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Rain/Snow Line To Drop South Through the Day...Coastal Flood Concerns...Parade of Storms to Continue Next Two Weeks As We Transition to Winter Again

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find 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 contact@mattnoyes.net.  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 powerful storm center will strengthen steadily as it passes south of New England on Tuesday.  Moisture extending north from this storm will continue to spread a mix of wintry precipitation across the region, with most areas changing to snow by afternoon and evening with accumulation either side of 2" most areas - higher amounts in the mountains of Western New England.  Caution should be exercised for areas of freezing drizzle, freezing rain and snow.  Expect winds to gust over 35 mph at coastlines where minor to moderate coastal flooding is a concern at midday high tide and two hours either side.  Mostly cloudy overnight Tuesday night as snow showers end, then breaks of sun give way to thickening clouds again on Wednesday.  A series of weak disturbances keep plenty of clouds around until a stronger storm moves in on Friday with rain and snow.  A parade of storms marches through New England for the next couple of weeks as we likely transition to much colder air by mid-month.

General Weather Summary:  A storm center moving off the North Carolina coast Tuesday morning will intensify rapidly as it moves over the Atlantic and south of New England.  Tapping deep moisture spilling northward out of the Gulf of Mexico, this strong, energetic disturbance has already been producing deep thunderstorm activity offshore, and will continue to pinwheel packets of moisture and precipitation northward into New England.  This will result in greatly varying results from the storm across New England, with a slowly southward settling rain/snow line, localized bands of precipitation and topography all playing a role in this storm. 

The obvious result from this storm is coastal wind, and a lot of it along the coastlines.  This raises a concern for coastal flooding for all east and northeast facing shorelines from the Central coast of Maine southward all the way to Nantucket, where a stiff northeast wind at 20-35 mph with gusts over 40 mph will combine with some of the highest astronomical tides of the season to produce problems at the time of a midday high tide cycle.

Moisture wrapping around the northern periphery of the storm center will clash with cold and dry air in place through the interior, and the broken band of snow that developed Tuesday morning through interior New England will pulse with regard to intensity and areal coverage, and will gradually fill in with areas of precipitation moving northward off the Atlantic into the remainder of New England.  Under these areas of precipitation, locally heavy bands of snow and rain will fall, while outside of the localized bands of precipitation, drizzle and freezing drizzle will continue.  As the storm strengthens and gradually pulls east later Tuesday, expect the cold air across Central, Northern and Western New England to bleed southward with a changeover to snow around mid-afternoon working southeast from the Interstate 495 belt of interior MA to the coastline through Boston, and by Tuesday evening, to Cape Cod.  A quick burst of a couple of inches of snow would be possible after this changeover late Tuesday into Tuesday night north of the MA Turnpike, with a coating up to an inch south (see maps).  IT'S CRUCIAL to understanding today's forecast to realize that variability will be the rule across New England on Tuesday - the banded nature of precipitation, combined with effects of elevation - will mean large variability in snowfall amounts by midnight Tuesday night.

Overnight Tuesday night, as the storm pulls slowly away from New England, winds will remain active from the northwest, and cold air will infiltrate all of New England, keeping ice and snowcover on the roads in many spots.  Once this storm pulls east of Nova Scotia, faster flow in the atmosphere can take hold and a fast-moving, weak disturbance will race east into New England later Wednesday.  The result will be an increase in clouds after only limited morning sunshine Wednesday morning, with a few flurries possible Wednesday night into Thursday morning, especially across the mountains.  Again, in this fast flow with the jet stream winds roaring well above our heads, expect partially clearing skies later Thursday.

By Friday, yet another disturbance will be racing eastward, but this time the jet stream winds aloft that steer our storm systems will begin to buckle southward, allowing the new storm to track southward as it crosses the Lower Mississippi River Valley early Friday.  This storm will tap moisture from the Gulf of Mexico, though its final storm track has yet to be determined - the most likely scenario would be a snow north/rain south result to start the upcoming weekend, but with plenty of storms marching across the Pacific, there's a line of storms waiting to move into the Northeast later this weekend and again early next week.

As for the remainder of February, remember what we've reviewed together in these discussions in the past - the abnormal warmth of January and the end of December has resulted in a large amount of available atmospheric energy across the United States.  And this warmth hasn't been confined only to New England - most of the nation has been abnormally warm, and therefore most of the nation houses a higher amount of available energy than would normally be present this time of the year.  Strong indications are that by the second weekend of February, a significant pattern shift will have occurred across the nation, allowing much colder air that's been locked on the opposite side of the globe and near the North Pole to spill southward into the United States.  In this transition, the available atmospheric energy will have to be expended, and large storms are likely to be the result.  The question for these will of course be storm timing and track - though with warmth bubbling up from the southeastern U.S., this does favor a track that would put New England on the snowy northern side of storms over the next couple of weeks.  Time periods that look to feature potential big bangs to usher in this new weather pattern include this coming Tuesday, then again approximately one week later, on the following Tuesday which may be a larger storm that really marks the change to a new cold and wintry pattern.  There are no guarantees and the world of the atmosphere, of course, but certainly the atmospheric signs are that February may begin with a bang, before significant cold may move in for the middle of the month.  Time will tell....

Have a great day!

Matt

Matt's Technical Meteorological Discussion:  Turns out just too much going on today (Tuesday).  Looking forward to quieter weather for the opportunity to include a techie discussion Wednesday.  See you then.


Powerful Coastal Storm Taking Shape Tuesday...Multiple Storm Threats Continue

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find 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 contact@mattnoyes.net.  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 cold area of Canadian high pressure will continue feeding chilly air into much of New England.  Scattered showers of snow, rain, sleet and freezing rain will continue across Northern New England while the remainder of the area will be cool, gray and watching for patches of ice as temperatures hover around freezing.  One to two inches of snow will fall in parts of New England - north of the MA State line - overnight Monday Night.  A strong coastal storm winds up southeast of New England Tuesday, bringing coastal wind gusts over 35 mph, the threat for midday coastal flooding, and periodic rain and snow, with a band of accumulating snow through parts of interior New England totaling an additional 1"-3"...likely extending into Eastern New England late in the day where we watch the storm closely for additional accumulation potential Tuesday evening and night.  More clouds than sun rule the extended forecast, with snow showers late Wednesday Night into Thursday Morning, and a larger storm of rain and snow Friday.

General Weather Summary:  A Canadian area of high pressure is serving as a cold air source Monday Morning, feeding chilly northeast winds southward across Eastern New England and draining cold air into most of the six-state region.  While western Vermont southward through Western Connecticut will feel the weakest effects of this cold air drainage, most locales will find temperatures holding steady through the afternoon under gray skies.  With temperatures near the freezing mark from Central MA northward, please be cautious for icy patches.  Additionally, dense fog will be slow to burn off.

The weather features on the map this Monday morning include a cold and strong area of high pressure north of New England - the source of low-level cold air that's been holding temperatures down in most of New England - and a cold frontal boundary with a developing area of low pressure moving into the Tennessee River Valley.  It will be this area of low pressure that all eyes will be focused on tonight through Tuesday night, as it interacts with copious amounts of moisture spilling north out of the Gulf of Mexico and strong coastal storm development ensues.

The ingredients certainly are in place for storm development - the aforementioned moisture and developing storm center associated with a strong bundle of upper level energy moving toward the coastline, and a large difference in temperature producing a clash of airmasses, from highs in the teens across Northern Maine on Monday to high temperatures reaching into the 60's in Southeast Pennsylvania.  Riding through this warm and moist air to our south, then directly over New England Monday night, will be a weak disturbance carrying a new shot of increased moisture.  The result will be Monday night precipitation - falling as rain in most of Southern New England, but encountering the ample supply of low-altitude cold air from near the Massachusetts state line points north, where one to two inches of snow will fall overnight Monday Night, leaving a slick commute for folks in these areas Tuesday morning.

But remember, this slick and patchy snow-covered Tuesday morning commute for the northern three states of our region will only be the initial surge of moisture riding overhead.  To the south of New England, deeper moisture will interact with the strong energetic disturbance for a rapidly strengthening coastal storm through the day on Tuesday.  Always important in these situations are the storm track and the amount of available cold air.  Both of these have been in question with this storm, and therefore, the challenges have been and continue to be considerable.  One of the inherent problems with a forecast like this, is the difficulty our guidance has in seeing and accurately handling shallow cold air like what's moving in today.  Often, this cold air is a major player in determining both storm track, and precipitation type, as the clash between incoming Gulf of Mexico moisture and warmth and this cold arctic air is critical in determining the final outcome.  At this juncture, we as a meteorological community are still striving to find points of agreement among our guidance and with the real-time, real-world weather pattern that can give us insight to the way this storm will unfold.  One fact that seems quite clear is that the storm center will pass southeast of New England, as it rides the boundary between cold and warm air.  The other is that is will be strengthening quickly as it does so, feeding off contrasting airmasses to its north and south.  The obvious result from this is wind, and a lot of it along the coastlines.  This raises a concern for coastal flooding for all east and northeast facing shorelines from the Central coast of Maine southward all the way to Nantucket, where a stiff northeast wind at 20-35 mph with gusts over 40 mph will combine with some of the highest astronomical tides of the season to produce problems at the time of a midday high tide cycle.

In addition to wind, moisture wrapping around the northern periphery of the storm center is likely to spread into New England during the day on Tuesday.  As this moisture clashes with cold and dry air still trying to build southward, a band of snow is likely to develop through interior New England - from Central and Western MA through Western and Southern ME (and including most of NH) either side of midday Tuesday.  Though removed from the storm center by hundreds of miles, these areas may pick up a couple of inches of fresh snow on Tuesday under this developing snow band.  Farther west, it's likely there will be less moisture to contend with and the influence of cold, dry Canadian air will limit amounts to below one inch, while farther east, enough warm air will be in place for precipitation to fall as rain until Tuesday afternoon.  As the storm strengthens and gradually pulls east later Tuesday, however, expect colder air to come into play with a changeover to snow around mid-afternoon working southeast from the Interstate 495 belt of interior MA to the coastline through Boston, and by Tuesday evening, to Cape Cod.  A quick burst of either side of 3" of snow would be possible after this changeover late Tuesday into Tuesday night.  It's also important to note that a significantly larger amount of precipitation is forecasted to fall just offshore, so this storm needs to be watched very carefully, as a northward jog in the track would bring more moisture into New England.

Overnight Tuesday night, as the storm pulls slowly away from New England, winds will remain active from the northwest, and cold air will infiltrate all of New England, keeping ice and snowcover on the roads in many spots.  Once this storm pulls east of Nova Scotia, faster flow in the atmosphere can take hold and a fast-moving, weak disturbance will race east into New England later Wednesday.  The result will be an increase in clouds after limited morning sunshine, with a few flurries and periods of light snow possible Wednesday night into Thursday morning.  Again, in this fast flow with the jet stream winds roaring well above our heads, expect partially clearing skies later Thursday.

