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Summary: As the long range models projected last week, the jet stream wave pattern has amplified over North America, generating a deep, cold trough, which is presently plunging southward over the Great Lakes. A strong, arctic cold front at the leading edge of this trough is generating a narrow band of moderate to heavy snow over the upper Midwest, including southern Minnesota and Wisconsin, northern Illinois, and central Michigan. A Continental Polar (cP) airmass, which originated over central and northern Canada, is plunging southward behind the front, bringing the first truly arctic air of the season into the continental U.S.. Air temperatures are in the teens, with gusty northwest winds dropping wind chill temperatures below zero, in the Dakotas and northern Minnesota. This arctic air will be modified somewhat as it passes over the still mild water of the Great Lakes. However, temperatures will hover in the lower half of the 30s in Berkshire County on Tuesday, drop well down into the teens overnight Tuesday, and then will struggle to make it out of the 20s on Wednesday. A cold, blustery northwest wind will add insult to injury through Wednesday morning as well. If you have been waiting for winter, this will be your first real taste. Fortunately, the arctic air will be short-lived as the trough lifts out to our northeast and a broad mild ridge builds in for the remainder of the week and into the weekend. Temperatures will moderate back into the 40s on Thursday and possibly hit 50 on Friday. It also appears that surface high pressure will hold at least through the end of the work week so we will remain dry with a fair amount of sunshine through the period.

It is also likely that we will get a coating of snow overnight in most locations as the front moves through. The higher terrain could see as much as between 1/2″ and 1″. The precipitation should start around 11 pm to midnight and may be a mix of snow and rain at the onset in the valleys. It should turn to all snow by 1 am and then end around 4 am. Temperatures will drop to below freezing by daybreak so there could be a few slick spots, particularly over the secondary roads in the elevated terrain.

Monday Night

Mostly cloudy. Precipitation developing between 11 pm and midnight and ending around 4 am. There will be a mixture of rain and wet snow at the onset, particularly in valley locations but the precipitation should turn to all snow by 1 am. Probability of precipitation 80%. Melted liquid totals between 0.05″ and 0.10″. Most likely snow accumulation a dusting/coating in the valleys with 1/2″ to 1″ at the higher elevations.

Low temperatures in the mid to upper 20s, mid 20s over the elevated terrain.

Southwest winds at 10-15 mph, shifting to northwest between midnight and 1 am and becoming gusty.

Tuesday

Mostly cloudy in the morning. Clearing skies from north to south in the afternoon. Becoming mostly sunny to partly cloudy everywhere by mid-afternoon. It will be blustery and cold.

High temperatures in the low to mid 30s in Pittsfield; low 30s in North Adams, Adams and Williamstown; mid 30s in Lee, Stockbridge, Great Barrington and Sheffield and; upper 20s to around 30 over the elevated terrain and hilltowns, depending on elevation. Wind chills in the teens and 20s.

Northwesterly winds at 10-15 mph in the lower elevations, 15-20 mph over the elevated terrain. Gusts to 25-30 mph.

Tuesday Night

Mostly clear and very cold. Still somewhat breezy.

Low temperatures generally in the mid teens with some low teens over the elevated terrain. Wind chills in the single digits to as low as the single digits below zero in gusts.

Northwest winds at 8-15 mph with gusts to 25 mph.

Wednesday

Mostly sunny, breezy and cold.

High temperatures near 30 in Pittsfield, North Adams, Adams and Williamstown; low 30s in Lee and Stockbridge; low to mid 30s in Great Barrington and Sheffield and; mid to upper 20s over the elevated terrain and hilltowns.

Northwest winds at 10-15 mph, diminishing somewhat as the afternoon progresses.