Below Zero This Morning

The next several hours will be brutally cold and the wind chills will make it feel like Central Canada.  This cold air should keep the next storm system to our south.  I expect a light dusting for most people, much like the last storm.  I also expect the highest snow amounts to be in Southwest Connecticut and the Outer Cape, Martha's Vineyard, and Nantucket.  As has often been the case this winter, computer guidance has picked up on a storm days away and then loses it as the event comes closer.  Here are the current temps

5 AM 2 m temps (image wxbell)

Here are the projected wind chills for 7 am EST

09z RAP windchills (image wxbell)

Air temperatures should slowly moderate into the lower to mid teens.  Wind chills will briefly climb above zero this afternoon before increasing again when the sun goes down.  Tonight we again drop down close to zero with windchills again approaching -20 F.  Try not to stay outside in this too long today it will be nasty.  

Moving along to the potential snow Friday night into Saturday.  Guidance has is in good agreement of a track well south of the region and agree on phasing taking place too late for a major winter storm.  Now that we are within 48 hours of the event I do not expect any big changes from the models (but you never know).  Its still not a slam dunk forecast.  Here are some probabilities 

Probability of 1 inch in 6 hours snow blue rain green ice yellow

The relative measure of predictability  (RMOP)

Relative measure of predictability Friday 7 PM 

These two figures will update today but what the RMOP shows is uncertainty in the depth of the trough in the year and uncertainty in the ridge in the west.  It will be important to watch for jet streaks at 300 mb today to see if the ridge really wants to pump in the west or amplify the trough in the east.  As it stands the latest Short range ensembles are not big on precip but have good RH at 700 mb.  This should help the concerns over the air mass being too dry for snow.

03z SREF 700 mb RH

For what its worth there is a quite a system moving into the west

354 AM radar PST

Finally here is the North American surface chart.  Check out the high pressure on the US/Canada border

530 AM EST surface analysis

The US temps...very cold in New England and the Upper Midwest

4 am US Temps (wxbell)

Have a good day.