By Friday, yet another disturbance will be racing eastward, but this time the jet stream winds aloft that steer our storm systems will begin to buckle southward, allowing the new storm to track southward as it crosses the Lower Mississippi River Valley early Friday.  This storm will tap moisture from the Gulf of Mexico, though its final storm track has yet to be determined - the most likely scenario would be a snow north/rain south result to start the upcoming weekend, but with plenty of storms marching across the Pacific, there's a line of storms waiting to move into the Northeast later this weekend and again early next week.

As for the remainder of February, remember what we've reviewed together in these discussions in the past - the abnormal warmth of January and the end of December has resulted in a large amount of available atmospheric energy across the United States.  And this warmth hasn't been confined only to New England - most of the nation has been abnormally warm, and therefore most of the nation houses a higher amount of available energy than would normally be present this time of the year.  Strong indications are that by the second weekend of February, a significant pattern shift will have occurred across the nation, allowing much colder air that's been locked on the opposite side of the globe and near the North Pole to spill southward into the United States.  In this transition, the available atmospheric energy will have to be expended, and large storms are likely to be the result.  The question for these will of course be storm timing and track - though with warmth bubbling up from the southeastern U.S., this does favor a track that would put New England on the snowy northern side of storms over the next couple of weeks.  Time periods that look to feature potential big bangs to usher in this new weather pattern include this coming Tuesday, then again approximately one week later, on the following Tuesday which may be a larger storm that really marks the change to a new cold and wintry pattern.  There are no guarantees and the world of the atmosphere, of course, but certainly the atmospheric signs are that February may begin with a bang, before significant cold may move in for the middle of the month.  Time will tell...

Overnight Monday Night Accumulation Map:  Accums_cne

Happy Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Monday, January 30 at 2:05 PM

Lots of weather going on, obviously, and not much time to get all of my thoughts typed out, so bear with me as I try to pack as much in as possible and will write until I'm out of time for today.

Tremendous and classic shallow cold advection example underway in NewEng today with backdoor-type front around backside of departing low pressure center.  Heart of cold air north of Maine means business in association with sfc pressure rises, but so does warmth boosting temps into 60's SW CT and NYC area.  20 degree difference in 18-20 miles along this front today.  Icy patches remain a concern thru the day in the cool air as standing water from Sun Ngt rain froze early morning with cold air moving in.  Inversion in place as a result of the shallow cold dome, tho in some cases multiple inversions existed such as Burlington, VT, who remained 1/4 mile visibility in fog for quite some time before breaking thru.  CT River Valley another example.

Warning shot fired across the bow this afternoon at coastal communities.  Minor splashover wasn't a big deal with regard to impact, but is when considered this comes with a NNE 8 knot wind, and tomorrow's wind will be closer to 30 kts with churned seas at high tide.  NWS Coastal Flood Watch for moderate flood potential certainly warranted - and while the NWS are the ones with the extensive database and correllations regarding coastal flooding, remember that a "moderate" event can have significant impacts to low-lying coastal communities and first-floor/basement businesses and residences.

Initial impulse of moisture aloft comes with a deamplifying southern stream shortwave overnight Mon Ngt and this will result in precip breaking out across interior NewEng.  Thermal profile at 850 mb begins quite diffuse and as a result, rain snow line somewhat difficult to pinpoint.  That being said, surface and low level cold is impressive and I've been going with a southern weighted blend of the major model guidance, keeping a rain/snow line very close to the northern MA state border.  North of this line, should be a uniform 1-2" for the most part - though NAM/GFS/WRF/GGEM all indicate highest amounts to be focused from Western ME to Southern ME/NH and I see no reason to argue with this, so that's where I've centered my 2" amounts.  This enhanced precip takes shape along a midlevel 700 mb thermal gradient that will be establishing and will become important later in the forecast period.  Farther south than the MA state line, a dusting is possible thru Northern, Central and Western MA as snow should be sloppier and likely to have some rain mixed in.  Some freezing rain a distinct possibility, at least early in the precip overnight, as supercooled warm rain process takes hold - that is, subfreezing temperatures are present thru the vertical column, but no temps are cold enough in the saturated layer for active ice nuclei to form, and the result is supercooled water droplets in the lower levels resulting in freezing drizzle and light freezing rain.

Coastal creature to crank up steadily and handily on Tue from 995 mb center at 12Z Tue to 975 mb center at 06Z Wed.  First and most obvious result of this will be a strengthening and expanding wind field.  Winds sustained 30 knots likely coastline from the northeast and gusts to 50 kts are possible Outer Cape, 40 kt gusts more likely to be attainable other coastal locales of Southern NewEng.  Astronomically high tide combines with these winds for coastal flood threat as mentioned above.  Winds diminish away from the coastline.

At 850 mb, and to a larger extent at 700 mb, warm advection wrapped around the northern periphery of the storm circulation will collide with cold advection from cold high in Eastern Canada that will be strengthening into Tue.  Result will be a frontogenic zone from I-91 corridor of Western MA then hooking NE across NH and into Western ME.  Initially, this feature may not be a big player, but thru the day, as midlevel convergence and thermal gradient both increase, this is likely to result in a deformation band thru these areas.  Given forecasted passage of storm well southeast of NewEng, total QPF amounts under this band would likely be held to .2"-.3" liquid equivalent, but after early rain, wind shift to north and north-northeast will allow enough cold air to move south so there locations go to all snow by early afternoon, so a couple of inches of snow a real possibility here with a fairly straight 10:1 ratio after the changeover.  Thereafter, this frontogenic band will collapse quickly to the coastline Tuesday late afternoon and evening as the deepening storm strengthens ageostrophic flow into its center and thermal profiles cool thru all layers.  I would expect this to carry a band of accumulating snow all the way to the coastline - with a changeover sooner than the ptype algorythms suggest - occurring by 00Z the latest at even BOS.  With E and NE flow still ongoing at 500 mb, result would be to keep this wraparound band of snow going longer than models are anticipating, esp for the highly populated areas of BOS and Eastern MA, and the potential looks to be there for a solid 3"-4" quick late afternoon thru Tue Midnight snowfall as temperatures drop with northerly wind.  That being said, this is largely based on instinct from looking at the synoptic potential for this wraparound quick-hitting, southeast diving band of precip whose back edge will lag behind the low level push of cold advection, and the closest model support I can find is the widespread .10" QPF fairly uniform for these areas of Eastern NH/MA and well agreed upon by the NAM and GFS.

All winds down Tuesday night and though one would think tons of cold air will be available to come rushing in behind the low, a large amount of the cold is in Eastern Canada, east of where low level trajectory will be blowing from.  Instead, we'll tap the equally cold air across James Bay, but it has farther to travel and therefore by the time it arrives we're dawning Wednesday and the result is to bring the noticeable chill mainly into Northern/Western NewEng and the hills.

With fast flow, clouds are back in with next shortwave later Wed thru Wed Ngt when some light snow is possible, tho likely mostly confined to mountains given 850 mb ridge cresting over NewEng during the same time period.  Thu brings back the sun and in this fast flow it may come back sooner than the afternoon timeframe currently depicted by the guidance, and given a low level SW flow, this would mean I'll have to raise my temps for Thu highs.

Next storm is Fri and right now I'm not optimistic on anything gargantuan with this, although I also can't say the jet stream pattern favors an all-rain scenario.  Just flat enough and fast enough that mountains and Northern NewEng may be able to hold on for a snow event.  Regardless, I think there's more to get excited about toward the beginning of next week, as discussed in last week's techie discussion.

That's all for today.  Enjoy your Monday.

Matt


Hope We All Enjoyed the Month Off...Indications Are That Winter Means Business for February

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find 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 contact@mattnoyes.net.  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 Weather Summary:  Quick Note:  I'll be out of town this weekend, so the normal Monday through Friday schedule for updates holds here - we'll pick up on Monday where we leave off today. 

After areas of black ice and a very cold start to our Friday, ample sunshine Friday morning will continue to help us rebound.  Localized areas of freezing fog in some deeper valleys will continue to burn off quickly during the morning.  While the winds at ground level will remain from a cool northwest direction, a shift to warmer winds will be underway aloft and by afternoon, this will mean a rapid increase in high and middle altitude clouds.  These clouds will be a sure sign that warmer air is returning to New Englan, and they are likely to block out the sun for the second half of the day and halt temperature rises for most areas.  By Friday night, this increase in warm and moist air will begin to reach lower altitudes, and a few light showers of rain and snow will be possible in the mountains of Northern New England.

For most communities, this increasing warmth will be felt on Saturday afternoon.  Though the leading edge to cool and dense air in Eastern Canada - a cold front - will be settling southward toward New England, many locales will find a southwest wind continuing to feed mild air northward through Saturday afternoon, and temperatures will rise into the 40's.  In fact, the potential would be there - given enough sunshine - to rise to around 50 degrees in parts of Southern New England Saturday afternoon, but tempering this warmup a bit will be cloud cover sliding southward ahead of the Canadian cold front, and limiting the amount of available sunshine.  In Northern New England, this southward sliding cold front will keep more clouds than sun locked in through most of the day with scattered showers of rain and snow a possibility throughout the day.

This cold front will dig southward through the remainder of New England Saturday night, leaving cooler air in its wake on Sunday.  Meanwhile, a small piece of the same storm that brought rain to portions of the Southwestern U.S. on Wednesday...then snows to the Rocky Mountains on Thursday...was left behind in the Western United States and will trudge east across the nation, approaching the Northeast later Sunday.  The counterclockwise flow around this storm center will tap warmth and moisture from the Gulf of Mexico, and the collision of warmth from the south, and this new cool air from the north, will spell plenty of clouds for all of New England on Sunday.  By Sunday afternoon, it's likely that these clouds will grow heavy enough with moisture to begin producing light rain and snow from west to east across at least part of the six state region.  This precipitation will fill in and become steadier and heavier Sunday night.  There will be enough of a contrast between these two airmasses to allow for a rain/snow line Sunday night, and while these can be difficult to determine even just prior to a storm, at this early juncture it appears likely that most of Northern New England will receive an accumulating snowstorm, while most of Southern New England will find a mainly rain event - but likely beginning with a burst of snow that may accumulate a few inches through the interior.

But even if this assessment is correct, snow lovers in Southern New England should not fret, because another bundle of significant Pacific energy will be moving in on the heels of the leading storm.  In the wake of Sunday night's storm, it's entirely likely that northwest winds will have dragged cold air southward across most of New England in time for the approach of the follow-up Monday night storm.  As a result, there is a much better chance of a colder, snowier storm Monday night into Tuesday.    This storm is likely to bring windswept precipitation, heavy at times, to New England later Monday through Tuesday.  While ocean waters are around and just over 40 degrees, the southern edge to a cold Canadian area of high pressure will be building southward across New England and sending cold air southward.  As the storm approaches Monday night and Tuesday, winds will come out of the northeast, tapping this nearby well of cold air, and even coastal locales excepting perhaps the South Coast would turn cold enough for significant accumulating snow.  At this point, it's still early to lay out the precise details, but a plowable snow looks like a real possibility for especially Central and Southern New England Monday night into Tuesday with a nor'easter underway.

