MATTNOYES.NET - Weather Website & Blog: December 2006

WHILE THE MILD PATTERN ROLLS ON, COLDER PATTERN AWAITS IN THE LONGER TERM

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

General Weather Summary:

New England continues to live life on the "mild side" as mild air has gripped a large portion of the nation. Gradually, this weather pattern will change over the coming days as a strong storm roaring through the Pacific Northwest today - hampering search efforts for the missing climbers in Oregon - redefines the flow of the jet stream winds across the nation. Those of you who read this discussion regularly or follow the weather know how important the jet stream winds are - a corridor of fast wind aloft that steers disturbances and storms, and acts as a thermostat for the atmosphere, separating cold air to the north from warm to the south. The strong storm pushing off the Pacific Ocean Friday will surge eastward, then slow in Southern Canada. A second strong storm will push into the Western U.S. coast on Saturday, into California, and will dive southward across the Southwestern US this weekend. In time, these two storms will interact to fill the Western United States with Canadian cold by the beginning of next week.

In the meantime, a fast flow of the jet stream overhead here in New England means pieces of energy riding our way, with cold air not far to the north, and mild air available from the south. The end of this past week has brought a mild win in the atmospheric struggle, though Friday afternoon's upper level disturbance is driving a cold front quickly southeastward, and this will deliver noticeably cooler air overnight Friday night into Saturday. The result will be scattered Friday afternoon and evening showers along the leading edge to the cooler air - the cold front - then drier and cooler air moves in Friday night. In the North Country, the combination of a west-northwest wind pushing up against the mountain faces, and cool air filtering in, will breed snow showers late Friday night through Saturday morning. In the higher terrain of the Green and White Mountains, a couple of inches of snow may fall early Saturday, giving a wonderful fresh coating to northern ski slopes.

Elsewhere, expect lingering Saturday morning clouds to give way to emerging sunshine and - though the air will be noticeably cooler than Thursday and Friday were - a pleasant afternoon. With a break between disturbances and the jet stream winds aloft poised to ride northward again, Sunday will bring continued mild conditions. An approaching Northern stream disturbance, however, will tug cold air southward out of Canada by later Sunday, and ahead of this cool air expect clouds to thicken from north to south later Sunday, and a few rain showers are possible by Sunday evening. This southward bleed of cold air will not come with any well defined surge, however, and therefore the cold front leading the sagging Canadian airmass will only sluggishly settle southward across New England on Monday. This is likely to bring a pronounced difference in high temperatures from north to south on Monday with plenty of clouds in milder Southern New England, where a few rain showers will be likely. Farther north, clouds and cool air are likely to outnumber breaks of sunshine, and a few snow showers are possible if enough cold air presses south. Expect a similar setup on Tuesday, though a stronger disturbance will ride overhead at the jet stream level, providing a heartier dose of rain and snow to the six-state region, with precipitation type highly dependent on the location of the frontal boundary, but more likely to be raindrops south and snowflakes north.

Meanwhile, let's not forget about the important slug of energy and cold unloading into the Western United States this weekend into next week. Though it will take some time to churn across the Rockies and move into the Ohio Valley next week, it will eventually tap Gulf of Mexico moisture. The most likely scenario is for this Gulf warmth and moisture to significantly overwhelm any Canadian cold very quickly, and this would result in a storm of mostly rain toward the end of next week. The trick comes from the chunk of cold air to the west of the storm - the same air that spills out of Canada and into parts of the Western US this weekend - as it follows the departing storm heading into next weekend. This will set up a chilly weekend leading into Christmas, but an active Pacific jet stream flow will keep bundles of energy streaming eastward across the country, and the next in line will follow in the footsteps of its predecessor, picking up Gulf of Mexico moisture. The difference this time around will be that cold air will be already present in New England. While the final outcome will depend on the storm track - a storm east leaves us cool and dry - there's well-grounded scientific reasoning to expect this storm to track within a couple of hundred miles of the East Coast. An inland track would bring a shot of snow - perhaps Christmas Eve or Christmas Day - as the incoming warmth and moisture collides with the cool airmass in place, though this inland track would also mean a change to rain. A track up the coastline or just off the coast would result in snow for most of us, and a track close enough to the coastline would mean a decent storm. This is why I insist that - for now - there remains plenty of hope for a last-minute Christmas miracle of a White Christmas. Still lots that would have to come together, but still certainly a reasonable possibility.

Enjoy your weekend!

Technical Discussion: Out shortly.

Matt

Matt's Technical Meteorological Discussion: Updated Friday, December 15 at 11:10 AM

Short term features shortwave rippling east and driving band of showers along cold front. Given vort max aloft, these showers should survive the trip in scattered form. As for temps and sky cover, inversion is developing and this will continue to make it harder to break the clouds in advance of shortwave, but increased llvl flow in warm advection ahead of wave should allow for at least a few breaks in the clouds. Still, insolation will be a small factor in temps today given the sky cover and advection does most of the work, tho I think 60 is likely out of reach for most.

Clouds will linger overnight most areas as we await actual shortwave passage, and the combo of cold advection behind cold/occluded front and upslope flow with PVA will change rain showers to snow showers in Nrn Mountains, where heavier snow squalls will likely wait until Sat AM to take hold when upslope flow establishes. Elsewhere, downsloping will help to ensure low levels dry while midlevel clouds move out with shortwave after early morning. Temps will be noticeably cooler from Thu/Fri regionwide, but also a north-south gradient as shot of Canadian cold on cool side of baroclinic zone sinks southward into Nrn NewEng but will be less pronounced south.

Shortwave rippling across Quebec induces warm advection early Sun before cold advection sags cold front southward later Sun with numerous llvl clouds given destabilization with falling temps a few thousand feet above warm ground. Actual sfc boundary to stall over NewEng on Mon and will induce plenty of clouds and at least some sct precip Mon PM near the boundary, likely mostly over Srn NewEng. Both Mon and Tue are truly somewhat tentative, however, as even small shortwave ripples could have moderate consequences along a tightly packed baroclinic zone, tho Tue looks like the more likely candidate for more widespread precip, which will contain at least some snow north of the frontal boundary, likely to lay across Nrn NewEng. The ECMWF is cranking out a monster storm on the front that would be a full-fledged nor'easter with snow on Tue, but given confluent and fast flow, this seems unlikely and thus far the Euro is the clear outlier. Most guidance indicates a wave, but a much weaker and flatter version. There is decent possibility that some of Southern New England could see snowflakes Tue given the tremendous packing of isotherms along this front - even a slight deviation south would mean a better chance of flakes.

