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Weekend Forecast Gains Clarity...Colder and Wintry Pattern Still En Route

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is 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 storm riding west of New England spreads rain over most areas Friday, heavy at times through the morning then tapering by early afternoon in Southern New England where breaks of sun are possible before sunset.  In the Northern Mountains, enough cold air is in place for accumulating snow.  Coastal winds will gust over 40 mph from the Southeast through the day Friday.  A break in the action early Saturday allows for some possible breaks of sunshine, but clouds thicken and our next storm brings showers by Saturday evening - rain Saturday night.  This is the storm we've been carefully watching for the weekend, and it looks as though it will cut west of New England - which is what keeps a quicker and warmer scenario for New England.  This would leave active but drying west winds on Sunday with emerging sunshine, except snow squalls in the Northern and Western Mountains.  Monday and Tuesday should be dry but turning colder as we begin to settle into a colder winter pattern that brings a chance of snow by midweek.

General Weather Summary:  Morning rains for most and snow in the mountains are a product of significant warmth and moisture streaming northward ahead of a storm center winding up over the Eastern Great Lakes.  As this storm drags a cold front east toward New England, a new wave of low pressure will develop along this front and move over New England Friday, helping to enhance rainfall amounts with most areas picking up between .75" and 1.25" of rain.  Farther north, enough cold air lingers in the mountains of Northern New England - from the Northeast Kingdom of VT east through the White Mountains and into the Mountains of Maine - for accumulating and plowable snow.  Behind this new developing wave of low pressure, however, a sharp back edge is evident to the precipitation in association with a slug of dry air that's been wrapped into the storm circulation, and this dry air will bring steady rain to a close in Southwestern New England around midday, the Boston area by mid-afternoon, and the remainder of New England except Central and Northeastern Maine by Friday evening.

The newly developing wave of low pressure passing through New England on Friday comes complete not only with this rain and snow, but also with gusty coastal and hilltop winds from the southeast, which may reach 40 mph gusts at times.  As the center of the disturbance passes, winds will shift and blow from the southwest, decreasing in intensity.  Thereafter, expect a relatively quiet Friday night with only lingering spritzes of rain and mountain flurries, and otherwise partial clearing and somewhat breezy conditions.

Saturday dawns with breaks of sunshine through the clouds, but I expect clouds to thicken through the day Saturday in advance of our next storm.  This is indeed the storm we've been watching so closely for this weekend, and the one I've been hesitant to commit to one way or the other until we had more information.  As mentioned yesterday - as a viewer/reader there's very little that aggravates me more than flip-flopping forecasts.  The trend in guidance over the past 24 hours has been decidedly toward a faster and more western storm track - somewhat amazing from an analytical standpoint, considering just a few days ago, the question posed was would the storm come close enough to us to even affect us, or just sail out to sea.  This change in track is part of a delicate interaction with a slow-moving and weakening storm over the Great Lakes, which will be just strong enough to tug an area of moisture and energy northward from the Gulf Coast, and up the spine of the Appalachian Mountains.  This will drag increasing clouds through New England on Saturday, followed by late afternoon and evening rain showers that may begin as snow in the mountains.  Saturday night, it appears enough warm air is pulled northward for most areas to see a period of rain - perhaps around .75" - with winds gusting over 35 mph Saturday late afternoon and evening ahead of and for the first few hours of rainfall.

As the primary storm to our west cranks up through Sunday, expect winds to shift later Saturday night, blowing from the west - a drying direction for most of New England, though ushering in significantly colder air during the afternoon.  This will mean a very windy but mainly dry Sunday in most spots, with morning clouds breaking a bit for afternoon sunny breaks, though temperatures will fall from mid-morning to mid-afternoon for almost all areas, and the northern and western mountains will find snow squalls depositing localized amounts of a few fresh inches through the day Sunday. 

