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AFTER MILD THURSDAY, WINTRY MIX TO AFFECT NORTH COUNTRY...HEAVY RAINS AND WIND FARTHER SOUTH

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:

A huge swing in temperature along a sharp cold front in the nation's midsection is separating air producing high temperatures around zero in the Northern Plains from air warming to near 90 in Texas.  Sure enough, this clash of airmasses has created a major storm that will paralyze parts of the Central U.S. before drawing northeast and eventually serving as the impetus for heavy rain, damaging wind, and heavy snow for some of New England by the time Friday night is done.

For now, however, New England weather remains comparitively quiet.  After a slow start in most areas with clouds and some fog Thursday morning, sunshine has continued to break through the cloud deck.  In fact, Thursday's sunny breaks will be far more evenly distributed across New England than Wednesday's were, as most of the dense, cold air has been displaced, lessening the clash of airmasses taking place.  Still, an influx of warm and moist air will provide for plenty of clouds to mix in with the sun, and a few scattered showers will continue to pop up through the day and into the evening.  Nonetheless, an active southwest wind - the result of being sandwiched between the clockwise wind flow of a departing high pressure cell and the counter-clockwise flow of an incoming storm center - will transport enough mild air into New England to bring Southern New England temperatures to over 60 degrees, with 50s spreading across much of the North.

Meanwhile, the strong storm to our west is already evident on the weather map, moving northeast across Oklahoma.  This storm is sandwiched between air that produced a difference in high temperatures of 97 degrees from Northern Plains to Southern Plains on Tuesday, and 87 degrees yesterday.  This tremendous difference in high temperatures was the perfect recipe for a mega-storm to develop, and the storm will continue to travel along this clash of airmasses, making its way through the Ohio Valley and eventually across Northern New England, straddling the battlezone between the mild air across most of New England and the cold air sitting across Quebec.

But on it's trip northeast, this storm will continue to be a powerhouse, and will leave what will be paralyzing impacts from Oklahoma City and Tulsa to St. Louis due to the ferocity of the wraparound snows, and a heavy snow continuing on a stripe northeast across Chicago, Detroit and Toronto, as cold air is drawn south toward the storm center, only to clash with deep tropical warmth and moisture feeding north Thursday (OK), Thursday night (through Detroit) and Friday (Toronto).  Farther south, this storm will make headlines for its severe weather, which should produce multiple tornadoes from Arkansas and Louisiana eastward through the Lower Mississippi River Valley, Tennessee Valley and lower Ohio Valley Thursday night.  This severe weather will continue to roar northeast on Friday, ripping through the Mid-Atlantic and perhaps as far north as extreme Southern New England.  Meanwhile, the wind feeding this system will be tremendous both ahead of the storm in the warm air, and behind it where blizzard conditions will likely verify in the Central U.S. areas described for heavy snow above.

Here in New England, we will wait until Friday for any direct effects from this storm.  The energy aloft that is associated with this storm is quite impressive, and the storm will still yank a slug of fast winds across New England on Friday as south winds just a few thousand feet off the ground are forecasted to blow at over 80 mph.  Though I don't think we'll see 80 mph gusts at all, mild air that's in place and a well-mixed atmosphere will mean favorable conditions for allowing winds to transport toward the ground later in the day, especially as downpours and thunderstorms move through.  This will produce locally damaging winds across New England late Friday into Friday night. 

It appears as though the push of cold air from the north will be sufficient enough to push a cold front out of Quebec, across Northern New England on Friday morning, and settle that front near the Route 2 corridor of Northern Massachusetts.  North of this front, cool air will come spilling south, and this will ensure quite a bit of snow for parts of Northern Maine on Friday.  South of the front, mild air will continue to pour into Southern New England, and along the front itself - through Southern Vermont, Southern New Hampshire and Northern Massachusetts - heavy rains will fall with up to two inches of rainfall.  Through the day, the reinforcement of Canadian cool air to the North Country will continue through Friday evening, and this means an area of sleet and freezing rain will continue to push southward, as well.  So what about snow?  Yesterday I'd mentioned that a brief period of whiteout conditions would impact the North Country...the track of the upper level energy driving the impending storm appears to be moving a bit farther northwest, and this means that temperatures aloft will be warm enough to melt snowflakes upon descent for an extended period of time through much of Northern Vermont and New Hampshire.  Still, by the end of the storm later Friday night into Saturday morning, cold air will come sweeping in from the west and this will turn raindrops to snowflakes across most of Northern New England.

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Elsewhere, the weekend will begin a bit brisk, but bright on Saturday with a blend of sun and clouds.  The problem we face in the atmosphere by the end of the weekend into early next week is that the pattern still isn't comfortably settled.  That is, cold air will have been tugged into the North and plenty of energy will linger across both the Great Lakes and the Central Plains.  This sets the stage for another possible interaction of northern and southern stream energy - weaker than the first time around, but still with an available feed of tropical moisture off the U.S. East Coast.  If the two systems were to interact, and they could tap some of the available moisture, we'd be looking at a snowstorm for New England and some rain and snow farther south.  That said, at this point the pattern seems to favor limited - but still evident - interaction between the northern and southern disturbances.  This would produce increasing Sunday clouds, then a period of possible light snow Sunday night into Monday, but the heaviest of the precipitation falling over the fish as the storm takes off just east of New England.  It's, of course, still early, and I'll continue to keep you posted on the setup.

Nonetheless, the pattern for the upcoming couple of weeks - the first half of December - will feature a fast flowing jet stream with numerous disturbances embedded in it, thanks largely to the weak El Nino flow and therefore the steady stream of disturbances racing across the Pacific and through the Western United States.  This will mean repeated tugs of cold air at the surface into New England, with plenty of availability to tap additional moisture from the tropical Pacific and Gulf of Mexico if any of these disturbances can grow strong enough, which they'll have a better chance of doing after the first week of December, when Pacific input strengthens even a bit more.

Have a good Thursday!

Technical Discussion:  Barely got the summary out!  None today, my friends.

Matt

Matt's Technical Meteorological Discussion:  Updated Wednesday, November 29 at 2:40 PM

Cold is eroding where you'd expect it to today - that is, south and west with winds shifting from that direction, and southeast where warmer ocean waters have also assisted.  Otherwise, shallow cool dome is doing its part in creating clouds and areas of fog that have been migrating gradually northeast in response to the wind shift.  I'd expect Essex County, MA, points N and E to remain mostly cloudy until sunset with breaks of sun most other locales farther S and W and responding temps.  Clouds and fog will fill back in overnight as temps cool briefly until they meet the rising dewpoint.  This slow start on Thu will give way to emerging breaks of sun as mixing gets underway with increasing boundary layer flow from the SW.

Tried to go into as much detail as possible on the upcoming storm in the General Wx summary, but my technical reasoning on such a paralyzing potential for OK City to St. Louis comes from the combination of tremendous dynamics with...more importantly...extreme baroclinicity.  I would venture that the rate of deepening will be deeper than progged, the wind will be more fierce than progged in the Central US, and the wraparound precip will be just as fierce as progged with heavier banding resulting from the combo of differential advection as warm air wraps around the north side of the circulation and into the falling midlevel temps.  This will be a fun show to watch from afar on Thu and then also on Thu night as the snow band carries NE while severe weather breaks out from the MS Valley to the OH/TN valleys as tropical air streams north and intersects strong PVA.

Here in NewEng, as mentioned already, boundary layer flow increases Thu.  This, of course, increases low level WAA and with breaks of sun likely at times, that will only help to boost sfc temps with airmass supporting around or just above 60 in Southern NewEng and 50s north.  Various levels of the atmosphere showing high RH on Thu and with continuous WAA bringing bursts of isentropic lift, scattered showers possible at just about any time as is being witnessed on radar scopes to the west of NewEng today, so will hold the forecast to that regard.

Fri storm is extremely dynamic.  Yesterday I mentioned to Tim Kelley that the vort max itself reminds me a bit of the December 9 storm of last year, and in fact the dynamic low level setup is quite similar, as well.  There are, of course, some major differences that will make this a very different scenario - for example the storm is going to track hundreds of miles farther north and west, it's reaching its peak intensity aloft while it crosses the Ohio Valley, and the fact that it's removed from the ocean takes away a great deal of additional baroclinicity and moisture input.  So how are they similar?  The strength of the 500 mb vorticity maximum is quite similar, the system is closed aloft, and it's taking on a negative tilt as it crosses NewEng.  Track across Nrn NewEng puts Nrn VT, NH and ME in the bullseye of this storm for dynamically forced precip.  At first there is enuf mild air that this will mean heavy rain Fri for Central and esp Nrn NewEng.  FFG values are running around 2-2.75" in 6 hours, and that may be exceeded, so small rivers and streams may flood far North Country Fri night.  The dynamic cooling should be so intense, however, that we will tug cold air southward faster than progged by guidance and this will mean a quicker changeover to snow in the far North Country - esp north of the 500 mb circulation - with white-out conditions likely for a time overnight Fri Ngt and snow falling at the rate of a couple of inches per hour for a brief time.

Of course, that's only for the Nrn NewEng part of a storm that will bring widespread effects.  Though there is some excitement for snow lovers of any prospect of snow - and that means some getting giddy about next Monday's potential (more on that below) - it's critical that meteorologists and the public remain focused not on what plays better to emotion but what will have the most immediate impact on life, which will be the potential for damaging wind on Fri.  Southerly winds in advance of the storm are progged to blow to 85 knots at 850 mb and though the core of the 925 mb winds stays immediately south of NewEng in the latest NMM prediction, even those winds are blowing at 75-80 kts!  This may be somewhat mitigated in extreme Srn NewEng where mixing will be a bit limited due to flow off ocean waters that will be cooler than the air aloft, but Richardson Numbers indicate mixing all the way to 850 mb farther north and over the interior!  The combination of this southerly llvl jet prior to arrival of the front, convection likely to develop along and immediately ahead of the front, and CAA with assoc downward momentum transport behind the front gives plenty of cause for concern over damaging winds later Fri in NewEng.  As for the convective threat, there is no question the deepest instability is found to our south, from the Mid-Atlantic to the Southeastern US where I would expect a squall line to sweep east later Fri ahead of the front.  But while the same llvl instability is not present in NewEng, mid-lvl lapse rates are moderate over Srn NewEng where slug of warmth and moisture above 800 mb is just as impressive as it is farther S.  Combined with available dynamics and low level jet structure, there certainly appears to be a slight chance of that squall line extending/expanding north into Srn NewEng late Fri.

Though Sat looks fairly quiet for most of us, winds will still be 40-50 kts at 850 mb with cold advection from the NW and this favors upslope snows until the dry air can overcome those processes, and would expect these upslope snows in the favored locales of the Greens, Whites and mountains of Maine first half of Sat.  Elsewhere, downsloping flow and removal from rather channeled vorticity will leave most areas dry with sunshine between cold Cu.  Additionally, with the trof axis still well to our west, the deep cold will not carry all the way thru NewEng and we should find a rather pronounced temp difference from N to S by Sat afternoon.

Of course, this failure to move the trof axis farther east is what leaves such an interesting setup for late Sun into Mon.  That is, the jet stream will be laid over Srn NewEng with a baroclinic zone similarly ribboned across the region, and with two vorticity lobes to our west - one over the Upper Great Lakes holding back arctic air, and the other dipping thru the Rockies and Central Plains - the intriguing questions of potential phasing come back to give NewEng meteorologists and weather enthusiasts alike something to scratch our heads over.  I have to be completely honest that my thoughts this morning were that phasing would happen farther east than NewEng, and I held this thought largely because of the progressive nature of the flow over the Northeastern US, leading into the confluent flow locked east of NewEng, which, of course, will also serve to hold in the cold.  This idea of progressive disturbance and later phasing found good agreement among both Canadian and GFS Ensemble products, along with most operational runs, though one overwhelming feature was the presence of a rather well-defined inverted trof between the northern and southern disturbances that swings thru NewEng later Sun into Mon.  This, in combination with shortwave energy sheared out in the upper flow and running ahead of the main southern disturbance, was among my primary reasons for increasing Sunday clouds and putting at least light snow in the fcst late Sun into Mon.  This also set off an alarm, however, as I've seen cases in the past where a well-defined inverted trof is the precursor that the guidance is picking up on more interaction than it would appear, and the 12Z model guidance certainly has trended in this direction, at least in the case of the GFS and GGEM.  I should make it clear that I don't think storm track is a huge question here, contrary to what the instinct is to worry about (ie: will it come close enough?).  I don't think there's any question it will come close enough to affect New England - the baroclinicity is laid over us at 850 mb, the jet is over us at 300 mb and 500 mb flow is just south of the coast.  In fact, I think the track of any surface reflection would be farther north and west than currently progged.  What the question revolves around here is simply over how quickly the interaction and phasing takes place, and exactly where that happens.  12Z GFS started looking too progressive but then retrogrades the system, which is not only possible but in fact likely to happen when in fact phasing does occur.  With 12Z Canadian phasing early, but hot-off-the-presses ECMWF phasing late, this really doesn't help much, does it?!  So, for now will hold the line with the public forecast in expressing likelihood of light snow Sun Ngt/Mon and explain potential of earlier strengthening.

