multiple opportunities for cold and moist systems will exist in the new pattern.  It's obviously not a comfortable feeling to make a prediction of a return to cold and multiple chances for snow, then see even a brief return of warmth, but indications of this being only a brief stint with milder air are fairly strong, so I remain confident that winter turns back on at the end of the month.

Updates will follow through the weekend.

Details on January Warmth:  The nation checked in with an average temperature of 39.5 degrees for the month of January - the warmest January ever recorded with regard to national average.  The previous record was 37.3 degrees set in 1953.  Over 75% of the nation was "much above normal", which has only happened twice in history - once in March of 1910, and the other time in November of 1999.  This remarkable warmth marks an abundance of energy available in the atmosphere as we enter a new, colder, stormier pattern.

Matt

Matt's Technical Meteorological Discussion:  Updated Friday, February 10 at 4:45 PM

Most of the details on the overall evolution of the system have been laid out here over the past couple of days, and especially touched upon yesterday, but let's polish up the technical side of things as best we can.

Cloud field that expanded over NewEng today is evidence of warm advection setting back in aloft, and the clash between this weak warm advection and the arctic frontal boundary that settled south of NewEng and is now returning back northward, coupled with vorticity maximums being pulled into confluent flow east of NewEng, will be the impetus for tonight's periods of light snow in most of Southern NewEng.  Limited amounts from this - a dusting is all that should be received in most spots - but as the 850 mb trof swings thru overnight Fri Ngt, confluent flow shifts a bit farther north and east, and 850 mb winds slacken quickly early Sat.

Low level RH that saturates overnight tonight in Central/Southern NewEng really doesn't go anywhere tomorrow and low gray clouds are likely to linger in these areas thru the day, even tho air above this level is fairly dry thru the day.  Additionally an onshore flow develops as center of surface high pressure moves over Gulf of Maine, and this onshore flow of cold air is able to work a bit deeper up into the atmosphere as the 850 mb winds die down, and this should generate ocean effect snow bands in Eastern MA and esp on Cape Cod.  If an onshore flow was more quickly establishing aloft, I'd say this could produce some significant bands well in advance of the storm, but given that we need to go from an offshore to onshore flow aloft thru the day on Sat, it's probably going to be more disorganized spray of snow showers that comes off the Atlantic.  WRF doing a nice job of picking up on this activity (has been for the past several runs) and the NAM continues to obtain a better grasp on this with each run.

But while the mesoscale effects will produce some snow showers in these Eastern areas, there's no question the synoptics are featuring a slowing trend among the guidance.  A large part of this is due to the strongly confluent flow at 700 and 500 mb just east of NewEng, and while confluent flow is necessary to lock in cold air, this strong and this close has been a concern all week long with this storm that it's not going to allow the moisture to spread northward.  Admittedly, this is still a bit of a concern for me, but there comes a point when we have to examine the storm and decide which features will dominate its evolution.  As mentioned yesterday, the baroclinicity and low level dynamics are impressive enough that surface cyclogenesis should overpower the progressive tendency of this flow, though if someone told me to find where the forecast might bust, certainly this close confluent flow would be the way to do it.  Nonetheless, there is a decided midlevel wind shift that moves northward to the South Coast of NewEng by 00Z as the northern stream 850 mb trough pulls out, and the snow shield should follow this directional convergence zone.

Theta-e progs at all levels show a direct tap from the Gulf of Mexico up a warm SW wind conveyor belt feeding off the Eastern Seaboard.  This is a huge reason to support the idea of dynamics and baroclinicity taking center stage, not to mention the cold core aloft that's rotating east with the upper low across the OH Valley, the relatively warm ocean temperatures sitting offshore, and an airmass that is DRY extending all the way down the Eastern Seaboard.  Amazing that...even as the storm moves east across the Gulf Coast...dewpoints are still in the teens and 20's all the way down the Eastern Seaboard.  Lots of 50's/20's in the Carolinas - yikes!  This should stand out to many meteorologically inclined folks as further evidence of how well entrenched the land airmass truly is - and remember that those temperatures are going to plummet on the cold northwest side of the storm as the column saturates.

So how does this play into the evolution of our storm?  First and foremost, it guarantees we'll be setting up a land/ocean contrast once the storm winds up along the Carolina coastline.  Second, this should serve to increase the baroclinicity present along the coastline.  Now, with the models beginning to sway from run to run after great agreement in the 00Z cycle last night, meteorologists are having heart attacks throughout NewEng.  Of course, those of you who read often know how much I hate a flip-flopping forecast, so what we need to do in order to avoid such a forecast is find something worth hanging our hat on.  We've already agreed together in this discussion that baroclinicity is going to be a key player, so let's think in terms of airmasses.  My absolute favorite airmass indicator is theta-e, or equivalent potential temperature.  A fancy term, but basically a measure of both warmth and moisture in an airmass.  Theta-e values are quite high across the Gulf Coast, and moderately high SE of Florida - indicating lots of warmth and moisture.  Normally this would be a "no kidding, Noyes" comment...of course there's warmth and moisture there.  But the important key is that it is MUCH warmer and MUCH more moist air than the exceptionally dry and soon to be cool air all up and down the Eastern Seaboard.  Additionally, buoy 44001 east of the Carolinas is reporting a water temperature of 66.2 F this afternoon with an air temp of 52 F, and 44004 which is 200 mi E of Cape May, NJ, has a water temp of 57.7 and an air temp of 42.1.  The thing to focus on here is not the air temp, but water temps.  Warmth surging north out of the Gulf and Bahamas is going to thrive over 66 degree water temps, and should be able to boost air temps well into the 60's even over the 57.7 degree water.  Remember, this isn't model data we're looking at, this is real data - far more important in this situation.  But now we can incorporate model data, and a model such as the WRF is doing a fantastic job, in my estimation, of carrying this high Theta-E air up over the Western Atlantic ahead of the storm track for no only tons of available warmth and moisture, but also a tremendous increase in baroclinicity between the Eastern Seaboard dry and soon to be evaporatively cooled air, and the downright tropical airmass that will be advecting northward off the coastline.  So the key as we come into New England territory is to nail down this gradient of airmasses - the battle zone that will serve as the storm path.  Then don't forget to add the retreating but very evident arctic boundary into the equation.  This arctic boundary is likely going to play a more important role regarding coastal front development and heavy snow banding during the storm as it retreats across the interior, but I think the important point to make with regard to storm track here is that the natural baroclinic zone is farther north than even the GFS would indicate from its forecasted surface low track, meaning I think even the 12Z GFS is probably too far south.  Again, the confluent flow aloft so close to us can make us nervous, but if we're going to agree that the extreme baroclinicity is going to be the dominant force here, than we need to follow through on that theory by finding real data, not model data, to hang our hat on.  I think we've done that above.

So, the bottom line on this is that the forecast laid out in the Weather Summary and maps above stands for now.  I can't say I was surprised, though I will admit I was relieved, to see the 18Z NAM come back northwest, and I expect that trend to continue at 00Z.  Blizzard conditions still appear likely not only for the areas already in a blizzard watch in Srn CT, but also in at least part if not most of the coastal plain of Eastern MA.

