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Summary: As a surface low pressure system moves through the northern Great Lakes and into southeastern Canada it will drag its trailing cold front through our region tonight. The same system’s warm front came through last night, opening the door to a warm, moist, southerly flow of air from the subtropics. As the heavier, cold air behind the front plows into the lighter, warm, moisture laden air it is rapidly lifting it and generating strong upward motion in the atmosphere. As this air is lifted, it cools, which leads to condensation of all of that moisture (clouds and precipitation), essentially like squeezing a moisture laden sponge. As a result, a band of heavy rain and showers, and even some imbedded thundershowers, has developed in advance of the front. As of 2 pm, 0.76″ of rain has already been recorded. And the snow and ice on the ground….gone. The front will pass through this evening so the rain and showers will wind down and end before midnight.

The trough in the jet stream wave pattern which is generating the surface low and its associated cold front is not deep and will pass through the region quickly tomorrow with a ridge building in for Sunday night and Monday. Therefore, there will be a brief cool down for Sunday but then it will become unseasonably mild again on Monday. A deeper, and broader, jet stream trough will advance to the east, with a cold front at its leading edge moving through overnight Monday. There will be another, much lighter, band of rain associated with this frontal passage.  The front will advance quite slowly so it will still remain relatively mild on Tuesday.

It appears that a disturbance in the jet stream flow will rotate through the base of the trough and generate a weak surface low over the Northeast during the day on Wednesday. The air should be cold enough so that any precipitation it generates should be snow. Right now it looks like a light snowfall on the order of 2-4″ late Wednesday and/or Wednesday night. Any snow that we get should remain on the ground for awhile as the cold air associated with the jet stream trough becomes centered over us for several days as temperatures will likely remain below normal through the weekend.

Saturday Night

Rain and showers winding down this evening and ending before midnight. Remaining mostly cloudy and becoming windy and turning colder with the chance of a snow shower or flurry after midnight.

Low temperatures generally near 30, upper 20s over the elevated terrain.

Southwesterly winds at 10-15 mph, shifting to west-northwesterly after midnight and increasing to 15-20 mph, 20-25 mph over the elevated terrain with gusts up to 35-40 mph.

Sunday

Partly sunny, windy and colder during the morning with the chance of a snow flurry. Decreasing cloudiness and lightening winds as the afternoon progresses.

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

West-northwesterly winds at 15-25 mph with gusts to 35-40 mph, decreasing late in the afternoon.

Sunday Night

Partly cloudy and seasonably cold.

Low temperatures in the low to mid 20s.

West-northwesterly winds at 10-15 mph early in the evening, shifting to southwesterly and decreasing to 5-10 mph.

Monday

Mostly sunny in the morning, the sun will be dimmed by increasing high clouds during the afternoon. Becoming breezy and unseasonably mild.

High temperatures in the mid to upper 40s in Pittsfield, Adams, NorthAdams and Williamstown; upper 40s in Lee, Stockbridge, Great Barrington and Sheffield and: low to mid 40s over the elevated terrain.

South-southwesterly winds at 10-15 mph.