But again, very important to note that this won't be the highlight of the public forecast for now - while it entices meteorologists and weather enthusiasts, the major primary concern is Friday's blow of damaging winds, and must not be overshadowed by a storm potential at 5 days out.

Have a good day!

Matt

Monday's Discussion

1:30 PM:  30 degree spread across NewEng as of this writing from snow and 32 in Caribou, ME, to 62 and sun through Ci in OWD, SFZ, PVD, FIT.  Not bad for peak diurnal heating on what some would consider a quiet weather day!  Shortwave prompting rain and snow across Nrn ME will remain progressive, but so will the next shortwave upstream over Ontario as of this writing, which has been well-evidenced on radar and now shows good cloud top cooling on infrared imagery.  This shortwave will regenerate the swath of rain and snow across Nrn ME, and will a cooling boundary layer this should go to mostly snow with the I-95 corridor valleys starting as rain then changing to snow.  The shield of precip will drop south across Central ME and Bangor area may see a dusting by AM with temps around freezing which means black ice/icy spots a possibility, and accums of 2" possible higher terrain north of BGR area, esp from Millinocket points north.  Elsewhere, periods of clouds with shortwave passage seem rather innocuous but come prior to surge of shallow but meaningful cold that will migrate south behind Mon night's shortwave.  This cold has been brewing in Quebec and is a breakaway from gargantuan anticyclone in Central and Western Canada - therefore, this breakaway nature of the airmass means the cold is not overly deep but instead is a rather typical Eastern Canada surface dome that will be marked by a shift of winds to the northeast and brief gusts to over 20 mph with the wind shift.  Timing is 04-06Z in Portland and by 12Z most of NewEng has seen frontal passage.  Temps behind the front today are verifying in the 30s and NMM will verify best with this airmass thanks to its higher low level resolution.  Some areas in Srn NewEng will see falling temps after morning highs thanks to this cold advection.

Cold airmass remains locked in thru Tue Ngt, and areas of drizzle and light showers will be likely thanks to substantial low level instability.  Inversion present aloft, however, will strengthen Wednesday as warm advection commences above the boundary layer, but contrary to guidance forecasts I don't think the cold, dense air is going to give way to warm advection and mixing will be little if any, meaning low level deck remains locked in, isolated to scattered showers are possible thanks to warm advection aloft and temps remain cool.  Next system winds up enough to increase gradient and move air at the surface, so I do expect some warm advection in the boundary layer on Thu, though was looking at GFSX Ensemble members mostly in the middle 60s for Lawrence, MA, area Thu and I have a very hard time believing this with limited insolation and a stronger tendency for the cold to be rather begrudging in its departure.

In fact, as explained in the General Weather Summary above, I'd be surprised to find this cold air losing any meaningful battles in the next couple of weeks, and that includes Friday night, which is a critical battle in the world of meteorology, as nearly everything in the forecast will ride upon it.  I do mean quite literally "ride upon it" as the cold front will serve to be the path of the next incoming low.  I made my mind up which way to go with this for now when I reviewed the 00Z suite early today, and I have seen the warmer GFS solution even in its more recent 12Z run.  That said, I also see that the 00Z to 12Z has shown a rather substantial displacement to the southeast in the track of the low center - not yet where I'd expect it, but getting there.  So where would I expect the track?  Given the passage of a Thursday night shortwave similar to this coming night's wave, there's no reason to doubt whether the cold is capable of pushing thru NewEng.  It would appear as though the cruxt of the argument is the speed at which it sinks southward, to which we find good agreement among the Canadian Ensemble members and operational GGEM of a quick progression, GFS Ensemble mean position east and south of NewEng, and an ECMWF solution that is a bit more sluggish tho not nearly as sluggish as the GFS.  One could say that given the tendency for cold air to win the battles this time of the year, and the agreement among the Canadian Ensembles on the progression of this Canadian air - along with an NMM that also appears to be trending in a quicker cold direction, this certainly seems like the best forecast for the time-being.  Of course, in our discussions that's not quite enough, as I like to see synoptic reasoning to support guidance, and that synoptic reasoning is founded in the presence of confluent flow east of Maine, indicating the cold will come pouring in, then will hold.

Perhaps an equally challenging question is how the incoming Pacific vort will track and whether it will hold its identity as it encounters the confluent flow.  Thus far, the trend is only stronger with this Pacific energy as it lifts northeast across the OH/TN valleys, tho logic would say it should weaken as it approaches confluence.  I do think the guidance in general are still too far west with the vort max given the confluence east of NewEng and the colder surge as described above.  All of these factors raises my awareness of the potential for carrying accumulating snow farther south through New Eng than we've done so far this year, tho exactly where that is still remains up for grabs at 5 days out.  Heck, at 5 days out we know the whole thing remains up for grabs as described above, but of the solutions I prefer it would make the most sense to carry a moist Pacific-moisture loaded system either south of NewEng or over Southern NewEng Fri Ngt into early Sat, and this would mean the potential for accumulating snow even in Central NewEng.  It's also important to remember that shallow but strong cold can mean freezing precip, which wouldn't be impossible for interior locales if enuf cold air weren't present for snow.

So...plenty to work thru in the next couple of days.  In the meantime, enjoy the mild Monday (south) and the following chill Tuesday.

Matt


POTENTIALLY PARALYZING STORM FOR SOME CENTRAL U.S. CITIES TO HEAD INTO NEW ENGLAND ON FRIDAY

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 it's been a mild November for New England, the oscillations associated with the transition from fall to winter have begun across the six-state region, featuring surges of offsetting warmth and cold.  This setup - tightly packed airmasses of very different origin - is favorable to breeding storms, and a strong one will crank up from the Central Plains to Northern New England over the next 60 hours.  Eventually, this storm will be the impetus for heavy rain, damaging wind, and heavy snow for some by the time Friday night is done.

In the meantime, a raw Tuesday afternoon continued through the overnight and greeted many New Englanders Wednesday morning.  Over the course of the day, some areas will break into sunshine while others will be harder pressed to find brightening.  A lot of this depends upon sunshine, as there's warmer air moving in aloft that would make a tangible difference if mixed down to ground level.  In the atmosphere, however, in order to bring that air downward, we need to stir the atmosphere around, often done by adding sunshine, or bringing milder air in at ground level.  Since there's nothing but cool air near the ground today, this stirring must be accomplished by sunshine, which will only break through where enough dry air is present to erode the clouds - specifically in Western and most of Southern New England.  From Northeastern Massachusetts points north and east, however, many lingering clouds will hold temperatures down through Wednesday afternoon.

As milder air continues to filter into New England - gradually moving in not only above our heads but also here at the surface - fog will develop Wednesday night into Thursday morning in especially Southern New England.  After the slow start in some areas, I'd expect this pattern of increasing warmth and moisture to result in plenty of clouds amidst a few breaks of sun, along with a few scattered showers throughout the day.  Nonetheless, an active southwest wind - the result of being sandwiched between the clockwise wind flow of a departing high pressure cell and the counter-clockwise flow of an incoming storm center - will transport enough mild air into New England to bring Southern New England temperatures around and even just over 60 degrees, with 50s spreading across much of the North.

Meanwhile, strong lobes of energy across the Plains States will organize into a new, strong, end-of-week storm.  This storm is already evident on the weather map, moving northeast across Oklahoma with additional energy aloft and another surface storm center over the Southern Rockies, ready to merge with the leading disturbance.  This storm is sandwiched between air that produced high temperatures into the middle 80s across the South-Central United States (87, Southern TX), and below zero in the Northern Plains (-10, NW Montana).  This 97 degree difference in high temperatures is the perfect recipe for a mega-storm to develop, and the focus now becomes where the storm will track, and therefore how it will effect New England.  First, expect the storm to travel along this clash of airmasses, making its way through the Ohio Valley and eventually across Northern New England, straddling the battlezone between the mild air across most of New England and the cold air sitting across Quebec.

But on it's trip northeast, this storm will be a powerhouse, and will leave what may be paralyzing impacts from Oklahoma City and Tulsa to St. Louis due to the ferocity of the wraparound snows, and a heavy snow continuing on a stripe northeast across Chicago, Detroit and Toronto, as cold air is drawn south toward the storm center, only to clash with deep tropical warmth and moisture feeding north Thursday (OK), Thursday night (through Detroit) and Friday (Toronto).  Farther south, this storm will make headlines for its severe weather, which should produce multiple tornadoes from Arkansas and Louisiana eastward through the Lower Mississippi River Valley, Tennessee Valley and lower Ohio Valley Thursday night.  This severe weather will continue to roar northeast on Friday, ripping through the Mid-Atlantic and perhaps as far north as Southern New England.  Meanwhile, the wind feeding this system will be tremendous both ahead of the storm in the warm air, and behind it where blizzard conditions will likely verify in the areas described for heavy snow above.

Here in New England, we will wait until Friday for any direct effects from this storm.  The energy aloft that is associated with this storm is quite impressive, and the storm will still yank a slug of fast winds across New England on Friday as south winds just a few thousand feet off the ground are forecasted to blow at over 80 mph.  With mild air in place, and a well-mixed atmosphere allowing winds to transport toward the ground, damaging winds are likely across New England later Friday.  Adding to this threat will be the development of downpours and thunderstorms as the storm swings through, and these will help to carry potentially damaging wind to the surface, as well. 

Across Northern New England, the heaviest precipitation will fall, and at this point it looks like a combination of rain and snow.  Heavy rains certainly look to be in the cards for the North Country early on in the storm, Friday into the first part of Friday night, as cold air retreats into Canada given the fierce strength of the winds mentioned above.  This major clash in airmasses and input of tropical warmth and moisture will focus heavy rains over the North Country, where some flooding of streams and small rivers is likely Friday night.  Also during Friday night, however, the cold air lurking just over the border will surge south, and change heavy rain to heavy snow.  Though this will focus the heaviest swath of snow on Southern Canada, it will extend southward Friday night into Northern Vermont, New Hampshire, and Maine.  Given the amount of energy present with this storm, and the invasion of cold air Friday night, it's entirely possible that these far northern reaches of New England will find a brief period of white-out conditions late Friday night as all of the ingredients come together.  On Saturday, a northwest wind surges cold air southward into Northern New England, and we're likely to see snow in favored areas of the Green and White Mountains, and the mountains of Maine, as the northwest wind pushes up against the northwest facing mountainslopes and prolongs pockets of snow for the first half of Saturday.

Elsewhere, the weekend will begin a bit brisk, but bright on Saturday with a blend of sun and clouds.  The problem we face in the atmosphere by the end of the weekend into early next week is that the pattern still isn't comfortably settled.  That is, cold air will have been tugged into the North and plenty of energy will linger across both the Great Lakes and the Central Plains.  This sets the stage for another possible interaction of northern and southern stream energy - weaker than the first time around, but still with an available feed of tropical moisture off the U.S. East Coast.  If the two systems were to interact, and they could tap some of the available moisture, we'd be looking at a snowstorm for New England and some rain and snow farther south.  That said, at this point the pattern seems to favor limited - but still evident - interaction between the northern and southern disturbances.  This would produce increasing Sunday clouds, then a period of possible light snow Sunday night into Monday, but the heaviest of the precipitation falling over the fish as the storm takes off just east of New England.  It's, of course, still early, and I'll continue to keep you posted on the setup.

Nonetheless, the pattern for the upcoming couple of weeks - the first half of December - will feature a fast flowing jet stream with numerous disturbances embedded in it, thanks largely to the weak El Nino flow and therefore the steady stream of disturbances racing across the Pacific and through the Western United States.  This will mean repeated tugs of cold air at the surface into New England, with plenty of availability to tap additional moisture from the tropical Pacific and Gulf of Mexico if any of these disturbances can grow strong enough, which they'll have a better chance of doing after the first week of December, when Pacific input strengthens even a bit more.