This storm truly is the beginning of the shift to a new pattern, and the one that we've been waiting for over the past several weeks if you read this discussion regularly.  The initial signs of change were actually already on the U.S. map late Thursday as a wind shift across the Northern Plains marked the leading edge to the first installment of arctic air to that region in quite some time.  Over the course of this weekend and into the beginning of next week, the combination of our back-to-back storm systems will provide the impetus - thanks to the counterclockwise flow of air around them - to pull this air eastward and into New England.  Meanwhile, the busy storm track featuring an active jet stream driving storms across the Pacific Ocean and into the Lower 48 will continue.  And remember the thinking we've been sharing together here for the past several weeks that the abundant warmth across the nation manifests itself as available energy...and as colder air moves into the Northern Tier of the United States, this certainly raises the stakes for winter weather for most of February.

Have a wonderful weekend!

Matt

Matt's Technical Meteorological Discussion:  Updated Friday, February 3 at 11:45 AM

Most areas will be close to one inch of rainfall by the time this event winds down with lesser amounts far northwest and southeast NewEng.  Snow still holding on in the mountains where Maine mountains end up with 5"-6" in the highest amounts - Sunday River reports snow falling heavily as of 10 AM.

Winds along the coastline will gust to 40 mph today but system is progressive and I don't see us going much higher.  Coast of Maine to turn gusty later in the afternoon but inversion prevents a lot of mixing and this, too, keeps wind gusts around 40.  Wind velocity decreases with wind shift as front and associated triple point move thru.

Valley fog is possible overnight but breezes stay active enough to avoid fog most other locales.  Next storm already evident over Arklatex region this morning on satellite and radar imagery...so here we go again.  Of course, this is the one we've wrestled with, and in the end, the outlying and seemingly awry NAM solution of an early phase ends up being the winner, as became apparent when most operational models jumped on board in their 12Z cycle yesterday, and have stayed on board since.  I find this amazing considering it was just 48 hours ago I was typing out my thoughts on why this storm shouldn't sail out to sea like most of the guidance was indicating, and now not only is it coming close, but it's going west.   What hints were there, we ask?  Well, we did see the 500 and 700 mb RH hanging back early in the game with an upper level flow parallel to the surface flow and we said that shouldn't allow the front to move too far off the coastline, and remember that's why we maintained a chance of rain for Saturday (by "we" in these discussions, by the way, I mean you and me - I like to consider all of us part of the same meteorological team!).  Now reality has set in and we'll deal with a primary low tracking to our west, a triple point once again developing overhead, winds out of the east and gusting up to 35 mph ahead of the triple point, then dying down briefly before becoming the story on Sunday.  Precip comes once again ahead of and with the passage of the triple point, then shifting winds help to end precip.  Also with a bit of deja vous, cold enough for a mix to start in the Northern Mountains, but this will be quite brief for all areas except Northern Maine as warm air moves in aloft and changes most areas to rain.  Total precip amounts look less than the current storm, perhaps centered around .75".

Cold advection wraps in around the back of the wound up low on Sunday.  Originally I'd been bringing in significant chill on Sunday and keeping forecasted highs only near 30 but really had to boost these up today - may have gone a bit too far in the other direction...and you know how I hate flip-flopping forecasts...but the problem is that with a slackening wind Saturday night as the dynamics come together over Eastern Canada, it's tough to get cold advection going all that quickly.  The forecasted morning profiles support highs in the 50's, while by 00Z Mon the profiles support temps in the 20's.  Knowing that surface cold can sometimes come in sooner, it becomes a tricky balancing act, but I think reality has temps topping out in the 40's in the morning on Sunday, then dropping during the day.

Next system for Monday is one we looked at yesterday and dismissed the upper flow as too confluent for this thing to really crank up this far north, and that still looks to be the case, as this will probably instead be a Mid-Atlantic snow event.  There is always this concern that a system like this comes farther north than expected - especially in a pattern where the warmest solution possible seems to be winning out - but right now the flow just doesn't look conducive.  I still believe, however, that the next shortwave in line will be a different story for us.  With confluent flow shifting east of us, cold air will still be locked in at the surface but the upper level flow relaxes enough over the Eastern Seaboard to allow the next in line of the vigorous shortwaves to come farther north.