I will spare you from the rest of the details on this storm regarding things like timing, duration and intensity, for the most part, because these are factors that I think...once we get through the hard part of not worrying so much about forecast track, like we've done above...become rather self-evident as we examine the guidance products.  I will say that I see enough warm advection and cyclonic vorticity advection both in the lower and midlevels for 2"-4" per hour snows in eastern Southern NewEng during the heart of the storm, and that the most intense period certainly appears to be centered on early Sun AM.

If you're interested in the extended period beyond this storm, I'd invite you to check out yesterday's post below, or the archives at left.

That's all for today.  Now we wait and see what transpires in the guidance - awaiting the northwest shift I'm anticipating - and we'll see where we are tomorrow.

Matt


Northern and Western Squalls Today...Heavy Weekend Snow Looking Increasingly Likely

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  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. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is [email protected].  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  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 (New!):  Morning clouds and Cape Ann, Cape Cod/Island flurries will continue to gradually give way to breaks of sunshine with a light wind across New England for our Thursday.   Late Thursday afternoon and Thursday evening, an arctic cold front will push south out of Canada, delivering a shot of snow squalls to the mountains of Northern and Western New England Thursday evening, and migrating across most of the remainder of Northern New England - from most of Vermont to the White Mountains to points north of Augusta - Thursday Night with a quick 1"-2" with higher amounts in the mountainous terrain.  A series of energetic disturbances zipping through the Northeast on Friday will keep mostly cloudy skies and a few flurries in the forecast, with a chance of steady light snow dropping an inch or two in some areas Friday Night.  Saturday starts cloudy but quiet in most areas, though a storm center taking shape along the Gulf of Mexico coastline will turn north up the Eastern Seaboard and spread light snow into New England late in the day.  By Saturday night, this storm will charge northeast, delivering a blow of snow, heavy at times to most of New England Saturday sunset to Sunday morning with over a foot a distinct possibility for parts of interior New England depending on how things play out, lesser amounts at the immediate coast (perhaps) and a rain/snow mix with lesser accumulations on Cape Cod.  Windy and cold after the departing snow on Sunday. -Matt

General Weather Summary: 

Late Afternoon Update:  I've seen enough for this upcoming Saturday storm to warrant 6" amounts all the way from Central VT/NH/ME southward, pending a dramatic shift to a more progressive solution, which is still possible but looking less likely.  Timing will be light snow developing Saturday evening and becoming heavier Saturday evening after sunset.  Snow falls heavily Saturday night into early Sunday morning as storm center moves over Nantucket and Chatham - this means if all comes together as it's currently looking (and do remember from 48 hours out, things can change) a foot or more of snow possible through the interior of Southern New England, 10" or so closer to the coast with less possible at extreme coastlines where onshore flow may warm temps a bit, rain/snow mix at the Cape limiting amounts, and only a gradual drop off north into Northern NewEng.  More on this tomorrow.  -Matt

Previous:  The current weather pattern across the nation is one that features plenty of energy, but very little moisture.  This type of a pattern can yield major storms when moisture is introduced, and there are some indications this may be the case by this upcoming weekend, though this is certainly not set in stone.  There is plenty more to share than can be expressed in a two minute television broadcast, and you and I will examine some of these additional factors for consideration in this discussion today.

First of all, the overall jet stream flow - the pattern of the fast river of air aloft that steers our storm systems and acts as a thermostat for the atmosphere, separating cold air to the north from warm air to the south - will be changing over the next few days.  The first change is already underway, across the Western U.S. where the jet stream is rising northward rapidly, allowing a strong and mild area of high pressure to build along the West Coast and Eastern Pacific.  In the atmosphere, a major change to the weather pattern in one part of the globe often leads to major changes in the other, and the result of a rapidly building ridge in the Western U.S. is often a strengthening trough - favorable for stormy weather - in the east.

Certainly we've already seen the results of this trough to a large extent, with cold air maintaining its hold on New England through the week, and another cold day expected on Thursday with morning clouds and flurries over Cape Cod, the Islands and outer Cape Ann, gradually giving way to increasing breaks of sunshine and light winds.  Aloft, and approaching from the northwest, a strong upper level disturbance is heading directly for New England, and is dragging yet more cold air southward out of Canada.  The leading edge to this reinforcing shot of cold air is evident at the surface as an arctic cold front, which will carry snow showers and heavier squalls into the mountains and hills of Northern and Western New England late Thursday afternoon, and especially Thursday evening and night.  Some of these squalls will pack enough of a punch to reduce visibility dramatically, slicken roadways, and will drop a general 1"-2" across most of Vermont, the White Mountains of NH, and most of Maine north of Augusta.  Locally higher amounts will be found in the higher terrain.  For the remainder of New England, northwest winds sloping down the mountains and hills should help to dry the air enough to squash most of these squalls as they move southward, leaving only some Thursday night flurries for most of Central and Southern New England.

By Friday, another energetic disturbance in the upper levels of the atmosphere will move toward New England, this time coming from the nation's midsection, and ushering slightly warmer air into our six-state region.  The clash of airmasses between Thursday night's reinforcing cold air, and this new approaching warm air aloft, will create lots of clouds for most communities on Friday.  With very little moisture near the ground, however, it's unlikely that anything more than flurries will fall from these clouds.  By Friday night, this clash between airmasses aloft becomes a bit stronger, and the approaching disturbance moves overhead.  This combination is likely to lead to widespread light snow Friday night through most of New England, tapering off by Saturday morning.

While Saturday dawns cloudy and relatively quiet here in New England, the atmosphere several thousand feet above the earth's surface will be very busy through the end of the week and into the weekend, and this will manifest itself in storm development for the upcoming weekend.  After a series of strong energetic disturbances drop south along the east side of the ridge of high pressure over the Western United States, they will merge and aid in developing a new storm at ground level, along the Northern Gulf of Mexico coastline.  The proximity of this storm to such a significant source of warmth and moisture will feed storm intensification, and as the area of low pressure draws northeast over the Eastern Seaboard later Saturday, light snow will develop across New Enlgand.  As the storm center moves northeast and along the Eastern Seaboard, snow will intensify Saturday night.  The real questions on how this will evolve take over at this stage in the game.  Aloft, at the jet stream level, the pattern is very progressive, and will be eager to pull this storm quickly off to the east, giving Southern New England a glancing blow of accumulating and perhaps plowable snow but not a blockbuster storm.  The fly in the ointment revolves around the shear amount of moisture feeding in from the Gulf, the warm ocean temperatures off the east coast, and the cold air that will be in place through New England.  The combination of all these factors will allow this storm to develop handily, and if it should develop quickly enough, it would slow the ambient wind flow, allowing the storm to pull north along the Eastern Seaboard.  At this point, it's truly too early to speak with certainty on which of these scenarios will play out, but I can say that I would like to see indications that the jet stream winds will slow down a bit more than I'm currently seeing before I can feel comfortable forecasting a blockbuster storm for New England, and that while I feel snow - accumulating and plowable snow - is likely through a majority of Southern New England, I'm waiting a bit longer before "pulling out all of the stops" on this storm.  Should it reach it's maximum potential, however, it would be a very impressive creature with blizzard conditions Saturday night into Sunday, so the stakes are certainly high with this storm development.