Enjoy your Wednesday!

Matt

Matt's Technical Meteorological Discussion:  Updated Wednesday, November 29 at 2:40 PM

Cold is eroding where you'd expect it to today - that is, south and west with winds shifting from that direction, and southeast where warmer ocean waters have also assisted.  Otherwise, shallow cool dome is doing its part in creating clouds and areas of fog that have been migrating gradually northeast in response to the wind shift.  I'd expect Essex County, MA, points N and E to remain mostly cloudy until sunset with breaks of sun most other locales farther S and W and responding temps.  Clouds and fog will fill back in overnight as temps cool briefly until they meet the rising dewpoint.  This slow start on Thu will give way to emerging breaks of sun as mixing gets underway with increasing boundary layer flow from the SW.

Tried to go into as much detail as possible on the upcoming storm in the General Wx summary, but my technical reasoning on such a paralyzing potential for OK City to St. Louis comes from the combination of tremendous dynamics with...more importantly...extreme baroclinicity.  I would venture that the rate of deepening will be deeper than progged, the wind will be more fierce than progged in the Central US, and the wraparound precip will be just as fierce as progged with heavier banding resulting from the combo of differential advection as warm air wraps around the north side of the circulation and into the falling midlevel temps.  This will be a fun show to watch from afar on Thu and then also on Thu night as the snow band carries NE while severe weather breaks out from the MS Valley to the OH/TN valleys as tropical air streams north and intersects strong PVA.

Here in NewEng, as mentioned already, boundary layer flow increases Thu.  This, of course, increases low level WAA and with breaks of sun likely at times, that will only help to boost sfc temps with airmass supporting around or just above 60 in Southern NewEng and 50s north.  Various levels of the atmosphere showing high RH on Thu and with continuous WAA bringing bursts of isentropic lift, scattered showers possible at just about any time as is being witnessed on radar scopes to the west of NewEng today, so will hold the forecast to that regard.

Fri storm is extremely dynamic.  Yesterday I mentioned to Tim Kelley that the vort max itself reminds me a bit of the December 9 storm of last year, and in fact the dynamic low level setup is quite similar, as well.  There are, of course, some major differences that will make this a very different scenario - for example the storm is going to track hundreds of miles farther north and west, it's reaching its peak intensity aloft while it crosses the Ohio Valley, and the fact that it's removed from the ocean takes away a great deal of additional baroclinicity and moisture input.  So how are they similar?  The strength of the 500 mb vorticity maximum is quite similar, the system is closed aloft, and it's taking on a negative tilt as it crosses NewEng.  Track across Nrn NewEng puts Nrn VT, NH and ME in the bullseye of this storm for dynamically forced precip.  At first there is enuf mild air that this will mean heavy rain Fri for Central and esp Nrn NewEng.  FFG values are running around 2-2.75" in 6 hours, and that may be exceeded, so small rivers and streams may flood far North Country Fri night.  The dynamic cooling should be so intense, however, that we will tug cold air southward faster than progged by guidance and this will mean a quicker changeover to snow in the far North Country - esp north of the 500 mb circulation - with white-out conditions likely for a time overnight Fri Ngt and snow falling at the rate of a couple of inches per hour for a brief time.

Of course, that's only for the Nrn NewEng part of a storm that will bring widespread effects.  Though there is some excitement for snow lovers of any prospect of snow - and that means some getting giddy about next Monday's potential (more on that below) - it's critical that meteorologists and the public remain focused not on what plays better to emotion but what will have the most immediate impact on life, which will be the potential for damaging wind on Fri.  Southerly winds in advance of the storm are progged to blow to 85 knots at 850 mb and though the core of the 925 mb winds stays immediately south of NewEng in the latest NMM prediction, even those winds are blowing at 75-80 kts!  This may be somewhat mitigated in extreme Srn NewEng where mixing will be a bit limited due to flow off ocean waters that will be cooler than the air aloft, but Richardson Numbers indicate mixing all the way to 850 mb farther north and over the interior!  The combination of this southerly llvl jet prior to arrival of the front, convection likely to develop along and immediately ahead of the front, and CAA with assoc downward momentum transport behind the front gives plenty of cause for concern over damaging winds later Fri in NewEng.  As for the convective threat, there is no question the deepest instability is found to our south, from the Mid-Atlantic to the Southeastern US where I would expect a squall line to sweep east later Fri ahead of the front.  But while the same llvl instability is not present in NewEng, mid-lvl lapse rates are moderate over Srn NewEng where slug of warmth and moisture above 800 mb is just as impressive as it is farther S.  Combined with available dynamics and low level jet structure, there certainly appears to be a slight chance of that squall line extending/expanding north into Srn NewEng late Fri.

Though Sat looks fairly quiet for most of us, winds will still be 40-50 kts at 850 mb with cold advection from the NW and this favors upslope snows until the dry air can overcome those processes, and would expect these upslope snows in the favored locales of the Greens, Whites and mountains of Maine first half of Sat.  Elsewhere, downsloping flow and removal from rather channeled vorticity will leave most areas dry with sunshine between cold Cu.  Additionally, with the trof axis still well to our west, the deep cold will not carry all the way thru NewEng and we should find a rather pronounced temp difference from N to S by Sat afternoon.

Of course, this failure to move the trof axis farther east is what leaves such an interesting setup for late Sun into Mon.  That is, the jet stream will be laid over Srn NewEng with a baroclinic zone similarly ribboned across the region, and with two vorticity lobes to our west - one over the Upper Great Lakes holding back arctic air, and the other dipping thru the Rockies and Central Plains - the intriguing questions of potential phasing come back to give NewEng meteorologists and weather enthusiasts alike something to scratch our heads over.  I have to be completely honest that my thoughts this morning were that phasing would happen farther east than NewEng, and I held this thought largely because of the progressive nature of the flow over the Northeastern US, leading into the confluent flow locked east of NewEng, which, of course, will also serve to hold in the cold.  This idea of progressive disturbance and later phasing found good agreement among both Canadian and GFS Ensemble products, along with most operational runs, though one overwhelming feature was the presence of a rather well-defined inverted trof between the northern and southern disturbances that swings thru NewEng later Sun into Mon.  This, in combination with shortwave energy sheared out in the upper flow and running ahead of the main southern disturbance, was among my primary reasons for increasing Sunday clouds and putting at least light snow in the fcst late Sun into Mon.  This also set off an alarm, however, as I've seen cases in the past where a well-defined inverted trof is the precursor that the guidance is picking up on more interaction than it would appear, and the 12Z model guidance certainly has trended in this direction, at least in the case of the GFS and GGEM.  I should make it clear that I don't think storm track is a huge question here, contrary to what the instinct is to worry about (ie: will it come close enough?).  I don't think there's any question it will come close enough to affect New England - the baroclinicity is laid over us at 850 mb, the jet is over us at 300 mb and 500 mb flow is just south of the coast.  In fact, I think the track of any surface reflection would be farther north and west than currently progged.  What the question revolves around here is simply over how quickly the interaction and phasing takes place, and exactly where that happens.  12Z GFS started looking too progressive but then retrogrades the system, which is not only possible but in fact likely to happen when in fact phasing does occur.  With 12Z Canadian phasing early, but hot-off-the-presses ECMWF phasing late, this really doesn't help much, does it?!  So, for now will hold the line with the public forecast in expressing likelihood of light snow Sun Ngt/Mon and explain potential of earlier strengthening.

But again, very important to note that this won't be the highlight of the public forecast for now - while it entices meteorologists and weather enthusiasts, the major primary concern is Friday's blow of damaging winds, and must not be overshadowed by a storm potential at 5 days out.

Have a good day!

Matt

Monday's Discussion

1:30 PM:  30 degree spread across NewEng as of this writing from snow and 32 in Caribou, ME, to 62 and sun through Ci in OWD, SFZ, PVD, FIT.  Not bad for peak diurnal heating on what some would consider a quiet weather day!  Shortwave prompting rain and snow across Nrn ME will remain progressive, but so will the next shortwave upstream over Ontario as of this writing, which has been well-evidenced on radar and now shows good cloud top cooling on infrared imagery.  This shortwave will regenerate the swath of rain and snow across Nrn ME, and will a cooling boundary layer this should go to mostly snow with the I-95 corridor valleys starting as rain then changing to snow.  The shield of precip will drop south across Central ME and Bangor area may see a dusting by AM with temps around freezing which means black ice/icy spots a possibility, and accums of 2" possible higher terrain north of BGR area, esp from Millinocket points north.  Elsewhere, periods of clouds with shortwave passage seem rather innocuous but come prior to surge of shallow but meaningful cold that will migrate south behind Mon night's shortwave.  This cold has been brewing in Quebec and is a breakaway from gargantuan anticyclone in Central and Western Canada - therefore, this breakaway nature of the airmass means the cold is not overly deep but instead is a rather typical Eastern Canada surface dome that will be marked by a shift of winds to the northeast and brief gusts to over 20 mph with the wind shift.  Timing is 04-06Z in Portland and by 12Z most of NewEng has seen frontal passage.  Temps behind the front today are verifying in the 30s and NMM will verify best with this airmass thanks to its higher low level resolution.  Some areas in Srn NewEng will see falling temps after morning highs thanks to this cold advection.

Cold airmass remains locked in thru Tue Ngt, and areas of drizzle and light showers will be likely thanks to substantial low level instability.  Inversion present aloft, however, will strengthen Wednesday as warm advection commences above the boundary layer, but contrary to guidance forecasts I don't think the cold, dense air is going to give way to warm advection and mixing will be little if any, meaning low level deck remains locked in, isolated to scattered showers are possible thanks to warm advection aloft and temps remain cool.  Next system winds up enough to increase gradient and move air at the surface, so I do expect some warm advection in the boundary layer on Thu, though was looking at GFSX Ensemble members mostly in the middle 60s for Lawrence, MA, area Thu and I have a very hard time believing this with limited insolation and a stronger tendency for the cold to be rather begrudging in its departure.

In fact, as explained in the General Weather Summary above, I'd be surprised to find this cold air losing any meaningful battles in the next couple of weeks, and that includes Friday night, which is a critical battle in the world of meteorology, as nearly everything in the forecast will ride upon it.  I do mean quite literally "ride upon it" as the cold front will serve to be the path of the next incoming low.  I made my mind up which way to go with this for now when I reviewed the 00Z suite early today, and I have seen the warmer GFS solution even in its more recent 12Z run.  That said, I also see that the 00Z to 12Z has shown a rather substantial displacement to the southeast in the track of the low center - not yet where I'd expect it, but getting there.  So where would I expect the track?  Given the passage of a Thursday night shortwave similar to this coming night's wave, there's no reason to doubt whether the cold is capable of pushing thru NewEng.  It would appear as though the cruxt of the argument is the speed at which it sinks southward, to which we find good agreement among the Canadian Ensemble members and operational GGEM of a quick progression, GFS Ensemble mean position east and south of NewEng, and an ECMWF solution that is a bit more sluggish tho not nearly as sluggish as the GFS.  One could say that given the tendency for cold air to win the battles this time of the year, and the agreement among the Canadian Ensembles on the progression of this Canadian air - along with an NMM that also appears to be trending in a quicker cold direction, this certainly seems like the best forecast for the time-being.  Of course, in our discussions that's not quite enough, as I like to see synoptic reasoning to support guidance, and that synoptic reasoning is founded in the presence of confluent flow east of Maine, indicating the cold will come pouring in, then will hold.

Perhaps an equally challenging question is how the incoming Pacific vort will track and whether it will hold its identity as it encounters the confluent flow.  Thus far, the trend is only stronger with this Pacific energy as it lifts northeast across the OH/TN valleys, tho logic would say it should weaken as it approaches confluence.  I do think the guidance in general are still too far west with the vort max given the confluence east of NewEng and the colder surge as described above.  All of these factors raises my awareness of the potential for carrying accumulating snow farther south through New Eng than we've done so far this year, tho exactly where that is still remains up for grabs at 5 days out.  Heck, at 5 days out we know the whole thing remains up for grabs as described above, but of the solutions I prefer it would make the most sense to carry a moist Pacific-moisture loaded system either south of NewEng or over Southern NewEng Fri Ngt into early Sat, and this would mean the potential for accumulating snow even in Central NewEng.  It's also important to remember that shallow but strong cold can mean freezing precip, which wouldn't be impossible for interior locales if enuf cold air weren't present for snow.