It's quite clear that there's also a followup strong shortwave coming in behind this one, and while the operational guidance has trouble nailing down an interaction, Ensemble means show a significant deepening of the Eastern US trough as this follow-up shortwave comes into play.  500 mb height anomalies drop sharply behind this feature, 850 mb temp anomalies also respond dramatically, and what this all indicates to me is that there is an interaction leading to a powerful and rapidly deepening storm along or east of the East Coast Wednesday, reaching full maturity as it occludes late Wednesday and perhaps even retrogrades during its cyclogenesis phase.  All that being said, the window in which this happens finds its western edge at the Appalachian mountain chain and eastern window over the Scotian slopes, southeast of Nova Scotia.  So, we need to work on nailing this down, but I have very little doubt there will be a rapidly deepening storm in this window the middle of next week, and the longwave Ensemble mean pattern suggests closer to rather than farther from the coast.  Behind this storm, regardless of exact location, arctic air unloads on New England right on time...

Have a great weekend,

Matt

Rains Push North By Friday...Still Eyeing Late Weekend Storm Potential

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is 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!):  Thursday morning patches of clouds come courtesy of a weakening storm system that moved overhead with a few flurries, and these clouds will continue to break for sunshine through the day with a few mountain flurries Thursday afternoon.  Yet another storm is picking up moisture from the Gulf of Mexico already and will spread into New England with Central and Southern New England rain showers after midnight Thursday night, and Northern Mountain accumulating snow.  Rain will be heavy at times Friday morning, then taper around early afternoon in Southern New England, while Northern snows change to rain and the coast of Maine sees rain continuing into Friday evening.  Limited sun through clouds is expected on Saturday with afternoon showers or rain possible.  The forecast for Saturday night through Sunday remains a tricky one with a new storm moving toward New England - and its track making all the difference in the world between rain or snow, and for timing!  After appearing as though the storm would go to our east, the trend now is westward which would be a quicker rainstorm rather than a later snowstorm.  I absolutely hate flip-flopping forecasts, so for now, most fair thing to do is leave it at an honest chance of rain or snow...this should become more clear tomorrow.

Weather Summary out later this morning.

General Weather Summary: 

1:15 PM Update:  Microscale bursts of snow developing along Maine coast including city of Portland in association with northwest side of an ill-defined circulation.  Best bet to monitor these snowbursts is through my main webpage and follow the radar links:  www.mattnoyes.net

Previous Discussion:  Interested in the history of Groundhog Day?  I found this link to be one of the most informative, so feel free to check it out!  http://www.stormfax.com/ghogday.htm

As for the weather, the hits just keep coming!  Another storm is heading for New England, as the jet stream winds - the fast river of air aloft in our atmosphere that steers storms and acts as a thermostat for the atmosphere, separating cold air to the north from warm air to the south - continue to roar across the Pacific, carrying strong storms into the United States, then keeping the fast-paced barrage of storms rolling across the Lower 48.  A morning weather analysis places one area of low pressure across the Lower Mississippi River Valley, producing thunderstorms and embedded tornadoes overnight across the Gulf Coast, and now beginning to pull northeast.  This will be our Friday rainstorm, but in the meantime, we enjoy another relatively quiet day on Thursday.

Many communities starting with plenty of Thursday morning clouds in the wake of a moisture-starved disturbance that moved overhead Wednesday night will see these clouds gradually breaking up for some sunshine most of the day.  Meanwhile, as the center of a surface high pressure cell moves east of New England, the clockwise flow of air around it is allowing for a south and southwest wind to take hold of New England, and this warmer wind direction combined with some sunshine will team up to boost Thursday afternoon temperatures into the 40's in Southern New England, and well above freezing across most of the North Country.  Just as we enjoy this break in the action, however, high altitude clouds will spill back into New England late in the afternoon and through Thursday evening, in advance of the moist Mississipi Valley storm trekking northeast toward New England.  With a southerly wind direction continuing through the overnight Thursday night, temperatures will be warm enough for rain through most of Central and Southern New England as showers develop after midnight.  Farther north, however, enough cold air will be present for a start as snow, and in fact, Northern Mountains will remain as snow into Friday morning with plowable amounts likely (see accumulation maps).

