Light Snow Today

A disturbance passing south of New England will deliver 1-3 inches of snow South of the Mass Pike.  A dusting to an inch is likely from the Pike to the MA/NH/VT border.  Isolated 4 or 5 inch amounts appear possible in NE and NW CT into Western Worcester County as well as along the South Shore.  Winter Weather Advisories are up for CT/RI/SE MA
NWS Boston Advisories 12/10/13
The Big Picture
NWS Northeast Regional Radar 458 am
The radar shows moisture streaming Northeast.  The system is what we call "progressive".  In other words it moves quickly and is gone by this evening.  The upper level atmosphere behaves as a wave.  In the strongest storms the waves really dig deep; we do not have that in this pattern it is a shallow pattern with a bunch of quick hitting systems.  Here is the 500 mb chart
06z NAM 500 mb geo height 4 am (image weatherbell)
On the surface chart we see low pressure in the Southeast US riding along a stalled frontal boundary
WPC Surface Analysis 4 am EST
Now lets look at temperatures.  First at the surface
2 m temperatures 4 am EST (image weatherbell)
Its below freezing in much of Southern New England.  Temperatures will not rise much today.  Temperatures a few thousand feet up are running above freezing at the moment but that will change this morning
06z NAM hires 850 mb temps 5 am (image weatherbell)
The Forecast
Precipitation will break out in New England (starting in SW CT) between 9-11 am this morning.  Am expecting all snow.  Here are 850 temps at 10 am (850 is located in the snow growth zone.  Generally a good approximation of where the rain snow line will be).
06z NAM hires 850 mb temps 10 am (image weatherbell)
Surface temperatures will be around 30.  There are signals that a moderate band of snow will set up somewhere in SNE.  Odds favor this developing along the Southern Coast of Bristol County in MA.  The heaviest snow will fall between 11-4 PM today.  Total snow...I am using the NAM hires for accumulations as it seems to have the best handle on this system.  
06z NAM hires total accumulated snow (using 10-1 ratio) (image weatherbell)
Several points about this image.  The snow should be fluffy as one gets near the pike.  So we could be looking at higher amounts, but less liquid content.  Second I do think someone approaches 6 inches in Southern New England.  These are the snow storms that deliver surprises one way or another.  Should impact the afternoon commute from school and work so allow some extra time.

It looks cold for the rest of the week and there is potential for a storm this weekend.  More on that later, have a good one.

-Zack Green


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