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Wednesday 12/8 Possible Snow/Ice/Rain? Discussion

Torch Tiger

By Torch Tiger,
in New England

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weathafella
weathafella

Hi everyone!  Thanks so much for the multitude of good wishes-it means a lot and touches my heart!  We were watching a movie around 12:30AM when out of nowhere I got lightheaded and experienced severe

weathafella
weathafella

I’m heading to the hospital-some concerning symptoms so I doubt I’ll do pbp…

ORH_wxman
ORH_wxman

My son was up at 6am and made me come outside in the snow with him.....what a weenie.    

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40/70 Benchmark

40/70 Benchmark

Posted
Posted

 Early Season Winter Storm Possible Mid Week

The Situation:

There appears to be a take two on the early winter "lion" that failed to materialize last week. Clearly not all of the potential for mischief in the atmosphere is realized, otherwise the plant earth would be nearly inhabitable and only individuals such as your's truly would rejoice. However, there appears to be yet another, higher percentage opportunity for winter to fire the first significant shot across the bow of southern New England next week, as illustrated by the mass convergence evident in the major teleconnections of the both the pacific:
 
Pacific.png
 
 

 
And the arctic:
 
Arctic.png
 
While the overall pattern across the hemisphere is relatively hostile both with respect to the pacific and polar domains, the shape and orientation of the polar vortex is such that it allows periodic intrusions of polar air into the our sector of the western hemisphere.
cold.png
One such episode will occur on the heels of a very mild and blustery day on Monday. 
 
Warm%2BMonday.png
 
 
It is this system that will bring early week rainfall and scattered wind damage before propelling a strong cold front through the region overnight on Monday into early Tuesday morning.
 
Colder%2BTuesday.png
 
It is this polar airmass that will set the stage for what is likely to be region's first significant and widespread snowfall of the 2021-2022 winter season on Wednesday.
 
Wednesday%2Bsnower.png
 
The initial upper air shortwave over the Saint Lawrence river valley will initially induce a southwest flow aloft that will cause precipitation to break out during the day on Wednesday. However, as the system encounters the relatively stout antecedent polar airmass in place it will begin to transfer the energy to the coast. Since there is no high latitude blocking or west coast ridging in place to provide the impetus for this evolution to transpire as such, it is subject to the nuances of timing. Thus far, it appears as though the system will arrive while the antecedent airmass provides enough resistance to produce a winter storm, however, there is still about a day or so for that to change. Just how quickly said resistance induces a transfer of energy to the coast in order to end the southwest flow aloft will determine how much of the snowfall transitions to rain, sleet, ice and how much  precipitation falls. More diffuse primary energy and more pervasive antecedent polar air will promote a faster transfer of energy and heavier snowfall totals across the region. However, if polar air provides less resistance and the primary energy persists for a longer duration, than the protracted southwest flow aloft will ultimately advect milder, and drier air into the region ensuring nothing more than a modest to moderate snowfall across the entirety of the region.
 

Preliminary Anticipated Storm Evolution:

The warm front in association with the first system driving far to the northwest should advance through the region on Monday warming, followed by rainfall and very gusty southwest winds with some sporadic damage and power outages.
 
RAD%2B1.png
 
The region will spend Monday in the warm sector before the trailing cold front begins to advect colder air into the region overnight on Monday.
 
RAD%2B2.png
 
 
 
The follow up disturbance will approach the area and induce an initial southwest flow aloft, which collide with the antecedent polar air mass in place to cause snow to break out from southwest to northeast on Wednesday morning.
 
RAD%2B3.png
 
 
Precisely just how long the primary parent energy remains prominent will determine how extensive the period of southwesterly flow will last. It is likely that precipitation will mix with/change to sleet and rain inside of route 128 and near and to the south of the Mass pike. The Wednesday morning commute should be especially problematic across SW New England.
 
RAD%2B4.png
 
 
However, the Wednesday evening commute should be a messy across the region, especially north and perhaps across northern Connecticut, as a significant period of glaze is possible. While some freezing rain is also possible outside of I 495 and south of the Mass pike, it should be most prevalent across the northern  section of Connecticut, where the southwest flow aloft is likely to persist the longest and is able to thin the layer cold sufficiently in the mid levels of the atmosphere. 
Mix.jpg
 
Regardless of what exactly transpires, the system looks to exit the area early Thursday.
 
RAD%2B5.png
 

First Call:

The primary question to ponder over the weekend and into early next week is just how fast that coastal energy transfers and consolidates off of the coast. The 12z GFS is very aggressive in closing off the coastal low in the mid levels late Wednesday night.
H85:
H85%2BHeights.png
 
H700:
 
H7%2BHeights.png
 
This has important implications on the forecast because it shifts winds in the mid levels of the atmosphere from south and southwesterly:
 
H7%2BWinds%2B1.png
 
to more easterly, which limits precipitation type issues both in duration and extent by and duration.
 
H7%2BWINDS%2B2.png
 
This also acts to protract the period of accumulating snowfall overnight Wednesday into early Thursday, especially across the northern and eastern third of the region. This cold have significant implications on the Thursday morning commute.
H7%2BRH.png
 
 
Hopefully there will be more a consensus with respect to the evolution of coastal cyclogenesis over the next day or two, but here is the current best estimate.
 
FIRST%2BCALL.png
 
 
 
Final Call be issued on Tuesday-
  
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Typhoon Tip

Typhoon Tip

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Posted
3 hours ago, ineedsnow said:

18z GEFS does have more meh members now though

I honestly thought the 18z version was a little bit of a shirk job for route 2 corridor and up.  It was snowier ptype for more people but it was also less QPF bombing low or not;  it was strengthening low but it was also tracking it slightly south of the previous tracks which were better for the interior

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