The standing, amplified jet stream wave pattern persists, with a ridge over the eastern Pacific and western North America and a trough over central and eastern North America. This is permitting unusually cold arctic air over the central to eastern U.S. to be repeatedly reinforced as cold arctic pools of air slide south into the base of the trough. This pattern has persisted since last week. One of these pools of arctic air is residing over us today and tomorrow. As this unusually cold air flows over the still warm Great Lakes on strong westerly winds a band of heavy lake-effect snow is being generated and persisting to the south of Buffalo. Four feet of snow have already fallen and up to six feet may fall by the time winds shift and weaken tomorrow.

The next reinforcing shot of arctic air will be moving in from Thursday night into Saturday. Then it looks like the pattern will change, at least temporarily, as the trough lifts out on Saturday, the jet stream pattern flattens out (becomes zonally [west to east] oriented) and a milder ridge builds in for Sunday and Monday. Temperatures will likely reach the 50s on Monday. However, it looks like the cold trough may re-establish itself over the eastern U.S. again by mid-week next week.

It will be quite cold tonight, with temperatures falling into the low to mid teens with wind chills near zero. However, the strong westerly winds will limit radiational cooling and keep us from getting anywhere near the record low temperature of 6° F. Surface high pressure will build in from the south tomorrow and this will keep skies mostly sunny but it will remain unseasonably cold despite the sunshine. There is the chance for a few snow showers Wednesday evening as a weak “warm” front moves through the county. This warm front is extending eastward from a weak surface low pressure center being generated over the Great Lakes by the next pool of arctic air diving into the base of the trough. Once the warm front moves through it will be slightly milder on Thursday with temperatures rising into the 30s. However, as the surface low in the Great Lakes rides northeast along the eastern edge of the trough it will drag its trailing cold front through here during the day on Thursday. The frontal passage will not generate any precipitation but temperatures will, once again, drop down into the teens Thursday night and only rise into the 20s on Friday.

Tuesday Night

Mostly clear, breezy and unseasonably cold.

Low temperatures in the mid teens, low teens over the elevated terrain and mid to upper teens in South County. Wind chills in the single digits.

West-southwesterly winds at 10-15 mph with gusts 20-25 mph.

Wednesday

Mostly sunny and continued cold but with diminishing winds.

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

West-southwesterly winds at 10-15 mph early, diminishing to 5-10 mph and then becoming light late in the afternoon.

Wednesday Night

Becoming overcast with a chance of a snow shower in the evening. The greatest chance will be in North County. Clearing skies after midnight. Probability of precipitation 30%. A dusting of snow is possible in a few spots, predominantly in North County.

Low temperatures near 20.

South-southwesterly winds at 5-10 mph.

Thursday

Mostly sunny in the morning, a mix of sun and clouds in the afternoon. Slightly milder than previous days.

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

South-southwesterly winds at 5-10 mph in the morning, shifting to west-southwesterly and then westerly during the afternoon.