Sunday's forecast hinges largely upon how quickly and exactly where this storm develops and moves, but most likley snow lingers in the morning regardless of which storm scenario plays out, and as the storm draws east of New England and intensifies, winds will be gusty and cold air will spill into New England.  The next upper level disturbance swings through on Monday, bringing a chance of snow showers later in the afternoon. 

Obviously there's plenty to keep an eye on over the next several days, but for those of you who enjoy looking farther into the future, there are some signs coming back on how the rest of February may play out.  Though I think we've shifted into what will - on average - be a wintry pattern through the end of the month, some atmospheric reshuffling appears to be in the cards around and just after Valentine's Day.  As mentioned above, while we're currently in the heart of cold Canadian air, and this cold air extends west into the Northern Plains, heat is building under a strengthening high pressure center in the Western United States.  Strong signs are for this high pressure center to grow very large and very warm over the next several days, and though we deal with a storm threat Saturday night into Sunday, this will mean that our replenishing supply of cold air will be temporarily cut off, since we've been feeding our cold in from Alaska.  While this is likely to result in 3-4 days of somewhat warmer weather - at or somewhat above normal temperatures for this time of the year - next week, I don't think it's the end of winter, or of the new wintry pattern by any stretch.  I continue to foresee a pattern shift allowing cold air to return once this Western high pressure ridge has reached its peak next week, and with an active subtropical jet stream nearby, multiple opportunities for cold and moist systems will exist in the new pattern.  It's obviously not a comfortable feeling to make a prediction of a return to cold and multiple chances for snow, then see even a brief return of warmth, but indications of this being only a brief stint with milder air are fairly strong, so I remain confident that winter turns back on at the end of the month.

Enjoy your Thursday.

Matt

Matt's Technical Meteorological Discussion:  Updated Thursday, February 9 at 4:10 PM

And away we go!  Time to dig in for what lay ahead this weekend, but let's do it one step at a time.

12Z 500 mb analysis shows a building ridge just off the West Coast as shortwave energy over Northwest Canada slides southeast across the Northern Plains and into the still-digging Eastern US trof.  We're going to be working with a number of factors this upcoming weekend - all factors that we've been monitoring together through these discussions for several weeks now, ranging from an anomalously high amount of available energy after record warmth across the United States (I forgot to mention that record earlier this week - will try to remember to include these stats in the Weather Summary tomorrow) to a tremendous clash of airmasses between Gulf of Mexico moisture and warmth with still southward building arctic air that's being reinforced by yet another arctic front overnight tonight, to a positively tilted trough that just barely diffuse enough to our west to actually help in storm development, as we looked at together a few days ago - rare to thank a positively tilted trough for future storm development, but this is a rare pattern, so we'll take what we can get.

Arctic front moving southeast this afternoon across New York State and toward New England, and will bring enough convergence and low level lift - coupled with orographic assistance - for snow squalls through most of Vermont, the Berkshires, snow showers in the Litchfield Hills of CT, and snow showers/squalls for most of Northern NewEng north of the Lakes Region of NH to Augusta, ME.  General accumulations in these areas should range between 1 and 2 inches, but a full-fledged overnight snowstorm is in store for localized portions of the higher terrain of the Northern Green Mountains, where close to 6" will fall overnight Thu ngt into Fri AM, and enhancement along the Eastern Maine coastline also looks like a good bet where dynamics and moist low level flow bisect.

The remainder of NewEng will see downsloping winds squashing most of the activity but enough cold advection a few thousand feet up for plenty of clouds to fill in during the night and perhaps a few flurries.  As cold advection wanes predawn Friday, skies will be allowed to partially clear briefly Fri AM before next shortwave already brings cyclonic vorticity advection into NewEng during the day on Friday with warm advection commencing relatively early not only aloft but even down to 850 mb by 18Z.  The natural reaction here is going to be for cloud formation at most levels through the day.  By late Friday, dominant NW flow takes hold and dry advection actually resumes as baroclinic zone nudged ever so slowly farther south, laid across Central and Southern NewEng and across MA, where light snow will develop Fri Ngt with the passage of vorticity maximums from both the west and the north thanks to confluent flow over NewEng.  This location of the light snow band is farther south than indicated by the NAM, but in good agreement with the WRF and the GFS - which isn't putting out much precip but has it in this location.  Total QPF will be light, but some enhancement will be possible all along the East Coast of MA with easterly flow providing ocean enhancement for 1-2" amounts possible in extreme eastern communities from Cape Ann to Cape Cod and Nantucket.

Then the real show begins.  Let's take this at what we know:  A series of shortwaves dropping into a positively tilted trough will merge, combining into a stronger upper level low that will dig and turn the trof neutral as the shortwave energy rotates around the base of a closing upper low.  Ample Gulf of Mexico moisture that has been locked south is tapped, and the the center of low pressure center jumps to the Carolina coast as upper level energy outruns the initial surface low.  From this point on, it's true that we have an upper level pattern that would appear at first glance to favor a rapidly moving storm that even would have the potential to shoot south of us.  When I first looked at everything early this morning, I saw the same things we're still seeing now, which is an upper level pattern that begs for a progressive storm, but low level dynamics that are a perfect setup for a very heavy dumping of snow over most of New England.  The trend now is to enhance the shortwave ridging ahead of the storm, which is providing enough of a westward track to bring the storm over Southeast NewEng.  I would argue that this storm will almost entirely follow the strong baroclinicity once it gets cranking along the east coast, and this means taking into account the same zone we mentioned above that sinks south of NewEng at 850 mb on Saturday.  Additionally, looking at the surface synoptics really helps to drive home the point that this could be an extremely productive snowmaker - a 1024 surface high pressure cell centered over the Mountains of Maine early Saturday under confluent flow low level and aloft helping to lock in the cold, -24 C at 850 C just northwest of the St. Lawrence River that's feeding directly from the Aleutian cold pool we've been eyeing for the past few weeks, waiting for it to lead us to our cold and snowy February pattern.  At long last it appears everything we've been patiently watching is fitting into place - the cold air drain at low levels, the positively tilted trough allowing for a conglomeration of energy, the abundant moisture and warmth - and therefore abundant energy - in the atmosphere, the warm ocean temperatures and the baroclinicity that sets up from all of these features.  Add to that strong diffluence aloft and we're developing what should be a very efficient precip producer on Saturday.

One excellent point that needs to be made is that this is a very progressive system, even with the shortwave ridging that may develop ahead of it.  The problem is that it's also a quickly intensifying system and this means inflow will be ample.  Winds will also be cranking and blizzard conditions will be possible briefly, especially along the coastal plain of Eastern NewEng and in the Southern Mountains, but let's remember that its likely to happen overnight Sat ngt which means weather nuts like us realize it but the public sleeps through it.  Power outages would be a concern, however, especially along the coastal plain.  Coastal flooding will need to be considered, but astronomically lower tide on Saturday night helps out.  Additionally, with Southern NewEng on the northwest side of the vort max track this keeps us in midlevel warm advection through Saturday night until the vort has passed, with 700 and 500 mb flow indicating wrap-around precip banding as well, later Saturday night and into Sunday.