So...plenty to work thru in the next couple of days.  In the meantime, enjoy the mild Monday (south) and the following chill Tuesday.

Matt


AS COOL AIR ESCAPES FROM CANADA, STUBBORN GRAY SKIES FOR MOST

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:

A surge of cold air has been sagging southward through New England on Tuesday and will bring a winter chill to some spots Tuesday afternoon, only begrudgingly letting go as the week progresses and milder, more moist air makes a run back at New England.

The passage of an upper level disturbance Monday night across the Canadian border brought minor snow accumulations to the higher terrain of Central and Northern Maine, where some slick road conditions began Tuesday morning.  But this disturbance also provided a southward tug of cold air that's been welled up across Quebec, marked by a shift in the winds to blow from the northeast.  This wind shift - a cold front - has continued settling south of New England on Tuesday, opening the gates for that cool air to seep southward from its Eastern Canadian well, knocking temperatures down through the day in some areas and bringing coastal gusts of wind in excess of 20 mph.  By the end of Tuesday, under gray skies with drizzle and mist for most Central and Eastern New England areas, and fog through parts of Vermont and Western Massachusetts on the edge of the deeper cool air, most communities will average around 40 degrees with a very raw feel. 

Those raw conditions will continue Tuesday night into Wednesday, even though warmer air will be moving back in thousands of feet above our heads.  Given the density of this heavy, cold air, that return of warmth will barely make it to ground level through the day on Wednesday, and instead will simply set up a continued clash between two airmasses, meaning continued patches of drizzle and light rain showers through the day, especially in Southern and Central New England.

Meanwhile, though midweek will bring raw but relatively quiet conditions to New England, the active jet stream trough to our west will still be breeding storms across the nation's midsection.  As each of these storms wind up into the Great Lakes with wind, rain and snow, pieces of energy will break northeastward into Canada, riding north of New England over the jet stream ridge as new energy is repeatedly fed into the Rockies and Plains from the Pacific Ocean.  Meanwhile, a weaker feed of energy and moisture will develop along the Eastern Seaboard, gradually filtering increasing moisture northward from the Gulf of Mexico and Southeastern coastal waters, and increasing the threat for showers - while gradually moderating temperatures - for Thursday.

By later Thursday into Friday, the much stronger lobes of energy across the Plains States - feeding off the clash of deep Northern cold and deep Southern warmth and humidity - will organize into a new, strong, end-of week storm.  This storm will sweep from the Central Plains to the Canadian border of New England, swinging a cold front and its associated slug of rain through New England.  The important question with this forecast was discussed here yesterday, and revolves around the timing of an incoming cold front, poised to drop out of Canada as the aforementioned storm charges across New England.  Though I'm willing to bring warm air into New England on Thursday as the cold dome erodes and winds increase from the south, there are two major reasons the pattern favors pulling cold air back into New England on Friday: 1) The amount of cold built up across Central and Southern Canada is quite heavy and dense, and the past two weeks has been eager to sag southward (remember 30s and rain last week, and the cool forecast for this midweek) and there is no sign that this cold will be any less dense or any less able to slide southward.  2) The jet stream winds aloft will converge just east of New England - that is, air will come together thousands of feet above our heads.  When air comes together aloft, it sinks through the atmosphere, favoring high pressure and therefore favoring a tug of cold air from Canada.

With the aforementioned active Pacific pattern continuing to bring energetic and rather moist disturbances across the country, there will be a moderate strength disturbance caught in the jet stream winds aloft over the Ohio and Tennessee Valleys, and the jet stream will steer this disturbance south of New England later Friday through Friday night.  The result of this disturbance will be HIGHLY dependent on the position of the cold air, the location of the cold front marking the leading edge to that chilly air (the front would serve as the pathway for the next storm) and, resultantly, the path of the next weak to moderate storm and therefore the track of its moisture.  If all were to come together, we'd be looking at some of the most southern reaching flakes of the season into Central and Southern New England, but as you've just read, there are quite a few factors still to watch.  At this point, the most likely scenario is to swing rain through most of New England on Friday, though Northern Vermont, Northern New Hampshire and Central/Northern Maine will be close enough to the significant cold air of Canada to warrant keeping a close eye on what may be an accumulating snow, especially Friday.  Farther south through the remainder of New England, it's possible that as the precipitation ends late Friday into Friday night, enough cold air moves in to end as some snow showers, though this is something that bears continued watching as it's far from set in stone.

Nonetheless, the pattern for the upcoming couple of weeks - the first half of December - will feature a fast flowing jet stream with numerous disturbances embedded in it, thanks largely to the weak El Nino flow and therefore the steady stream of disturbances racing across the Pacific and through the Western United States.  This will mean repeated tugs of cold air at the surface into New England, with plenty of availability to tap additional moisture from the tropical Pacific and Gulf of Mexico if any of these disturbances can grow strong enough, which they'll have a better chance of doing after the first week of December, when Pacific input strengthens even a bit more.

Have a great Tuesday!

Technical Discussion:  After a lengthy techie discussion yesterday (posted below), will use today to tend to busy behind-the-scenes day.

Matt

Matt's Technical Meteorological Discussion:  Updated Monday, November 27 at 1:30 PM

30 degree spread across NewEng as of this writing from snow and 32 in Caribou, ME, to 62 and sun through Ci in OWD, SFZ, PVD, FIT.  Not bad for peak diurnal heating on what some would consider a quiet weather day!  Shortwave prompting rain and snow across Nrn ME will remain progressive, but so will the next shortwave upstream over Ontario as of this writing, which has been well-evidenced on radar and now shows good cloud top cooling on infrared imagery.  This shortwave will regenerate the swath of rain and snow across Nrn ME, and will a cooling boundary layer this should go to mostly snow with the I-95 corridor valleys starting as rain then changing to snow.  The shield of precip will drop south across Central ME and Bangor area may see a dusting by AM with temps around freezing which means black ice/icy spots a possibility, and accums of 2" possible higher terrain north of BGR area, esp from Millinocket points north.  Elsewhere, periods of clouds with shortwave passage seem rather innocuous but come prior to surge of shallow but meaningful cold that will migrate south behind Mon night's shortwave.  This cold has been brewing in Quebec and is a breakaway from gargantuan anticyclone in Central and Western Canada - therefore, this breakaway nature of the airmass means the cold is not overly deep but instead is a rather typical Eastern Canada surface dome that will be marked by a shift of winds to the northeast and brief gusts to over 20 mph with the wind shift.  Timing is 04-06Z in Portland and by 12Z most of NewEng has seen frontal passage.  Temps behind the front today are verifying in the 30s and NMM will verify best with this airmass thanks to its higher low level resolution.  Some areas in Srn NewEng will see falling temps after morning highs thanks to this cold advection.

Cold airmass remains locked in thru Tue Ngt, and areas of drizzle and light showers will be likely thanks to substantial low level instability.  Inversion present aloft, however, will strengthen Wednesday as warm advection commences above the boundary layer, but contrary to guidance forecasts I don't think the cold, dense air is going to give way to warm advection and mixing will be little if any, meaning low level deck remains locked in, isolated to scattered showers are possible thanks to warm advection aloft and temps remain cool.  Next system winds up enough to increase gradient and move air at the surface, so I do expect some warm advection in the boundary layer on Thu, though was looking at GFSX Ensemble members mostly in the middle 60s for Lawrence, MA, area Thu and I have a very hard time believing this with limited insolation and a stronger tendency for the cold to be rather begrudging in its departure.

In fact, as explained in the General Weather Summary above, I'd be surprised to find this cold air losing any meaningful battles in the next couple of weeks, and that includes Friday night, which is a critical battle in the world of meteorology, as nearly everything in the forecast will ride upon it.  I do mean quite literally "ride upon it" as the cold front will serve to be the path of the next incoming low.  I made my mind up which way to go with this for now when I reviewed the 00Z suite early today, and I have seen the warmer GFS solution even in its more recent 12Z run.  That said, I also see that the 00Z to 12Z has shown a rather substantial displacement to the southeast in the track of the low center - not yet where I'd expect it, but getting there.  So where would I expect the track?  Given the passage of a Thursday night shortwave similar to this coming night's wave, there's no reason to doubt whether the cold is capable of pushing thru NewEng.  It would appear as though the cruxt of the argument is the speed at which it sinks southward, to which we find good agreement among the Canadian Ensemble members and operational GGEM of a quick progression, GFS Ensemble mean position east and south of NewEng, and an ECMWF solution that is a bit more sluggish tho not nearly as sluggish as the GFS.  One could say that given the tendency for cold air to win the battles this time of the year, and the agreement among the Canadian Ensembles on the progression of this Canadian air - along with an NMM that also appears to be trending in a quicker cold direction, this certainly seems like the best forecast for the time-being.  Of course, in our discussions that's not quite enough, as I like to see synoptic reasoning to support guidance, and that synoptic reasoning is founded in the presence of confluent flow east of Maine, indicating the cold will come pouring in, then will hold.

Perhaps an equally challenging question is how the incoming Pacific vort will track and whether it will hold its identity as it encounters the confluent flow.  Thus far, the trend is only stronger with this Pacific energy as it lifts northeast across the OH/TN valleys, tho logic would say it should weaken as it approaches confluence.  I do think the guidance in general are still too far west with the vort max given the confluence east of NewEng and the colder surge as described above.  All of these factors raises my awareness of the potential for carrying accumulating snow farther south through New Eng than we've done so far this year, tho exactly where that is still remains up for grabs at 5 days out.  Heck, at 5 days out we know the whole thing remains up for grabs as described above, but of the solutions I prefer it would make the most sense to carry a moist Pacific-moisture loaded system either south of NewEng or over Southern NewEng Fri Ngt into early Sat, and this would mean the potential for accumulating snow even in Central NewEng.  It's also important to remember that shallow but strong cold can mean freezing precip, which wouldn't be impossible for interior locales if enuf cold air weren't present for snow.

So...plenty to work thru in the next couple of days.  In the meantime, enjoy the mild Monday (south) and the following chill Tuesday.

Matt


REPEATED TUGS OF COLD AIR TO BRING PERIODS OF GRAY...BUT COULD GRAY + COLD = WHITE GROUND BY FRIDAY NIGHT?

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis 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:

Welcome back to the blog!  After nearly 5" of rain with the Turkey Day storm, and sustained winds to between 40 and 50 mph near the coastline of Southern New England, the weekend brought drying and pleasant conditions to most of the six-state region.  The upcoming week will bring a gradual breakdown of the mild conditions as cold air settles southward in surges - one surge for Tuesday into midweek, and another likely by the upcoming weekend.

In the meantime, the jet stream winds aloft that steer our storms and act as a thermostat for the atmosphere have been dipping into a trough across the Western United States, and rising as a ridge here in the East.  The result has been to keep New England on the warm side of the atmospheric thermostat, and at the surface, an area of high pressure parked over the Appalachian Mountains is playing a role, as well - it's clockwise circulation of air around its center will send light southwest winds and slightly warmer air seeping into New England on Monday.  The combination of mild air and dimmed sunshine through milky skies shrouded with high-altitude cirrus clouds will push temperatures near 60 in Central and Southern New England.  Farther north, the southern edge of deep Canadian cold ensures such mild air will not arrive to the Canadian border.  In fact, with a strengthening and southward shifting northern high pressure cell moving across Hudson Bay into Southern Quebec over the next few days, cold air will be forced farther southward.

The passage of an upper level disturbance later Monday into Monday night across the Canadian border will team with the leading edge to this new cold air to spawn an area of snow across Central and Northern Maine, where a dusting is possible in the valleys around Bangor by Tuesday morning, an inch especially on grassy surfaces in higher terrain, and one to two inches from Millinocket points north, and up to three inches in the higher terrain of Aroostook County, ME.  Elsewhere, expect clouds to continue to thicken Monday night as the leading edge to the deeper Canadian cold will settle farther south into Central New England, marked by a shift in the winds to blow from the northeast, perhaps with a brief gust to over 20 mph.

As this wind shift - a cold front - settles southward through the day on Tuesday, the cool air welled up over Quebec will take a stronger hold of New England, and in some Southern New England locales, temperatures actually may fall during the day Tuesday after being kept rather mild by a blanket of overnight cloud cover.  By the end of Tuesday, most of New England will average around 40 degrees with a very raw feel made all that much more brisk by an active northeast wind, lots of clouds, and a few patches of drizzle and light showers by day's end.  The raw conditions are expected to continue on Wednesday, as warmer air moves in thousands of feet above our heads but makes little difference here on the ground, where dense cool air will remain firmly in place.  The clash between these two airmasses is likely to continue producing patches of drizzle and light rain showers through the day, especially in Southern and Central New England.