As for the remainder of February, remember what we've reviewed together in these discussions in the past - the abnormal warmth of January and the end of December has resulted in a large amount of available atmospheric energy across the United States.  And this warmth hasn't been confined only to New England - most of the nation has been abnormally warm, and therefore most of the nation houses a higher amount of available energy than would normally be present this time of the year.  Strong indications are that by the second weekend of February, a significant pattern shift will have occurred across the nation, allowing much colder air that's been locked on the opposite side of the globe and near the North Pole to spill southward into the United States.  In this transition, the available atmospheric energy will have to be expended, and large storms are likely to be the result.  The question for these will of course be storm timing and track - though with warmth bubbling up from the southeastern U.S., this does favor a track that would put New England on the snowy northern side of storms over the next couple of weeks.  Time periods that look to feature potential big bangs to usher in this new weather pattern include this coming Tuesday, then again approximately one week later, on the following Tuesday which may be a larger storm that really marks the change to a new cold and wintry pattern.  There are no guarantees and the world of the atmosphere, of course, but certainly the atmospheric signs are that February may begin with a bang, before significant cold may move in for the middle of the month.  Time will tell...

Enjoy your weekend - see you back here and on NECN on Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Friday, January 27 at 8:15 AM

Below is a refreshed version of yesterday's discussion in case you missed it.  I'm off today but the Weather Summary above has been updated and I wanted to freshen this up for today...will be back at it on Monday.

Fri dawns with plenty of sunshine, valleys that decoupled with freezing fog see it burn quickly with diurnal heating.  Mid-level frontogenesis to occur directly over NewEng Fri afternoon as rapidly rising heights associated with sharp ridge building in from the west will be associated with rapid increase in mid-level temps and as cold air is slower to depart, elevated baroclinic zone to develop.  Sfc warmth will still lag significantly behind thanks to slower movement of sfc ridge, but warmth rushing in aloft will be responsible for rapid generation of mid and upper level cloud deck over NewEng Fri afternoon, so skies should become overcast thru the day.  This will help to temper any temperature rise as diurnal heating will be limited for the latter half of the day.  Clouds lower and thicken enuf across the Canadian border by Fri ngt with warm advection reaching lower levels of the atmosphere along with a strung out vort that whips thru aloft that it makes sense to hold chance of light snow/rain shower we've had for several days running for the North Country.  Farther south, low level baroclinic zone is more diffuse as it rolls thru and this brings little chance of precip and in fact, skies likely to be only scattered cover.  This strung out vorticity maximum really marks the beginning of faster flow - snapping through NewEng and clearing the way for a racing west to east flow.  It's this fast flow that's the reason the guidance is quicker to bring precip in on Sunday...more on that in a moment, first we have to get thru Saturday.

Saturday looks to be a fairly benign day with regard to sensible weather, though there are a few subtle details that not only are important for Saturday's forecast, but that setup the weather for the remainder of the weekend and into early next week.  The frontal boundary slides thru Northern NewEng on Sat propelled by a vort skirting across the North Country and an 850 low-level jet humming along at about 50 kts, so what seems like a benign frontal passing will likely bring strong wind-swept showers of rain and then snow squalls to follow to the mountains of Northern NewEng Sat afternoon thru eve.  Farther south into Southern and Central NewEng, front stalls as it encounters stubborn ridge off the SE US coast.  But critical to the end of weekend forecast is exactly where this front stalls, as this in conjunction with speed and amplification of approaching shortwave will determine all-important rain/snow delineation on Sunday when precip moves in.

ECMWF had been a loner with its forecast of cranking this storm up well to our west and bringing enough warm air in for a warm advection precip slug on Sunday then warm sectored into early next week but is coming around to the idea of a colder coastal scenario, which eases minds as we're now coming into an increasing agreement among the guidance on the scenario we looked at yesterday.   Developing confluent flow in Eastern Canada just north of NewEng that sets up thru the period suggests flow should be fast enough initially to pull leading vort in and probably allow it to shear a bit as it races across NewEng Sun Ngt with a slug of warm advection precip.  GFS keeps colder air in place farther S than the NAM and at this point I favor this solution, both due to the building ridge over Hudson Bay mentioned a couple of days ago, and due to the strongly confluent flow that establishes just north of NewEng and should force this front farther south.  Additionally, anticyclone building southeast through Canada is strengthening while warm anticyclone off SE US coast is retreating out to sea and weakening, also suggesting the northern high - full of cold dense air - should be able to win the battle in the lower levels, esp with the help of that confluent upper flow.  This means Sun afternoon and night precip is mainly snow in Northern NewEng and mainly rain farther South than South-Central VT to Lakes Region to Maine coast.

How this system plays out is critical to the following system for Mon Ngt and Tue.  If I was incorrect in my assessment of the Sunday shortwave, the following scenario will be incorrect, but increasing agreement on this solution has me thinking it was the right way to go.  But, the logical followup to my above thinking is that this first system races by and we're left with a break in the action before the next much stronger shortwave which will be digging and amplifying over the MS River Valley.  This next vorticity maximum and is associated area of low pressure should be significantly juicier than its predecessor, but ahead of it, the southeast migrating and still-strengthening anticyclone will be eager to throw cold air southward onto NewEng.  And why shouldn't it be able to with a northerly wind direction behind the departing dampening shortwave?  This would guarantee a farther south storm track with the Mon Ngt/Tue storm, putting most of NewEng on the cold side of the system and resulting in only coastal rain/snow issues that would have to be dealt with, though even those may be a moot point given what would be strong ageostsrophic northeast component to the wind, filtering air from a cold and strong Canadian high.  At this point, therefore, I favor a mostly snow scenario with the potential for significant windswept accumulating snow Mon Ngt/Tue with a full-fledged cranking nor'easter, but please keep in mind that this depends heavily on my idea of handling the first Sun Ngt system being correct.

As for the longer term, lots of inquiries from folks about how February is looking.  Those of you who read regularly know my thoughts on this:  The entire nation has seen above to much above normal temperatures for several weeks now, with very few exceptions.  Cold air has been situated on the opposite side of the globe, and locked at the north pole with a failure for the polar jet stream to tap this arctic supply.  In one sense, this gives the impression that winter will be a lackluster.  But in a much more important sense, this sets up a scenario where the ground, the air, the water all are filled with heat they wouldn't normally be filled with.  We know in the world of meteorology that heat is a form of energy, and furthermore, we've just watched a dazzling upper level low and associated cold pool move directly overhead with some remarkable dynamics given mild air at the surface.  It shouldn't be too much of a leap in our thinking to apply this to the bigger picture - once the jet stream pattern shifts and allows cold air to spill into the lower 48, the only way to find atmospheric equilibrium will be to reshuffle this energy, and that will have to happen in the form of storms.  Now, if this were an extended warm and DRY period, we'd be talking about a different story...but there's been no lack of moisture lately and indeed this has been a warm and moist extended period which has effectively loaded the cannon.

But the next important question is, does the jet stream ever really change?  Guidance has been wrong in the past and will be wrong in the future, but when I see every Ensemble member carving out a gargantuan trough in the US by the middle of February, that should be a first tip-off to a major change that may be in the works.  But to look at this as an ingredients-based thinking, the first step is to notice changes on the hemispheric scale.  The first shift that stands out is the breakdown of the strong upper low over Northern Russia as releases its grip and migrates east across the Eastern Asian continent.  This does a few things - first, it allows the Rex Block in place over Western Europe to release, and second, it sends a significant chunk of energy pinwheeling across the pacific during the first weekend in February.  This energy eventually hooks up with the Aleutian low, strengthening the below normal height deviations there.  This amplification of the pattern over the Aleutian Islands will force a restructuring of the longwave pattern, with a downstream amplification response in the Western US/Western Canada ridge.  In essence, this is the first step to a "build-your-own-cold-trof" recipe.  The reason I say this is because this amplification of the Western ridge will be so pronounced, that deep northerly flow will set up from the North Pole into Central Canada.  Finally, you've tapped the cold air that has been sitting across the far north, untouched for so long on this side of the Northern Hemisphere.  Of course, it doesn't all come at once, but what happens is that you bleed this cold air southward over the next two weeks in the low levels and thereby lower the heights gradually.  By somewhere around Feb 8 you've lowered heights enough that aside from the Aleutian low and associated polar vortex that's been tugged southward in response, the lowest heights in the Northern Hemisphere will be associated with the northern half of this trof...across Central and Northern Canada.  This is when we remember that the atmosphere works like a sink, and that colder air will rush to the lowest point - in this case the lowest heights.  That position will first be the polar vortex/Aleutian low, but thanks to the amplified western Canada ridge that will persist long enough for a very strong anticyclone to dominate western Canada at the surface, we'll see an additional pumping mechanism in the clockwise flow around this high pressure center to help usher not only North Pole cold, but also some Aleutian cold into our newly developing trough as well.

There should be two primary results to this:  1) Significant displacement of energy in the transition and 2) plenty of cold for the middle of February and likely beyond.  In the process of this transition, there are two time periods that are keyed in on for strong shortwaves driving in the changes to this new regime - the first shot across the bow comes Mon Ngt/Tue, and the second major shot appears to be slated for one week later.  There is enough energy present in the lower atmosphere for either of these to be very powerful storms, though if our thinking is to build our own trough the second week of February, it makes sense that the second of these storms would be the powerhouse.  And with cold air spilling in gradually and a southeast US ridge unwilling to fold, this should place the strong low level baroclinic zone south of NewEng with ample moisture available, which means substantial snow events will be of concern during this two week transition period.

Have a great weekend!

Matt


Milder Air En Route...February Holds Strong Wintry Potential

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find 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 contact@mattnoyes.net.  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 Weather Summary:  The much advertised Norlun Trough described in these discussions over the last few days brought thin, localized bands of quickly accumulating snow to the Central Maine coastline yesterday between Casco and Penobscot Bay.  Thursday morning featued a southward progression and revival of this trough - a weakness in the atmosphere that brings a wind shift and helps to focus precipitation - and this brought a quick and fluffy one to two inch accumulation to immediate coastal locales from extreme Southern Maine to Cape Cod.  As this trough moves southward, so too goes the thin band of accumulating snow.  The general rule for New England Thursday brings sunny breaks interrupted by scattered snow showers and locally heavier squalls - especially through midday - then a gradually drying atmosphere to yield increasing sunshine and fewer snowflakes.  The driving force for today's snow showers continues to be an upper level storm - a pool of cold air aloft that results in a big temperature difference contrasted to the relatively mild surface temperatures - that is now pulling away from New England.  This large vertical difference in temperature creates favorable conditions for clouds and precipitation - called "instability" in the world of meteorology - and this is the reason snow showers remain in the forecast for most of New England through midday, in between breaks of sunshine.  Thereafter, drier air ushered in on an active northwest wind gusting up to 40 mph at times, will combine with warming temperatures aloft (less instability) to squash the snow showers in most areas except the Green Mountains and Berkshires, where another few fresh inches of snow will fall Thursday.  With high temperatures only in the 20's north and 30's south, winds of this magnitude will bring wind chill values into the 10's and 20's respectively - a bit of a bite, for sure!