With such a moisture-loaded storm heading our way, rains will become heavy at times Friday morning through early afternoon in most of New England as the rain/snow line progresses steadily northward to Aroostook County in Northern Maine (where some sleet eventually will fall Friday afternoon) by late in the day.  Indications are that most of the energy associated with this system will merge and consolidate with an additional energy center over Eastern Canada - north of New England - and while this will be the track of the primary storm center, a new area of low pressure is likely to develop over New York City on Friday, and push over New England during the day.  The typical result of a pattern like this is for the heaviest rain to fall ahead of the new low pressure center - from Friday morning into early afternoon - then taper, with a few breaks of sun possible in parts of Southwestern New England later Friday afternoon.  Through northeastern New England, including most of Maine, the time frame will be delayed about 6 hours, so rains will not taper to showers until Friday evening.  As for temperatures on Friday, though lots of warmth and moisture will be streaming over our heads, at the surface a southeast wind is likely to prevail, and with ocean temperatures around 40, it will be difficult for most communities to warm more than the lower 40's.

As our storm center pulls north of New England, it will slowly drag a cold front across the region on Saturday.  It appears now as though this drier air would be allowed to seep into New England Friday night into Saturday, but that's not the end of the story for our weekend.  The trick here is that yet another disturbance will be moving across the Mississippi River this weekend, and will be ushering warmth and moisure northward ahead of the newly developing storm center.  The reason this becomes tricky is because, at some point, the cold front forecasted to cross New England on Saturday will slow and then stall.  This slowing motion means cold and dry air will be slow to drain into New England on Saturday, so plenty of clouds are likely to linger with only limited sunshine as a train of moisture continues to chug from south to north, just offshore.  Questions revolve around how far west this moisture will spread as pulses of low pressure ripple along this stalled frontal boundary, and I'm thinking there's a good chance we see plenty of clouds and even some late day rain showers in Eastern New England on Saturday.  With this front stalled offshore, however, that will also limit how quickly cold air can spill into New England, and it's likely that Saturday will be another relatively mild day.

The story doesn't stop here, though, because as cooler air finally does filter into New England Saturday night, the new storm to our south will be toward New England, tapping Gulf of Mexico moisture.  The path of this storm Saturday night into Sunday will depend entirely on the position of a slowing/stalled Saturday cold front, which will serve as a pathway for the next incoming storm.  If this front stalls close enough to New England, the next storm will affect us with rain.  Should the cold front stall farther east, the incoming storm may interact with cooler air for a Sunday snow.  But, there's still a lot of time between now and then, and with such a delicate interaction between that storm and the cold front to be left behind earlier in the weekend, this will continue to be a bit of a nail-biter for meteorologists for a couple of days, depending on how things shake out.  I plan on the meteorological community having a better handle on this Friday.

The overall pattern, though, remains clear in my eyes, and that is a parade of storms to continue the next two weeks as the Northern Tier of the United States gradually shifts into a cold winter pattern by the middle of the month.  There's sure to be plenty of excitement along the way!

Have a GREAT GROUNDHOG DAY!

Matt

Matt's Technical Meteorological Discussion:  Updated Thursday, February 2 at 1:05 PM

Unfortunately very short on time today, but here are the basics of what I'm thinking right now:

Fun vortex embedded in low level moisture off the ME coastline is presumably the result of a low level vorticity maximum.  Higher RH values were well progged by the guidance and clouds will prevail in most of ME thru the rest of Thursday.  Elsewhere, low level deck sneaking into CT/SW MA out of NY state will continue to spread gradually E.

Cirrus to ride overhead soon in advance of next system, in which the split of energy centers is already quite apparent on satellite and radar imagery.  Looks like between .75" and 1.25" of rain most of Central/Southern NewEng on Friday - most falling ahead of triple point low during morning thru early afternoon - later timeframe in ME.  Cold enough for snow in the mountains and rain/snow line will be slow to move northeast with cold air damming in the Northern Mountains.  By 00Z Sat rain/snow line is at northern tip of ME and sleet will be ongoing for Aroostook County, ME, but all other locales should have transitioned to rain during the early to mid afternoon.

It's looking like the NAM may not have been so out to lunch with its early phasing solution afterall...12Z runs coming around in both the GFS and GGEM to bring yet another inside runner as cold advection fails to make it far enough east to nudge front off the coast.  This means serious consideration has to be given to beefing up the showers/rain for later Saturday (thank goodness we left showers for Saturday in the forecast!) and to buy into slower front movement and farther west solution.  In fact, even the progressively biased NOGAPS is beginning to come around to this solution, so serious consideration has to be given to this warmer, windier, farther west scenario.