Meanwhile, though midweek will bring raw but relatively quiet conditions to New England, the active jet stream trough to our west will still be breeding storms across the nation's midsection.  As each of these storms wind up into the Great Lakes with wind, rain and snow, pieces of energy will break northeastward into Canada, riding north of New England over the jet stream ridge as new energy is repeatedly fed into the Rockies and Plains from the Pacific Ocean.  Meanwhile, a weaker feed of energy and moisture will develop along the Eastern Seaboard, gradually filtering increasing moisture northward from the Gulf of Mexico and Southeastern coastal waters, and increasing the threat for showers - while gradually moderating temperatures - for Thursday.

By later Thursday into Friday, the much stronger lobes of energy across the Plains States - feeding off the clash of deep Northern cold and deep Southern warmth and humidity - will organize into a new, strong, end-of week storm.  This storm will sweep from the Central Plains to the Canadian border of New England, swinging a cold front and its associated slug of rain through New England later Thursday through Thursday night.  The question - and it's an important one - is how quickly this front swings through the six-state region.  Though meteorological guidance products range from a quick progression, bringing cold air in for Friday, to a slow trudge, keeping mild air around until Friday night, the weather pattern would dictate the quicker surge of cold is more likely, and this would be important for a Friday night disturbance that would still need to swing through.  There are two reasons for the pattern favoring more cold into New England on Friday: 1) The amount of cold built up across Central and Southern Canada is quite heavy and dense, and the past two weeks has been eager to sag southward (remember 30s and rain last week, and the cool forecast for this midweek) and there is no sign that this cold will be any less dense or any less able to slide southward.  2) The jet stream winds aloft will converge just east of New England - that is, air will come together thousands of feet above our heads.  When air comes together aloft, it sinks through the atmosphere, favoring high pressure and therefore favoring a tug of cold air from Canada.

With the aforementioned active Pacific pattern continuing to bring energetic and rather moist disturbances across the country, there will be a weak to moderate disturbance caught in the jet stream winds aloft over the Ohio and Tennessee Valleys, and the jet stream will steer this disturbance south of New England later Friday into early Saturday.  The result will be HIGHLY dependent on the position of the cold air, the location of the cold front marking the leading edge to that chilly air (the front would serve as the pathway for the next storm) and, resultantly, the path of the next weak to moderate storm and therefore the track of its moisture.  If all were to come together, we'd be looking at some of the most southern reaching flakes of the season into Central and Southern New England, but as you've just read, there are quite a few factors still to watch.

Nonetheless, the pattern for the upcoming couple of weeks - the first half of December - will feature a fast flowing jet stream with numerous disturbances embedded in it, thanks largely to the weak El Nino flow and therefore the steady stream of disturbances racing across the Pacific and through the Western United States.  This will mean repeated tugs of cold air at the surface into New England, with plenty of availability to tap additional moisture from the tropical Pacific and Gulf of Mexico if any of these disturbances can grow strong enough, which they'll have a better chance of doing after the first week of December, when Pacific input strengthens even a bit more.

Enjoy your Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Monday, November 27 at 1:30 PM

30 degree spread across NewEng as of this writing from snow and 32 in Caribou, ME, to 62 and sun through Ci in OWD, SFZ, PVD, FIT.  Not bad for peak diurnal heating on what some would consider a quiet weather day!  Shortwave prompting rain and snow across Nrn ME will remain progressive, but so will the next shortwave upstream over Ontario as of this writing, which has been well-evidenced on radar and now shows good cloud top cooling on infrared imagery.  This shortwave will regenerate the swath of rain and snow across Nrn ME, and will a cooling boundary layer this should go to mostly snow with the I-95 corridor valleys starting as rain then changing to snow.  The shield of precip will drop south across Central ME and Bangor area may see a dusting by AM with temps around freezing which means black ice/icy spots a possibility, and accums of 2" possible higher terrain north of BGR area, esp from Millinocket points north.  Elsewhere, periods of clouds with shortwave passage seem rather innocuous but come prior to surge of shallow but meaningful cold that will migrate south behind Mon night's shortwave.  This cold has been brewing in Quebec and is a breakaway from gargantuan anticyclone in Central and Western Canada - therefore, this breakaway nature of the airmass means the cold is not overly deep but instead is a rather typical Eastern Canada surface dome that will be marked by a shift of winds to the northeast and brief gusts to over 20 mph with the wind shift.  Timing is 04-06Z in Portland and by 12Z most of NewEng has seen frontal passage.  Temps behind the front today are verifying in the 30s and NMM will verify best with this airmass thanks to its higher low level resolution.  Some areas in Srn NewEng will see falling temps after morning highs thanks to this cold advection.

Cold airmass remains locked in thru Tue Ngt, and areas of drizzle and light showers will be likely thanks to substantial low level instability.  Inversion present aloft, however, will strengthen Wednesday as warm advection commences above the boundary layer, but contrary to guidance forecasts I don't think the cold, dense air is going to give way to warm advection and mixing will be little if any, meaning low level deck remains locked in, isolated to scattered showers are possible thanks to warm advection aloft and temps remain cool.  Next system winds up enough to increase gradient and move air at the surface, so I do expect some warm advection in the boundary layer on Thu, though was looking at GFSX Ensemble members mostly in the middle 60s for Lawrence, MA, area Thu and I have a very hard time believing this with limited insolation and a stronger tendency for the cold to be rather begrudging in its departure.

In fact, as explained in the General Weather Summary above, I'd be surprised to find this cold air losing any meaningful battles in the next couple of weeks, and that includes Friday night, which is a critical battle in the world of meteorology, as nearly everything in the forecast will ride upon it.  I do mean quite literally "ride upon it" as the cold front will serve to be the path of the next incoming low.  I made my mind up which way to go with this for now when I reviewed the 00Z suite early today, and I have seen the warmer GFS solution even in its more recent 12Z run.  That said, I also see that the 00Z to 12Z has shown a rather substantial displacement to the southeast in the track of the low center - not yet where I'd expect it, but getting there.  So where would I expect the track?  Given the passage of a Thursday night shortwave similar to this coming night's wave, there's no reason to doubt whether the cold is capable of pushing thru NewEng.  It would appear as though the cruxt of the argument is the speed at which it sinks southward, to which we find good agreement among the Canadian Ensemble members and operational GGEM of a quick progression, GFS Ensemble mean position east and south of NewEng, and an ECMWF solution that is a bit more sluggish tho not nearly as sluggish as the GFS.  One could say that given the tendency for cold air to win the battles this time of the year, and the agreement among the Canadian Ensembles on the progression of this Canadian air - along with an NMM that also appears to be trending in a quicker cold direction, this certainly seems like the best forecast for the time-being.  Of course, in our discussions that's not quite enough, as I like to see synoptic reasoning to support guidance, and that synoptic reasoning is founded in the presence of confluent flow east of Maine, indicating the cold will come pouring in, then will hold.

Perhaps an equally challenging question is how the incoming Pacific vort will track and whether it will hold its identity as it encounters the confluent flow.  Thus far, the trend is only stronger with this Pacific energy as it lifts northeast across the OH/TN valleys, tho logic would say it should weaken as it approaches confluence.  I do think the guidance in general are still too far west with the vort max given the confluence east of NewEng and the colder surge as described above.  All of these factors raises my awareness of the potential for carrying accumulating snow farther south through New Eng than we've done so far this year, tho exactly where that is still remains up for grabs at 5 days out.  Heck, at 5 days out we know the whole thing remains up for grabs as described above, but of the solutions I prefer it would make the most sense to carry a moist Pacific-moisture loaded system either south of NewEng or over Southern NewEng Fri Ngt into early Sat, and this would mean the potential for accumulating snow even in Central NewEng.  It's also important to remember that shallow but strong cold can mean freezing precip, which wouldn't be impossible for interior locales if enuf cold air weren't present for snow.

So...plenty to work thru in the next couple of days.  In the meantime, enjoy the mild Monday (south) and the following chill Tuesday.

Matt


THANKSGIVING WEEK TO FEATURE BRUSH WITH COASTAL STORM FOR SOME...PERIODS OF DELIGHTFUL WEATHER AT TIMES

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:

Quick note:  Today's (Tuesday's) discussion will be the final of the week.  Discussions to resume after Thanksgiving weekend, on Monday.  Have a wonderful holiday!

As the holiday stretch moves along, the Thanksgiving week will feature a quiet start, a brush by a coastal storm, and gradual weekend improvement.  The weather map on Tuesday leading into Thanksgiving featured a strengthening storm off the Southeastern U.S. coastline, becoming increasingly infused with tropical moisture as it sits over warm southern waters, pulling air in from the Gulf Stream to its east as it spins.  Farther inland, cool and dry air remains locked in place, and this has made for a very cold rain through the interior Carolinas while the coastline around the outer banks is finding northeast winds sustained at 35 mph with gusts to 40 mph!  This storm has - as of this writing - shown no signs of tropical development, but will continue to be a windy and wet creature as it crawls up the Interstate 95 corridor.

Meanwhile, New England's sunshine through the first half of the week has come thanks to a large area of high pressure, chock full of cool and dry Canadian air as it sprawls across the Ohio Valley, moving across New England at midweek.  This air brings a chill and below normal temperatures both during the day and even more pronounced at night, with temperatures dropping into the teens and twenties Tuesday night, making for the coldest start of the season Wednesday morning.  The weather setup for the middle of the week will be one of great interest - with mild air moving in aloft, one would expect to find increasingly mild temperatures through the end of the week.  The trick here is that we'll also find the strong, cool, dry, fair weather center moving just barely northeast of New England while the southern coastal storm pulls north.  Because air tends to flow from high pressure to low pressure - from fair weather to storms - surface winds will blow from the north-northeast, maintaining a cool flow at ground level even though very mild air moves in aloft.  This was evidenced Tuesday afternoon on Cape Cod as clouds increased, it will be evidenced with pockets of clouds here and there on Wednesday, but the actual response in temperature here on the ground to this milder air thousands of feet high in the sky will be limited.

Even given complexity to the atmospheric setup on Wednesday, there will be no travel impediments weather-wise across the Northeast through the day as travel reaches a maximum.  Delays are likely on flights to areas along the Eastern Seaboard south of Virginia Beach, in particular, and also in the Pacific Northwest where another storm will be moving in from the Pacific Ocean.  All the while, the slow moving coastal storm to our south will be slowly snaking northward, parallel to the East Coast, before taking a right turn south of New England.  The complexity in this setup will be a clash of airmasses set up over Southern New England that will help to focus northward streaming moisture, and will result in showers spreading into extreme Southern New England early Thanksgiving Day, then gradually spreading northward through the remainder of Southern New England through the day.  By day's end on Thursday, we're likely to find rain from the coastal plain of Maine into Southern New Hampshire and Southern Vermont points southward.

Periods of rain and showers are likely to be found across New England Thursday night and Friday, as well, as the main slug of energy and moisture passes southeast of Nantucket but a relatively strong easterly wind flow keeps plenty of moisture in the lowest few thousand feet of the atmosphere across New England.

By Saturday and Sunday, indications are that we should find gradual improvement as the primary storm circulation moves east of New England.  Aloft, there will be a weak disturbance moving overhead Saturday afternoon, and while a few showers still may crop up, I'm optimistic on improvement into and through Sunday, as well!

Have a wonderful Thanksgiving...and I'll see you back here Monday!

Matt

Matt's Technical Meteorological Discussion:  Updated Tuesday, November 21 at 1:35 PM

Interesting blossom of clouds over Southeastern MA this afternoon and adjacent coastal waters appear to come thanks to some very complex differential advection as cold advection at the surface is overrun by warm advection immediately above in altitude, resulting in the sudden blossom of stratocumulus, as the result was effectually elevated instability through a thin layer just above the boundary layer.  These will only develop as long as there is warm advection above the cool dome, which should wane toward evening as the initial push of warmth and moisture diminishes.  Some patches of these clouds may linger into the overnight near the immediate coast, and with warm water and very cold air temps thanks to low Tds tonight, some percolating clouds are possible within 20 miles of the coastline.  Otherwise, high altitude cirrus will ride over Central and Northern NewEng and slightly hamper radiational cooling but temps will still fall rather dramatically.

