Winter Storm Watches Posted for Wednesday

A coastal storm will bring accumulating snow Southern New England Wednesday into Wednesday night/early Thursday morning.  Without any true Arctic air locked in there will be a fine line between rain/snow.  As it stand now this line should work back towards 495, but will struggle to get much further.  The Cape, Southern RI, and Coastal CT will likely be shut out.

NWS Boston Headlines

General Overview

Low pressure forms in the Gulf of Mexico tomorrow afternoon

WPC 1 PM surface forecast Tuesday

By Wednesday AM the system will begin to deepen off the North Carolina coast.  This storm will not "bomb" on its way up the coast nor will it phase with another low diving through the Midwest; the pattern is moving too fast.  

WPC 7 am surface forecast Wednesday

There is some relatively warm water off the East Coast so that will enable some strengthening 

OSPO NOAA Sea Surface Temperatures (C)

More importantly this system will develop in the Gulf meaning it will bring lots of tropical moisture with it.  Here are the 3 day precipitation totals, ending Thanksgiving night at 7 PM

WPC 3 day precipitation forecast, valid through Thursday 7 PM

Timing and Impacts

Precipitation will begin after the Morning Rush, but before lunchtime on Wednesday.  Temperature profiles are not ideal as mid level temperatures are initially warm.  This means many places begin as rain, but the colder spots will begin as the dreaded freezing rain.  As the intensity of the precipitation increases interior locations will flip to snow.  This looks to happen shortly after noontime.

Around 4-5 PM, as the sun sets, the snow should really begin to stick.  The heaviest is Wednesday PM.  So how much snow

Guidance is suggesting a possibility of more snow.  I may bring totals up closer to 495/95; it will depend on the temperatures.  

On Thanksgiving morning this should be pulling away.  The football games will be interesting on Thursday morning.  Temperatures will be in the low 30's with 15-25 mph wind gusts.  

12 years ago 6-10 inches of snow fell the day before Thanksgiving cancelling school for the day

NWS Boston snowfall map 11/27/2002

We also woke up to snow Thanksgiving morning 2005, though not as much and it warmed up nicely that day.

NWS Boston 11/24/2005 snowfall map

Its also been 65 (2003, 2007, 2009) or pouring with rain (2004, 2006).  

Questions? twitter @zgreenwx .