Region Wide Wintry Precipitation Saturday

Temperatures dropped to 4 degrees in Boston this AM which made today the coldest morning in the city since 1989.  Worcester dropped to -1 which is impressive but it is tied with 12-21-2004 for the coldest morning this century,  The winds were strong but not as impressive as I thought they would be.  A warm front will lift north and kick high pressure offshore tonight.  With Arctic air firmly in place moisture will overrun the front and fall as snow.  Snow should begin to accumulate between 3-4 AM and it will continue until late morning.  Warmer air will then flow in aloft but it will remain below freezing at the surface and a round of freezing rain will complete the precipitation.  The storm finishes as rain everywhere south of Boston.

General Overview
The National Weather Service has issued a *Winter Weather Advisory* for most of the region from 1 AM until early afternoon.  The advisory expires in SE MA and RI at 1 PM.  Wintry precipitation lingers longer in Central/Western MA and NE CT so the advisory continues until 3 PM.  The advisory also continues until 3 PM in NE MA.
NWS Boston Headlines Friday 4 PM
Temperatures will remain in the upper teens to low 20's across SNE until 7 AM.  It will warm into the low 30's on the Outer Cape/Islands around daybreak.  Snow begins between 2-4 AM from SW to NE from CT to ME.  It will be slow to accumulate at first but by 7 AM it will be snowing steadily.
18z NAM hires parallel sim radar Saturday 7 AM (image Weatherbell)
At 10 AM the rain/snow line has advanced just north of route 44 in SE MA and route 6 from Providence to Hartford.  Snow may be thumping at 1"/hr between 9-11 AM in NE, C, and W Mass.
18z NAM hires parallel simulated radar Saturday 10 AM (image Weatherbell)
Between 11-12 sleet and rain will mix in with snow.  Warmer air aloft will turn all precipitation to rain.  Temperatures at the surface will remain below freezing so rain will freeze on contact.  This will add weight to snow but it will also make travel difficult for much of tomorrow AM/early PM.
18z NAM hires parallel simulated radar Saturday 12 PM (image Weatherbell)
I am in agreement with the NWS on snow and ice.  I do think we are closer to 6 in Northern CT, Western MA and Northern Worcester County.  Southern Worcester into Middlesex and Essex counties will be on the lower end.
Temperatures stay in the upper 20's but they will steadily climb into the 30's by midnight.  By Sunday morning temps will rise into the upper 40's/low 50's.  Winds will likely gust 40-50 mph on Sunday as a cold front passes offshore and a strong area of high pressure builds in the Central US.
WPC Surface Fronts/Precipitation Sunday 7 AM 
Up to a half inch of rain may fall with this.

-Zack Green


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