The active winds across New England will only gradually slacken overnight Thursday night, even as temperatures drop into the single digits and teens, which means wind chill values are likely to drop below zero.  With dry air continuing its push into New England and a bubble of high pressure - fair weather - building in from the west, remaining snow showers in the mountains of Northern and Western New England will draw to a close.  Black ice will be a threat across all of New England, as melting snow refreezes on roadways during the overnight.

The workweek rounds out on Friday with a sunny start for all of New England, excepting localized areas of freezing fog in some deeper valleys that will burn off quickly during the morning.  While the winds at ground level will remain from a cool northwest direction, a shift to warmer winds will be underway aloft.  By afternoon, this will mean a rapid increase in high and middle altitude clouds Friday afternoon, blocking out the sun for the second half of the day and halting temperature rises for most areas.  By Friday night, this increase in warm and moist air will begin to reach lower altitudes, and a few light showers of rain and snow will be possible in the mountains of Northern New England.

Friday afternoon and night's increased cloud cover will serve as a sure sign that warmer air is rebounding into New England, and the effects will be felt on Saturday for most communities.  Though the leading edge to cool and dense air in Eastern Canada - a cold front - will be settling southward toward New England, many locales will find a southwest wind continuing to feed mild air northward through Saturday afternoon, and temperatures will rise well into the 40's.  In fact, the potential is there - given enough sunshine - to rise near and over 50 degrees in Southern New England Saturday afternoon, but tempering this warmup a bit will be cloud cover sliding southward ahead of the Canadian cold front, and limiting the amount of available sunshine.  In Northern New England, this southward sliding cold front will keep clouds locked in through most of the day with scattered showers of rain and snow a possibility throughout the day.

This cold front will dig southward through the remainder of New England Saturday night, leaving cooler air in its wake on Sunday.  Meanwhile, a small piece of the same storm that brought rain to portions of the Southwestern U.S. on Wednesday...then snows to the Rocky Mountains on Thursday...was left behind in the Western United States and will trudge east across the nation, approaching the Northeast later Sunday.  The counterclockwise flow around this storm center will tap warmth and moisture from the Gulf of Mexico, and the collision of warmth from the south, and this new cool air from the north, will spell plenty of clouds for all of New England on Sunday.  By Sunday afternoon, it's likely that these clouds will grow heavy enough with moisture to begin producing light rain and snow from west to east across at least part of the six state region.  This precipitation will fill in and become steadier and heavier Sunday night.  There will be enough of a contrast between these two airmasses to allow for a rain/snow line Sunday night, and while these can be difficult to determine even just prior to a storm, at this early juncture it appears likely that most of Northern New England will receive a significant snowstorm, while most of Southern New England will find a mainly rain event - possibly beginning with a burst of snow through the interior.

But even if this assessment is correct, snow lovers in Southern New England should not fret, because another bundle of significant Pacific energy will be moving in on the heels of the leading storm.  In the wake of Sunday night's storm, it's entirely likely that northwest winds will have dragged cold air southward across most of New England in time for the approach of the follow-up Monday night storm.  As a result, there is a much better chance of a colder, snowier storm Monday night into Tuesday.

As for the remainder of February, remember what we've reviewed together in these discussions in the past - the abnormal warmth of January and the end of December has resulted in a large amount of available atmospheric energy across the United States.  And this warmth hasn't been confined only to New England - most of the nation has been abnormally warm, and therefore most of the nation houses a higher amount of available energy than would normally be present this time of the year.  Strong indications are that by the second weekend of February, a significant pattern shift will have occurred across the nation, allowing much colder air that's been locked on the opposite side of the globe and near the North Pole to spill southward into the United States.  In this transition, the available atmospheric energy will have to be expended, and large storms are likely to be the result.  The question for these will of course be storm track - though with warmth bubbling up from the southeastern U.S., this does favor a track that would put New England on the snowy northern side of storms over the next couple of weeks.  No guarantees, but certainly the atmospheric signs are that February may begin with a bang, before significant cold may move in for the middle of the month.  Time will tell...

Have a great day!

Matt

Matt's Technical Meteorological Discussion:  Updated Thursday, January 26 at 2:30 PM

Lowering RH and drying/stabilizing downslope flow helping out most of NewEng today tho upslope flow keeps snow showers going Northern VT, Green Mountains, Berkshires and Whites.  Some lake enhancement with low level funneled N wind down Champlain Valley and over the lake, and some ocean effect flurries evident on Cape Cod behind morning trof.  As drier air and subsidence take hold from building sfc ridge in from the west, most convective activity will be squashed and trend will be for skies to clear into Thu Ngt.

Breezes stay active overnight which keeps min temps from bottoming out as low as dewpoint would indicate except in deepest and most sheltered valleys, esp of Northern NewEng.  Wind chills should mostly be below zero overnight with wind 10-20 mph from NW and melted snow on roads and walkways refreezes for black ice.

Fri dawns with plenty of sunshine, tho aforementioned valleys that can decouple will see freezing fog that will burn quickly with diurnal heating.  Mid-level frontogenesis to occur directly over NewEng Fri afternoon as rapidly rising heights associated with sharp ridge building in from the west will be associated with rapid increase in mid-level temps and as cold air is slower to depart, elevated baroclinic zone to develop.  Sfc warmth will still lag significantly behind thanks to slower movement of sfc ridge, but warmth rushing in aloft will be responsible for rapid generation of mid and upper level cloud deck over NewEng Fri afternoon, so skies should become overcast thru the day.  This will help to temper any temperature rise as diurnal heating will be limited for the latter half of the day.  Clouds lower and thicken enuf by Fri ngt with warm advection reaching lower levels of the atmosphere along with a strung out vort that whips thru aloft that it makes sense to hold chance of light snow/rain shower we've had for several days running for the North Country.  Farther south, low level baroclinic zone is more diffuse as it rolls thru and this brings little chance of precip.  This strung out vorticity maximum really marks the beginning of faster flow - snapping through NewEng and clearing the way for a racing west to east flow.  It's this fast flow that's the reason the guidance is quicker to bring precip in on Sunday...more on that in a moment, first we have to get thru Saturday.

Saturday looks to be a fairly benign day with regard to sensible weather, though there are a few subtle details that not only are important for Saturday's forecast, but that setup the weather for the remainder of the weekend and into early next week.  The frontal boundary slides thru Northern NewEng on Sat propelled by a vort skirting across the North Country and an 850 low-level jet humming along at about 50 kts, so what seems like a benign frontal passing will likely bring strong wind-swept showers of rain and then snow squalls to follow to the mountains of Northern NewEng Sat afternoon thru eve.  Farther south into Southern and Central NewEng, front stalls as it encounters stubborn ridge off the SE US coast.  But critical to the end of weekend forecast is exactly where this front stalls, as this in conjunction with speed and amplification of approaching shortwave will determine all-important rain/snow delineation on Sunday when precip moves in.

ECMWF has been a loner with its forecast of cranking this storm up well to our west and bringing enough warm air in for a warm advection precip slug on Sunday then warm sectored into early next week.  This doesn't mean it's incorrect, though developing confluent flow in Eastern Canada just north of NewEng that sets up thru the period suggests flow should be fast enough initially to pull leading vort in and probably allow it to shear a bit as it races across NewEng Sun Ngt with a slug of warm advection precip.  GFS keeps colder air in place farther S than the NAM and at this point I favor this solution, both due to the building ridge over Hudson Bay mentioned a couple of days ago, and due to the strongly confluent flow that establishes just north of NewEng and should force this front farther south.  Additionally, anticyclone building southeast through Canada is strengthening while warm anticyclone off SE US coast is retreating out to sea and weakening, also suggesting the northern high - full of cold dense air - should be able to win the battle in the lower levels, esp with the help of that confluent upper flow.  This means Sun afternoon and night precip is mainly snow in Northern NewEng and mainly rain farther South than South-Central VT to Lakes Region to Maine coast.

How this system plays out is critical to the following system for Mon Ngt and Tue.  If I'm incorrect in my assessment of the Sunday shortwave and the ECMWF is correct, the following scenario will be incorrect.  But, the logical followup to my above thinking is that this first system races by and we're left with a break in the action before the next much stronger shortwave which will be digging and amplifying over the MS River Valley.  This next vorticity maximum and is associated area of low pressure should be significantly juicier than its predecessor, but ahead of it, the southeast migrating and still-strengthening anticyclone will be eager to throw cold air southward onto NewEng.  And why shouldn't it be able to with a northerly wind direction behind the departing dampening shortwave?  This would guarantee a farther south storm track with the Mon Ngt/Tue storm, putting most of NewEng on the cold side of the system and resulting in only coastal rain/snow issues that would have to be dealt with, though even those may be a moot point given what would be strong ageostsrophic northeast component to the wind, filtering air from a cold and strong Canadian high.  At this point, therefore, I favor a mostly snow scenario with the potential for significant accumulating snow Mon Ngt/Tue, but please keep in mind that this depends heavily on my idea of handling the first Sun Ngt system being correct.

As for the longer term, lots of inquiries from folks about how February is looking.  Those of you who read regularly know my thoughts on this:  The entire nation has seen above to much above normal temperatures for several weeks now, with very few exceptions.  Cold air has been situated on the opposite side of the globe, and locked at the north pole with a failure for the polar jet stream to tap this arctic supply.  In one sense, this gives the impression that winter will be a lackluster.  But in a much more important sense, this sets up a scenario where the ground, the air, the water all are filled with heat they wouldn't normally be filled with.  We know in the world of meteorology that heat is a form of energy, and furthermore, we've just watched a dazzling upper level low and associated cold pool move directly overhead with some remarkable dynamics given mild air at the surface.  It shouldn't be too much of a leap in our thinking to apply this to the bigger picture - once the jet stream pattern shifts and allows cold air to spill into the lower 48, the only way to find atmospheric equilibrium will be to reshuffle this energy, and that will have to happen in the form of storms.  Now, if this were an extended warm and DRY period, we'd be talking about a different story...but there's been no lack of moisture lately and indeed this has been a warm and moist extended period which has effectively loaded the cannon.