Later in the period, I'm still looking at two periods for storms. As described in detail in the General Weather Summary above, the first comes around Thu/Fri. This is energy that's been evident as a large storm on satellite pics as it's been crossing the Pacific - moving S of Alaska yesterday and ready to move into the Wrn US coast on Sat. There, as described in the General Wx Summary above, it will interact with today's Pac NW storm. The signals on this have been steady, which makes sense given a strong upper low that will eject from the SW US and move over the OH valley then S of or over NewEng. The question with this system will be how much cold is available. An established flow of Gulf moisture assures plenty of available moisture and it's likely that the warm will win once again with no strong high forecasted to hold the cold. There will be a northern stream wave and cold front diving SE at the same time period, so solid ptype isn't out of the question, esp in Nrn NewEng where overrunning may begin and cold advection may end the event, tho at this point I'm not so excited about solid over liquid in Srn NewEng.

What I do see here, though, is this storm opening the gates to colder Canadian air late next week as it passes, and a cool Canadian high building in for the weekend leading into Christmas. Thereafter, there is disagreement on the handling of the next Pacific shortwave for the 24th/25th, but I remain rather optimistic that the chances are there for a Christmas snow. My reasoning is a trough axis that will be over the Midwest combined with a strong shortwave that will come racing across the NW US in tight, fast flow, and be ready to drop into this Midwest trof. The key to this setup is the combination of available energy from the shortwave combined with a broad area of low heights across the Ohio and TN valleys. This broad area of low heights will mean the addition of the shortwave energy will have the potential to both shift the trof position eastward to the Ohio Valley, and turn the base of the trof negatively tilted. This is key to getting a large East Coast storm brewing, and given the cold air in place over the weekend, one would expect a good chance of overrunning snow to begin a storm as long as one can make it up this way. From there, it would depend on storm track, tho I think the 850 mb warm temp anomaly in SCentral Canada the 23rd-25th is actually a plus for us to receive snow, as this is indicative of a ridge building over Ontario, and reflected in Ensemble mean MSLP plots as a bubble of high pressure. Though warmth would rebound behind this bubble high, NewEng would still be ahead of the sfc ridge axis, which would be crucial inholding cold air in place after its arrival that weekend. Therefore, I think there's more hope for a White Christmas that we've seen as hope for a White "any other day in December" so far this month. We'll see if nature decides to cooperate.

Make it a great one.
Matt

Monday's Discussion:

5:15 PM: Series of shortwaves next several days comes after ridging and assoc Canadian sfc high breaks down. Nonetheless, dense sfc cold is always sluggish to erode and that's the reasoning for keeping wintry mix in for Nrn NewEng for Wed. Earlier timing of GFS is likely to be the closest to correct, at least with regard to shower initiation thanks to warm advection and overrunning into cold llvl airmass. First upper low will be decaying when it finallly moves NE from the Ohio Valley but will have decent Gulf tap and this will help to generate precip, tho fairly progressive pattern of quickly eastward shifting ridge will help to keep things moving, and fast active flow currently over Wrn US will migrate east. This will keep a parade of shortwaves into NewEng middle to end of week, timed nearly equally between disturbances. Though each will tug at cold air in Canada, the progression of the ridge means not much cold is left to tap by mid and late week, not to mention SW flow ahead of each wave will aid in WAA. This is what leaves me with the thought that Srn NewEng will warm enuf for liquid while Nrn NewEng will be cold enuf for solid precip next several days.

Any phasing of Srn and Nrn streams looks at this point to occur safely out at sea. Well, perhaps not safely, but with no guidance currently supporting the westward phasing we saw in guidance cycles last week, no bona fide reason for deep concern at this stage.

It will get milder before it gets colder...with 850 mb temp anomalies peaking once this weekend, then again middle of next week before deep tropical tapped storm winds up in advance of strong Aleutian energy mentioned in General Wx summary. Close call on whether cold or storm come in first, but pattern shift will begin in earnest with this storm as Ern US trof redevelops and active Pacific flow continues, shifting mean track of shortwave trofs farther south and bringing likelihood for numerous moisture-laden Pacific waves with intensifying sfc waves near New Eng as each wave emerges into the diffluent region downstream from the longwave trof.

Have a good evening.
Matt

NEAR RECORD WARMTH THURSDAY...MILDER THAN NORMAL PATTERN UNTIL SERIES OF STORMS BRINGS HOPE OF CHRISTMAS SNOW...BUT LOTS OF TIME STILL TO GO!

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

General Weather Summary:

Increasing warm and moist air colliding with lingering cool air was the impetus for dense fog and black ice across New England Thursday morning. This moisture was extremely low in altitude, however, and quite thin - some spots dawned with sunshine - and the sun was able to burn through this thin cloud deck through the day on Thursday. Our milder than normal pattern will produce near-record and perhaps a few record highs Thursday, and will continue through the middle of next week before a change in the weather pattern will bring cooler temperatures and an increasing chance of snow for the end of December - perhaps in time for the Christmas if everything plays out well!

In the meantime, a new approaching upper level disturbance will spread new high-altitude clouds over Northern New England later Thursday, and across most of New England Thursday night. Ahead of this disturbance, a steady southwest wind has put the air in place needed to team with sunshine in rivaling records across New England - especially in Northern New England, and the passage of the disturbance overnight Thursday night will continue to spread high cirrus clouds overhead. These thin clouds, in association with a southwest wind slowly becoming south and continuing to pump mild air into New England, will keep temperatures relatively mild and will result in new areas of dense fog and perhaps a few areas of black ice in the Northern White Mountains and through interior Maine.