With the cold air in place, we have to acknowledge a fluff factor here as well, and this snow will be quick to accumulate.  The bottom line here is that this storm will be a perfect one for those who have been longing for snow - widespread snow all the way to the Canadian border, and timed almost perfectly with regard to limiting disruption to plans as the worst comes between Saturday sunset and Sunday sunrise to mid-morning.  QPF amounts of 1" should be widespread across Southern NewEng with a stripe of 1.25"+ across much of MA and Nrn CT to the northwest of the low track, which I expect to be over Nantucket and Chatham.  The arctic air sets up a low level coastal front that will establish through interior Eastern MA and enhance snow amounts from interior Southern NH to the Merrimack Valley to the Worcester Hills/Metro West area into Nrn RI.  Additionally, the track I'm forecasting will mean a rain/snow mix on Cape Cod significantly cutting back on accumulations there.  I don't really need to mention it here in the technical discussion for those who are weather savvy, but this solution is based upon the undeniable trends in the guidance.  Should a dramatic shift toward a more progressive solution occur - and we do know that significant changes can occur over 48 hours...ESPECIALLY with this storm where we've noted different models chiming in at different times thanks to a very delicate shortwave interaction - this overall thinking would have to be ammended significantly for a tamer solution.

After snow winds down Sunday morning, winds will howl from the northwest and a chunk of the cold air in Eastern Canada slides south to hold temps well below guidance, in the middle 20's most areas.

Part of what keeps this system moving is a strong kicker coming in from the west, and this shortwave will bring snow showers and heavier squalls later Monday as it moves through NewEng.

As for my thoughts on the longer range, those laid forth in the weather summary above hold, which is that this wintry pattern rolls on, though perhaps a brief interruption from the 15th to 17 or 18th when temps will be at or above normal, but only in preparation for the real fun to begin.  Consistent signs of multiple major storm threats the week of the 19th need to be monitored and it's late enough that I'll skip that opportunity now, but the bottom line is that the cold is cutoff only briefly next week thanks to the ridge pulse over the Western US and Eastern Pacific, but that's the only way to pinch of the supply of cold, and it simply won't pulse strong enough, long enough, to hold back the flood of cold that will return for the remainder of the month and into march, and with both the Pacific and Gulf open the last half of February, this will help to feed the major storms I'm expecting.  Does every one of them hit New England?  That would be crazy to answer right now.

But we all have to start somewhere, and it appears New England starts Saturday night.

That's all for today.

Matt


The Wintry Beat Will Continue to Roll On Through the Weekend...Still Plenty to Keep Our Eyes On

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  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. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is [email protected].  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  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 (New!):  Quick Note:  The homepage, www.mattnoyes.net, has been updated with some new links to supplement the ones that were already there.  If you haven't already checked it out, feel free to browse on over.

Weaether:  With the storm in Eastern Canada that kept windy conditions across New England the past couple of days departing, and no major storms on the map, winds will be lighter and the weather quiet across New England for our Wednesday.  Sunshine will gradually give way to increasing high altitude clouds in many spots, but these clouds will be of little consequence.  Wednesday night, a storm passing hundreds of miles south of New England may throw just enough moisture northward that Southeastern CT, RI and Southeastern MA see predawn and early morning flurries on Thursday.  Elsewhere, expect most of Thursday to be dry under clouds and some sunny breaks, though an arctic cold front pressing south from Canada will bring afternoon and evening snow squalls to Northern and Western New England that may reduce visibility and make roads slick in these areas.  This front will carry a few flurries farther south Thursday night, but will stall out in Southern New England as a new storm system moves toward us from the west.  This next storm will be moisture starved, and for the most part will bring only periodic light snow on Friday, though a band of heavier accumulating snow may set up somewhere between the Massachusetts Turnpike and Concord, NH (too early to pinpoint where this band may be).  A similar scenario will set up on Saturday - developing periodic light snow with heavier banding possible for some areas, and that will last through Saturday night as the storm center begins to grow just offshore.  At this point, it appears drier air tries to nose in on Sunday and nudges this storm farther offshore, but we'll keep a close eye on this setup, for sure.

General Weather Summary:  Quick Note:  The homepage, www.mattnoyes.net, has been updated with some new links to supplement the ones that were already there.  If you haven't already checked it out, feel free to browse on over.

Weather:  Winds will ease across New England on Wednesday, with a dry but chilly day for everyone with a break between energetic disturbances aloft.  A brief glance at the nation as a whole indicates lots of energetic disturbances - evident on satellite imagery as clouds blossom in many areas - but a lack of moisture, evident in the lack of radar returns, which help to illustrate areas of precipitation.  In a moisture-starved environment like the one in place across the nation currently, it's quite difficult to generate large areas of organized precipitation, though strong storm systems high in the sky at the jet stream level hold the potential to squeeze out what little moisture is present.  A strong upper level storm is cranking out that limited moisture as accumulating snow in Missouri Wednesday morning, and will split into two separate disturbances as it moves east Wednesday night.  Needless to say, while New England, and most of the nation seems very quiet at the surface today, the atmosphere is quite busy aloft.

Clouds across parts of Vermont Wednesday morning are in association with a westerly wind - picking up moisture off of the Great Lakes, then carrying this moisture into the mountains, where air is forced upward (called "upslope flow") creating clouds and snow showers.  Elsewhere, dry air is in place, and northwest breezes are sloping DOWN off of the hills and mountains, further helping to dry out the air.  High altitude clouds will increase later Wednesday and through Wednesday night on the far northern fringe of the energy center moving east from the Midwest.  This energy center actually will split into two separate disturbances, moving parallel to one another Wednesday night.  As the pass off of the Mid-Atlantic coast, they will finally encounter the moisture they've been depleted of during the eastward trek, when they reach the Atlantic Ocean.  The result will be a rapidly blossoming area of precipitation over the ocean...too far south for most of us to see any effects other than lots of clouds Thursday morning, though far Southeastern MA, RI and Southeast CT may be just close enough to this developing swath of precipitation to see some flurries or light snow Thursday morning.  Total amounts would likely be negligible, but the potential is there for a grazing.  Elsewhere, Thursday should dawn dry but mostly cloudy, with breaks of sunshine poking through during the day.

A storm far to our south won't be the only system we'll be watching on Thursday, however.  Approaching from the northwest, a strong upper level disturbance will be heading directly for New England, steered in our direction by the jet stream winds aloft.  At the surface, the reflection of this disturbance will be an arctic cold front - the leading edge to a surge of reinforcing cold air.  As the front moves into Northern and Western New England Thursday afternoon, snow squalls will likely develop along it, with a quick reduction in visibility and a quick accumulation of snow on roadways possible in these areas when the squalls move through later Thursday afternoon and evening.  By Thursday night, this front begins to lose most of its punch as it slows through Southern New England, where only a few flurries are likely to result.

