Monday, December 30, 2013

Snow Likely Thursday-Friday

Winter is poised to return to the Northeast this week after a brief spell of above average temperatures.  The timing is Thursday morning into Friday and the precipitation type is snow for everyone except the Cape/Islands.  The details...

General Overview/Short Term Forecast
Over the past week the East and West Coasts have seen above average warmth while the Central US has been mainly below average
NCEP Weekly Temperature Anomalies (image weatherbell)
Overall most of the nation was below average for December with the exception of the SE US
NCEP December to date Temp Anomaly (image weatherbell)
A tongue of cold water exists along the West Coast while the Atlantic remains warmer than normal.  This is consistent with the Cold PDO/Warm AMO ocean regime.  The PDO appears to be weaker than normal. 
NOAA/OSPO Sea Surface Temp Anomaly 12.30.2013
This is important because the warm Atlantic will likely juice up any storm that reaches the coast.  Today a cold front pushed offshore and temperatures dropped this afternoon.  Here is the current surface chart

WPC Surface Analysis 1 PM 
Temperatures tonight will fall to around 10 degrees
18z NAM hires 2 m temps 6 am Tue (image weatherbell)
Another front with a weak low pressure system will push through New England tomorrow
WPC Surface Forecast Tuesday 7 PM
This may fire off some snow squalls tomorrow afternoon. Temperatures tomorrow and New Years Day will be around 20-25 degrees.  So lets talk about the storm.

Thursday-Friday
A storm system will drop out of the Rockies while another storm develops in the Gulf.  By Thursday morning this is what the surface chart is projected to look like
WPC Surface Forecast 7 am Thur
The low in the Ohio Valley will begin to transfer energy off the East Coast.  Due to high pressure in an ideal position to the north, snow will break out well in advance of the storm Thursday AM.  As the storm moves up the coast it will deepen and winds will increase in Southern New England.

The snow will be fluffy for everyone except the South Coast/Cape Island.  This means snow will pile up and some significant accumulations are possible.  
First Guess Snowmap
Furthermore the winds WILL be a factor with the system.  Expect snow drifts.  Blizzard like conditions will be possible at times in certain locations.  I will make more specific forecasts tomorrow and Wednesday.  

-Zack Green










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