Cold start Wed won't help to get temps on the rebound but sunshine should.  Can't promise full sun all areas on Wed even given the dry RH forecast, largely thanks to the same mechanism that produced clouds in extreme SE NewEng on Tue - that is, various levels of differential advection through the day that will result in pockets of clouds, nearly impossible to pinpoint.  Keep in mind that the overall transition for the next 60 hours brings the upper low and sfc reflection off the SE US coastline northward with tap to tropical moisture while maintaining sfc flow from the NNE due to pressure gradient flow from high to low pressure.  All the while, 850 mb warmth to the tune of +8 to +12 C anomaly will be streaming east across the Great Lakes and OH valley, and will spread over NewEng.  This will result in strongly anomalous warmth over NewEng on Thu, but with the sfc flow still north and northeast for most spots, low dewpoint air will continue feeding into NewEng.

As the storm center moves north and assoc moisture invades NewEng Wed Ngt/Thu, this dry Td air will be very important for temp forecasts, as MOS guidance are likely woefully overdone with fcsts of lower 50s max temps.  This seemed reasonable in previous guidance cycles, but 12Z guidance is in good agreement on a NNE flow, which means the dry air, and therefore means when moisture moves in the temp will fall.  This shouldn't be shocking, and truly has been dependent upon both wind direction and how much moisture moved into NewEng - obs over interior NC/SC show temps in the 30s and lower 40s under heavy rain bands.  For what it's worth, interesting that Outer Banks have been sustained 35 mph and gusting 40 mph today, and this is actually around a meso low center that developed well north of the upper level support, in clusters of convection.  Nothing about this appears tropical with regard to its core right now, tho visible satellite imagery certainly does show an impressive cold core spiral and assoc convection does contain tropical moisture.  As this storm presses north - only slowly on the south side of sfc ridging - the assoc warm and moist advection presses north.  Believe NMM is too fast in spreading steady precip into Srn NewEng - after being much too far south in previous runs - Wed Ngt, and instead think anything that makes it into Srn NewEng Wed Ngt will be showery in nature as it outruns most of PVA driven dynamic forcing, which shifts farther west from PA to Ern NY.  The approach of the upper low and assoc vort lobe rotating around NE side of circulation will bring steadier precip along and SE of low level thermal boundary that should be draped across Srn NewEng.  Lighter precip immediately on cool side of boundary may extend up ME coastline.  Have gone with a timing slower than the NMM - similar to the GFS tho shifted farther north areally...more in line with a solution weighted toward the Canadian Ensembles, which did a tremendous job picking up on this yesterday, and are a big reason I haven't had to change the Turkey Day forecast and have kept precip in throughout.  Yet another win for an Ensemble team that's been performing exceptionally well this season.

My gut tells me to beware of Sat, when the upper low may decide to linger, which would especially be a problem given the weak to moderate shortwave in the Northern stream set to move overhead on Sat.  But, guidance has become insistent and in very good agreement on moving the upper low along, so even my thoughts of keeping showers in NewEng early Sat seem overdone now.  Nonetheless, with combo of insecurity on speed of upper low departure, and possible reflection of inverted trough across NewEng ahead of incoming shortwave, have decided to keep chance of a shower in the fcst.

Sunday brings improvement before what will be a very interesting week next week.  The tremendously tight thermal packing across Canada will settle southward into the Northern Plains while the Pacific feed of disturbances continues.  This will place tremendous baroclinicity in the path of these disturbances, and the 12Z Operational GFS is keying in on this, developing a very strong storm over the Upper Midwest and Upper Great Lakes.  Given strength of cold surface high descending south across Southern Canada at the time - two anticyclone centers bridging from west to east, I believe the GFS storm position may be in error, and may crank up farther east.  A position closer to NYS would put NewEng into potential for heavy rain midweek, then frontal passage, then with trough position over Great Lakes, cool air moving in, and another strong shortwave still to round the base of the trough, quick development of a northeast-scooting coastal would have to be watched around December 1, which has also been hit hard by GFS Ensemble means.

Should get exciting again next week!

Enjoy your holiday - back on Monday.

Matt


QUICK SHOT OF COOL TO EASE BY MIDWEEK...SOUTHERN MOISTURE HELD AT BAY UNTIL TURKEY DAY

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:

Quick note:  Tomorrow's (Tuesday) discussion will be the final of the week.  Discussions to resume after Thanksgiving weekend, on Monday.  Have a wonderful holiday!

New England has made the switch from mild to cool this week - with an active northwest wind carrying cool, dry air out of Canada.  Aloft, an upper level storm is pivoting overhead, with moderate amounts of energy elongated up and down the Eastern Seaboard.  Closest to some of the more energetic bundles, rain and snow showers have resulted with one over Northern Maine Monday morning resulting in one to two inches of snow in the higher terrain with a sloppy coating at lower elevations.  Elsewhere in New England, we will find protection from an area of high pressure settling overhead for most of the week, as a strengthening storm churns off the Southeastern US coastline.

In the meantime, the cool flow of northwest winds across New England will hold temperatures in the 40s for most spots - barely exceeding 50 at South Coastal locales and struggling just to get to 40 in the higher terrain of Northern and Western New England.  This air is cold both at the surface and aloft - certainly the coolest shot of air we've seen in the last couple of weeks - and the chilly nature of the air thousands of feet aloft will promote cloud development through the day, though the dry nature of the air will also mean some decent breaks of sun will be found from time to time.

With light winds, clearing skies and cool, dry air still in place Monday night, expect chilly temperatures for one and all, with most spots bottoming out in the 20s and a few valleys falling into the teens.  This chilly start on Tuesday will help to ensure another cool day regionwide, with most spots finding the core of the cold air moving through, holding temperatures a bit cooler than Monday's highs, though a bit more in the way of sunshine will help to mitigate the chill somewhat.

Meanwhile, to our south, bundles of energetic disturbances aloft will be congregating along the Southeastern US coastline.  Though this energy has produced only scattered bursts of rain and snow showers thus far, the development and strengthening of a storm center along the coastline will initiate moist Atlantic onshore flow, introducing plenty of moisture to the system and allowing both for strengthening and for expansion of the precipitation shield.  Cut off from the strongest of the jet stream winds aloft that steer our storm systems, however, this storm will only slowly meander northward, spreading rain up the Mid-Atlantic seaboard and the I-95 corridor on Wednesday.  North of Virginia Beach, however, the same area of fair weather cresting over the Northeast will hold moisture at bay.  All the while, the cold nature of this air will begin to diminish from the top down, as warmth brewing across the Plains states makes an eastward run, pinching off the source of cool air to New England as warmth cuts across Southern Canada, and eventually erodes the cold over our region.  The combination of this new warmer air, and slowly increasing moisture from the south in advance of the southern storm, will mean that another dry and slightly milder day on Wednesday will give way to increasing clouds on Thanksgiving.  In fact, by later Thanksgiving Day - especially by evening and night - indications are that showers will fall in Southern New England.

With very slow progression of the storm up the Atlantic Seaboard - and likely southeast of New England as it becomes embedded in the jet stream winds once again - rain will be equally slow to exit as it was to enter.  That is, while Northern New England may never get into more of this precipitation shield than just a few showers, Southern areas that are more squarely into the moisture spreading north of the storm center may have to contend with showers Friday into Saturday.  While the cold above our heads will be gone, ensuring anything that falls should be in the form of rain - at the surface a shallow dome of cool air will linger, and temperatures will be held down on Friday and Saturday as a result.

Happy Turkey Day - see you back here tomorrow.

Matt


AFTER LONG STRETCH OF MILD WEATHER, TEMPERATURES TO RETURN BELOW NORMAL

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 a soaker!  The heavy, tropical rains moving through New England Thursday night into Friday dropped between one and two inches of rain to many areas, with some locally higher amounts.  This amount of rain in such a short period of time - only a few hours - prompted flooding of streams and streets, and some small rivers continue to rise as of this morning.  To check river levels near you, feel free to utilize the Northeast River Forecast center webpage by clicking here.

Friday's weather map features a cold front nudging east into New England, bringing a wind shift and heralding in cooler and drier air.  This cooler air comes in two installments, however, and the first has been sparking downpours in Vermont Friday morning, though should be rather innocuous elsewhere.  In fact, the passage of this front will be so delayed in Central, Southern and Eastern New England, that the combination of mild air and emerging sunshine will push temperatures well into the 60s and even a bit over 70 in a few communities!  This kind of warmth will spell record warmth for a few areas - perhaps in Bridgeport, CT, where the record is 66 on Friday, and we've already broken the old record of 52 in Caribou, ME, when we began the day at 62 and continue to climb!

Cooler is will stream into New England on a steady west wind Friday night, and a few snow showers will develop in the far northern mountains with partly cloudy skies elsewhere.  This will bring a blend of clouds and sun on Saturday with high temperatures still near or perhaps slightly above normal, but noticeably cooler than they've been.  This will be the beginning of a new jet stream pattern that will feature a trough - or dip - in the jet stream winds over New England, returning the six-state region to a near or below normal temperature pattern for at least a few days after two weeks of above to much above normal temperatures.  Though this will not be a bona fide, long-lasting and well-defined cool pattern - lasting only until Wednesday of next week - it's enough so that ski areas should plan on making hay while the sun shines, so to speak, as snowmaking conditions should be good for this window of time.  In fact, while most of New England sees a brisk blend of clouds and sun on Saturday, northern mountains may be graced with snow showers from time to time.

Meanwhile, the jet stream winds aloft - the fast river of air high in the sky that steers our storms - will still flow over New England.  This means a disturbance aloft will be subject to riding overhead on Sunday with increased clouds Saturday night into Sunday, and the chance of early Sunday rain showers south and snow showers north.  Thereafter, Sunday afternoon would likely bring plenty of lingering clouds among breaks of sun.  Monday looks to be a break in the action here in New England for at least part of the day with a few rain or snow showers possible later, then we'll wait and watch a developing coastal storm off the Southeastern US coastline, which may take until midweek to churn north.

Technical Discussion:  None today.

Matt

Matt's Technical Meteorological Discussion:  Updated Wednesday, November 15 at 2:25 PM

Short term fcst to carry pulsing showers fed by low level tropical inflow northward from SCoast of NewEng thru remainder of area overnight Wed Ngt.  Combo of mostly cloudy skies and active S wind at sfc and moreover a few thousand feet off the ground will inhibit cooling and overnight low temps will be remarkably mild, with 50s in many Srn NewEng cities - evidence provided by mid 50s Tds as of this writing.  Tho KBOS is unlikely to stay above 59 degrees overnight Wed Ngt, KCON record warm min temp is 51 from 1960 and a new warm min may be set tonight.  KCAR is within one degree of record high of 56 as of this writing.

Expect any light showers early Thu caused by combo of low level WAA and PVA with vort moving from S to N to wane as NVA sets in for most of the day and brings drier air to the midlvls, and breaks of sun shud result for a time.  Wind will strengthen along SCoast first, then across most of NewEng by later Thu as pressure gradient tightens between 1024-1026 mb high S of Nova Scotia and 988 mb low over OH.  Intense llvl jet at 850 mb will be to our W across PA/NY and this is where heaviest flooding rains will fall on Thu.

Trend continues to be slower with the upper low but this shud not be too surprising, as it is truly a continuation of the pattern we've already been dealing with.  Two weeks ago we saw a similar scenario with our upper low originally looking as though it would deliver a solid chunk of cold but then backing farther and farther west until finally it was evident it would be unable to pull deep cold this far east.  With an Ensemble longwave pattern forecast of pulling the upper low to James Bay by Friday evening and a new strong shortwave coming thru the NW US at the same time, while amplified ridge axis peaks over Ern Canada and Maritimes, it's simply not possible to pull the upper low far enough east to deliver a formidable shot of deep cold to NewEng.