Unfortunately, I'm out of time for today...so more in depth weekend analysis will have to wait until tomorrow.

Enjoy your Thursday.

Matt

A Midweek Break in the Action...Parade of Storms To Resume Later This Week

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  You'll find a quick weather synopsis and a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is 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 few slippery spots Wednesday morning on walkways and sidewalks thanks to yesterday's ice and overnight snow.  Otherwise, with one storm pulling away and another moving east across the Great Lakes, New England finds ourselves between storms and, under more clouds than sun, temperatures will rise to near 40.  A weakening storm system moves overhead Wednesday Night with a few flurries into early Thursday morning, then more clouds than sun again will be the rule with mountain flurries Thursday afternoon.  Yet another in this parade of storms picks up moisture from the Gulf of Mexico Thursday night and spreads into New England during the day on Friday with rain likely in Southern New England, and perhaps enough cold air for accumulating snow across Northern Mountains.  Rain ends Saturday and emerging sun helps to boost temperatures into the 40's before a coastal storm takes a swipe at us Sunday.  If it hits, accumulating snow moves in later Sunday and Sunday night, but at 5 days out, we'll wait and see on this close call.

General Weather Summary:  Though only on the northern periphery of yesterday's rapidly strengthening storm over the Atlantic, bands of heavy snow dumped nearly a foot on parts of Eastern New York, up to 5 inches fell in Western Massachusetts, widespread light accumulations of ice and snow made for slippery travel, while midday coastal flooding closed roadways and washed away beachfront in some communities.

Wednesday features a break in the action as our departing storm wraps up a snowstorm for Nova Scotia and a new storm center races east across the Great Lakes carrying a swath of rain and snow with it.  In this brief break between weather systems, an axis of high pressure will move gradually over New England, allowing winds to subside a bit Wednesday afternoon, and keeping most of New England dry, save for a few mountain flurries.  By Wednesday evening, however, the next storm in line will be making a bee-line for New England and will move directly overhead overnight Wednesday night.  Without a well-established tap of moisture from the Gulf of Mexico, and its previous source of Pacific moisture also cut off, this moisture starved system will carry a shriveling area of rain and snow as it moves east.  In fact, most of New England will find only clouds and some flurries - perhaps a few areas of very light snow - Wednesday night into very early Thursday morning.

Fast winds at the jet stream level - high in the sky - will keep this storm moving, and also means that a parade of storms marching across the Pacific Ocean will continue to cross the nation and affect the Eastern Seaboard.  So, while Thursday dawns cloudy and with a few areas of flurries and light snow, breaks of sun are out by afternoon, poking between plenty of lingering clouds.  Just as soon as we enjoy this next break in the action, however, we turn our attention to the Southeastern United States, where the next storm system will already be producing a swath of rain and thunderstorms through the Gulf Coast and Tennessee Valley as it feeds off of Gulf moisture.  As this storm pulls northeast Thursday night, clouds will race back into New England.

Rains develop Friday as this storm passes south of New England, taking a path that normally would favor snow for most of New England.  As has been the case of late, however, a lack of cold air will make snow difficult to produce through most of Central and Southern New England, especially given that an area of high pressure over the Western Atlantic ahead of this storm with its clockwise wind flow around it, will bring southerly winds ahead of the storm.  The exception to this may be across the Northern Mountains of New England if enough cold air can hold on, and accumulating snow would be the result for the North Country.  This potential for Northern New England will become clearer over the coming day or so.

Indications are that most of the energy associated with this system will merge and consolidate with an additional energy center over Eastern Canada - north of New England, and this will slowly drag a cold front across the region on Saturday.  The result would likely be a period of rain that lingers through Friday night into Saturday morning, then, provided the cold front keeps moving, drier air would be allowed to spill into New England Saturday afternoon.  The trick here is that yet another disturbance will be moving across the Mississippi River this weekend, and will be ushering warmth and moisure northward ahead of the newly developing storm center.  The reason this becomes tricky is because, at some point, the cold front forecasted to cross New England on Saturday will slow and then stall.  This slowing motion means cold air will be slow to drain into New England on Saturday, so if the sun comes out Saturday afternoon, temperatures could respond to that sunshine quite nicely.  The other option, of course, is that the front stalls sooner and clouds linger through the day on Saturday.  At this point, I'm banking on the more optimistic solution of afternoon drying.