This cold front will be slowing in large part because a new storm will already be winding up across the Great Lakes, and the counter-clockwise flow of air around that storm will be ushering slightly warmer, slightly more moist air northward into New England.  The collision of the cold air surging southward and the warmer air riding north not only will put the breaks on Thursday evening's cold front, but this battle between "cold" and "cool" air also will mean plenty of Friday clouds with at least periodic light snow for parts of New England.  While Friday's snow looks quite light in most locales, it's not uncommon to see a heavier band of accumulating snow setting up for some communities, near the actual battleground of the two dueling airmasses, and I'll keep a close eye on that potential, though nailing down where that may happen, or even if it will for sure, is nearly impossible from this far out.

Periodic snow is in the forecast again for later Saturday, as a more significant upper level energy center is driven immediately south of New England.  This Saturday storm, however, is one we'll likely have plenty of anxious watching to do over the next couple of days.  Reason being, remember that these moisture-starved systems really blossom once they have moisture made available to them.  If this storm moves east off the New Jersey coastline early Saturday, it will be over Long Island Sound and the Atlantic Ocean during the day Saturday.  It's possible that enough moisture would come into play to bring a round of more significant snow to some of New England, depending on how quickly this system can get its act together.  It's also possible that, as we'll watch for Friday, the battle zone between "cold" and "cool" air sets up a zone of slightly steadier snow.  At this point, the most honest forecast is to convey the likelihood of at least periodic snow on Saturday, mostly light in nature but with the potential for something meatier in Eastern New England later in the day.

Sunday's forecast hinges largely upon how quickly and exactly where this storm develops and moves, but the most likley scenario would keep clouds and perhaps some lingering snow around early, then bring in partial clearing later in the day as the storm trudges east.

Obviously there's plenty to keep an eye on over the next several days, but for those of you who enjoy looking farther into the future, there are some signs coming back on how the rest of February may play out.  Though I think we've shifted into what will - on average - be a wintry pattern through the end of the month, some atmospheric reshuffling appears to be in the cards around and just after Valentine's Day.  Currently, while we're in the heart of cold Canadian air, and this cold air extends west into the Northern Plains, heat is building under a strengthening high pressure center in the Western United States.  Strong signs are for this high pressure center to grow very large and very warm over the next several days, and this will mean that our replenishing supply of cold air will be temporarily cut off, since we've been feeding our cold in from Alaska.  While this is likely to result in 3-4 days of warmer weather - and perhaps a rainstorm for some - next week, I don't think it's the end of winter, or of the new wintry pattern by any stretch.  I continue to foresee a pattern shift allowing cold air to return once this Western high pressure ridge has reached its peak next week, and with an active subtropical jet stream nearby, multiple opportunities for cold and moist systems will exist in the new pattern.  It's obviously not a comfortable feeling to make a prediction of a return to cold and multiple chances for snow, then see even a brief return of warmth, but indications of this being only a brief stint with milder air are fairly strong, so I remain confident that winter turns back on at the end of the month.

Happy Hump Day!

Matt

Matt's Technical Meteorological Discussion:  Updated Wednesday, February 8 at 11:20 AM

Limited time today so will tackle the big issues:

Tonight/Thursday system stays far enough south to avoid problems tho increased midlevel RH still has me a bit nervous and WRF has continued to trend north along with the GFS, coming far enough north with precip to bring it immediately south of the South Coast and over Nantucket, so will keep a chance of late night/early Thu AM flurries in the forecast for SE CT/RI/SE MA, tho given guidance insistence on keeping the low levels dry - which makes sense with cold and dry surface flow and Tds in the lower teens in these areas - would expect negligible results.  Famous last words, right?

Thu vort max looking less impressive with each successive model run, though coupled with orographic lift, still enough for squalls in the mountains and higher terrain of Northern/Western NewEng.  Really expect front to throw on the brakes Thu Ngt in Southern NewEng as it encounters developing warm advection flow ahead of next shortwave.  Hints for Friday may be found upstream with the vort moving thru the Midwest today, in that we're seeing bands of light snow north of the vorticity track.  I think with this low level baroclinic zone in the form of a dying arctic boundary over us on Friday, this may favor similar banded development of snow, though increasing agreement is that this will be more evidenced across NY State than NewEng due to lack of available moisture farther east into NewEng.  Once again, upslope areas may be where we end up looking, but will hold a general chance of light snow for Fri afternoon in NewEng until this becomes a bit more clear.

By Saturday, next shortwave is ready to move in, embedded in fast flow aloft.  Obvious differences in the guidance here, from a relatively boring NAM that carries periods of light snow thru later Sat, to the GFS that attempts to develop a more robust system at the last minute for Eastern NewEng, to the ECMWF that paints a similar picture but not until later in the game and a bit farther E.  The bottom line on this system is that all models agree it will develop, the differences come with regard the when and where that happens.  The positively tilted trough was discussed in the technical discussion earlier this week, and the role it may play here by slowing shortwave progression just enough to allow disturbances to merge ahead of a digging trough axis, and this is what the GFS is keying in on.  Remember that earlier in the week it was the ECMWF that harped on coastal development.  With at least one guidance product keeping a coastal in the forecast for the past few days - though trading off which model shows it - this indicates to us just how close we are to having a rapidly developing storm.  The 12Z GFS is now the model to pick up on this potential, as it slows the northern stream shortwave moving over the St. Lawrence River enough to keep confluent flow over NewEng on Saturday, leaving energy behind over the Ohio Valley and creating a neutrally tilted trough for a rapidly developing storm late Saturday into Sunday.  The ETA/GGEM (00Z) and to a lesser extent the ECMWF all are faster with the northern stream shortwave and leave less energy back across the Ohio Valley for a strongly positively tilted trough and a fast moving disturbance.  I actually liked the 00Z GFS run best of what I've seen - really a middle of the road solution of a storm that just starts to take off as it moves past our longitude, allowing Eastern New England to stand the chance of getting hit with some heavier snowfall amounts as the circulation starts to wind up.  But truth be told, there are several possible routes to follow at this juncture, and with only limited time to get my thoughts out to you today, I think it's best to leave it here, leave ourselves with a few more cycles to digest the trends and data, and acknowledge that there certainly is the potential for something more significant later Saturday, with widespread periods of light snow likely regardless of how this plays out.

If you're aching for more on the longwave pattern, please feel free to read previous technical discussions (yesterday's posted below, rest are in the archives).  My take on a possibile warmup for next week before more winter is expressed in today's Weather Summary (above) so I won't rehash it here today since I'm out of time.

Here's to a wonderful Wednesday.

Matt


Reinforcing Cold Settles In...Multiple Storms to Our South Bear Watching Next Several Days...

