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The Commons
News

Winter settles in for a week as season's seesaw continues

Dave Hayes operates a daily blog on Facebook (facebook.com/WesternMassWeather), where he produces hyper-local reports, answers questions, and keeps more than 20,000 followers informed and educated about the weather.

Originally published in The Commons issue #393 (Wednesday, February 1, 2017). This story appeared on page C4.



Good day to you! After an above-average January in terms of temperatures we have flipped the pattern, at least temporarily.

For January, we had a trough of lower pressures in the western U.S. and a ridge of higher pressures in the east. This allowed for milder air to flow in off of the Pacific and glide right into New England. These large-scale weather features have reversed for the time being, and is the reason we’re seeing snow and cold in southern Vermont into early next week.

For Wednesday, our Alberta Clipper low pressure system floats off into the Gulf of Maine, leaving behind a few inches of snow to pretty up the place. Meanwhile, an upper level low will be moving from northern NY into northern New England. One component of precipitation production is rising air, with ample low and mid-level moisture being a second prerequisite.

Given the nearby upper low, along with leftover moisture and westerly winds off of the Great Lakes, we will see some scattered snow showers in Windham County. Highs will reach the low to mid 30s and lows will be down near 20 degrees.

In addition, much colder air will be moving in aloft out ahead of a cold front that will pass through on Thursday. The colder air aloft will create steeper lapse rates.

What’s a lapse rate, you ask? A lapse rate refers to the temperature gradient from the surface of the Earth to the sky. Once you achieve a temperature reduction of 6 degrees Celsius or more for every kilometer you rise in altitude, air is encouraged to rise more rapidly.

This is one ingredient that produces thunderstorms in the Summer, and also snow squalls in the Winter. Since we’ll have pretty steep lapse rates overhead on Wednesday, some snow squalls with brief whiteout conditions and additional light accumulations are possible.

For Thursday through Sunday, we’ll experience the coldest temperatures we’ve seen in about a month or so, but it should be mainly dry and fair with partly sunny skies.

Some mountain snow showers are possible on Thursday. Highs on Thursday will be in the upper 20s, with highs Friday through Sunday in the mid 20s. Lows will be in the teens through the period, with some single digits Saturday night.

Sunday night into Monday could feature some more snow showers, and possibly a bigger snowstorm if southern stream energy links up with another northern Clipper system.

Thereafter, we might see a brief warm-up to near 40 by next Wednesday. Have a great week!

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