Cool air starts flowing into New England Wednesday…will continue into the weekend

Posted by Matt Noyes November 3, 2009 at 8:40 am

Today’s weather feature is a cold front marching east out of the Great Lakes, poised to cross New England Tuesday afternoon. This front will bring a wind shift with it – from a southwest wind early Tuesday to a northwest wind late…

The shifting wind at the surface, combined with an energetic disturbance aloft, will create at least a few rain showers in the hilly and mountainous terrain of Northern and Western New England Tuesday afternoon, though clouds are expected to remain more scattered the farther south one is. Overnight Tuesday night, a steady northwest wind carries colder air into New England, and that wind continues on Wednesday, ensuring that cooler air stays in place across the Northeast, and creating a wind chill factor Tuesday night that will bring “feels like” temperatures in the 20s! This cool air complicates the forecast for Thursday, when we’ll be watching a hand-off of atmospheric energy from a weakening storm moving east out of the Great Lakes, to a newly developing storm southeast of New England. By Friday, the ocean storm will be powerful and impressive, but also should be pulling away from New England. Therefore, the key to the forecast is to nail the timing and rate of strengthening of the storm later Thursday off our coast, to determine how much precipitation will fall, and what type it will be – rain or snow – given the abundance of cool air in place. Right now, the setup favors a Norlun trough – a weakness in the atmosphere extending west or northwest from an ocean storm center – that should focus bursts of rain and snow later Thursday into early Friday morning. It’s early to predict how much, but if this comes together as a typical Norlun trough, a couple of inches of snow aren’t out of the questions for the mountains of Northern NH, Northwest ME, and perhaps even down to the coastal plain of Maine. By Friday morning, chilly but drier air is snapping back into New England as a northwest wind freshens behind the departing storm, and the weekend is expected to start cool, as well.

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