Friday, March 17, 2017

Minimal Snow Threat Saturday in SNE, Sunday??


High pressure is in charge today but it will shift offshore tomorrow as an approaching clipper dives south of New England.   While there may be some light snow tomorrow, it will struggle to accumulate on the roads.  A more interesting scenario is in play late Saturday night into Sunday.   The clipper will "explode" as it reaches the Gulf Stream.  These systems love strong thermal gradients and really develop when they encounter one. How far north/east this happens will determine how much, if any, snow will fall.

General Overview
Here is the forecast surface map as of 8 PM tonight.  
WPC Surface Fronts/Precipitation Friday 8 PM
Cloud cover will be minimal tonight and winds will be light.  The clipper will slide south and east as the NW floor keeps a cold, dry Canadian air mass in place.  The deep snowpack across the interior will work with the dry air, clear skies, and light winds to drop temps into the single digits.  Closer to the big cities temperatures will drop into the teens.
NWS Minimum Temperatures Saturday AM (image Weatherbell)
Clouds will increase on Saturday and most of the day will be gray.  There might be a few light snow showers.  I can't see any snow sticking before sundown, except in the highest elevations in Western MA and Northern Worcester County.  Even there it would be a coating if that.  Temperatures tomorrow afternoon will be in the mid to upper 30's across Worcester, Middlesex, Essex, Suffolk, and Norfolk counties.  In SE MA/RI max temps will get into the low 40's.
NWS Maximum Temperature Saturday PM (image Weatherbell)
Things will get interesting Saturday Night.  This is when the clipper low will begin transfer into an extratropical ocean storm.  At a minimum, a period of strong winds will occur over the Cape and Islands as the surface low develops.
WPC Surface Fronts/Precipitation Saturday 8 PM
Any precipitation would not stick until after midnight in RI/ E MA.  Temperatures will be dropping into the mid 20's by Sunday AM.  A couple of bands of snow are possible if the low forms closer to SNE.  If that were to occur, 1-3" would be possible from Hampton Beach -Fitchburg - Springfield -Fairfield south and east and perhaps 3-6" for SE MA and S RI,  The most likely solution is generally 1-2" South of the Pike and 2-4" S coastal MA and the Cape/Islands.
NWS Snowfall Accumulation Sunday 2 AM to Sunday 2 PM
 I'll be out of town until Sunday AM, but I will try to get some information up tomorrow if a trend to the North happens and it looks like we get more snow.

-Zack Green

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