But that doesn't mean we're not looking at cold enough conditions for snow making in the mountains once again, and that also doesn't mean the above to much above normal pattern rolls on, as shallow cold is still cold nonetheless, even if there is no monster high to drive it south, and this will make for chilly nights and cool days.  That said, there may be more than one devil in the details with regard to the weekend forecast, as the longwave pattern indicates there should be little comfort for NewEng forecasters.  Tho Sat features a break between systems as the upper low recoils a bit into SCentral Canada, this recoiling will yank shortwaves down from the active Pacific flow and they will round the base of the trof - the first rounding the trof base in the OH Valley Sat ngt and ejecting NE.  This shortwave will move over NewEng late Sat Ngt or more likely on Sun.  Those of you who read regularly know that I find the upper level RH field to be a very telling sign of what may follow in surface trends, largely because it is devoid of low level baroclinicity, which can certainly be a driving factor, but in this instance will largely be determined by the upper level flow.  Not only is the 12Z NAM picking up on this upper level RH extending northward toward NewEng, but it would make sense that if we're banking on the upper level flow being sluggish we should also bank on the low level baroclinic zone not shifting as far east as forecasted by the guidance currently.  This raises concern for precip Sat Ngt into Sun, esp early Sun with the passage of the vort max overhead.  This introduces an event of low forecastabillity thanks to the variation between expected longwave pattern and forecasted results at the surface by the guidance, but instinct says be cautious and introduce a chance of precip for at least early Sun and have adjusted fcst accordingly as of this writing.

But this isn't the end of the story, as the Pacific NW shortwave mentioned earlier in this disc will traverse the Nrn Plains and then drop into the base of the trof in the OH valley, like its predecessor, and will force the longwave trof to tilt neutrally Mon, likely prompting low pressure development at the Mid-Atl coast.  Mon Ngt into Tue, this surface low will be captured by the upper level support, and the low will attempt to stack vertically.  This introduces tremendous uncertainty with regard to where and when this interaction of vertical circulations takes place, and this uncertainty is reflected in Ensemble spread, as well, though it's worth noting that some GFS Ensemble members and ECMWF Ensemble members paint moderate precip onto Ern NewEng while Canadian Members miss and keep precip offshore.  Of course, my thoughts on precip forecasts with such an uncertain pattern at such a long forecast period is that they should be taken with a grain of salt, and the message we're getting from the longwave pattern is far more important.

As for Sergio...strengthening off the western coast of Mexico...indications are that his moisture will filter rather than surge over the next several days, as it's tugged both northward by the intense Pacific disturbances, and eastward as these systems strengthen in the OH and TN valleys, so rather than a rapid integration, a slow feed of fuel from the system is more likely.

While colder air will undoubtedly bleed into NewEng under the belly of the large upper low by James Bay, and a more significant chunk of surface cold may wrap south behind any disturbances Sat Ngt/Sun and then again later Mon/Tue, without a mechanism to hold this cold into NewEng, average temp regime is likely to return to near or somewhat above normal by middle of next week, though not by nearly as much as the past two weeks, still bringing cool enuf nights for snowmaking and returning us to an oscillating pattern of warmth ahead of shortwaves and brief shots of shallow cool behind them.

Enjoy your Wednesday.

Matt


FLOODING RAINS, DAMAGING WINDS AND THUNDERSTORMS ALL POSSIBILITIES ACROSS NEW ENGLAND

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:

A very late post today due to lots going on behind the scenes here at NECN.

An intense round of heavy, locally flooding rain, gusty and potentially damaging wind, and embedded thunderstorms will sweep across New England late Thursday night through early Friday.  A potent storm system moving slowly across Kentucky has established a deep feed of tropical moisture out of the Gulf of Mexico and the Tropical Atlantic, and this is feeding a combination of severe weather and tornadoes from the Carolinas through the Mid-Atlantic coastline, to heavy rainfall up the spine of the Appalachians.

For New England, the surge of tropical warmth and moisture brought dense morning fog early Thursday for many areas, and this fog was quite stubborn to lift in Central New England, in the battlezone of incoming tropical air and the relatively cooler, drier air that was in place.  This boundary is draped across Southern New England Thursday afternoon and is evident as a wind shift and the back edge to low altitude clouds.  The front will serve as the focus for heavy rainfall later Thursday night into Friday, and already has been responsible for scattered heavy downpours.

What were expected to be simply scattered showers along this leading edge of tropical warmth instead have blossomed into scattered downpours for some Thursday afternoon.  This trend will continue into Thursday evening, as the flow of increasingly warm and humid air continues.  In fact, in areas squarely into this warmth through Connecticut, Rhode Island and Southeastern Massachusetts, breaks of sun have emerged and pushed temperatures well into the 60s and to near 70 degrees!

The well-defined swirling storm system to our southwest is gradually nosing toward New England, and it's the very fast corridor of wind ahead of the low pressure center that has tapped such deep tropical moisture.  Of course, just because this air is moisture loaded doesn't mean its speed slows any in that fast corridor of wind, and winds just a few thousand feet off of ground level are blowing at over 60 mph.  This corridor of wind, and the moisture it carries, will progress northeast ahead of the storm center and the energetic upper level disturbance that's driving it.  The result will be twofold: 1) Winds will increase across Vermont and will likely gust over 60 mph Thursday night with scattered power outages and downed trees, and 2) steadier and heavier rain develops late Thursday night, and a band of narrow but intense rainfall marches into New England from late Thursday night through Friday morning.

This band of rain will be so intense, that between one and three inches of rain is likely to fall in a very short period of time, with locally higher amounts possible!  This would result in nearly-certain street flooding and hydroplaning concerns for the morning drive on Friday, especially in Central and Eastern New England where the band of rain would move through at peak commute times, and also is likely to push at least some streams out of their banks for flash flooding, especially where 3" amounts of rain are observed.  In these locales, small rivers also may briefly spill their banks.  Given the amount of warmth and moisture in the lower few thousand feet of the sky, and the energy aloft, thunderstorms are likely to be embedded in this line of downpours, and any thunderstorms would have the capability of pulling down the strong winds aloft, producing damaging wind gusts in excess of 60 mph in at least a few communities that see thunderstorms Friday morning, and this would produce isolated power outages.

This corridor of wind and water will be focused along and ahead of a cold front sweeping east, and the drier and cooler air behind the front will ensure the rain band keeps moving, as well as providing an effort to break some sunshine out later Friday.  With cool and dry air spilling into New England, expect gradual clearing Friday night to bring a blend of clouds and sun on Saturday with high temperatures still near or perhaps slightly above normal, but noticeably cooler than they've been.  This will be the beginning of a new jet stream pattern that will feature a trough - or dip - in the jet stream winds over New England, returning the six-state region to a near or below normal temperature pattern for at least a few days after two weeks of above to much above normal temperatures.  Though this will not be a bona fide, long-lasting and well-defined cool pattern - lasting only until Wednesday of next week - it's enough so that ski areas should plan on making hay while the sun shines, so to speak, as snowmaking conditions should be good for this window of time.  In fact, while most of New England sees a brisk blend of clouds and sun on Saturday, northern mountains may be graced with snow showers from time to time.

The complication to the weekend forecast is that the jet stream winds aloft - the fast river of air high in the sky that steers our storms - will still flow over New England.  This means a disturbance aloft will be subject to riding overhead on Sunday with increased clouds Saturday night into Sunday, and the chance of early Sunday rain showers south and snow showers north.  Thereafter, Sunday afternoon would likely bring plenty of lingering clouds among breaks of sun.  Monday looks to be a break in the action here in New England for at least part of the day, but another upper level disturbance will spawn a coastal storm off the Mid-Atlantic, and this storm may pass close enough to deliver rain and snow to some of New England late Monday into Tuesday, though that is highly uncertain at this point.

Technical Discussion:  None today.

Matt

Matt's Technical Meteorological Discussion:  Updated Wednesday, November 15 at 2:25 PM

Short term fcst to carry pulsing showers fed by low level tropical inflow northward from SCoast of NewEng thru remainder of area overnight Wed Ngt.  Combo of mostly cloudy skies and active S wind at sfc and moreover a few thousand feet off the ground will inhibit cooling and overnight low temps will be remarkably mild, with 50s in many Srn NewEng cities - evidence provided by mid 50s Tds as of this writing.  Tho KBOS is unlikely to stay above 59 degrees overnight Wed Ngt, KCON record warm min temp is 51 from 1960 and a new warm min may be set tonight.  KCAR is within one degree of record high of 56 as of this writing.

Expect any light showers early Thu caused by combo of low level WAA and PVA with vort moving from S to N to wane as NVA sets in for most of the day and brings drier air to the midlvls, and breaks of sun shud result for a time.  Wind will strengthen along SCoast first, then across most of NewEng by later Thu as pressure gradient tightens between 1024-1026 mb high S of Nova Scotia and 988 mb low over OH.  Intense llvl jet at 850 mb will be to our W across PA/NY and this is where heaviest flooding rains will fall on Thu.

Trend continues to be slower with the upper low but this shud not be too surprising, as it is truly a continuation of the pattern we've already been dealing with.  Two weeks ago we saw a similar scenario with our upper low originally looking as though it would deliver a solid chunk of cold but then backing farther and farther west until finally it was evident it would be unable to pull deep cold this far east.  With an Ensemble longwave pattern forecast of pulling the upper low to James Bay by Friday evening and a new strong shortwave coming thru the NW US at the same time, while amplified ridge axis peaks over Ern Canada and Maritimes, it's simply not possible to pull the upper low far enough east to deliver a formidable shot of deep cold to NewEng.

But that doesn't mean we're not looking at cold enough conditions for snow making in the mountains once again, and that also doesn't mean the above to much above normal pattern rolls on, as shallow cold is still cold nonetheless, even if there is no monster high to drive it south, and this will make for chilly nights and cool days.  That said, there may be more than one devil in the details with regard to the weekend forecast, as the longwave pattern indicates there should be little comfort for NewEng forecasters.  Tho Sat features a break between systems as the upper low recoils a bit into SCentral Canada, this recoiling will yank shortwaves down from the active Pacific flow and they will round the base of the trof - the first rounding the trof base in the OH Valley Sat ngt and ejecting NE.  This shortwave will move over NewEng late Sat Ngt or more likely on Sun.  Those of you who read regularly know that I find the upper level RH field to be a very telling sign of what may follow in surface trends, largely because it is devoid of low level baroclinicity, which can certainly be a driving factor, but in this instance will largely be determined by the upper level flow.  Not only is the 12Z NAM picking up on this upper level RH extending northward toward NewEng, but it would make sense that if we're banking on the upper level flow being sluggish we should also bank on the low level baroclinic zone not shifting as far east as forecasted by the guidance currently.  This raises concern for precip Sat Ngt into Sun, esp early Sun with the passage of the vort max overhead.  This introduces an event of low forecastabillity thanks to the variation between expected longwave pattern and forecasted results at the surface by the guidance, but instinct says be cautious and introduce a chance of precip for at least early Sun and have adjusted fcst accordingly as of this writing.

But this isn't the end of the story, as the Pacific NW shortwave mentioned earlier in this disc will traverse the Nrn Plains and then drop into the base of the trof in the OH valley, like its predecessor, and will force the longwave trof to tilt neutrally Mon, likely prompting low pressure development at the Mid-Atl coast.  Mon Ngt into Tue, this surface low will be captured by the upper level support, and the low will attempt to stack vertically.  This introduces tremendous uncertainty with regard to where and when this interaction of vertical circulations takes place, and this uncertainty is reflected in Ensemble spread, as well, though it's worth noting that some GFS Ensemble members and ECMWF Ensemble members paint moderate precip onto Ern NewEng while Canadian Members miss and keep precip offshore.  Of course, my thoughts on precip forecasts with such an uncertain pattern at such a long forecast period is that they should be taken with a grain of salt, and the message we're getting from the longwave pattern is far more important.

As for Sergio...strengthening off the western coast of Mexico...indications are that his moisture will filter rather than surge over the next several days, as it's tugged both northward by the intense Pacific disturbances, and eastward as these systems strengthen in the OH and TN valleys, so rather than a rapid integration, a slow feed of fuel from the system is more likely.

While colder air will undoubtedly bleed into NewEng under the belly of the large upper low by James Bay, and a more significant chunk of surface cold may wrap south behind any disturbances Sat Ngt/Sun and then again later Mon/Tue, without a mechanism to hold this cold into NewEng, average temp regime is likely to return to near or somewhat above normal by middle of next week, though not by nearly as much as the past two weeks, still bringing cool enuf nights for snowmaking and returning us to an oscillating pattern of warmth ahead of shortwaves and brief shots of shallow cool behind them.

Enjoy your Wednesday.

Matt


MIDWEEK BREAK TO BE FOLLOWED BY INTENSE BUT SHORT-LIVED BAND OF RAIN AND WIND TO END MILD STREAK

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:

FYI:  All Tsunami Watches and Warnings were discontinued this morning after a magnitude 8.1 (estimated) earthquake in the Kuril Islands of Russia - in the Northwestern Pacific - prompted concern from the Pacific Tsunami Warning Center.  If you would like a direct link to the infomation, click here.