The story doesn't stop here, though, because as cooler air finally does filter into New England later Saturday and Saturday night, the new storm to our south will be moving over the Southeastern U.S., tapping Gulf of Mexico moisture.  The path of this storm on Sunday will depend entirely on the position of a slowing/stalled Saturday cold front, which will serve as a pathway for the next incoming storm.  If this front stalls close enough to New England, the next storm will affect us later Sunday afternoon and night, and may interact with the cooler air that will be in place for a Sunday evening snow.  But, there's still a lot of time between now and then, and with such a delicate interaction between that storm and the cold front to be left behind earlier in the weekend, this could be a bit of a nail-biter for meteorologists for a couple of days, depending on how things shake out.

The overall pattern, though, remains clear in my eyes, and that is a parade of storms to continue the next two weeks as the Northern Tier of the United States gradually shifts into a cold winter pattern by the middle of the month.  There's sure to be plenty of excitement along the way!

Have a wonderful Wednesday.

Matt

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

2:05 PM Update:  Posted!

1:55 PM Update:  I always go back and read the discussion to make sure I didn't forget anything, and realized today I forgot my section on Tuesday, so that's going to be added as a second-to-last paragraph any minute...just have to type it up.

Discussion:  Abundant low level moisture will allow stratocumulus to bubble up thru the day, so morning large breaks of sunshine will continue to fill in.  Enough subsidence to limit vertical growth of these clouds, however, and the day finishes dry for almost all of New England with the exception of a few mountain flurries.  Approaching shortwave races thru overnight but is dying a quick death thanks to lack of moisture input as conveyor belt from the Pacific was cutoff early Wed AM and no Gulf conveyor belt is available.  Result will be overcast skies tonight with passage of vort max, and with vort cutting directly across NewEng, cyclonic vorticity advection may team up with low level moisture for flurries and some areas of very light snow, esp where orographic influence can assist, but that's about all.  Clouds linger Thu AM.

Very fast flow will continue to be the rule thru the period and this leaves very little time for the atmosphere to really dry out between events, esp with no strong push of dry and cold arctic air available in the short term.  While some breaks of sun are likely later Thu in the subsidence assoc with negative cyclonic vorticity advection behind departing shortwave, cirrus are likley to come back in later Thu and clouds thicken again Thu night in advance of amplifying shortwave trof interacting with copious Gulf moisture.  With surface anticyclone shifting E of NewEng ahead of this storm, warm air should have no problem returning to most of NewEng before enuf moisture moves in for precip to commence.  Trend across the board has been to bring precip in quicker and late Thu ngt precip start looks to be in line with guidance.  Warm air comes flooding in aloft and while 850 mb warmth is present, surface warm front gets held up at the South Coast of NewEng thanks to easterly surface wind component and triple point moves over Wrn Long Island then sweeps ENE as occluded front swings thru NewEng.  Heaviest rain should come ahead of and with passage of this triple point Fri AM into early afternoon.  Thereafter, good agreement on dry slot in midlevels coming thru to end precip from south to north mid afternoon and lasting thru the night.

From there, NAM is anxious to bring next shortwave in with a pounding rainstorm for most areas Saturday evening and night as it phases southern and northern stream energy quickly over the OH Valley.  NAM is also, however, the outlier in this solution.  GFS/Canadian/Canadian Ensemble Mean/ECMWF all resist this phasing until later in the game.  This affords the front an opportunity to slide off the coast Saturday night and serve as a pathway for the next intense shortwave riding across the Gulf Coast states.  By this point, cold air advection has occurred later Saturday evening and night, and cold air is in place across NewEng for either a miss by this system to the southeast, or an accumulating snow later Sunday through Sunday night.

