Sunday, March 12, 2017

Winter Storm Stella Set To Deliver Blow To Region

Winter Storm Stella will come together off the Mid-Atlantic coast on Monday and she will deliver a quick hitting strike that will drop over a foot of snow for much of Southern New England.  Snow will begin between 5-7 AM and will continue until late Tuesday evening.  Winds will be very strong on Tuesday and as a result, a *Blizzard Watch* has been issued for parts of the region.  A *Winter Storm Watch* is up for much of the rest of SNE.
NWS Boston AM Headlines 
After reviewing the latest data, I think the blizzard watches may be expanded west to Providence and Worcester and east to include Martha's Vineyard and the Lower Cape.    The dominant feature that will contribute to the coastal development of Stella is moving across the Great Plains today.  IL/IN/OH are all expecting 4-8" of snow as the feature progresses east the next 24-36 hours.
NWS/NOAA/NCEP GOES Water Vapor Satellite 1115 AM
The energy moving off the Carolina coast dropped a bit of snow in the South this morning.  It was nothing major but it's clear that air mass preceding Stella is incredibly cold for March.  Temperatures at 12 PM are in the 20's still for much of the northern 1/3 of the country.
15z HRRR 2 m temps Sunday 12 PM (image Weatherbell)
Temperatures tonight will fall to the upper single digits/low teens.  It will be a little warmer tomorrow when compared to the past few days.  Max temps will rise into the low to mid 30's.  Winds will be light and skies will be sunny tomorrow.  Even a light wind at the bus stop tomorrow morning will give wind chills around 0.  This all sets the stage for Stella.  Here is the forecast surface map tomorrow at 8 PM.
WPC Surface Fronts/Precipitation Monday 8 PM
Snow flies after 3 AM in Western New England and it flies in Central/Eastern Southern New England around 5 AM.  Once it hits it will stick.  This is not like last Friday when the snow did not stick to the roads. The cold this weekend will allow for snow to stick to all surfaces immediately.
12z NAM hires 3 km Simulated Radar Tuesday 5 AM (image Weatherbell)
The worst of the storm is from Tuesday 7 AM to 5 PM.  Winds will gust 40-50 mph while heavy snow falls.   Temperatures will be in the low 20's when the snow begins.  Temps should rise to near 30 by Tuesday afternoon, before falling back into the low 20's.
WPC Surface Fronts/Precipitation Tuesday 8 AM
The center of the storm is forecast to cross near Nantucket.  If the track is a little further offshore, higher snow totals will verify in SE MA.  One signal that is really jumping out to me is the potential for extremely heavy snowfall Tuesday AM.  The commute will be nearly impossible in Southern New England if this is to verify.  Some guidance is suggesting 4-6" of snow by 8 AM in the Blackstone Valley (also most of Metrowest and SE MA).  By 11 AM we are over a foot!  Do the math- it will be snowing at of rates of 2"/hr.
12z NAM 3km sim radar Tuesday 9 AM (image Weatherbell)

The storm will thump all morning and into early afternoon before the intensity begins to wane.  That mix line is very important along the south coast.  It will push inland; how far is the question.  I don't see it getting past Plymouth/Providence.  Tuesday night there will be some backlash snow, but the intensity of this remains in question.  It will likely to be hard to tell at times if snow is falling or blowing Tuesday evening into Wednesday AM, however.

NWS Boston Snowfall Forecast Tuesday-Wednesday
Please don't get too excited about the 18". I think many towns will check in the 12-14" range and a few will be 16-20".  That's something to fine tune as Stella approaches.  The incredible intensity of the initial snow burst will introduce a huge bust potential into the snow totals.  If you miss that band you may miss the high range.   I will post again tomorrow AM with updates to timing, totals, and watches/warnings.  I also think Stella has a surprise or two up her sleeve.

PS- Since everyone is probably heading to the store today/tomorrow, why not pick up some Stella's in honor of the storm?  If you are in that sort of thing, that is.
If you went to the store yesterday,

-Zack Green

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