No changes today to the overall weather pattern, which is still slated to bring an end to our two week stretch of above to much above normal temperatures in New England with a reconfiguration that will bring better news for ski areas.  Temperatures cold enough for making snow should return to New England this weekend, and a few mountains will see some natural snow showers, as well.

Widespread Wednesday morning clouds continue to slowly break up through the day, promising more widespread sunny breaks than were seen on Tuesday, when sun and milder temperatures were confined to the immediate coastline of Northern MA, and most of Southeast MA.  Though plenty of moisture remains in the lowest few thousand feet of the atmosphere on Wednesday, the combination of drier air aloft and a weak mixing of the atmosphere will continue to erode clouds enough for widespread sunny breaks across New England, though enough moisture remains present in the North Country for many clouds to fill back in Wednesday afternoon, keeping temperatures a bit cooler as a result.

A vigorous storm is brewing over the Lower Mississippi River Valley on Wednesday, however, launching tropical moisture out of the Gulf of Mexico and into the Southeastern United States, where some severe weather is likely this afternoon.  This new moisture adds to an already Pacific-moist system that dumped heavy rain and snow to the Northwestern U.S. on Monday and brought overnight windswept snows to the Central Plains Tuesday night.  After plowing through the Southeast, this storm will curl northward, poised to deliver a shot of tropical moisture to New England once again.  The slow movement of this storm is likely to hold substantial rainfall to our west through most of the day Thursday.  It's important to keep in mind, however, that - like our previous surges of warmth and moisture - there will likely be several surges of new moisture.  The result will be scattered showers pushing into the South Coast of New England Wednesday evening, then spreading north in scattered form overnight Wednesday night into Thursday morning, lifting from Southern New England to Northern New England, separate from the main slug of moisture associated with the incoming storm.

The heaviest rainfall to move through New England associated with the next system will move through overnight Thursday night into Friday morning, and the commute is likely to be very difficult Friday morning.  This band of heavy rain will be accompanied by strong winds aloft and is likely to bring at least some gusty winds to the surface, especially in thunderstorms that develop where wind gusts to over 50 mph may result.  With the band of rain, thunder and wind relatively quick-moving, however, gradual clearing is expected Friday afternoon as drier and cooler air pours into New England.  This will be the beginning of a new jet stream pattern that will feature a trough - or dip - in the jet stream winds over New England, returning the six-state region to a near or below normal temperature pattern after two weeks of above to much above normal temperatures.  Though this will not be a bona fide, long-lasting and well-defined cool pattern - lasting only until Wednesday of next week - it's enough so that ski areas should plan on making hay while the sun shines, so to speak, as snowmaking conditions should be good for this window of time.  In fact, while most of New England sees a brisk blend of clouds and sun on Saturday, northern mountains may be graced with snow showers from time to time.

After next Wednesday, an oscillating pattern is expected - that is, temperatures averaging near normal with warmups ahead of each disturbance and shots of cool air behind them.

Matt

Matt's Technical Meteorological Discussion:  Updated Wednesday, November 15 at 2:25 PM

Short term fcst to carry pulsing showers fed by low level tropical inflow northward from SCoast of NewEng thru remainder of area overnight Wed Ngt.  Combo of mostly cloudy skies and active S wind at sfc and moreover a few thousand feet off the ground will inhibit cooling and overnight low temps will be remarkably mild, with 50s in many Srn NewEng cities - evidence provided by mid 50s Tds as of this writing.  Tho KBOS is unlikely to stay above 59 degrees overnight Wed Ngt, KCON record warm min temp is 51 from 1960 and a new warm min may be set tonight.  KCAR is within one degree of record high of 56 as of this writing.

Expect any light showers early Thu caused by combo of low level WAA and PVA with vort moving from S to N to wane as NVA sets in for most of the day and brings drier air to the midlvls, and breaks of sun shud result for a time.  Wind will strengthen along SCoast first, then across most of NewEng by later Thu as pressure gradient tightens between 1024-1026 mb high S of Nova Scotia and 988 mb low over OH.  Intense llvl jet at 850 mb will be to our W across PA/NY and this is where heaviest flooding rains will fall on Thu.

Trend continues to be slower with the upper low but this shud not be too surprising, as it is truly a continuation of the pattern we've already been dealing with.  Two weeks ago we saw a similar scenario with our upper low originally looking as though it would deliver a solid chunk of cold but then backing farther and farther west until finally it was evident it would be unable to pull deep cold this far east.  With an Ensemble longwave pattern forecast of pulling the upper low to James Bay by Friday evening and a new strong shortwave coming thru the NW US at the same time, while amplified ridge axis peaks over Ern Canada and Maritimes, it's simply not possible to pull the upper low far enough east to deliver a formidable shot of deep cold to NewEng.

But that doesn't mean we're not looking at cold enough conditions for snow making in the mountains once again, and that also doesn't mean the above to much above normal pattern rolls on, as shallow cold is still cold nonetheless, even if there is no monster high to drive it south, and this will make for chilly nights and cool days.  That said, there may be more than one devil in the details with regard to the weekend forecast, as the longwave pattern indicates there should be little comfort for NewEng forecasters.  Tho Sat features a break between systems as the upper low recoils a bit into SCentral Canada, this recoiling will yank shortwaves down from the active Pacific flow and they will round the base of the trof - the first rounding the trof base in the OH Valley Sat ngt and ejecting NE.  This shortwave will move over NewEng late Sat Ngt or more likely on Sun.  Those of you who read regularly know that I find the upper level RH field to be a very telling sign of what may follow in surface trends, largely because it is devoid of low level baroclinicity, which can certainly be a driving factor, but in this instance will largely be determined by the upper level flow.  Not only is the 12Z NAM picking up on this upper level RH extending northward toward NewEng, but it would make sense that if we're banking on the upper level flow being sluggish we should also bank on the low level baroclinic zone not shifting as far east as forecasted by the guidance currently.  This raises concern for precip Sat Ngt into Sun, esp early Sun with the passage of the vort max overhead.  This introduces an event of low forecastabillity thanks to the variation between expected longwave pattern and forecasted results at the surface by the guidance, but instinct says be cautious and introduce a chance of precip for at least early Sun and have adjusted fcst accordingly as of this writing.

But this isn't the end of the story, as the Pacific NW shortwave mentioned earlier in this disc will traverse the Nrn Plains and then drop into the base of the trof in the OH valley, like its predecessor, and will force the longwave trof to tilt neutrally Mon, likely prompting low pressure development at the Mid-Atl coast.  Mon Ngt into Tue, this surface low will be captured by the upper level support, and the low will attempt to stack vertically.  This introduces tremendous uncertainty with regard to where and when this interaction of vertical circulations takes place, and this uncertainty is reflected in Ensemble spread, as well, though it's worth noting that some GFS Ensemble members and ECMWF Ensemble members paint moderate precip onto Ern NewEng while Canadian Members miss and keep precip offshore.  Of course, my thoughts on precip forecasts with such an uncertain pattern at such a long forecast period is that they should be taken with a grain of salt, and the message we're getting from the longwave pattern is far more important.

As for Sergio...strengthening off the western coast of Mexico...indications are that his moisture will filter rather than surge over the next several days, as it's tugged both northward by the intense Pacific disturbances, and eastward as these systems strengthen in the OH and TN valleys, so rather than a rapid integration, a slow feed of fuel from the system is more likely.

While colder air will undoubtedly bleed into NewEng under the belly of the large upper low by James Bay, and a more significant chunk of surface cold may wrap south behind any disturbances Sat Ngt/Sun and then again later Mon/Tue, without a mechanism to hold this cold into NewEng, average temp regime is likely to return to near or somewhat above normal by middle of next week, though not by nearly as much as the past two weeks, still bringing cool enuf nights for snowmaking and returning us to an oscillating pattern of warmth ahead of shortwaves and brief shots of shallow cool behind them.

Enjoy your Wednesday.

Matt


WEATHER PATTERN SHIFT TO FOLLOW MILD END OF WEEK

Welcome to the weather blog - a regular Monday through Friday discussion of the weather!  While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants.  I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible.  You'll find a quick weather synopsis 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:

After a two week stretch of above to much above normal temperatures in New England, changes are in the offing as the weather pattern reconfigures heading into the upcoming weekend, meaning better news for ski areas who - at this point - would be thrilled just to get temperatures cold enough for making snow.  That air will return to New England this weekend.

In the meantime, a the same slow-moving, tropically-infused storm that's been spinning parallel to the Eastern Seaboard since the weekend will make its move northward and cross New England on Tuesday.  While this low pressure center has been spinning bands of rain into New England on the north side of its circulation, the south side of the storm has consistently been producing a swath of sunshine and very mild temperatures.  After the passage of morning showers and downpours - even a few thunderstorms in the deeper tropical air on Cape Cod - this pocket of drier air will follow the storm center on Tuesday as it moves northward across Eastern Massachusetts, and thanks to the tropical origin of the air embedded in this storm, temperatures will respond very quickly to sunshine, boosting into the 60s and even perhaps near 70 in parts of Eastern Massachusetts.  The trick to this scenario, however, is that a little sun goes a long way and whoever doesn't see sun, simply doesn't see the quick temperature rebound.  With cooler and somewhat drier air in place across most of New England, this will mean most of New England remains cloudy and cool, with what will likely be a sharp western line to the sunny breaks, likely set up somewhere near Interstate 495 in Eastern MA.  The overall trend certainly will be for showers to end in Southern New England by midday Tuesday, however, with bands of rain breaking up to scattered showers in Northern New England, though bands of heavy and locally flooding rains will continue in Maine through most of the day.  In these heavier rain bands, localized flooding of streets and small streams will be possible, and though winds will be gusty at the coastline, I'd be surprised to see anything damaging.

Even in areas of Eastern Southern New England where clouds may break up for a time, a moist near-surface airmass will allow clouds to redevelop Tuesday night, along with a few areas of fog, while showers taper across Maine.  With a break in the action to begin Wednesday, most early clouds will give way to emerging sunshine in Southern New England, though Northern Mountains are likely to see more clouds than sun through most of the day.  As we approach afternoon on Wednesday, however, another upper level disturbance will move from southwest to northeast across New England - much weaker than its predecessors and devoid of moisture in comparison, but still strong enough to crank out a few showers across New England Wednesday afternoon into Wednesday evening.

When we examine the bigger picture today - outside of the Northeast - a series of strong jet stream disturbances are evident from the Rocky Mountains to the Upper Midwest.  These disturbances are quite energetic, and as they converge to develop a strengthening surface storm, moisture will once again be tapped from the Gulf of Mexico, adding to an already Pacific-moist system that dumped heavy rain and snow to the Northwestern U.S. on Monday.  The result will be severe thunderstorms across the Southeastern United States Wednesday afternoon before this storm curls northward, poised to deliver a shot of tropical moisture to New England once again.  The trend with this storm has been to slow it upon approach, and this is likely to hold substantial rainfall to our west through most of the day Thursday.  It's important to keep in mind that - like our previous surges of warmth and moisture - there will likely be several surges of new moisture.  The result will be showers Wednesday night into Thursday morning, lifting from Southern New England to Northern New England, separate from the main slug of moisture associated with the incoming storm.

The heaviest rainfall to move through New England associated with the next system will move through overnight Thursday night into Friday morning, and the commute is likely to be very difficult Friday morning.  This band of heavy rain will be accompanied by strong winds aloft and is likely to bring at least some gusty winds to the surface, especially in thunderstorms that develop, but will be relatively quick-moving, leaving drier and cooler air pouring into New England later Friday.  This will be the beginning of a new jet stream pattern that will feature a trough - or dip - in the jet stream winds over New England, returning the six-state region to a near or below normal temperature pattern after two weeks of above to much above normal temperatures.  Though this will not be a bona fide, long-lasting and well-defined cool pattern - lasting only until Wednesday of next week - it's enough so that ski areas should plan on making hay while the sun shines, so to speak, as snowmaking conditions should be good for this window of time.  In fact, while most of New England sees a brisk blend of clouds and sun on Saturday, northern mountains may be graced with snow showers from time to time.

After next Wednesday, an oscillating pattern is expected - that is, temperatures averaging near normal with warmups ahead of each disturbance and shots of cool air behind them.

Matt