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  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. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is [email protected].  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  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 (New!):  A breezy day with morning snow showers and chilly temperatures will greet you this morning as a weak cold front settles south through New England, though the trend through Tuesday will be for increasing sunshine in most areas.  With temperatures only in the 30's south and 20's north, and a wind gusting up to 30 mph, wind chill factors ("feels like" temperatures) will be in the 20's and 10's, respectively.  Aside from mountain snow showers, Tuesday night will be mostly clear and cold, and Wednesday will dawn bright in most areas, yielding a mostly sunny and dry day for midweek.  Wednesday night into Thursday morning, a storm will pass well south of New England.  Indications continue to be that most of the precipitation will stay south of New England, though there are subtle signs that enough moisture will spread northward for some light snow Thursday morning in far Southeastern New England, so a chance of light snow remains in the forecast Thursday morning for Southeast MA, CT and RI until I can find enough evidence that it may stay farther south.  Thursday afternoon snow squalls will cross New England from north to south with another cold front, keeping wintry temperatures in place through the weekend, with a chance of snow later Friday into Saturday.

General Weather Summary:  The same strong storm that brought gusty winds to New England on Monday will present us with another breezy day through Tuesday.  The large storm, wound up just to our north in Eastern Canada, is bringing a fast flow of air not only here on the ground, but also high in the sky, at the jet stream level where storms are steered and that fast corridor of winds acts as a thermostat for the atmosphere, separating cold air to the north from warm air to the south.  This corridor of jet stream winds has dipped south of New England, and that means the active storm track will also be south of our region - through the Southeastern U.S. and off the Mid-Atlantic coast - at least for the time being. 

The first result of a pattern like this is a continued feed of cold and relatively dry air, interrupted by spokes of energy rotating around the Canadian storm and through New England, picking up moistue off of the Great Lakes, and cranking out snow flurries and squalls.  These flurries and squalls can be found scattered across New England through Tuesday morning, but as dry air continues to set up shop in New England, Tuesday afternoon will bring a trend toward mostly sunny skies with flurries continuing mostly in the mountainous and hilly terrain.  Winds gusting up to 30 mph from the west-northwest will bring windchill values into the teens north and 20's south through the day.

After a mostly clear and cold night Tuesday night with a few mountain snow showers continuing from the Northern Green Mountains through the Northern White Mountains, Wednesday should be a dry but chilly day for just about all of New England with a break between energetic disturbances aloft, and a continued storm path to the south of New England.  Meawhile, another storm will be taking shape in this active track across the Mississippi River Valley later Wednesday and toward the Mid-Atlantic coast Wednesday night.  While it certainly appears from all guidance that the bullk of this next disturbance should also stay south of New England Wednesday night into Thursday, there are some subtle hints that the moisture associated with it may try to expand farther northward up the East Coast early Thursday morning and this potential needs to be monitored.   Even if this snow should spread as far north as Souteastern MA, RI and Southern CT - where I'm still carrying a chance of light snow to be on the safe side until I can feel more comfortable dropping it from the forecast - it would be light in nature and likely have little impact.

Regardless of how this system riding south of New England plays out on Thursday morning, a new energetic disturbance will dive southeast across the Great Lakes and into New England Thursday afternoon.  Having traveled all the way from the North Pole, this disturbance will be dragging plenty of cold air southward as it moves in our direction, and the leading edge to this reinforcing surge of cold air - a cold front - will spark snow squalls Thursday afternoon into Thursday evening from North to South.  It's possible these squalls lose their punch as they come into Southern New England - south of Southern New Hampshire - but they should bring a quick round of heavy-hitting snowbursts to Central and Northern New England, and if they do indeed hold together, Southern New England would see the effects Thursday evening or night.  The passage of this cold front opens the door for a shot of deep cold air, which will come charging into New England Thursday Night.

The next in a string of energetic disturbances racing from west to east across the nation will move toward New England Friday into Friday night.  As the counter-clockwise flow of air around this disturbance attempts to force warmer and more moist air into New England, this air will collide with the deep cold in place, and the result will be increasing and thickening clouds followed by a chance of developing snow.  While most guidance brings this snow into New England Friday night, the typical error in a fast moving atmosphere is for guidance to be too slow with these systems, and a timing of bringing snow in sometime during the day on Friday may be more accurate, so I've tried to make this correction accordingly.

This will not be the final disturbance we'll hear from, as another several energy centers caught in the jet stream winds aloft will be dropping into the Central United States and may end up merging into a stronger storm system during the weekend as they move toward the Eastern Seaboard.  All tolled, cold air will continue to pour into New England through next weekend, with an active storm path keeping us on our toes for snow threats through the rest of the month.  The bottom line here is that this week marks the first week in our transition to the active winter weather you and I have been ready for in these discussions for the past few weeks.

Enjoy your Tuesday!

Matt

Matt's Technical Meteorological Discussion:  Updated Tuesday, February 7 at 1:00 PM

Flurries across NewEng are the result of a dying cold front dropping thru NewEng, tho the colder air behind the boundary continues to feed south as was evidenced by morning temp drops in most Northern and Central NewEng locales.  Winds freshen behind the boundary, then slacken farther upstream, and temps will hold steady thru the day most locales - rises more than a couple of degrees thanks to diurnal heating will be the max that will be seen.  Drier air, warming midlevel temps and decreasing cyclonic flow will all contribute to diminishment of flurries and clouds this afternoon, lending to a mostly sunny afternoon excepting orographically favored mountain locales where enough low level forcing to keep snow showers in the forecast.

Pressure gradient force decreases and wind dies down overnight.  With dewpoints in the single digits north and teens south, and decoupling expected in the valleys, these values should be reached as low temps for sheltered valleys - and some communities well sheltered that can decouple earliest will fall below these values.  Mainly clear skies should rule as we find ourselves between systems.

Cirrus quick to spill in on Wednesday - in fact, some moisture 400-300 mb may be in before dawn as thin veil - but mostly cirrus will increase during the daylight hours.  The next system is progged to move off the Georgia coast at the surface around 18Z Wed, then move NE, intensifying several hundred miles southeast of NewEng.  Yet, I'm still carrying a chance of light snow southeast CT to Cape Cod late Wed Ngt into early Thu AM.  Reasoning for this is same concern as described in yesterday's technical discussion - while primary vort shoots well southeast, second vort max travels north of primary and parallel in track, passing much closer to NewEng.  There is no question that very little low level support will be found with this feature, as cold and dry advection will still be ongoing in the boundary layer on a north-northwest surface flow.  At 850 mb, however, a weak convergence zone is present and Theta-E advection actually goes neutral to even weak warm/moist advection briefly late Wed Ngt/predawn Thu.  Additionally, 300 mb divergence is ongoing in that same timeframe as a weak interaction/handoff occurs between the southern vort described here, and the strong northern stream vort dropping across the Great Lakes Wed Ngt/Thu and heading for NewEng by Thu eve.  Many of the ideas here build off of those laid out in yesterday's discussion (posted below), but the bottom line is that this weak interaction not only generates diffluence aloft, but also occurs as upper level temps are cooling (increasing instability) and moisture is fed northward while widespread weak lift develops across most of Southern NewEng.  Chances are good that this really isn't going to amount to much of anything, anyway, given that these areas would be only on the northern shield of precip, but given spurious bullseyes of precip just south of NewEng that most guidance is putting out - most pronounced on NAM/GFS/SUNYSB MM5, I feel the need to keep a chance of light snow in the forecast for these areas late Wed Ngt into Thu AM.  Perhaps this is overly cautious, but the reasoning is set forth above and with 48 hours left, there's time for the guidance to continue their northward trend.  Again, this likely wouldn't amount to much, unless one of those spurious bullseyes ends up on top of us, and that is part of my reasoning for maintaining the slight chance.