Though some sunshine may shine dimly early Friday, our next disturbance will zip east across New England later in the day, driven by the jet stream winds aloft. This corridor of wind steers our storms and acts as a thermostat for the atmosphere - separating cold air to the north and warm to the south. With these jet stream winds flowing over New England, not only will this next disturbance bring a round of scattered rain showers late Friday into Friday evening, but it will also provide just enough of a ripple in the atmosphere to tug a quick shot of chilly air southward from Canada. This, combined with a northwest wind pushing up against the mountain faces of the north, will allow rain showers to turn to snow showers, and even some heavier snow squalls, across the mountains of Vermont, New Hampshire and Maine, where a couple of fresh inches are likely to fall into Saturday morning.

This mountain snow will be the perfect way to kick off what will be a pleasant weekend for one and all, with Southern New England temperatures rising significantly above normal again, while Northern New England gradually transitions from cool but comfortable Saturday weather to returning mild Sunday style.

Meanwhile, a stronger disturbance will push into the Pacific Northwest next Friday and Saturday, and will eventually mark the change in our weather pattern that not only gives those hoping for a White Christmas a good reason not to give up hope, but also should put a holiday twinkle in snow-lovers eyes for at least the realization of what could be. This major disturbance will be what was a well-established Aleutian low - a major storm swirling south of Alaska. As this slug of energy and cold unloads into the Western United States, it will first take its sweet time to churn across the Rockies, but as it moves into the Ohio Valley next week, it will both tap Gulf of Mexico moisture, and open the gates for cold to pour southeast out of Canada. This chunk of cool air will carve out a trough in the jet stream - in other words, a dip in the jet stream winds that will direct both storms and cool air our way beginning on or around December 21-22. This change in the pattern will likely be accompanied by a strong and moisture-loaded storm in the days preceding the Christmas holiday, though at this point it looks as though mild air would stream into New England ahead of the storm - much too warm for snow. Nonetheless, the passage of this storm would tug southward the nearby chill, and indications are the storm path will lay near the coastline thereafter, with another disturbance loading up on Gulf moisture December 24 and 25 as it heads north. This bodes well for those hoping for a White Christmas, at least to the fact that we'll have cold in place and substantial moisture on the move north. Of course, those of us who follow New England weather know how much things can change so far out, but it's quite encouraging to have a storm and cold air both forecasted to be nearby heading into the holiday, especially given the pattern that we've been in . Keep those fingers crossed!

Have a great Thursday.

Technical Discussion: Yet another appearance today, so unlikely.

Matt

Matt's Technical Meteorological Discussion: Updated Monday, December 11 at 5:15 PM

Series of shortwaves next several days comes after ridging and assoc Canadian sfc high breaks down. Nonetheless, dense sfc cold is always sluggish to erode and that's the reasoning for keeping wintry mix in for Nrn NewEng for Wed. Earlier timing of GFS is likely to be the closest to correct, at least with regard to shower initiation thanks to warm advection and overrunning into cold llvl airmass. First upper low will be decaying when it finallly moves NE from the Ohio Valley but will have decent Gulf tap and this will help to generate precip, tho fairly progressive pattern of quickly eastward shifting ridge will help to keep things moving, and fast active flow currently over Wrn US will migrate east. This will keep a parade of shortwaves into NewEng middle to end of week, timed nearly equally between disturbances. Though each will tug at cold air in Canada, the progression of the ridge means not much cold is left to tap by mid and late week, not to mention SW flow ahead of each wave will aid in WAA. This is what leaves me with the thought that Srn NewEng will warm enuf for liquid while Nrn NewEng will be cold enuf for solid precip next several days.

Any phasing of Srn and Nrn streams looks at this point to occur safely out at sea. Well, perhaps not safely, but with no guidance currently supporting the westward phasing we saw in guidance cycles last week, no bona fide reason for deep concern at this stage.

It will get milder before it gets colder...with 850 mb temp anomalies peaking once this weekend, then again middle of next week before deep tropical tapped storm winds up in advance of strong Aleutian energy mentioned in General Wx summary. Close call on whether cold or storm come in first, but pattern shift will begin in earnest with this storm as Ern US trof redevelops and active Pacific flow continues, shifting mean track of shortwave trofs farther south and bringing likelihood for numerous moisture-laden Pacific waves with intensifying sfc waves near New Eng as each wave emerges into the diffluent region downstream from the longwave trof.

Have a good evening.
Matt

CLOUDS TO OBSCURE METEOR SHOWER FOR SOME TONIGHT

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

General Weather Summary:

Wednesday showers mark the combination of passage of an upper level disturbance with a flow of mild and more moist air into New England. As the jet stream winds aloft rise farther to the north, this helps to solidify our warmer than normal temperature pattern through the middle of next week.

This week, we've witnessed an energetic and active weather pattern taking shape across the Northern half of the United States, with a fast flowing polar jet stream rippling across the Northern Tier of the country, ushering energetic disturbances from west to east aloft. The southern subtropical jet stream supplying additional energy and deep moisture has taken up residence flowing parallel to the polar jet stream, not favorable for phasing the streams into a big storm until east of New England, but able to input pieces of tropical moisture and energy to each disturbance. We've seen the most recent disturbance tap the Gulf of Mexico Tuesday into Wednesday, though the flow of deeper tropical moisture has weakened considerably, and this has left a relatively narrow band of rain migrating east across New England through the day Wednesday. You'll be able to follow this rain through the radar links at right through the day, and while there may be a few elements of heavier rain embedded in a swath of mainly light rain, I'm only expecting area-wide average amounts of a quarter to perhaps half an inch of rain. This will be limited enough for ski areas to sustain virtually no damage from the rain, and the highest terrain of the White Mountains and mountains of Maine are likely to find some sloppy snow mixed in, too.

The passage of this band of rain actually helps to define the leading edge to some milder air, and this will be marked by a wind shift from southeast to southwest later in the day that will set New England up for a mild Wednesday night, though chances are good clouds will stick around most of the night, obscuring our view of the Geminid meteor shower. While some clearing may take place early in the evening, more substantial clearing would be likely to wait until late, toward the predawn hours of Thursday morning. This is also the best time to view the meteor shower, so if you're willing to get up early - especially in Southern New England - you may be rewarded!