But the next important question is, does the jet stream ever really change?  Guidance has been wrong in the past and will be wrong in the future, but when I see every Ensemble member carving out a gargantuan trough in the US by the middle of February, that should be a first tip-off to a major change that may be in the works.  But to look at this as an ingredients-based thinking, the first step is to notice changes on the hemispheric scale.  The first shift that stands out is the breakdown of the strong upper low over Northern Russia as releases its grip and migrates east across the Eastern Asian continent.  This does a few things - first, it allows the Rex Block in place over Western Europe to release, and second, it sends a significant chunk of energy pinwheeling across the pacific during the first weekend in February.  This energy eventually hooks up with the Aleutian low, strengthening the below normal height deviations there.  This amplification of the pattern over the Aleutian Islands will force a restructuring of the longwave pattern, with a downstream amplification response in the Western US/Western Canada ridge.  In essence, this is the first step to a "build-your-own-cold-trof" recipe.  The reason I say this is because this amplification of the Western ridge will be so pronounced, that deep northerly flow will set up from the North Pole into Central Canada.  Finally, you've tapped the cold air that has been sitting across the far north, untouched for so long on this side of the Northern Hemisphere.  Of course, it doesn't all come at once, but what happens is that you bleed this cold air southward over the next two weeks in the low levels and thereby lower the heights gradually.  By somewhere around Feb 8 you've lowered heights enough that aside from the Aleutian low and associated polar vortex that's been tugged southward in response, the lowest heights in the Northern Hemisphere will be associated with the northern half of this trof...across Central and Northern Canada.  This is when we remember that the atmosphere works like a sink, and that colder air will rush to the lowest point - in this case the lowest heights.  That position will first be the polar vortex/Aleutian low, but thanks to the amplified western Canada ridge that will persist long enough for a very strong anticyclone to dominate western Canada at the surface, we'll see an additional pumping mechanism in the clockwise flow around this high pressure center to help usher not only North Pole cold, but also some Aleutian cold into our newly developing trough as well.

There should be two primary results to this:  1) Significant displacement of energy in the transition and 2) plenty of cold for the middle of February and likely beyond.  In the process of this transition, there are two time periods that are keyed in on for strong shortwaves driving in the changes to this new regime - the first shot across the bow comes Mon Ngt/Tue, and the second major shot appears to be slated for one week later.  There is enough energy present in the lower atmosphere for either of these to be very powerful storms, though if our thinking is to build our own trough the second week of February, it makes sense that the second of these storms would be the powerhouse.  And with cold air spilling in gradually and a southeast US ridge unwilling to fold, this should place the strong low level baroclinic zone south of NewEng with ample moisture available, which means substantial snow events will be of concern during this two week transition period.

Have a great Thursday.

Matt


Norlun Trough Snows Setup in Central Maine Coast...Slightly Offshore...Scattered Snow Showers and Squalls Elsewhere

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find 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 contact@mattnoyes.net.  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 Weather Summary:  Quite a test from nature today across New England.  The strong upper level storm system we've been watching together for the past few days is moving into New England and brought morning squalls to many areas.  Now, drier air has moved into New England and has brought the sunshine out for many communities, though there are some important exceptions to the rule.  Along the Berkshires and the spine of the Green Mountains, westerly winds pushing up against the mountainfaces are resulting in bands of snow that will accumulate for these mountain communities.  You can follow these bands of snow by watching the radar, linked from my main webpage.  The other exception is along the coast of Maine, where the much advertised "Norlun Trough" (see yesterday's discussion for a more detailed explanation of the Norlun Trough) has developed between Casco and Penobscot Bays, centered over coastal Knox and Lincoln Counties.  This trough has mostly developed offshore, and that's where a large area of heavy snow will fall, but the northern edge of this heavier snow will continue backing into these coastal locales.  Due to the localized nature of these bands, it's strongly encouraged that Coastal Maine residents also monitor radar imagery.  Elsewhere in New England, the upper level pattern is a cold and wintry looking one, while the surface pattern will remain rather mild and allow temperatures to rise into the middle and upper 30's.  When we see a mismatched atmosphere like this, the result is always that air has to move - either horizontally (wind) or vertically (clouds and precipitation).  In this case, a large amount of the atmosphere's energy will likely go into creating scattered snow showers and heavier snow squalls Wednesday afternoon - with a presentation very similar to summertime scattered showers and thunderstorms.  With most areas above freezing, this will help to mitigate icing potential on roadways, but in heavier squalls, brief icing will remain possible.

With a persistent flow of northwest winds Wednesday night - and a steady stream of disturbances caught in the jet stream winds aloft, diving from Canada and settling into the slow and energetic disturbance that will be prodding east of New England while bringing continued snow showers and squalls to the mountains - cold air situated in Central Canada will finally be tapped, and begin to charge southeast.  By Thursday morning, expect the cold air to be moving into place here at ground level, as it catches up with the precursor wintry cold pattern aloft.  Thursday will begin with lots of clouds and continuing snow showers in the mountains, though most of New England will break out sunshine during the day.  By far, the biggest weather feature for Thursday will be the active northwest wind, which will be sustained up to 30 mph at times and is likely to gust to 35 or 40 mph, especially on hilltops and along the coastal plain.

The workweek rounds out on Friday with a blend of sun and clouds for the daylight hours as New England finds ourselves sandwiched between the large and energetic storm departing slowly to our east, and a new bundle of energy the jet stream winds will be driving in our direction from the Central Plains.  This new disturbance will spread clouds and precipitation over New England Friday evening and night, as a slug of warmth and moisture riding northward in the counterclockwise airflow around this approaching disturbance clashes with the cool air that will already be in place in New England, resulting in a few Friday night snow and rain showers, primarily in the mountains and across the North Country.

The upcoming weekend is likely to begin rather benign on Saturday, though a cold front will be sinking southward out of Canada and into Northern New England.  This cold front will be important for a few reasons - 1) It will bring lots of clouds to New England on Saturday morning, then slide those clouds southward through the rest of New England later in the day, 2) It may come accompanied by additional Saturday morning rain and snow showers across Northern New England, 3) It will mark the leading edge to cooler air settling into our area.  Though it's still somewhat uncertain just how far south this cold front settles by Sunday, it appears to me that it is likely to push completely through New England Saturday night.  Meanwhile, a strong bundle of energy associated with a storm currently bringing rains to the Southwestern U.S. will be moving east across the nation.  Ahead of this disturbance, caught in the counter-clockwise flow of air, will be a flow of warm air moving north toward New England on southerly winds.  The most likely scenario is for this incoming warm air to collide with the cold air that will have just settled over our region, and the result will be increasing and thickening clouds on Sunday.  By Sunday evening, it appears right now that snow will develop across New England from southwest to northeast.  With plenty of warmth and moisture streaming into New England determining the progression of a rain/snow line is difficult this far out.  Regardless, the pattern at this point seems to feature a mostly snow event for the mountains of Northern New England, and likely a snow to rain event for interior Southern New England.  But remember, it's early and we'll see how this evolves.

Happy Hump Day!

Technical Discussion:  Far behind today, so will have to pass, but tomorrow looks more promising...

Matt


Arctic Squalls for Most of New England Tuesday Night...Norlun Trough Likely to Bring Seacoast Snowstorm Wednesday

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find 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 contact@mattnoyes.net.  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 Weather Summary:  Tuesday dawned with a blend of mountain clouds, sunshine and widespread black ice, though with the help of sun and a light southwest wind, temperatures will rise above freezing in most communities during the afternoon.  While the day will be quiet, the atmosphere is in a state of flux.  A strong disturbance dropping through South-Central Canada is racing east-southeast toward New England, and is strengthening as it makes the trip.  This upper level storm - a strong bundle of energy driven by the jet stream winds aloft that steer our storms - will bring with it plenty of cold air thousands of feet above our heads.  At ground level, however, cold air will be lacking, and by later Tuesday, this difference between warm ground and cold sky will begin to manifest itself as a developing area of low pressure at the surface over the Eastern Great Lakes, poised to drag an attendant front across New England Tuesday night.

Expect clouds to build later Tuesday afternoon ahead of the storm, and as the cold air associated with this system high in the sky moves overhead, snow showers and heavier snow squalls will develop from west to east across New England Tuesday evening and night.  Some of these squalls will drop a quick couple of inches of snow, and will create some snow-covered and slippery spots for Wednesday morning's commute.  Though there's not a lot of moisture forecasted to fall with this disturbance, the cold air aloft combined with warmer air in the lower levels of the atmosphere will be the perfect setup for big, quickly accumulating snowflakes, which will allow fluffy snow to pile up quickly.  Please see accumulation maps at the bottom of this discussion for forecasted amounts by Wednesday 8 AM - NOT including Wednesday snowfall (read on...).

Wednesday's forecast is a tricky and intriguing one - as it features an attempt to match an upper level pattern and surface pattern that just don't seem to go well together.  By that, I mean the upper level pattern is a cold and wintry looking one, while the surface pattern will remain rather mild and allow temperatures to rise into the middle and upper 30's.  When we see a mismatched atmosphere like this, the result is always that air has to move - either horizontally (wind) or vertically (clouds and precipitation).  In this case, while localized breezes may be gusty, a large amount of the atmosphere's energy will likely go into creating scattered snow showers and heavier snow squalls.  In addition, the front that will have swung through New England Tuesday night will be stalling on top of us and beginning to fade - but still helping to focus precipitation as it extends from the White Mountains to a developing area of low pressure in the Gulf of Maine.  With relatively mild air at the surface and cold air aloft, plenty of "instability" - favorable conditions for clouds and precipitation - will be in place across New England, and this dying front will act as an infrequently seen "Norlun Trough" - a disturbance that can create localized bands of persistent accumulating snow along them - specifically from South Coastal Maine to South Coastal New Hampshire on Wednesday.  In these locales - and, of course, we'll need to monitor this closely for Northeastern MA - we'll find additional accumulations of snow through the day Wednesday and total storm accumulations of Tuesday night and this extra snow Wednesday may exceed half a foot anywhere between Portland and Salisbury - wherever this localized band of snow sets up.  Elsewhere, snow showers will continue to bring scattered fresh coatings through the day, which may keep some roads slippery even after recovering from the early morning snows.

With a persistent flow of northwest winds Wednesday night - and a steady stream of disturbances caught in the jet stream winds aloft, diving from Canada and settling into the slow and energetic disturbance that will be prodding east of New England - cold air situated in Central Canada will finally be tapped, and begin to charge southeast.  By Thursday morning, expect the cold air to be moving into place here at ground level, as it catches up with the precursor wintry cold pattern aloft.  Most of Thursday will bring lots of clouds, some sunshine, and scattered snow showers with an active northwest wind.

The workweek rounds out with a blend of sun and clouds for the daylight hours as New England finds ourselves sandwiched between the large and energetic storm departing slowly to our east, and a new bundle of energy the jet stream winds will be driving in our direction from the Central Plains.  This new disturbance will spread clouds and precipitation over New England Friday evening and night, as a slug of warmth and moisture riding northward in the counterclockwise airflow around this approaching disturbance clashes with the cool air that will already be in place in New England, resulting in a period of Friday night snow and rain.

The upcoming weekend is likely to begin rather benign on Saturday, but will feature a stronger storm developing to our west, and likely moving into New England by late Sunday and into Monday.  This one may be a moisture-loaded system, and there are still large questions looming on how quickly a cold front situated north of New England plows through - if it comes through soon enough and before the storm, we'll be talking about an accumulating snow event, which is a real possibility, so it's one I'll likely focus on more as the week progresses.

