(As always, click on images to enlarge) The jet stream winds aloft that steer our storm systems and separate cold air to the north from warm to the south will dip deep across the Southeastern United States this weekend into early next week - this dip is called a "trough," and allows cold air to spill southward out of Canada. Central Canada is terribly cold as of this writing - to the tune of -40° Farenheit - and the deep jet stream trough will open the door to this deep cold, particularly from the Great Lakes to New England. Eventually, this will mean heavy lake effect snow in the lee of the Great Lakes, and subzero wind chill values all the way through the Mid-Atlantic, but first the arrival of this cold air with an arctic front will prompt snow squalls on both weekend days near the Canadian border, with several inches of snow accumulation likely...particularly in the northern mountains of New England...this weekend.
In Southern New England, cold air will lay in wait just to the north through most of the weekend, until the arctic front plunges south on Sunday. Though temperatures may rise above freezing in much of Southern New England Sunday midday, the afternoon cold frontal passage will increase a northwest wind and bring falling temperatures below freezing by late in the day. Cold air will continue to race into all of New England behind this wind shift Sunday evening through night, and wind chill will make the air feel at least 10-15 degrees colder than actual air temperature. Of course, Sunday evening is the big Patriots/Ravens game at Gillette Stadium in Foxborough, and the cold air surge is likely to arrive just prior to kickoff, starting the game in the upper 20s and finishing it in the lower to middle 20s, but producing a wind chill in the teens on a stiff northwest wind. Of course, a slight delay in the arrival of the arctic cold front would keep it milder, but I'm not optimistic on that happening at this point.
Behind the cold front, the coldest air of the season will arrive on Monday. At the same time, an energetic disturbance will dive off the Northeast U.S. coast, prompting storm development. We'll certainly want to pay close attention to this storm and exactly where it develops for the potential of snow, but regardless of the track, the storm will increase northerly winds, locking in brutal cold for several days and driving wind chill values to dangerously cold values in some of the Northeast Monday night through Tuesday night.
Monday Afternoon Forecast High Temperatures: