(As always, click on all images to enlarge) A building ridge in the jet stream winds aloft - the fast river of air, high in the sky, that steers storm systems and separates cold air to the north from warm to the south - will mean the storm track shifts across the Ohio Valley, northeast into Southern Canada. With storms going west of New England and the Northeastern United States, the counter-clockwise flow of air around a series of storm centers taking that path toward the end of this week and into the weekend will mean a northward surge of warmth on a prolonged southerly wind through a deep layer of the atmosphere. The end result will be widespread temperatures in the 50s on both weekend days.
Remarkably, this exceptional January warmth - some 20 degrees above normal - may come without much if any rainfall on both weekend days in New England. Though a shot of rain surely seems likely on Friday, marking the leading of warmth colliding with what's left of lingering cool air, and perhaps starting as a period of mixed precipitation in Northern New England, that rain should move on by Saturday, leaving drier conditions with plenty of warmth. An increasing southerly wind Sunday is expected to further boost temperatures, assuring that most of New England rises well into the 50s, before a sharply defined cold front arrives Monday. Cool air may stream in quickly enough Monday to allow rain to change to a period of accumulating snow in Northern New England, and we should watch carefully the potential for another wave of low pressure along this front by next Wednesday - if it develops, that second wave could deliver more widespread accumulating snow.