Make it a great Tuesday.

Accums_sne_2 Accums_nne

Matt

Matt's Technical Meteorological Discussion:  Updated Tuesday, January 24 at 1:25 PM

Inversion well established Tue AM across NewEng will have an uphill battle to mix out with very little wind as sfc ridge moves overhead.  Diurnal heating will create thermals and help to create some mixing, though fresh snowpack will limit these effects as well, and have gone close to NAM MOS for today's temps...well below GFS MOS numbers.

SW wind picks up a bit later in the day ahead of extremely impressive vortex dropping across the Great Lakes.  Satellite presentation is excellent with this upper level disturbance and spokes of abundant energy have been interacting with low level moisture - some lake enhancement, too - to create bands of convective snow across the Great Lakes.  As this upper level low pinwheels east, a tremendous amount of vorticity and associated upper level cold pool will migrate over NewEng tonight thru Thu, and this will bring truly intriguing weather across all six states.  The best way to think about just how crazy this weather is going to be is to realize that the upper and lower levels of the atmosphere simply aren't going to match up beginning tonight - that is, 500 mb temps to -37 C (truly winter air) moves in aloft, while 850 mb temps closer to -8 C and boundary layer temps in the +0's C are going to make for a tremendously steep lapse rate in the lower and middle levels.  As an example, 850 to 500 mb temp diff described above brings widespread lapse rates of 7.7 C/km beginning Tue ngt and lasting thru Wed.  As far as the atmosphere goes, this is a powderkeg of instability.

Surface reflection of upper level storm moves east into Tue Ngt and thrusts associated occluded front east thru NY state Tue eve and into NewEng mainly after midnight Tue Ngt from W to E.  Normally in a situation like this, one would expect to see an arctic front driven in association with a disturbance of this magnitude, but the abnormal warmth of Central and Western Canada has prohibited a strong release of cold air, and instead the deep cold that was in place over the Upper Midwest on Monday has been thrust northeast into Eastern Canada, and while it will be available to pull down by the end of the week, that will only come after persistent NW and Nly flow tugs at it long enough.  In the meantime, it's a rare and meteorologically active combination of cold air aloft and energy normally associated with the leading edge to an arctic outbreak, but we're going to sit it on top of an airmass that's still abnormally warm and moist.  There are two basic parameters that govern meteorology that we learn about early in meteorological coursework - one is airmasses, and the other is energy.  In this case, we have a vertical clash of airmasses, AND we have plenty of energy.  Not just cyclonic vorticity advecting in, but also the energy present through the warmth and moisture in the lower levels.  This will create a tongue of CAPE (convective available potential energy) in Eastern New England, and eventually that will be an important ingredient in what may wind up being a localized snowstorm for Southern Maine, Coastal NH and perhaps extreme NE MA...more on that below.

But first we need to tackle the cyclonic vorticity advection and attendant occluded front for the overnight.  QPF amounts that were varying between guidance have come closer in line with a general .10-.25" of QPF expected for overnight Tue Ngt, and this looks reasonable given: a) upstream activity, b) amount of energy involved, c) warm and moist Theta-E tongue and positive theta-e advection that occurs ahead of trough axis.  But caution must be exercised here by meteorologists and weather enthusiasts alike.  Greatest upward vertical motion coincides nearly perfectly with a thermal profile favoring dendritic crystal growth in the midlevels, followed by subfreezing but sufficiently warmer temperatures in the lower levels for aggregates to develop as dendritic crystals will develop sticky ends and form large, quickly and nearly ideally accumulating snowflakes.  The ratio, therefore, is likely to be closer to 18 and even in some spots greater than 20:1 with this event - excepting Southern CT, Providence, RI to Duxbury, MA, points south where profile warm enough for mix or even all rain event.  Elsewhere, fluff factor to be an issue, but equally important and not to be overlooked with this event is the intensity at which snow will fall.  The rate of snow will be for these 2, 3 and 4" amounts to fall after midnight Tuesday night - and in most areas during the predawn hours.  This will be too fast for road crews to keep up in many areas, and it will take awhile to catch up.

This occluded front begins to lose its frontal characteristics during the day Wednesday as it encounters easterly flow ahead of it around a developing low pressure center over the Eastern Gulf of Maine.  But what this occluded front does not lose is its ability to enhance low level convergence.  Feeding off the available CAPE, and interacting with the very steep lapse rates, this setup will favor the development of a Norlun Instability Trough.  These events are notorious for providing an outlet for available CAPE by creating a path of surface and low level convergence, and with moist east and northeast flow ahead of the trough, most often the heavy precip will occur along and east of the trough axis.  As mentioned above, profiles will favor quickly accumulating snowflakes with high ratio, and given the amount of deep instability in the atmosphere, I wouldn't be surprised if model QPF is too low - at least in the case of the NAM...the GFS with .75 to 1.0" under the center of this band is probably closer.  Coupled with high ratios, I don't need to tell you the amounts this could result in.  Now is when the difficult part comes into play - placing the band.  I've seen these events work out wonderfully, and I've seen these events end up verifying beautifully just 20 miles offshore where the fish get a great snowstorm.  The trick here is from a scientific perspective is to key in on where the synoptic scenario would favor placement of the trough, and from a broadcasting/public dissemination perspective the key is to leave the door open for surrounding areas and afford the public the opportunity to know there's going to be some high intensity snow that will persist through most of the day, but uncertainty is present and this MUST be conveyed to the public given the high stakes to the forecast.  The best position estimate is to line the trough up under the upper level low as the surface weakness will be driven by the upper level cold pool resulting in enhanced vertical motion, and this should lay across the NH seacoast, placing the persistent band of snow from the north shore of MA through the South Coast of ME.  Heaviest amounts under the band should total over 6", and if all plays out right it would be much higher than that, but there is a great risk to the forecast with the public if this thing goes offshore, so the best bet seems to be to hit that over 6" mark and convey the point that it will be a significant event without going overboard.

Elsewhere, scattered snow showers and heavier squalls are just about a given thanks to the lapse rates, upper low and available surface moisture and warmth.  Icy road conditions will recur during the day as a result.  Some mountain locales will continue to pile up signficant amounts, but this will be largely orographically and convectively driven and are nearly impossible to pinpoint.

Cold air will finally be on the move at the surface Wed Ngt, though now even slower in the progs and just ready to move into Northern NewEng Thu AM.  I haven't raised temps yet as cold advection does begin in earnest Thu AM and falling temps thru the day not impossible, tho I'll likely have to bump temps up just slightly tomorrow.

Cold stays with us on Fri as ridge prepares to crest overhead, then behind ridge axis I'm still carrying clouds and chance light precip Fri Ngt as warmth returns aloft along with weak vort embedded in the flow.  Behind this, it makes sense to bring warmth back in on Sat - there is an impending arctic front pushing toward NewEng but agreement almost across the board favors bringing this front thru later Sat or Sat Eve so will follow this solution appropriately and bring increasing SW wind Sat to help boost temps up ahead of frontal boundary, then cold air arrives Sun.

This sets up a quandry for Sunday/Monday, doesn't it, when next storm is set to move thru and question becomes to rain or to snow?  My take on it is that we're dealing with a well defined shortwave trough that comes thru in NW flow Sat.  Though the trough will naturally deamplify as it encounters confluent flow, the air behind it is cold to the tune of -15 to -18 C at 850 mb.  I don't think we'll see a direct transfer of this air behind the shortwave, but an 850 mb ridge builds over Hudson Bay Sat Ngt into Sun AM behind this trof as it moves over NewEng, and this should serve to enhance northwest flow urging cold air to filter southeast toward NewEng.  Therefore, right now I'm thinking the push of cold will be a bit deeper and colder than forecasted currently.  Not A LOT deeper and colder, but enough so that the next storm for Sun eve into Mon is going to be a snowy problem at least to start for Southern NewEng before a changeover, and likely a mostly snow event for the mountains.  The next few days will, of course, be crucial in determining just how cold that Central Canadian air will be, and whether my idea of carrying deeper cold will be fortified by successive model runs.

That's all for today.  Good luck with your forecasts.

Matt


Winter Storm Ending...Midweek Squalls Precede Cold Shot

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find 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 contact@mattnoyes.net.  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 Weather Summary:  The fast-moving but intense storm that brought a quick half foot or more of snow to much of Massachusetts continues to race northeast and away from New England.  The snows associated with this storm were the result of warm and moist tropical air being swept northward in advance of the storm, colliding with the cold air in the lower levels that was in place across New England.  As the storm moves east, so too does the intense snow banding, moving through the Maine coastline through Monday evening while the remainder of New England gradually dries out.

With a relatively mild airmass - at least by January standards - left in this storm's wake, Southern and Western New England will climb above freezing as the precipitation draws to a close with snow tapering to light rain and flurries, then eventually patchy drizzle by Monday evening.  Overnight Monday night, skies will only slowly clear, and with temperatures dropping well below freezing - into the teens and twenties - treated and plowed roadways that melted during the day will refreeze overnight for widespread slippery driving conditons.

Expect Tuesday to begin with sunshine, though the atmosphere will be in a state of flux.  A strong disturbance dropping through South-Central Canada will be racing east-southeast toward New England, but will be strengthening as it makes the trip.  This upper level storm - a strong bundle of energy driven by the jet stream winds aloft that steer our storms - will bring with it plenty of cold air thousands of feet above our heads.  At ground level, however, cold air will be lacking, and by later Tuesday, this difference between warm ground and cold sky will begin to manifest itself as a developing area of low pressure at the surface, poised to cross New England Tuesday night.

Breezes will increase from the southwest ahead of this developing surface low pressure center, and expect clouds to build later Tuesday afternoon ahead of the storm.  As the cold air associated with this system high in the sky moves overhead. snow showers and heavier snow squalls will develop from west to east across New England Tuesday evening and night.  Some of these squalls will drop a quick couple of inches of snow, especially across hilly and mountainous terrain, and will create some snow-covered and slippery spots for Wednesday morning's commute.

Wednesday's forecast is a tricky and intriguing one - as it features an attempt to match an upper level pattern and surface pattern that just don't seem to go well together.  By that, I mean the upper level pattern is a cold and wintry looking one, while the surface pattern will remain rather mild and allow temperatures to rise into the middle and upper 30's.  Winds will be gusty, and this difference in airmass from surface to jet stream level will likely mean more snow showers and heavier squalls on Wednesday.

With a persistent flow of northwest winds Wednesday and Wednesday night - and a steady stream of disturbances caught in the jet stream winds aloft, diving from Canada and settling into the slow and energetic disturbance that will be prodding east of New England, cold air situated in Central Canada will finally be tapped, and begin to charge southeast.  By Thursday morning, expect the cold air to be in place here at ground level, as well, as it catches up with the precursor wintry cold pattern aloft.  Most of Thursday will bring lots of clouds, some sunshine, and scattered snow showers.