Everything looks on target from yesterday's assessment for Thursday afternoon with passage of vort.  Guidance indicates ascent is primarily held across the Northern half of NewEng, tho it's a no-brainer to include hilly upslope areas of Western NewEng in this, as well, and with the moderate strength of the vort - and equally important the direct-hit angle of the cyclonic vorticity advection coupled with a moderately unstable atmosphere given falling midlevel temps - these could end up being some significant squalls in the orographically assisted areas, and still may carry squalls into Southern NewEng.  I have to be careful on this because, due to my initial exposure to arctic frontal passages being at my first job in Upstate NY, I'm used to a nice injection of moisture from the Great Lakes to these systems, and while that usually holds for upslope areas, downslope areas farther east can really get robbed.  Still, while models are holding 700 and 850 mb moisture back and suggesting timing should be Thu ngt for passage of the front, quicker vorticity speed indicates passage around diurnal max - at least in Western and Northern NewEng - is likely, which will further enhance lapse rate, progged to be a bit greater than 6 C/km from 850-500 mb Thu afternoon.

Behind the arctic front, a reinforcing shot of cold.  There's no question about how cold this air is going to be - I think the question revolves more around just how far south it penetrates, given that the next shortwave will already be inducing warm advection ahead of it during the day on Friday.  This is likely to turn the arctic baroclinicity around before it can make it that deeply into NewEng, but still I've opted to go WAY below guidance on Friday given the following:  If it's warm advection that's going to turn this around, keep in mind there will be quite a clash of airmasses and a moderate speed convergence boundary assisting in upward vertical motion.  The end result should be lots of Friday clouds, and - coupled with the thoughts you and I shared in this discussion yesterday about shortwaves coming in faster than progged in fast flow like this and warm advection underway - wise to bring snow in during the day Friday, and of higher intensity than models would suggest.  Period of time for this shortwave passage isn't all that long...should be passing by early Friday night.

The real questions revolve around how everything comes together with the parade of shortwaves that follow for this weekend.  If you haven't had a chance to read yesterday's technical discussion regarding the extended period and rest of the month, please reference it below, in yesterday's post.

Have a terrific Tuesday.

Matt


Winter Pattern Returns At Last...Step One In This Transition is Underway

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  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. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is [email protected].  While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants.  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 (New!):  A strong storm winding up in Eastern Canada is feeding cold air around its belly, into New England.  Southwest winds will gust as high as 40-45 mph on Monday, ushering in this chilly air and holding temperatures in the 30's for most spots.  Scattered snow showers and some heavier squalls will continue to fly through the day, hitting some communities hard with briefly heavy snow, while sparing others entirely.  Especially vulnerable will be the mountainous and hilly terrain.  Otherwise, more clouds than sun prevail.  Breezes stay active overnight Monday night and with temperatures falling into the 20's, wind chill values will be in the teens.  Tuesday brings more clouds than sun early, then increasing sunshine, while scattered snow showers and squalls continue in the mountains.  Expect a dry day Wednesday, though colder temperatures will be with us through the week.  The active storm track stays south of New England, though we may be grazed with the northern edge of a snow shield on Thursday morning.  Expect the cold to stick around for weeks - winter has returned to New England.

General Weather Summary:  The same storm that pounded parts of Michigan with wind-driven snow on Saturday has continued to wind up as it migrates north into Eastern Canada.  The result has been for the counter-clockwise flow of air around this system to drag cold air out of Canada and carry it into the Great Lakes and the Northern Tier of the United States.  Through the day on Monday, active southwest winds (normally a warm wind direction!) will yank this cold air out of the Great Lakes and Ohio Valley, and drag it into New England.

In the transition, snow squalls will continue to fire up across our six-state region under a windy blend of more clouds than sun.  Bundles of energy interacting with near-surface moisture will wring out flurries, snow showers, and heftier, wind-blown snow squalls that can quickly coat roadways with snow and ice, and reduce visibility dramatically.  Otherwise, new, chilly Canadian air streaming in on 40-45 mph wind gusts at times, will mark the beginning of the much anticipated return to wintry weather you and I have discussed here together over the past several weeks, slated to be in place by mid-month.  After Monday's blustery near-40 degree readings in some areas, the remainder of the week will bring a noticeably colder and wintry feel, as we dig in for what will be a few if not several weeks of winter's return.

With such a large storm wound up just to our north in Eastern Canada, a fast flow of air will be present not only here on the ground, but also high in the sky, at the jet stream level where storms are steered and that fast corridor of winds acts as a thermostat for the atmosphere, separating cold air to the north from warm air to the south.  This corridor of jet stream winds has dipped south of New England, and that means the active storm track will also be south of our region - through the Southeastern U.S. and off the Mid-Atlantic coast - at least for the time being.  The result is a continued feed of cold and relatively dry air, interrupted only by spokes of energy rotating around the Canadian storm, picking up moistue off of the Great Lakes, and cranking out snow flurries and squalls through Tuesday morning, especially in the mountainous and hilly terrain.  Expect drier air to assist in brightening the skies Tuesday, as we transition from more clouds than sun, to just the opposite by day's end.

Wednesday should be a dry but chilly day for just about all of New England with a break between energetic disturbances aloft, and a continued storm path to the south of New England.  Meawhile, another storm will be taking shape in this active track across the Mississippi River Valley later Wednesday and toward the Mid-Atlantic coast Wednesday night.  While it certainly appears from all guidance that this next disturbance should also stay south of New England, there are some subtle hints that the moisture associated with it may try to expand farther northward up the East Coast sometime on Thursday - likely early in the day if it were to occur at all - and this potential needs to be monitored.   As a result, I've felt it wisest to put a chance of snow in the forecast, and we can of course fine tune this as we near it, and drop it from the forecast if appropriate.

Cold air will continue to pour into New England through next weekend, with an active storm path orienting itself on a slightly more south to north axis, which will keep us on our toes for snow threats through the rest of the month.  I truly believe the bottom line here is that this week marks the first week in our transition to the active winter weather you and I have been ready for in these discussions for the past few weeks.

Here's to a great Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Monday, February 6 at 2:15 PM

Multiple shortwaves combined with low level convergence zones associated with attendant surface troughs and steep low to mid level lapse rates allowing for widespread snow showers.  Heavier snow squalls embedded from time to time in this environment and dropping quick half inch to inch of snow - into surface temps that are in the mid to upper 30's and cold enough for some icing of roadways in heavier squalls.

Atmosphere stays mixed as breezes stay active Mon Ngt which introduces wind chill into fcst overnight.  Squalls continue - primarily in upslope favored regions where topography aids in forcing combined with lingering moderate to steep lapse rates as -30 C 500 mb temp cold pool rides over Nrn VT/NH/ME.  A few fresh inches for the higher terrain of the Greens, Whites and NW ME should be the result.

