Perspective on December Arctic Assault

Can you hear that?  That's the Arctic hound knocking at the walls of your home.  The National Weather Service changed the Wind Chill Watch to a *Wind Chill Advisory*.  The High Wind Watch has been upgraded to a *High Wind Warning*.  Several records will be in reach tonight and tomorrow morning.  We are on track for the coldest December day in over 10 years in Boston, Worcester and Providence.  The coldest of the air looks to stay just north of Hartford.
NWS Boston Headlines Thursday December 15, 2016
Worcester has a chance to tie the record low for today December 15 just before midnight.  The record is 1 set in 1933.  The other 3 climate sites are safe for 12-15.
The record low max and record low temps for Dec 16 are in play.  The National Weather Service is forecasting several records tomorrow in Boston and Worcester.  
NWS forecast through 7 PM 
The latest high resolution computer guidance is forecast -3 in Worcester, -1 in Boston, 3 in Providence and 5 in Hartford.  Here is that models forecast for 7 AM.  This does not factor in the wind.
18z HRRR 2 m temps Friday 7 AM (image Weatherbell)
Here is the wind chills at 7 AM.  Most places are -10 to -15 below zero.
18z HRRR wind chill temps 7 AM (image Weatherbell)
Winds peak overnight, but the coldest air is at day break so the combination will be bitterly cold for the next 12-18 hours.  The winds will be strong enough to knock out power tonight so make sure all appliances (cell phones, lap tops, tablets) are charged.  Please be careful driving as I saw a lot of trash barrels flying around already this afternoon.   Also heads up for snow squalls tonight.  They will be isolated and the threat peaks this evening.

So how common or uncommon is this for December?  This chart shows the lowest max temps and lowest min temps for the month since 2000.  Blue reflects the coldest values during the 15 year period (16 seasons).
Boston, Worcester, and Providence are forecast to have their lowest temperatures in at least 16 years.  It looks like the minimum high temperature records will be close in Boston and Providence but Worcester and Hartford will lose out to 2004 and 2013 respectively.  Any way you slice it this is impressive and it will be one of the coldest December days this century.  I went back into the 20th century to find the last time we were this cold.  
December 27, 1993 was also very cold in Worcester (13, -1) but it was not as bad in the other cities.  This Arctic blast will stand along side some of the colder December days of the last 25-30 years.    December 22-23, 1989 deserves its own post.  Tune in for that but just know it snowed 14" in Myrtle Beach, SC and several communites in Northeat Florida had a White Christmas in 1989.

Saturday Snow
I believe a winter weather advisory will be needed Saturday AM.  Snow begins around dawn and continues through late morning.  The snow will change to rain around 11 AM and continue until 2 PM or so.  Winds pick up Saturday afternoon and evening as the region drys out.  Temperatures climb into the 50's on Sunday with rain before temperatures crash AGAIN.  We may finish as snow Sunday night/Monday AM so roads will have to be treated for snow/black ice.  More on this tomorrow.

I think 3-6 inches of snow Saturday AM.

-Zack Green


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