The workweek rounds out with a blend of sun and clouds for the daylight hours as New England finds ourselves sandwiched between the large and energetic storm departing slowly to our east, and a new bundle of energy the jet stream winds will be driving in our direction from the Central Plains.  This new disturbance will spread clouds and precipitation over New England Friday evening and night, as a slug of warmth and moisture riding northward in the counterclockwise airflow around this approaching disturbance clashes with the cool air that will already be in place in New England, resulting in a period of Friday night snow and rain.

The upcoming weekend is likely to feature a stronger storm - likely moving into New England by Sunday - and this one may be a moisture-loaded system, so it's one I'll likely focus on more as the week progresses.

Have a wonderful remainder of your Monday, and many thanks again to all of you who sent me your observations and weather reports for today's storm.

Technical Discussion:  None today.  Should resume Tuesday.

Accumulation Maps:

Accums_ern_ma_3 Accums_ct_wrn_ma_2 Accums_vt_nh_wrn_me_6 Accums_me_5

-Matt


Breezy and Mild Weather to Cool Down...Northern Wintry Mix Falls Late Tonight and Saturday

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find 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 contact@mattnoyes.net.  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 Weather Summary:  A mild start Friday morning will provide a platform to build from as the day progresses, and even with fading sunshine, temperatures should still climb into the upper 40's in Southern New England by day's end.  This comes as a continued southwest wind ushers in the northern edge of a warmer airmass laid across the Southeastern quarter of the nation, and with the change in airmass, expect morning sunshine to fade behind increasing afternoon clouds, and the end of our Friday will be overcast, with a few flurries and sprinkles continuing in the mountainous terrain as a weak disturbance at the jet stream level moves across Northern New England, dragging an associated surface cold front very gently southward across the North Country.

There's more than meets the eye, however, to this scenario.  The combination of this southward ooze of cold air into New England from Canada, and the northward nudge of warmth nosing into Southern New England later Friday, will help to set the stage for storm development - establishing a sharp contrast in airmasses over our six-state region.  In fact, the cold air oozing southward is part of an airmass that's meant business - a chunk of this air that has been pouring into the Northern Tier of the United States has brought low temperatures below zero in the Upper Midwest and Upper Great Lakes, as well as across Southern Canada!  Remember that storms feed off of a temperature contrast like this, and energetic disturbances, when moving through sharply contrasting temperatures, can result in storm formation.  With our active weather pattern, there's no shortage of these energetic disturbances sweeping east, caught in the jet stream winds aloft, and another of these disturbances will eject from the Midwest and across the Ohio Valley Friday night.

Ahead of the incoming disturbance, winds aloft will increase from the southwest, carrying a continued supply of warm and moist air toward New England.  Remember, however, that colder air will be draining into the North Country, and this process of gliding warm air over a cold dome is the perfect scenario for clouds and precipitation.  My expectation, therefore, is for precipitation to develop on the cool side of this temperature boundary on Friday night - Northern VT, NH and Central and Northern ME - and the air in these northern locales will likely be just cold enough for a borderline event, with precipitation to begin falling as rain in many areas except Central and Northern Maine and along the immediate Canadian border where it will begin as all snow.  This blend of rain and snow will fall Friday night, but by Saturday morning, the deeper cold air across the Canadian border will seep southward as winds veer to a northwest direction.  This will tug the rain/snow line Southward Saturday morning, and accumulating snow will fall on Saturday in most of the northern mountains.  Amounts are likely to range from six inches in Central and Northern Maine, where the event is almost all snow, to a general 4" in Northern VT, to 2"-4" in the White Mountains and Central Vermont. 

Meanwhile, Saturday should be a day of clouds, some sun, windy, mild and relatively dry conditions with just the chance of a few showers for the Southern half of New England.  The reason for this?  It's really the clash of airmasses that will be driving precipitation and cloud production in this case - so as we head south...squarely into the milder air and away from the battle zone...we head away from the mechanism allowing for precipitation.  As the weak and progressive center of low pressure helping to focus this precipitation moves through Northern New England, it will shift surface winds out of the north, and this will drain colder air southward on Saturday, likely carrying some of the clouds and a few rain showers southward Saturday afternoon, and ushering in cooler and drier air for Saturday night and Sunday.

Again, this southward drain of cold air is a subtle change in the weather, but one that may become quite important down the line.  Sunday should bring dry and cool conditions to all of New England under plenty of sunshine.  But to our west, yet another upper level disturbance and its associated area of low pressure will be racing toward the East Coast.  With colder air in place for most of New England, the increasing clouds this system throws our way Monday morning will give way to precipitation as warm and moist air from the south once again collides with a cooler airmass in place.  In essence, the mechanism behind this will be similar - though stronger - that what brings Northern New England snow early in the weekend, and with colder air in place farther south through New England, this certainly raises the likelihood of accumulating snow through interior New England later Monday or Monday night, though a rain/snow line is likely to exist, and may penetrate inland quite a way in Southern NewEng.

The overall pattern still appears to favor a very gradual cooling of the atmosphere over the next couple of weeks.  Of course, this is with regard to the average state of the atmosphere...there will surely be large deviations either side of the average trend.  But one thing that's important to keep in mind is that all of this heat that's been across the U.S. is a form of energy.  This energy was spilled east with each successive storm that's battered the West Coast.  Eventually, these storms battering us will succeed in carrying the energy east into the Atlantic, and this could allow for a colder and snowier pattern to develop in February.  Food for thought, anyway...

Have a wonderful weekend - I'll look forward to seeing you back here on Monday!

Technical Discussion:  No techie discussion today...please reference yesterday's though do know that I've had to nudge the rain snow line farther north, as indicated in the weather summary above, for the Northern New England precipitation on Friday night/Saturday.

Matt


Gradual Warming South...Weekend Snows for the North Country

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find 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 contact@mattnoyes.net.  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 Weather Summary:  Furious winds resulted in widespread damage on Wednesday and if you'd like to get a taste of just some of the damage reports, the National Weather Service compiles them at the following web address:  http://www.erh.noaa.gov/box/lsr.shtml  The highest wind gust I received a report of here in the NECN Weather Center came from the Blue Hill Observing team at the Blue Hill Observatory in Milton, MA - just southwest of Boston.  Peak wind gust was 92 mph shortly after midday.

Thursday's weather map sandwiches New England between this departing storm center well to our northeast, and a bubble of high pressure over the Ohio Valley.  The result is another windy day - though child's play compared to Wednesday - with sustained winds of 15-30 mph and gusts to 40 or 45 mph...not strong enough to cause additional damage.  Enough moisture lingered in the lowest levels of the atmosphere for Thursday morning snow showers in the mountains of Northern and Western New England, though as dry air continues to spill in at the surface, these snow showers will dwindle, and breaks of sun will emerge in the mountains.  Elsewhere in New England, abundant sunshine begins the day as we make the most of the dry air that's in place.

Our very active weather pattern, however, won't allow us to enjoy a dry atmosphere for long.  Satellite imagery shows a small energy center racing northeast toward New England that will arrive Thursday afternoon.  This disturbance carries very little moisture at ground level, but is accompanied by a patch of high and middle altitude clouds that will filter out the sunshine from southwest to northeast later Thursday.  These clouds will also help to keep temperatures relatively mild during Thursday night in conjunction with a light southwest wind, while there may be just enough moisture to squeeze out a few flurries and sprinkles across the mountains of Northern New England.

A mild start Friday morning will provide a platform to build from as the day progresses, and even with limited sunshine, temperatures should still climb into the upper 40's in Southern New England by day's end.  This comes as a continued southwest wind ushers in the northern edge of a warmer airmass laid across the Southeastern quarter of the nation, and with the change in airmass, expect any morning sunshine to fade behind quickly increasing clouds, and most of our Friday will end up overcast, with a few flurries and sprinkles continuing in the mountainous terrain as a weak disturbance at the jet stream level moves across Northern New England, dragging an associated surface cold front very gently southward across the North Country.

There's more than meets the eye, however, to this scenario.  The combination of this southward ooze of cold air into New England from Canada, and the northward nudge of warmth nosing into Southern New England later Friday, will help to set the stage for storm development - establishing a sharp contrast in airmasses over our six-state region.  In fact, the cold air oozing southward is part of an airmass that's meant business - a chunk of this air that has been pouring into the Northern Tier of the United States has brought low temperatures below zero in the Upper Midwest and Upper Great Lakes, as well as across Southern Canada!  Remember that storms feed off of a temperature contrast like this, and energetic disturbances, when moving through sharply contrasting temperatures, can result in storm formation.  With our active weather pattern, there's no shortage of these energetic disturbances sweeping east, caught in the jet stream winds aloft, and another of these disturbances will eject from the Midwest and across the Ohio Valley Friday night.

Ahead of the incoming disturbance, winds aloft will increase from the southwest, carrying a continued supply of warm and moist air toward New England.  Remember, however, that colder air will be draining into the North Country, and this process of gliding warm air over a cold dome is the perfect scenario for clouds and precipitation.  My expectation, therefore, is for precipitation to develop on the cool side of this temperature boundary on Friday night - Northern VT, NH and Central and Northern ME - and the air in these northern locales will likely be just cold enough for precipitation to fall as accumulating snow that develops late Friday night and lingers into early Saturday afternoon.  Amounts are likely to range between three and six inches of snow from valley to hilltop, respectively, by the time snow winds down Saturday afternoon.  A very narrow corridor of rain showers will be possible during this same time frame from Rutland County, VT, to the Central Lakes Region of NH, to the Central Maine Coast, with snow found north of these areas and no precipitation south of them.  This means that Saturday should be a day of clouds, some sun, windy, mild and relatively dry conditions with just the chance of a few showers for the Southern half of New England.  The reason for this?  It's really the clash of airmasses that will be driving precipitation and cloud production in this case - so as we head south...squarely into the milder air and away from the battle zone...we head away from the mechanism allowing for precipitation.  As the weak and progressive center of low pressure helping to focus this precipitation moves through Northern New England, it will shift surface winds out of the north, and this will drain colder air southward on Saturday, likely carrying some of the clouds and a few rain showers southward Saturday afternoon, and ushering in cooler and drier air for Saturday night and Sunday.

Again, this southward drain of cold air is a subtle change in the weather, but one that may become quite important down the line.  Sunday should bring dry and cool conditions to all of New England under plenty of sunshine.  But to our west, yet another upper level disturbance and its associated area of low pressure will be racing toward the East Coast.  With colder air in place for most of New England, the increasing clouds this system throws our way Monday morning will give way to precipitation as warm and moist air from the south once again collides with a cooler airmass in place.  In essence, the mechanism behind this will be similar - though stronger - that what brings Northern New England snow early in the weekend, and with colder air in place farther south through New England, this certainly raises the likelihood of accumulating snow through interior New England later Monday or Monday night, though a rain/snow line is likely to exist, and may penetrate inland quite a way in Southern NewEng.

