Summary: The cold trough in the jet stream wave pattern, which has been centered over eastern North America for the past several days, has broadened and flattened somewhat so that it has become slightly “milder” in Berkshire County. In fact, temperatures have reached the 30 degree mark in a few locations (33 in Great Barrington) for the first time since last Thursday. We have had a few dustings of snow over the last several days as weak disturbances in the jet stream rotate through the base of the trough. The last of these will come through tonight with, you guessed it, a dusting of snow, and then depart on Wednesday. Surface high pressure will build in from Canada for Wednesday night and early Thursday behind a weak cold front associated with the departing surface low from tonight, giving us a brief period of quiet but cold conditions (calm before the storm?).

The jet stream will then become more active across the country, with multiple waves in the jet stream developing. In fact, we are likely to get our first substantial snowfall in Berkshire County in quite awhile on Friday. The models have not been consistent with their solutions for this event, either between models, or temporally within each model. However, the trend is toward a more amplified jet stream with a deeper coastal surface low pressure system developing. Therefore, I think it likely that we will receive 6 inches or more of snow sometime between after midnight on Thursday into Friday evening with the heaviest snow falling during the day on Friday. I will try to update this forecast tomorrow so “stay tuned”.

Tuesday Night

Overcast with intermittent light snow likely. Probability of precipitation 70%. Accumulations generally between a dusting and 1/2″ although a few isolated spots over the higher terrain could receive as much as 1″.

With overcast skies and plenty of moisture in the air, temperatures will only fall to the low 20s in Pittsfield, Adams, North Adams and Williamstown, mid 20s in Great Barrington and Sheffield, and upper teans over the elevated terrain and hilltowns.

Winds very light to calm, shifting from southeasterly to southerly and eventually westerly by morning.

Wednesday

Mostly cloudy with the chance of a little lingering light snow in the early morning hours, then clearing skies. Mostly sunny from late morning through most of the afternoon. There may be some more clouds, and even an isolated snow shower, and it will become breezy during the late afternoon as the weak cold front associated with the departing weak surface low pressure system moves through. Probability of precipitation 30% early morning and late afternoon. Nothing more than a light dusting expected.

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

West-northwesterly winds at 5-10 mph, increasing to 10-15 mph, 15-20 mph over the elevated terrain during the late afternoon. A few gusts over 30 mph are possible, particularly over the elevated terrain.

Wednesday Night

Clear, with diminishing winds, and quite cold.

With clear skies, a light snow cover, and light winds after midnight, we will have very good radiational cooling conditions. Low temperatures should reach the mid single digits in most locations, with upper single digits in South County and low single digits in the elevated terrain, particularly in locations shielded from any breeze.

West-northwesterly winds in the evening, diminishing to 5-10 mph by midnight, become light to calm after midnight.

Thursday

Increasing clouds during the morning, mostly cloudy during the afternoon, becoming overcast by dark.

It will be cold, with high temperatures in the low 20s in Pittsfield, Adams, North Adams and Williamstown, low to mid 20s in Great Barrington and Sheffield, and mid to upper teens over the elevated terrain and hilltowns.

Light northwest winds in the morning, becoming light easterly during the afternoon.

Thursday Night through Friday Night

Snow developing after midnight Thursday Night, continuing moderate at times into Friday Night. Snowfall accumulations likely greater than 6 inches….I will update this tomorrow.