Given the fact that upper level flow becomes parallel to low level flow later Saturday, this favors slowing the eastward progression of the frontal boundary significantly.  It's important for the Saturday forecast that we notice the high RH values progged for 500 and 700 mb returning later in the day, and that this lines up well with the vorticity axis and the west side of a 150+ knot jet streak at 250 mb.  The result may be for very thick cirrus thru the day even tho midlevels would indicate drying, though I think the other result of this setup would be only a slow cold advection into NewEng, allowing temps to warm into the 40's again on Sat.  As for the Sunday scenario, even if we buy the model consensus to bring a wave up the coast offshore, this doesn't necessarily guarantee an all snow scenario.  The biggest factor working against a snowstorm in this scenario is that we have a very similar synoptic setup to this past storm, whereby one decaying low pressure center is over the Eastern Great Lakes and serves to retard any cold advection into NewEng, forcing the cold air instead to wrap around that low and feed in from the west.  There are helping factors, as well, though, which is why this is not an easy forecast, including the fact that this next round of cold wrapping around the decaying low is colder than the last time around.  Additionally, more cold advection occurs before this decaying low is in position to block deeper cold from coming in, and as opposed to a marginally too warm scenario, instead we may see a marginally just cold enough scenario.  Let's not forget that there WAS plenty of snow with this last storm - just under a foot of it in the higher terrain of Eastern NY and just under a half foot in part of the Berkshires.  If this Sunday setup does indeed end up being a similar synoptic setup but shifted just a bit farther east, snowy problems may still result.  With all of these factors considered, it's these positive snow factors that tip the scale to the snowy side of things for now, and I've put a chance of snow in the forecast for later Sunday accordingly.  That being said, as meteorologically inclined folks we know how much about this forecast is tenuous and can change - from a public perspective, however, we need to step much more delicately and I'm basically handling this Sunday storm as a wait-and-see, does it hit us or not coastal.  Very casual from 5 days out when it's nearly impossible to explain all of these possibilities, plus the other 4 days of weather, in a two minute segment.

Thereafter, nature lets loose with the pattern readers of this blog and I have been waiting for so patiently as we eyed the February pattern.  That is, energetic systems ready to tap abundant moisture as each pulls down progressively colder air in the low levels, thereby lowering heights and developing deeper troffing with time.  So, after our Sunday system either hits or misses, it doesn't seem to matter much, as the next in the parade of strong shortwaves will be diving through the nation's midsection.  By this point, the jet stream flow should be broad enough across the Northeastern quarter of the US to prohibit a significant amplification of this system across the Southeastern US, and confluent flow will exist over NewEng and the Mid-Atlantic.  So, this energetic shortwave is sucked into the confluent flow on Monday and gets sheared out to our south.  Bummer, game over, right?  Not so!  Because in this crazy parade of storms, here comes yet another energetic shortwave - straight out of the Aleutian low and yes, a playing out of the pattern we've been waiting for - remember last week when we examined that Aleutian low together and expected pieces of energy and cold to break off, ride of the Western Canada ridge and dump into the US?  Looks like that may be in the cards immediately following Monday's failed shortwave as another races east on Tuesday.  With confluence aloft easing over the Northeast, this leaves a much more favorable setup for the shortwave to develop.  In fact, there is great agreement among a number of medium-range operational models on this system developing a closed circulation midl-level and at the surface.  This is a classic setup for a quick 6-8" of snow, but remember...easy does it...still early...but we are at least seeing a potential realization of the pattern we've been leaving the light on for over the past few weeks, and to see it forecasted to come together just as we'd expected is exciting, but no guarantee.  Still...we're making progress toward claiming winter back.

With regard to the overall pattern, I know those of you who read regularly are up to speed on my thoughts for the next couple of weeks, and I invite those of you who've missed it to peruse the archives at your leisure.  But the bottom line is that this pattern change still seems to be unfolding for us as we've been looking at together in these discussions, using largely common sense as the driving force.  Multiple shortwaves will continue to beat down the Southeast US ridge while tapping the abnormal amount of available energy thanks to abundant warmth and moisture.  As heights lower in the North Central and Northern United States - and more importantly over Central Canada - one of the deepest troughs in the Northern Hemisphere, next to the Aleutian low and associated troughs - will begin to develop thanks to low level cold drainage lowering heights and thereby allowing cold air to spill in deep through the atmosphere.  This should allow for arctic air to spill in by the middle of the month, with a parade of moisture laden storms turning progressively colder and snowier to usher in the change.

Enjoy your day.

Matt