The same rather progressive pattern of weather systems will persist for the end of the week, with another two disturbances caught in a rather uniform westerly flow, meaning they'll each be nearly equally spaced, and in this case that temporal spacing is roughly 24 hours. Thursday may bring a few snow showers to the North Country, though farther south the migrant disturbance moving overhead will bring intervals of clouds, but no precipitation and milder west-southwest winds to boost temperatures. The next disturbance later Friday comes with what some would consider the perfect scenario - cold enough for nocturnal snowmaking in the Northern Mountains, cold enough for some natural snow showers in the mountains, as well, but warm enough for mostly just raindrops in Central and Southern New England both Thursday and Friday. The disturbance slated for later Friday looks as though it will be a bit stronger than its Thursday predecessor as it strengthens just a bit more, and this will bring somewhat longer-lived, steadier precipitation to New England Friday evening and night, with lots of leftover clouds possible early Saturday.

Meanwhile, a stronger disturbance will push into the Pacific Northwest next Friday and Saturday, and will eventually mark the change in our weather pattern that not only gives those hoping for a White Christmas a good reason not to give up hope, but also should put a holiday twinkle in snow-lovers eyes for at least the realization of what could be. This major disturbance will be what was a well-established Aleutian low - a major storm swirling south of Alaska. As this slug of energy and cold unloads into the Western United States, it will first take its sweet time to churn across the Rockies, but as it moves into the Ohio Valley next week, it will both tap Gulf of Mexico moisture, and open the gates for cold to pour southeast out of Canada. This chunk of cool air will carve out a trough in the jet stream - in other words, a dip in the jet stream winds that will direct both storms and cool air our way beginning on or around December 21-22. This change in the pattern will likely be accompanied by a strong and moisture-loaded storm in the days preceding the Christmas holiday, though at this point it looks to be a very tight call on whether cold air or moisture arrive first - thus, there's still a reasonable chance we could have a White Christmas afterall, though cold air arriving first would be a necessity. But indications are the snow potential doesn't stop there, as cool air will continue to pour into this jet stream trough, while the supply of Pacific energy would continue, posing the possibility of snow again on Christmas Eve, then again a day or two after Christmas. It seems every year we see these chances from several days out, and while it's exciting to have wishful thinking for those hoping for snow, the less biased scientific perspective here says the timing and exact evolution will remain tentative this far out, but an undeniable shift to colder and likely much snowier is in the cards after December 20-21.

Have a great Wednesday.

Technical Discussion: None today, unless appearances wrap up early.

Matt

Matt's Technical Meteorological Discussion: Updated Monday, December 11 at 5:15 PM

Series of shortwaves next several days comes after ridging and assoc Canadian sfc high breaks down. Nonetheless, dense sfc cold is always sluggish to erode and that's the reasoning for keeping wintry mix in for Nrn NewEng for Wed. Earlier timing of GFS is likely to be the closest to correct, at least with regard to shower initiation thanks to warm advection and overrunning into cold llvl airmass. First upper low will be decaying when it finallly moves NE from the Ohio Valley but will have decent Gulf tap and this will help to generate precip, tho fairly progressive pattern of quickly eastward shifting ridge will help to keep things moving, and fast active flow currently over Wrn US will migrate east. This will keep a parade of shortwaves into NewEng middle to end of week, timed nearly equally between disturbances. Though each will tug at cold air in Canada, the progression of the ridge means not much cold is left to tap by mid and late week, not to mention SW flow ahead of each wave will aid in WAA. This is what leaves me with the thought that Srn NewEng will warm enuf for liquid while Nrn NewEng will be cold enuf for solid precip next several days.

Any phasing of Srn and Nrn streams looks at this point to occur safely out at sea. Well, perhaps not safely, but with no guidance currently supporting the westward phasing we saw in guidance cycles last week, no bona fide reason for deep concern at this stage.

It will get milder before it gets colder...with 850 mb temp anomalies peaking once this weekend, then again middle of next week before deep tropical tapped storm winds up in advance of strong Aleutian energy mentioned in General Wx summary. Close call on whether cold or storm come in first, but pattern shift will begin in earnest with this storm as Ern US trof redevelops and active Pacific flow continues, shifting mean track of shortwave trofs farther south and bringing likelihood for numerous moisture-laden Pacific waves with intensifying sfc waves near New Eng as each wave emerges into the diffluent region downstream from the longwave trof.

Have a good evening.
Matt

PROGRESSIVE WEATHER PATTERN TAKES HOLD

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

General Weather Summary:

The overall milder than normal pattern touted for this week is certainly evolving, though as anticipated, this warmup is significantly slower to occur at the surface, where we're subject to heavy, dense, shallow cold airmasses penetrating southward out of Canada. One shot of this cool, dense air is in place across New England on Tuesday, with the southern flank of this air defined by a band of clouds spread across parts of Southern and Western New England, apparent in visible satellite imagery linked at left. With the jet stream winds flowing quickly across the Northern Tier of the United States, numerous disturbances will cross New England in the next several days, though this will also prevent any long-term establishment of remarkably mild or remarkably cool weather.

Tuesday's persistent clouds for the state of Connecticut have actually been expanding a bit up the Connecticut River Valley Tuesday afternoon and are the result of moisture trapped in the lowest few thousand feet of the atmosphere. One of the only ways to dry the atmosphere when a thin layer of clouds like this exists is to breath at least a bit of wind into an area. Tuesday's weather map, however, features a large and strong area of high pressure over New England, and while high pressure usually features fair weather, what it also brings is light wind. With nary a breath of wind across much of interior New England on Tuesday, even the thin layer of clouds present early in the day has been able to survive. Additional clouds are blowing in off of the Atlantic into Eastern Massachusetts, the result of a wind shifting to blow from the east.

Regardless of how much cloud cover you've seen in your community on Tuesday, expect clouds to increase and thicken gradually Tuesday night. With an influx of milder air from the southwest, fog will develop in parts of southwestern New England, and on the cusp of this fog - where temperatures drop below freezing - areas of black ice will develop later Tuesday night into Wednesday morning, likely to be focused through New Hampshire and Western Maine.

