Note: Clicking on underlined red text provides links to various weather maps.

Summary: All of the models have been trending “warmer” with Wednesday’s storm with the surface low tracking over Southern New England, almost directly over Berkshire County. With this path, there will be enough warm air wrapping into the low from off the ocean to drive temperatures in the lower 10,000 feet of the atmosphere above Berkshire County over the freezing point. As a result, most of the precipitation the County receives from this storm should be in liquid form.

After a weak disturbance moves by to our north and gives us the chance of a few mixed snow and rain showers tonight, Tuesday will turn out partly sunny and seasonably mild as we sit in a lull between systems. On Tuesday night a surface low pressure system will develop and strengthen rapidly over the Mid-Mississippi Valley in response to a deepening trough in the jet stream as the flow pattern becomes more amplified, with cold Canadian air diving south and colliding with a warm and moist atmosphere which has been developing over the Southeast. The low will track eastward through the Ohio Valley overnight becoming centered over Ohio by Wednesday morning. When the precipitation shield reaches Berkshire County early Wednesday morning the atmosphere should be just cold enough to support light snow at the outset. The counterclockwise circulation around the low center will push warmer air into the lower levels of the atmosphere as the morning progresses. A changeover to light sleet and then light rain will occur quickly in South County where only a dusting of snow at most is likely to fall. As warmer temperatures stream north, the changeover will occur next in central Berkshire during the mid to late morning and then, eventually, in North County by noon. Likely snowfall before the changeover is a dusting-1/2″ in central Berkshire and 1/2″-1″ in North County.

As the surface low tracks over Pennsylvania and southern NY during the afternoon and almost directly over Berkshire County during the evening there should be occasional rain, moderate at times, over the county. There may be some pockets of freezing rain over the elevated terrain for a time during the afternoon. Rainfall totals are likely to be between 0.25″ and 0.50″ South County and central Berkshire with 0.50″- 0.75″ in North County.

The jet stream pattern will be typical for a very strong East Coast storm with a “double jet streak” pattern generating substantial upper-level divergence in the wind flow pattern, creating marked ascent in the atmosphere. As a result, the central pressure in the center of the low will likely drop below 980 mb as the low intensifies as it approaches and reaches the coast late on Wednesday and Wednesday evening. In addition, the warming March atmosphere can hold more moisture available for condensation (clouds and precipitation) than a mid-winter scenario so there will be places that get over 2″ of liquid equivalent precipitation.  However, we should avoid the heaviest precipitation since, as is typical with these storms, the strongest ascent and, thus, the heaviest precipitation will fall north and west of the surface low center, with heavy rain in southern Vermont and heavy snow likely in the Adirondacks and central and northern Greens where 2 feet or more could fall in some spots.

The surface low should be centered over Boston by midnight on Wednesday night and as cold air circulates in behind the low our rain should change to snow. However, by that time most of the heavy precipitation will have shifted over NH and Maine. Light snow will likely fall from near midnight until Thursday morning with 1-3″ of accumulation likely by morning. Snow showers should continue during the morning on Thursday with an additional dusting-1″ of snow possible as moisture circulating around the low is lifted by our elevated terrain.

As the low pulls away Wednesday night and Thursday, the pressure gradient between the strong surface low and high pressure building in from the west will strengthen so it will become windy. Temperatures will also plummet as the cold trough in the jet stream that was responsible for generating the storm becomes centered over us. In fact, temperatures will not escape the teens on Thursday with wind chill temperatures below zero. Fortunately, the trough will swing by and temperatures will become more seasonable on Friday and into the weekend.

Monday Night

Overcast with a period of mixed rain and wet snow showers in the lower elevations and wet snow showers over the elevated terrain likely near midnight. Probability of precipitation 60%. There could be a light dusting of snow in a few spots over the elevated terrain. Partial clearing toward morning.

Temperatures will hold fairly steady, with low temperatures in the low to mid 30s over the lower elevations, near 30 to low 30s over the elevated terrain.

Southerly winds at 5-10 mph this evening, shifting to southwesterly and then westerly after midnight.

Tuesday

Partly cloudy, breezy and mild.

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

West-northwesterly wind at 10-15 mph diminishing toward evening.

Tuesday Night

Increasing clouds in the evening, overcast after midnight with a good chance of light snow or a snow shower toward daybreak. Probability of precipitation 50%. A dusting of snow possible in spots.

Low temperatures in the low 30s.

Light and variable winds in the evening, becoming calm overnight.

Wednesday

Light snow likely early, changing to light rain during the morning. Likely snow accumulations before the changeover to rain, none to a dusting in most locations, with as much as 1/2″-1″ in parts of North County. Breezy with rain, moderate at times during the afternoon. There could be a little freezing rain in spots over the elevated terrain early in the afternoon. Rainfall totals generally 0.25″-0.50″. Probability of precipitation 90%.

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

East-southeasterly winds at 10-15 mph.

Wednesday Night and Thursday

Occasional rain and mild during the evening. Rain changing to light snow near midnight. Light snow likely after midnight. Likely accumulations 1-3″ by morning. Snow showers likely during Thursday morning with an additional dusting-1″ possible. It will briefly turn quite mild during the evening with temperatures rising into the 40s. It will turn windy and much colder after midnight. Low temperatures by morning in the low teens with temperatures holding in the teens during the day, with wind chills occasionally below zero.