Winter Storm Watches Posted for Southeast New England

3 PM Update 
The National Weather Service in Taunton has increased their snowfall forecast.  This is much more in line with my thoughts from this AM when I held back just a bit.

NWS Boston snowfall forecast 230 PM Sunday through Tuesday 7 AM

Now most of the area is under Winter Storm Warnings or Blizzard Warnings

NWS Watches, Warnings Sunday PM

I don't have much more to add.  Timing, impacts are below. Traveling tomorrow will be difficult, especially south of Boston. 

Previous discussion below

For the second year in a row a winter storm will threaten Southern New England the day after the Super Bowl.  The storm last year was more of a direct hit and I don't think many people cared after this (video via NFL YouTube channel, have to watch on YouTube).  They really should be playing today I hope I win some money today.

The storm last year dropped a widespread 12-18".

Post Super Bowl Storm 2015 via NESIS

I am not expecting a widespread 12-18.  That said if someone on the South Coast, Cape, or even Nantucket get a foot I would not be surprised.  As of now Winter Storm Watches are posted for much of SE New England with the exception of Southern Rhode Island.  They should be added today.  Also it is possible (probable?) the second blizzard warning of the season could be posted for the Cape and Islands later today.

NWS Boston Sunday AM advisories

I'll get into the start/end times, the winds, and some coastal concerns in a moment.  First lets look at what the storm is doing right now.  Here is the water vapor satellite image.  The storm is intensifying as it feeds off the warm gulf stream

NOAA GOES_East water vapor satellite

Here is the surface chart

WPC surface analysis 7 AM

At this point it appears the storm will track safely south and east of Southern New England.  That said check out the wind field in the storm

12z NAM hires 900 mb winds 6 am Monday (image Weatherbell)

 These winds are a few hundred feet up in the atmosphere.  So lets take a closer look at near surface winds 8 AM Momday

12z NAM hires 10 m winds 8 AM Monday (image weatherbell)

With these winds east and northeast facing beaches will be vulnerable for minor to moderate coastal flooding.  Here is a list of beaches/harbors that may see flooding tomorrow during the late AM/early PM high tide.  We must be thankful this storm is well offshore.  Here is the forecast surface chart tomorrow morning.

WPC surface forecast Monday 7 AM

So why would we get plowable snow with a storm so far offshore?  Well first of all remember the large wind field.  The storm is massive.  Second see the cold front south of New England?  As that front moves through overnight it will bring a fresh shot of Arctic air with it.  By 1 PM temperatures inland are in the low 20's.

12z NAM hires 2 m temps 1 PM Monday (image Weatherbell)

Ocean temperatures are running around 40-41.

OSTIA Sea Surface Temps (C) (Image Weatherbell)

Why does this matter? That is huge difference between air and ocean temperatures.  There is also a lot of energy with the storm.  As a result the snow shield is pushed well inland.  Now let's time it out.  Snow begins to fly at the South Coast around 4 AM.  It gets to the Mass Pike around 7 AM.    The snow makes it Western expansion between 7-10 AM and most of Southern New England (including Southern NH and coastal Maine) is snowing at varying intensities at noon.

12z NAM hires simulated radar 12 PM Monday (image Weatherbell)

Snow collapses in Western MA/CT mid afternoon and in Central MA/RI in the evening.  Snow lingers in E MA until 8-9 PM.  Snow ratios will vary big time from Central MA down to the South Coast.  Given temps a 15-1 or 20-1 ratio is likely in interior SE New England.  Given the warmer ocean 10-1 is a better bet across the Cape.  So what does that mean for totals?  There is some guidance that holds back on the precipitation so I am going to respect that.  That said I think I am selling this system short a bit.

Snowcast for Monday

Probably some higher amounts in Maine but that isn't really my focus so check out weather.gov for more info on northern areas.  Questions, comments, concerns please reach out. Enjoy the game tonight.

-Zack Green