Another windy day on Tue as well mixed atmosphere combines with strong - though weakening - pressure gradient force.  Mid level temps warm considerably during the day and while day should begin with convective activity of at least plenty of clouds and some orographically favored snow showers in cyclonic flow that will be somewhat lake enhanced, esp in Western NewEng, would expect this to squash out as drier and more stable atmosphere takes hold.

Beyond...remember that last week, together we left off acknowledging upper level flow would be too confluent to allow today's shortwave to possibly come this far north (it's producing the precip across the SE US right now) but that there was more concern for the Tue shortwave.  Looking at progs now, it still appears as though the flow is too confluent, and the jet stream too far south on Tue for this next shortwave to come anywhere in our neighborhood.  So, given the slower retreat of the vortex to our north, does this mean we give up on our thoughts for this circulation from last week?  Not quite - or perhaps more accurately, not yet.  Even just a quick and dirty examination of the upper level plots for this week indicate there are TONS of shortwaves - or at least vorticity lobes sheared or otherwise - embedded in the flow.  Additionally, rising heights over the northeast the next couple of days will allow the jet stream winds to gradually ride farther north, which means we need to stay on guard for each shortwave embedded in the flow, especially considering a shortwave passing south of NewEng, if it could get its act together with a low or mid level circulation, would direct a moist easterly flow our way.  But...it's important to distinguish between "wishcasting" - done when someone either wants a solution to verify and comes up with all the reasons why it could - and forecasting - putting out the best possible representation of what may transpire.

So, let's stick to the forecasting, and stick to the facts:  There will be four shortwaves in particular to be watched over the next 6 days, not including the Tuesday wave that stays south of NewEng.  The first rides through the flow Wednesday night into Thursday morning, followed immediately by a strong northern stream shortwave and associated trough axis Thursday afternoon and evening.  This combo needs to be watched for possible trouble.  The next comes through Friday evening and night.  The fourth comes through Saturday evening or perhaps as late as Sunday dependent upon how it evolves.

At first glance, the Wed Ngt/Thu AM shortwave looks innocuous, esp considering the 250 mb wind forecast on the NAM is actually shifting S during that period.  It's always been the little inconsistencies, however, that I feel can bring the most interesting surprises.  One of these little inconsistencies is the forecast by both the NAM and the GFS to carry moisture farther northward (much farther north) than the precip shield, and bring it over at least part of Southern NewEng on Thu.  This northward push is really a cursory interaction with the incoming northern stream shortwave trough that is slated to swing thru Thu Eve, but the problem is an insistence to pull 500 mb and perhaps even 700 mb moisture northward well ahead of this northern stream trough axis Thu AM as the southern stream wave rides south.  Additionally, the GFS is creating a farther north, secondary jet streak aloft, which takes a position much more favorable to carry a northern shield of snow into parts of Southern NewEng.  The tricky part here is how to convey this to the public.  I HAVE put snow in the forecast for Thu in association with this system, and I've made sure to explain the tentative nature of it - watching the northern shield of snow from a storm to our south.  Meteorologically, though, I think these few inconsistent points in the guidance are important to keep an eye on.  I based my forecast on the 00Z Mon runs, and it's interesting to notice the 12Z Mon runs are trending even more in this direction.  So, we'll wait and see on this one.

Next in line is a shortwave slated for passage Fri eve.  Given the tendency of models to inaccurately estimate shortwave timing in a fast flow, this thing could come thru anytime between Fri daylight and Sat AM, though typical model error is to bring it east too slowly in fast flow, so earlier may be better.  Regardless, this shortwave scoots south of NewEng and is likely to throw warm advection out ahead of it, so we're likely to crank out a period of snow in isentropic lift later Fri or Fri ngt with its passage.  Arguing against this is the sheared nature of the vort in the progs, but if the jet stream forecasts are anywhere close to accurate, this thing should come close enough to give us at least a shot.

Next one in line would extrapolate through later Saturday given current forecasts, though one interesting feature to the upper level flow at this period is the multitude of shortwaves behind the leading one, helping to lower heights all the way to the Intermountain Region across the Northern Tier of the US, and thereby allowing the longwave trof to have a somewhat positively tilted orientation.  With weaker flow developing on the west side of the trof base, it's entirely possible for a situation to develop in which shortwaves dropping south out of Canada are coming in faster that shortwaves are ejecting out the eastern base of the trough.  The result here would be a merger of several vorticity maximums, yielding a slower but stronger solution as everything shifts east this weekend.  It's a trend to pay close attention to in the guidance over the next few days to see if trends head in this direction.  First product to jump on this bandwagon has been the 00Z ECMWF, whose solution is not as far-fetched as one may think given the pattern described above, but it's also simply a representation of what *could* result from this setup.

Looking even farther out, I'm going to save my fingers the typing on how and why the pattern will evolve as it will since it's been hashed out here the past couple of weeks (if you're new to reading though, feel free to peruse the archives at left), but the bottom line is that the longwave pattern transition is underway and the gears are in motion.  Cross polar flow prevails the next couple of weeks thanks to a tremendous ridge cranking up over Western North America, the Eastern Pacific and, eventually, over the Aleutian Islands.  Remember that it's this Alaskan and Aleutian cold we've been eyeing for almost two months together in these discussions, now, realizing that cold, though it correlates to Northeast and Eastern US warmth, would be money in the bank after the expected major pattern reshuffling as the upper low on the other side of the globe broke down.  But get this...I don't think it stops there.

Siberian cold continues to build and over the next several days will shift east to the coastlines of Russia along the Northwestern Pacific Ocean.  This cold shifts east - taking with it plentiful amounts of energy from the swirling vortices in this region - as the ridging established over the Western US and Western Canada retrogrades and explodes over the Aleutians and Alaska.  This ends up being critical to the way February unfolds, not only for the Northeast but for the country as a whole.  Reason being, the increasing baroclinicity between built up and deep cold over Eastern Asia with a pounding and monstrous ridge over the Eastern Pacific results in phenomenally fast flow from south to north around the west side of Alaska.  Multiple strong vorticity maximums eject from the East Asian upper low and are directed around the crest of the ridge, picking up serious surface cold from the North Pole and then carrying southward lock, stock and barrell in the establishing cross polar flow.  The result should be a continuation of the trough "development" over the Great Lakes and much of the Northern Tier of the US that we looked at a couple of weeks ago, as the trough continues to truly develop from the bottom up with low level cold the first to arrive - and this is already playing out nicely as each successive 500 mb analysis indicates a deepening upper low over Eastern Canada - a pattern that will first favor eastward ejecting shortwaves from the Intermountain Region south of NewEng with strengthening circulations capable of delivering shots of significant snow in easterly flow as they come by (harkening back to earlier in the discussion regarding upcoming potential) and eventually evolving into a pattern favoring more focus upon the baroclinic zone along the Eastern Seaboard.  The end result is to pour most of the cold out of Eastern Asia and into the U.S. by the third week in February, and as the northern periphery of the Eastern Pacific ridge breaks down, the troffing in the US becomes more broad, and cold air truly invades almost all of the nation by this time period.

That's all for today.

Matt