Saturday, January 31, 2015

More Snow For Monday

The National Weather Service in Taunton has issued a Winter Storm Watch for much of Southern New England 
NWS Boston Hazards 
The Winter Storm Watch (dark blue) is in effect in all of MA/RI/CT; however the active Wind Advisory (brown) and Wind Chill Advisory (light blue) supersede the future WSW.  The WSW is effective late Sunday PM through late Monday PM.

The wind chill is advisory is up because of bitterly cold AM temperatures today
8 am 2 m temperatures (image Weatherbell)
Strong overnight winds ushered in the Arctic hounds as high pressure to our Northwest and a strengthening storm in the Gulf of Maine tightened the pressure gradient
WPC Surface Analysis 7 am
As to our next storm...it is currently in the Western US.  Two pieces of energy will phase to create a wide swath of snow from Nebraska and South Dakota all the way to New England.  At the surface the lows are in the Southwest and Montana.  At the upper levels we look like this
12z NAM 500 mb vorticity (Image NCEP)
24 hours later (7 am tomorrow) we can see the phase taking place in the Plains (Kansas for the geography illiterate) 
12z NAM 24 hr 500 mb vorticity valid 7 am Sun (image NCEP)
At the surface we see this
7 am Sunday Surface Analysis (image WPC)
A healthy snow storm will greet our friends in the Missouri and Ohio Valleys as warm moist air from the Gulf rides up and over the cold Arctic boundary.  New England is fine throughout Sunday.  There are no worries for the Super Bowl other than the Seahawks.  In Connecticut some snow may break out before midnight but that's okay.  There are too many Jets and Giants fans in that state anyway.  Snowfall begins after 1 am in our Western regions, probably closer to 4 am in Eastern/Central regions.
12z NAM 1000-500 mb thickness, mslp, precip valid 7 am Mon (image Weatherbell)
Temperatures Monday are cold in the interior, a bit warmer towards SE MA/RI.  It should be all snow for most locales with the exception of the Islands.  It may mix on Cape Cod as warmer air is ingested into the system.  
12z NAM 54 hr temp snapshot valid 1 pm Mon (image Weatherbell)
Temperatures like that mean high snowfall ratios for Central and Western New England.  Therefore I am expected a general 1' of snow across SNE with a bit less SE (heavier, wetter snow) and North (less precipitation).  The NWS looks good but I would cut back in SE MA and go 8-12 north of the pike.
NWS Boston snowfall totals
This is gone by Monday evening.  Teachers you will be off Monday but should be back by Tuesday.  We will stay cold throughout the next 10 days so there will be more chances for snow.  I'll update tomorrow, have a good one.

-Zack Green








 

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