Over the course of the next 24 hours, the weather pattern becomes more active across the Northern half of the United States, with a fast flowing polar jet stream rippling across the Northern Tier of the country, ushering energetic disturbances from west to east aloft. The southern subtropical jet stream supplying additional energy and deep moisture will be flowing parallel to the polar jet stream, not favorable for phasing the streams into a big storm, but able to input pieces of tropical moisture and energy to each disturbance. The first of these is a slow-moving upper level feature moving through the nation's midsection. Given a building ridge of high pressure both behind this system and also ahead of it here along the East Coast, this disturbance has slowed noticeably over the Midwest and Ohio Valley, absorbing additional subtropical moisture and energy. By the time this disturbance replaces our eroding high pressure cell on Wednesday, cool air will be scoured out of many areas, allowing the incoming warmth and moisture to produce mostly rain showers across Central and Southern New England, though enough cool air will linger in the mountains of Northern New England to allow for snow showers and perhaps a period of steadier mountain snow to develop on Wednesday, especially in the Northern White Mountains and mountains of Maine. Eventually, even these areas will swing to rain for the end of the event, which appears timed from mid-morning through Wednesday evening from west to east across the six-state region. You'll be able to follow the rain and wintry mix throughout the day through the radar links at right.

The same rather progressive pattern of weather systems will persist for the end of the week, with another two disturbances caught in a rather uniform westerly flow, meaning they'll each be nearly equally spaced, and in this case that temporal spacing is roughly 24 hours. That is, we'll be back into scattered rain showers and snow showers in northern mountains Thursday midday and afternoon, then again later Friday. Though there will be substantially milder air to our south and southwest, the passage of each disturbance will tug down cool air behind it, and this will mean it'll be a constant battle to get milder air into all of New England. This is likely to result in what some would consider the perfect scenario - cold enough for nocturnal snowmaking in the Northern Mountains, cold enough for some natural snow showers in the mountains, as well, but warm enough for mostly just raindrops in Central and Southern New England both Thursday and Friday. The disturbance slated for later Friday looks as though it will be a bit stronger than its Thursday predecessor as it strengthens just a bit more, and this will bring somewhat longer-lived, steadier precipitation to New England Friday evening and night, with lots of leftover clouds possible early Saturday.

Meanwhile, a stronger disturbance will push into the Pacific Northwest next Friday and Saturday, and will eventually mark the change in our weather pattern that not only gives those hoping for a White Christmas a good reason not to give up hope, but also should put a holiday twinkle in snow-lovers eyes for at least the realization of what could be. This major disturbance will be what was a well-established Aleutian low - a major storm swirling south of Alaska. As this slug of energy and cold unloads into the Western United States, it will first take its sweet time to churn across the Rockies, but as it moves into the Ohio Valley next week, it will both tap Gulf of Mexico moisture, and open the gates for cold to pour southeast out of Canada. This chunk of cool air will carve out a trough in the jet stream - in other words, a dip in the jet stream winds that will direct both storms and cool air our way beginning on or around December 21-22. This change in the pattern will likely be accompanied by a strong and moisture-loaded storm in the days preceding the Christmas holiday, though at this point it looks to be a very tight call on whether cold air or moisture arrive first - thus, there's still a reasonable chance we could have a White Christmas afterall, though cold air arriving first would be a necessity. But indications are the snow potential doesn't stop there, as cool air will continue to pour into this jet stream trough, while the supply of Pacific energy would continue, posing the possibility of snow again on Christmas Eve, then again a day or two after Christmas. It seems every year we see these chances from several days out, and while it's exciting to have wishful thinking for those hoping for snow, the less biased scientific perspective here says the timing and exact evolution will remain tentative this far out, but an undeniable shift to colder and likely much snowier is in the cards after December 20-21.

Have a great Tuesday.

Technical Discussion: A couple of public appearances today, so no techie discussion today. Last evening's is below.

Matt

Matt's Technical Meteorological Discussion: Updated Monday, December 11 at 5:15 PM

Series of shortwaves next several days comes after ridging and assoc Canadian sfc high breaks down. Nonetheless, dense sfc cold is always sluggish to erode and that's the reasoning for keeping wintry mix in for Nrn NewEng for Wed. Earlier timing of GFS is likely to be the closest to correct, at least with regard to shower initiation thanks to warm advection and overrunning into cold llvl airmass. First upper low will be decaying when it finallly moves NE from the Ohio Valley but will have decent Gulf tap and this will help to generate precip, tho fairly progressive pattern of quickly eastward shifting ridge will help to keep things moving, and fast active flow currently over Wrn US will migrate east. This will keep a parade of shortwaves into NewEng middle to end of week, timed nearly equally between disturbances. Though each will tug at cold air in Canada, the progression of the ridge means not much cold is left to tap by mid and late week, not to mention SW flow ahead of each wave will aid in WAA. This is what leaves me with the thought that Srn NewEng will warm enuf for liquid while Nrn NewEng will be cold enuf for solid precip next several days.

Any phasing of Srn and Nrn streams looks at this point to occur safely out at sea. Well, perhaps not safely, but with no guidance currently supporting the westward phasing we saw in guidance cycles last week, no bona fide reason for deep concern at this stage.

It will get milder before it gets colder...with 850 mb temp anomalies peaking once this weekend, then again middle of next week before deep tropical tapped storm winds up in advance of strong Aleutian energy mentioned in General Wx summary. Close call on whether cold or storm come in first, but pattern shift will begin in earnest with this storm as Ern US trof redevelops and active Pacific flow continues, shifting mean track of shortwave trofs farther south and bringing likelihood for numerous moisture-laden Pacific waves with intensifying sfc waves near New Eng as each wave emerges into the diffluent region downstream from the longwave trof.

Have a good evening.
Matt

SHOTS OF SHALLOW COLD IN THE SHORT-TERM...PATTERN CHANGE TO COLDER AND SNOWIER TO COME FOR LAST WEEK OF DECEMBER

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

General Weather Summary:

Though the atmosphere is warming aloft, at the surface it's a slower process, and one that's more subject to heavy, dense, shallow cold airmasses penetrating southward out of Canada. One shot of this cool, dense air is settling south across New England on Monday, and will be slow to release its grip on New England as milder air clashes with it by midweek. Overall, mild air will rule the atmosphere through the middle to end of next week, though as is being witnessed Monday, to varying degrees.

In fact, Monday's light wintry mix across Northern New England created a few slick spots with pockets of light freezing rain showers and sleet pellets before dropping across Eastern Massachusetts as a period of light rain. This rain was enough that an observer in Lawrence reported puddles on the road and a rained out roofing job! Nonetheless, the band of showers has been progressive, but clouds will linger longer across the six-state region as cold air gradually is forced southward in association with a high pressure cell muscling its way across Quebec. Warmest temperatures are registering where the most sunshine has been making an appearance - in far Southern New England - and in these communities, temperatures will climb into the 50s!