The overall pattern still appears to favor a very gradual cooling of the atmosphere over the next couple of weeks.  Of course, this is with regard to the average state of the atmosphere...there will surely be large deviations either side of the average trend.  But one thing that's important to keep in mind is that all of this heat that's been across the U.S. is a form of energy.  This energy was spilled east with each successive storm that's battered the West Coast.  Eventually, these storms battering us will succeed in carrying the energy east into the Atlantic, and this could allow for a colder and snowier pattern to develop in February.  Food for thought, anyway...

Enjoy your Thursday,

Matt

Matt's Technical Meteorological Discussion:  Updated Thursday, January 19 at 2:25 PM

Quick Note:  Day off for me on Friday, so no techie discussion, though Weather Summary will go out, FYI.

Middle and high altitude clouds spreading toward NewEng from moisture starved vort racing northeast across Ohio Valley.  Warm advection aloft is keeping this cloud mass intact but fast flow keeps the culpable vorticity maximum progressive.  This carries clouds thru NewEng overnight and some sun is likely Fri AM after a relatively mild night thanks to the cloud cover and an active SW wind keeping the boundary layer mixed.

Input of low level moisture from Gulf of Mexico to low pressure center farther north in Eastern IL is already evident and well forecasted by low level RH progs of NAM.  Trend has been a bit slower with bringing this moisture into NewEng from the west and this matches up with reality fairly well.  So, bottom line is a sunny start to a cloudy finish on Friday, but active southwest winds keep mild airmass advecting in as surface wave of low pressure rides north of NewEng border.

From that point forward we monitor subtle weather changes that will have big impacts.  The first subtle feature is the cold front that will nudge southward behind the passing low pressure center on Friday.  With strengthening southwest flow in the middle and upper levels, and increasing SW 850 winds into Southern NewEng, this front will be fighting to push south and won't make it much farther south that Central VT/NH/Srn ME.  It's important to realize the effects of this front, however - the height falls that occur north of Georgian Bay (Eastern Great Lakes) allow deeper Southern Canada cold to spill south and east Friday, and confluent flow north of NY/VT helps to hold this cold in as it seeps southward.  At the same time, you can't argue with the deep southwest flow, and this should set up a very impressive 850 mb baroclinic zone over Northern NewEng.  As warm advection moves east ahead of the approaching shortwave, precipitation will develop late Friday night and last into Saturday afternoon.  Differences in the placement of the precip axis between GFS and NAM but superior handling of cold air in low levels by NAM will be bought here and going to take a NAM weighted solution to precip placement and therefore ptype.  This Canadian cold can be equated to a heavy slow liquid sloshing out of a bowl (that bowl is Canada for the cold) and it's going to be hard to keep it from dripping south into Northern NewEng.  Result is snow - and QPF amounts are increasing in all model guidance as event nears and more Gulf moisture tap is indicated.  Band of heavy and steady precip should be narrow thanks not only to the tight baroclinic zone and confined area of isentropic lift, but also thanks to channeled nature of vorticity and relatively limited area of cyclonic vorticity advection as vort max is funnelled through fast flow.  Total QPF likely to fall just above .5" which will equate to over half a foot in the mountains...probably closer to a 10:1 ratio or even a bit lower in the valleys given marginal thermodynamic profile.  Southern extend of precip band likely to fall as periodic rain showers outside of intense lift and on southern end of thermal gradient.

Southern NewEng will not entirely escape this event, though active SW wind feeding into the frontogenetic process across the north will mean mild air keeps coming into Southern areas through the day and even with plenty of clouds temps should be able to climb to around 50!  But one big limiting factor will be cloud cover, as attendant cold front will be quite eager to swing south Saturday afternoon with passage of low pressure wave and clouds will increase ahead of and along front, with scattered showers of rain in Southern NewEng with passage of this low level forcing mechanism.

Sunday brings drier and cooler shot of air which allows for sunshine and downsloping flow but low Td's set the stage for Monday storm.  Most guidance trend is to keep this storm south of NewEng but I really don't buy that solution for a few reasons, focused primarily on the fact that midlevel flow is shifting toward NewEng, baroclinic zone will be eager to wave northward ahead of low given lack of deep dense cold air, and finally, overall steering flow doesn't favor a storm that comes in at Oregon going off the coast south of DC.  So, I think this late Monday or Monday night storm is a distinct possibility for NewEng and enough cold and more importantly dry (which can offset the effects of downsloping that will be witnessed on Sunday) air is in place to allow for evaporational cooling.  The challenge here will be holding the cold with high center shifting east of NewEng as storm approaches, while 1015-1020 mb low deepens passing S of NewEng as will turn ageostrophic flow E and then NE.  End result may be an inland and mountain snow with a significantly inland displaced coastal front...but let's get a few more runs under our belt before we start hashing out rain/snow lines!

Have a great day.

Matt


Damaging Wind Event Unfolding Wednesday...Quieter to End the Week

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find 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 contact@mattnoyes.net.  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 Weather Summary: 

12:56 PM:  Blue Hill Gusts to 92 mph.

12:10 PM:  Blue Hill gusts to 81 mph.  Thank you for the report.  Widespread damage reported across New England.  1 Penn Place in New York City sees 27th floor windows blown out.  Concern for Boston, but the core of the highest winds just off ground level should stay just SE of Boston.

11:50 AM:  Thanks to Blue Hill Observatory for the report...70 mph.

Special Note:  A damaging wind event is already underway across New England.  By 9:15 AM, winds have already gusted to 68 mph in Oxford, CT, 58 mph at White Plains, and 62 mph in Bennington, VT.  Damage reports coming in en masse.  This tells me we're to stay the course for damaging winds today and I'm sticking to 70+ mph gusts Cape Cod to coastal Maine, with 55+ gusts many other areas resulting in power outages, lots of downed trees and lines, some road closures, the need to tie down loose lightweight objects to keep them from blowing around, a major hazard to mariners (storm force winds, hurricane force gusts possible), the need to secure vessels appropriately, and the threat for minor coastal flooding on southeast facing shorelines either side of an 11:30-12:00 noon high tide.

Today's Weather Summary:  Trends continue to indicate that damaging winds are likely through eastern New England on Wednesday, especially from mid-morning through mid-afternoon.  Winds gusts to hurricane force will be possible on Cape Cod and the Islands, as well as the coast of Maine, and scattered power outages are likley in most of Eastern New England, including the Boston Metropolitan area.  We'll continue to monitor this threat carefully - cool ocean temperatures will try to mitigate the wind threat a bit, but concern is that this won't be enough to keep wind gusts of over 70 mph from mixing to the surface in exposed locations and over the water, so mariners should plan to stay in port Wednesday unless you're ready for hurricane force gusts over the water, properly secure vessels in areas exposed to southeast winds, and costal residents should be advised that southeast facing shorelines may see some minor coastal flooding at the time of high tide either side of noon Wednesday.

New Englanders will deal with the passage of a strong low pressure center to our north, and its attendant cold front swinging through the six state region for our Wednesday, and before its passage, persistent southerly winds will help to flood New England - especially Southern New England - with mild air, and temperatures will continue rising into the 50's and 60's on Wednesday amidst periods of rain, heavy at times during the midday and afternoon east (morning onward west), areas of fog and gusty winds.  Even the mountains of the north, after Tuesday night snow, have been unable to ward off this warm air, and have transitioned to rainfall, with freezing rain in the deeper valleys of the White Mountains and Mountains of Maine that are most protected from a southeast wind.  In Northern Maine, the time table is delayed by about 8 hours, but the results are similar, with a few inches of Wednesday morning snow changing to Wednesday afternoon sleet, snow, freezing rain and rain. 

With a widespread 1"-2" of rain expected through much of New England, flooding is a concern for many riverbank communities, especially where flooding has already occurred and will be aggravated.  Thunderstorms are likely to swing through New England Wednesday afternoon with the passage of a cold front and as the center of low pressure moves north of New England, and winds ahead of this front will gust over 50 mph in most locales, over 60 mph in the mountains and hilltops, and over 70 mph in some communities along the coast of Maine and the South Coast of New England!  I wouldn't be surprised to see some areas record hurricane force gusts (74 mph or greater) and these winds are already bringing power outages and downed trees to some communities.  Heavy rains will result in street flooding of poor drainage areas in the downpours, and hydroplaning will be a concern.  Flash flooding also is a possibility along Western and Northern New England streams and small rivers.

While colder air will be poised to charge in behind this departing storm center, it does not appear as though the same magnitude of arctic cold will be available that we saw this time around, and that will mean a signficantly modified chill for Wednesday night and Thursday, and a quicker return to warmer air.  Still, temperatures will fall below freezing Wednesday night and some black ice is likely in many areas.  Sunshine returns Thursday with a brisk wind shifting to the southwest and allowing milder air to rebound into New Enlgand quickly.  But with this milder air will come an increase in clouds late Thursday and Thursday night with a few flurries and patches of light rain and snow in the Northern half of New England.  Behind this disturbance, milder air will be in place for Friday, and even with lots of clouds blotting out the sun from time to time, a stiff southwest wind will help to boost temperatures into the upper 40's.

Yet another weak disturbance will move east over New England on Friday night, keeping clouds and a few rain and snow showers around especially Central and Northern New England as the disturbance drags a weak cool front south across the region.  While this front will mark a strong temperature difference from south to north and be strong by definition, right now it appears that the southwest flow aloft will really prevent much southward push to the cool air behind the front, and temperatures should climb into the lower 50's in Southern New England Saturday afternoon, while Northern New England holds in the 30's.  This will set the path for the next energy center, moving east Saturday night and bringing snow to the mountains of Northern New England, and a shot of sunny, cool weather for all of New England on Sunday.

As for the overall pattern and changes that may be in store...we are likely in the process of turning the corner this week, but it will not be a sudden or abrupt change, and instead we may ease toward a colder pattern over the next couple of weeks.  The overall weather setup will feature a strong bulging of warm air from the lower latitudes (southern areas) of North America persisting for at least a couple of weeks longer.  At the same time, cold air building over Alaska will begin spilling into Canada little by little.  The result of this evolution here in New England will be the availability of shots of shallow cold air near the surface over the next 7-12 days, while the active stream of energy and moisture will continue to feed off the Pacific Ocean and across the Lower 48.  What this means for us is a delicate balance for a couple of weeks between cold air pulses, and warmth/moisture returns.  Time this out right, and we're looking at snow...propensity will be for rain especially in southern New England with Northern New England and the mountains hanging onto every cold shot of air, and the words of meteorologists as to how long the cold can hold as each successive storm draws near.  It's undeniable, though, that the overall TREND will be to cool things off in New England over the next two weeks.  And as the active pattern continues, that means the overall TREND will gradually be toward a colder and snowier scenario.  As mentioned over the past couple of weeks - this could make for a very interesting and active February and March.

Hang onto your hat!

Technical Discussion:  Will likely stay busy with TV updates, but if I have time I'll pound something out.  Yesterday's was fairly in-depth and covered the storm well for today's aspects, so feel free to check out the archives.

Matt