The winds of change, however, will bring both colder and drier air into New England Monday night as lingering late-day sprinkles and flurries come to a close and clouds gradually break from north to south, leaving partly cloudy skies and falling temperatures for a chilly night regionwide. As the center of high pressure settles over Northern New England on Tuesday, cool air will be well in place and the atmosphere will be slow to mix - that is, a rather stagnant airmass will be in place through the day with relatively light winds and a slow rise in temperatures, even though ample sunshine will be present.

By Wednesday, the weather pattern becomes more active across the Northern half of the United States, with a fast flowing polar jet stream rippling across the Northern Tier of the country, ushering energetic disturbances from west to east aloft. The southern subtropical jet stream supplying additional energy and deep moisture will be flowing parallel to the polar jet stream, not favorable for phasing the streams into a big storm, but able to input pieces of tropical moisture and energy to each disturbance. The first of these will be a slow-moving upper level feature that was diving over the Southern Rocky Mountains as of this Monday morning writing. Given a building ridge of high pressure both behind this system and also ahead of it here along the East Coast, this disturbance will slow over the Midwest and Ohio Valley, absorbing additional subtropical moisture and energy. By the time this disturbance replaces our eroding high pressure cell on Wednesday, cool air will be scoured out of many areas, allowing the incoming warmth and moisture to produce mostly rain showers across Central and Southern New England, though enough cool air will linger in the mountains of Northern New England to allow for snow showers and perhaps a period of steadier mountain snow to develop on Wednesday, especially in the Northern White Mountains and mountains of Maine.

The same rather progressive pattern of weather systems will persist for the end of the week, with another two disturbances caught in a rather uniform westerly flow, meaning they'll each be nearly equally spaced, and in this case that temporal spacing is about 24 hours. That is, we'll be back into scattered rain showers south and snow showers north Thursday afternoon and evening, then again later Friday. Though there will be substantially milder air to our south and southwest, the passage of each disturbance will tug down cool air behind it, and this will mean it'll be a constant battle to get milder air into all of New England. This is likely to result in what some would consider the perfect scenario - cold enough for nocturnal snowmaking in the Northern Mountains, cold enough for some natural snow showers in the mountains, as well, but warm enough for mostly just raindrops in Central and Southern New England both Thursday and Friday.

A stronger disturbance will push into the Pacific Northwest next Friday and Saturday, and will eventually mark the change in our weather pattern that not only gives those hoping for a White Christmas a good reason not to give up hope, but also should put a holiday twinkle in snow-lovers eyes for at least the realization of what could be. This major disturbance will be what was a well-established Aleutian low - a major storm swirling south of Alaska. As this slug of energy and cold unloads into the Western United States, it will first take its sweet time to churn across the Rockies, but as it moves into the Ohio Valley next week, it will both tap Gulf of Mexico moisture, and open the gates for cold to pour southeast out of Canada. This chunk of cool air will carve out a trough in the jet stream - in other words, a dip in the jet stream winds that will direct both storms and cool air our way beginning on or around December 21-22. This change in the pattern will likely be accompanied by a strong and moisture-loaded storm in the days preceding the Christmas holiday, though at this point it looks to be a very tight call on whether cold air or moisture arrive first - thus, there's still a reasonable chance we could have a White Christmas afterall, though cold air arriving first would be a necessity. But indications are the snow potential doesn't stop there, as cool air will continue to pour into this jet stream trough, while the supply of Pacific energy would continue, posing the possibility of snow again on Christmas Eve, then again a day or two after Christmas. It seems every year we see these chances from several days out, and while it's exciting to have wishful thinking for those hoping for snow, the less biased scientific perspective here says the timing and exact evolution will remain tentative this far out, but an undeniable shift to colder and likely much snowier is in the cards after December 20-21.

Enjoy your Monday!

Matt

Matt's Technical Meteorological Discussion: Updated Monday, December 11 at 5:15 PM

Series of shortwaves next several days comes after ridging and assoc Canadian sfc high breaks down. Nonetheless, dense sfc cold is always sluggish to erode and that's the reasoning for keeping wintry mix in for Nrn NewEng for Wed. Earlier timing of GFS is likely to be the closest to correct, at least with regard to shower initiation thanks to warm advection and overrunning into cold llvl airmass. First upper low will be decaying when it finallly moves NE from the Ohio Valley but will have decent Gulf tap and this will help to generate precip, tho fairly progressive pattern of quickly eastward shifting ridge will help to keep things moving, and fast active flow currently over Wrn US will migrate east. This will keep a parade of shortwaves into NewEng middle to end of week, timed nearly equally between disturbances. Though each will tug at cold air in Canada, the progression of the ridge means not much cold is left to tap by mid and late week, not to mention SW flow ahead of each wave will aid in WAA. This is what leaves me with the thought that Srn NewEng will warm enuf for liquid while Nrn NewEng will be cold enuf for solid precip next several days.

Any phasing of Srn and Nrn streams looks at this point to occur safely out at sea. Well, perhaps not safely, but with no guidance currently supporting the westward phasing we saw in guidance cycles last week, no bona fide reason for deep concern at this stage.

It will get milder before it gets colder...with 850 mb temp anomalies peaking once this weekend, then again middle of next week before deep tropical tapped storm winds up in advance of strong Aleutian energy mentioned in General Wx summary. Close call on whether cold or storm come in first, but pattern shift will begin in earnest with this storm as Ern US trof redevelops and active Pacific flow continues, shifting mean track of shortwave trofs farther south and bringing likelihood for numerous moisture-laden Pacific waves with intensifying sfc waves near New Eng as each wave emerges into the diffluent region downstream from the longwave trof.

Have a good evening.
Matt

GRADUAL TRANSITION FROM DEEP COLD TO MILDER SUNDAY AND MONDAY

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

General Weather Summary:

What was anticipated to be a line of squalls instead stalled as a snowstorm for parts of Maine on Friday morning. This resulted from the development of a low pressure center in the western Gulf of Maine, pulling relatively warm and moist air into the incoming arctic chill to create narrow but intense and slow-moving bands of snow that persisted through the first half of the day. Some spots reported in excess of 8" of snow! Elsewhere in New England, the expected snow squalls were scattered but intense, and those communities that were hit saw quickly accumulating snow.

The cold that's moved into New England is deep, accompanied by a biting northwest wind, sustained at 15-30 mph, with gusts to 40 mph at times. The combination of the cold Canadian air and fierce wind will keep wind chill values in the single digits for most areas Friday afternoon, and send them below zero Friday evening. Actual low temperatures are unlikely to drop below the single digits in colder northern locales and teens elsewhere Friday night, thanks to an active wind and skies that begin partly cloudy but bring increasing clouds late.

The incoming clouds Friday night will be evidence that the weather pattern is quite progressive, and that while the cold is deep, it won't be long before warmer air makes a return run at the six-state region. With warmer air returning to New England and running smack dab into the deep cold, plenty of clouds should result on Saturday, and this clash of airmasses is likely to result in at least patches of snow showers and flurries, with heaviest snow falling in the mountains of the north. Incidentally, it's not only the Maine coast that made out well with the Friday storm - the moutains of Vermont and New Hampshire reports amounts around 8", as well, and this means that weekend skiing will be phenomenal when this natural snow is combined with the manmade snow that's been cranking 24-7 for the past several days. An additional few inches of snow will fall Friday night into Saturday in the higher terrain of Northern New England in snow showers.

After stubborn Saturday clouds depart, milder air will have a new hold on New England, and a milder than normal atmosphere will govern most of the United States from Sunday right on through the middle of December. This will be evidenced on both Sunday and - in Southern New England - on Monday as noticeably milder temperatures. While the atmosphere will, on the whole, be warming across the nation and deep cold air will be exhausted from Canada for the timebeing, an area of high pressure is likely to settle southward out of Eastern Canada during the day on Monday. Though this Canadian airmass may not bring deep cold air, it IS likely to bring at least a shallow shot of cool air later Monday to Northern New England, accompanied by a new round of clouds and snow showers. This front would cross Southern New England Monday evening and night, carrying these snow showers southward as it presses through, and ushering in cooler air for all of New England on Tuesday. Though cool Canadian air is likely to linger in New England on Wednesday, rain will move in later Wednesday and Thursday, perhaps beginning as snow in the far Northern Mountains, though it's too early to know. The undeniable trend will be for deeper warmth by next weekend, though those folks hoping for a White Christmas shouldn't give up hope yet. The weather pattern will bring a tendency for a storm near the East Coast, and a return of cool air, in time for December 22-24. No guarantees, and right now just a general weather pattern that would at least seem favorable for storm development in the right place.

Techncial Discussion: Yesterday's below. None today.

Matt

Matt's Technical Meteorological Discussion: Updated Thursday, December 7 at 3:25 PM

It's been awhile since a technical discussion - a week of technological challenges behind the scenes at the station has kept me hopping, but nice to have this time to share some of my thoughts with you on the current pattern, especially on the cusp of what will be an impressive overnight and early morning snow squall event.

First, temps rise nicely under influence of southwest flow this afternoon in most of NewEng but the fun and games are over...or have just begun depending upon your view...in Northern VT where moderate snow has begun and temps are falling on an increasing north wind. Roads will deteriorate rather quickly this afternoon in these Nrn locales as well as thru most of VT and Wrn MA and far Nrn NH as front presses S and E. Sharp temp diff behind this front but truly is only the first shot of polar air, as arctic front is found across Niagara frontier as of this writing, with daily high temps only in the teens behind it. That will be the reality for Nrn NewEng on Fri, tho downsloping flow will put temps in the 20s for areas farther south. But let's not get ahead of ourselves because there should be quite a meteorological show between this writing and the arrival of the cold.

The polar front will march thru with rain showers that will change to snow showers quickly as tight thermal packing marches east across NewEng with 0C line at 925 thru most areas by 10 PM and the change to snow showers taking place. There is good lift in the mid levels with this polar front passage, and as we're seeing in the north country, some icing will take place behind this primary front passage. Of more consequence, however, will be the arctic front that marches thru from 2 AM to 8 AM, from west to east. This will hold special consequence for Eastern New England, where the interaction between polar front and ocean modified air will make a clean sweep unlikely with the first front, leaving increased theta-e air in place from the sfc thru the lowest several thousand feet of the atmosphere. The passage of the arctic front, coupled with 36 units of absolute vorticity with the upper low and 500 mb temps to -34 C will bring squalls of increasing intensity as they travel E, and this will likely create big problems for Ern New Eng from PVD to BOS to PSM to PWM to BGR. The combo of rain to snow early, then snow with intense cold later will mean great conditions for icing. What would save some areas is if we see low enuf relative humidity after the first frontal passage to evaporate the water from roadways, tho with upstream obs showing only a 3-6 F dewpoint depression, this doesn't seem like it's too likely. The result is a dangerous situation on area roadways Friday morning. I also think there's more than meets the eye going on over Eastern NewEng Fri AM, as what will appear to be a quick-moving band of squalls will slow substantially in Ern MA and coast of ME as upper level low grabs lower level feature and weak low develops just offshore Ern MA coastline. There are even indications that 850 mb wind goes NNE for a time, and this would incorporate at least some ocean moisture, so squalls may be peristent in increasing instability Fri AM, which is why I've broken Ern MA and coastal ME out for enhanced accums. I will re-evaluate before going on-air Fri AM. Worth noting also, for those of you in the mountains, that the higher terrain of VT, NH and ME will see a half foot or more - esp above 1800 feet - where upslope flow will have a grand ol' time cranking out the snow Thu night thru Fri.

Core of low level wind will move overhead on Fri with 45-50 kt 850 mb wind and I expect sustained 20-40 most areas (sustained 40 comes in the hills/mountains) and gusts to 50. This combines with cold air for wind chills in the teens south and single digits north. Snow showers all areas with aforementioned 500 mb cold pool overhead, enhanced most in Nrn mountains but surviving thru downsloped areas thanks to increasing instability as the day progresses. Cape will be vulnerable to ocean effect snow bands - though winds may be too fast to get good development, delta T from ocean to 850 is tremendous and will be plenty sufficient to crank out at least spraying bands. The reason I haven't made more of this is because so many areas will likely be experiencing snow showers that the meteorologically inclined like those of you reading this discussion will be the ones to know the difference.

As for Sat, there isn't much QPF guidance that can lend support for my thinking on bringing snow in for Sat AM, and this is because the mid-lvls are forecasted to be dry. But, passage of Nrn stream shortwave and its weak interaction with piece of polar energy farther south will create decent lift at and above 700 mb - which IS forecasted well by the guidance - and this will be found both in left front quadrant of jet, and in area of 850 speed convergence and warm advection. Therefore, I would expect at least patches of light snow across NewEng with the best chc for accums in the mountains of a couple inches as this new air chases out the cold quite quickly. With warming temps aloft and clouds present, a weak inversion can develop and that would trap clouds most of Sat.

By Sunday, I expect dry air to be rather overwhelming and inversion to release its grip, bringing sunshine and responding milder temperatures. The situation for next week is far from set in stone, so skiers and ski resort folks alike shouldn't fret. I say this because, while the atmosphere over us will undoubtedly trend to a warmer than normal pattern - anomalies of +4to +6 C are likely by mid to late week at 850 mb - there are also signals of high pressure settling south out of Canada early in the week, and holding on into midweek. This comes as confluent flow aloft sets up east of NewEng, and means that nights would be cold enuf to continue snowmaking in most areas, and disturbances rippling thru the flow later Mon and Tue could still bring overrunning snow to Nrn NewEng mountains. Farther south, I'm not convinced on a deep warmth, as this same high would mean a flow off the ocean, but certainly temperatures into the 40s by day would be likely.

Still signals that the next well-organized storm Thu would bring enuf warmth ahead of it for rain most areas, and tho cold would follow this storm - and in fact it may end as snow for some, esp in the mountains - a surge of much above normal temperatures would follow around the 19th of December. The fun part, however, may come around of after the 21st, and that's why I'm far from giving up on the prospects of a white Christmas. In fact, with energy digging across the Southern Plains in that time period, and a deepening Aleutian low, this would force a building Western US ridge to build just a bit farther east, nudging the Central US trof farther east as well. Though it's early and nothing definite can ever be given so far out, this type of gradually progressing yet amplifying pattern with available southern stream energy would favor development near the East Coast. So...don't give up the ship yet, for those of you rooting for something to develop before the holiday.

Enjoy your Thursday.

Matt

INTENSE POLAR AND ARCTIC FRONT TO BRING INTENSE SQUALLS THRU FRIDAY MORNING

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

General Weather Summary:

First: Updates have been laggard this week - normally out much earlier. I want to acknowledge this and let you know that we have been struggling with some issues with technology behind the scenes, and of course, NECN on-air product always must come first. That said...

Winds of change will roar through New England Thursday night, marking a surge of winter cold that will bring a difficult morning commute to some of New England Friday morning. This blast of Canadian chill won't last long, moderating through the weekend and giving way to a rather mild and pleasant Sunday.

Speaking of mild air, there's plenty of it around New England on Thursday. This boost in temperatures comes largely thanks to a continued southwest wind flow, ushering in warmer air that was over the Ohio Valley and Mid-Atlantic on Wednesday, though some help has come from large breaks of sunshine, as well. But roaring ominously across Upstate New York is a cold front producing a line of snow squalls all the way south into the Tennessee River Valley, and showing impressive sheared convective tops on visible satellite imagery, which you can access through the links at left. This cold front is the first of two surges of cold heading for New England Thursday night.

The first cold front is polar in nature - that is, a shot of cold air, but not brutal cold. This front is pressing through Western New England Thursday afternoon and will continue to push east overnight, developing rain squalls changing to snow squalls along the associated wind shift. The second front is an arctic front, and will finish the job that the polar cold front starts - that is, another wind shift with another surge of deeper cold that will wring out additional snow squalls after midnight Thursday night, lasting into the morning commute in Eastern New England. The first round of squalls will pose a threat on their own - rain or a rain/snow mix changing to all snow showers and ushering in sub-freezing air. With warm pavement after a mild day, snowflakes and raindrops will melt into one sheet of water on the roads, and will freeze as temperatures drop. The arctic front will complete the freezing process on roadways, but will also drop new snow squalls. This second round of arctic squalls will be intense for some communities, and will drop anywhere between a dusting to locally two inches of snow in Southern New England, and greater amounts in the higher terrain of the north. Therefore, salt and sand operators must be on the ready for Friday pre-dawn through the morning commute hours, and commuters must understand that if the road treatment folks in your area aren't paying attention to this forecast or getting it from another source that's not anticipating the squalls, you'll need to leave extra time. I do want to make it clear that different communities will be affected to varying degrees - much like summertime thunderstorms where some towns are hit much harder than others.

Expect the cold arctic air to continue pouring into New England on a biting northwest wind through Friday, with sustained winds of 20-40 mph, gusts to 50 mph, and temperatures not moving out of the twenties. This combo will put wind chill values into the teens across Southern New England and into the single digits across the North. Sunshine will break through for some of the day, but plenty of clouds and scattered snow showers will be around into Friday evening for one and all.

In a very progressive pattern, however, it won't be long before warmer air makes a return run at the six-state region, and the return on Friday night through Saturday morning is likely to bring a period of at least light snow. The patches of early Saturday light snow may yield stubborn clouds through most of the day, but will mark the beginning of a new, milder pattern that will take hold through the middle of December, evidenced first by a milder Sunday, followed by mild and likely continued fair conditions Monday.

Next week will bring a frontal passage early in the week that will deliver some showers and a shot of cool - though likely not deep cold - air on Tuesday, then another chance of a storm late in the week. Still, the overall pattern will feature warmer than normal air in place, and it would appear that while brief shots of shallow cold air may bring a day or two of temperatures below normal along the way, the general trend will be for milder air to rule the roost into the third week of December. Nonetheless, ski resorts have been running snow guns nearly 24 hours straight, and will continue to crank snow at least during nights even in the milder spell. As for chances for snow, each storm threat will have the ability to interact with shallow cold air, though at this point there aren't signs of a deep, sustainable cold through the aforementioned mid-December period.