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

Summary: It looks as if both coastal low pressure systems that I discussed yesterday, one on Thursday and one on Saturday, will miss us to the east. We may get a period of snow showers and/or snow squalls on Sunday as  we get sideswiped by an arctic cold front, otherwise our weather will remain unusually tranquil for January. 

Tuesday Night

Overcast with rain showers this evening, possibly ending with some wet snow mixing in. No snow accumulation expected. Skies will then partially clear after midnight.

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

West-northwesterly winds at 5-10 mph, becoming light after midnight.

Wednesday

Partly cloudy and unseasonably mild.

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

Southerly winds at 5-10 mph.

Wednesday Night

Partly cloudy.

Low temperatures generally in the mid 20s with some low 20s over the elevated terrain.

Light northwesterly winds.

Thursday

Mostly cloudy and a bit colder. There is the slight chance of a snow flurry or snow shower, especially late. Probability of precipitation 20%. No snow accumulation expected.

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

Light north-northeasterly winds.

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

Summary: It appears that our weather pattern may become quite interesting over the next week as a trough in the jet stream wave pattern slowly edges east and essentially stalls over the eastern half of the country. Colder air within this trough will then slowly become established over us as a series of disturbances in the jets stream flow pattern then dive into and rotate through the base of the trough. These disturbances will generate a series of surface low pressure systems along the east coast and also serve to reinforce the trough. However, before anyone gets too excited about this resulting in a series of snowstorms for Berkshire County, I think the situation is more complicated than that. In order for that to happen, the trough would need to be in a particular location and orientation relative to us and the disturbances would need to be strong and well timed. Right now the computer models are not particularly in sync with each other. I suspect this will change as the situation evolves. This is how things look right now….

The leading edge of the trough will move through as a cold front tomorrow. The mild, moist air presently over the region will be lifted by the advancing “colder” air and as a result we will have a fairly rainy day on Tuesday. However, the rain will be much lighter and more intermittent than this past weekend. We will then have a pause in the action until Thursday. The disturbance that looked like it might give us some snow on Wednesday in my last forecast now looks like it won’t rotate through until Thursday. Also, the coastal low pressure system that it generates looks like it will be fairly weak and too far to the east and that we will only get light snow, if any, although an inch or two still looks like a possibility. Another disturbance will rotate through the base of the trough Friday night into Saturday and generate another storm along the coast. This one looks a little more promising for a snow storm as the low develops closer to the coast and becomes a bit stronger. The European model (ECMWF) is generating a pretty big snowfall for us. The U.S. long range model (GFS) has it mostly missing us to the east. Everyone has been talking lately about how great the European model is. However, I think this model has been noticeably worse than the GFS model this winter. I will update this evolving situation tomorrow…..

In any case, it appears that we may be headed back into winter after our recent thaw with this pattern possibly persisting well into next week.

Monday Night

Mostly cloudy with rain showers likely developing by morning. Probability of precipitation 60%. Rainfall totals generally 0.10″ or less.

Temperatures will not drop much with southerly winds and a cloud cover. Low temperatures generally in the mid to upper 30s, near 40 in South County, mid 30s over the elevated terrain.

Southerly winds at 8-12 mph.

Tuesday

Overcast with intermittent rain and showers. Probability of precipitation 90%. Likely rainfall totals 0.20″ to 0.30″.

Temperatures not rising much, with high temperatures near 40 in Pittsfield, Adams, NorthAdams and Williamstown, Lee and Stockbridge; low 40s in Great Barrington and Sheffield and; upper 30s over the elevated terrain.

Light south-southwest winds shifting to westerly late.

Tuesday Night

Variably cloudy and remaining relatively mild for mid January.

Low temperatures generally in the upper 20s to near 30.

Light west-northwesterly winds shifting to southerly by morning.

Wednesday

Partly cloudy and still fairly mild.

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

South-southeasterly winds at 5-10 mph.

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

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.

Summary: Just a quick update on the upcoming snowstorm……It looks like a protracted period of light to moderate snow, on the order of 30 to 36 hours in duration, beginning around midnight tonight and ending sometime Friday morning. However, the snow will likely not be continuous through that period as the snow becomes spotty and light, and even stops for a time, late morning through a good part of the afternoon on Thursday. Snow should be steadiest and heaviest on Thursday night. By the time the snow ends on Friday expect total accumulations in the 8-14″ range. I would expect the least amount of snowfall in the lower elevations of South County as the snow band shifts to the north on Thursday. As usual, highest totals will be over the eastern highlands as strong northeast winds generate additional vertical motion over these regions. I will try to update these totals over the next few days as the storm evolves.

Another element with this weather scenario to keep in mind is that it will be quite COLD. The southern edge of an arctic airmass will edge south during the next few days. Record temperatures in south-central/southeastern Canada, on the order of -40 to -45 degrees have occurred in the center of this airmass. Obviously, it will not get that cold here but temperatures will struggle to stay in the teens on Thursday and then fall back into the low single digits Thursday night and remain there on Friday. As I had mentioned previously, we may see near record lows on Friday night, well below zero, before temperatures begin to moderate over the weekend.

The timeline looks like this: Snow developing around midnight. This snow will be occurring in a relatively narrow (north to south) band along a stationary front extending east from the approaching Midwest surface low, but looks to be centered over Berkshire County. Snow should be light to moderate and fairly continuous after midnight until daybreak, then will begin to shift north during the morning on Thursday. As it shifts, snow will become light and spotty and may completely stop for a time, first over South County, and then over the entire county by late morning. Snow will then pick-up again towards evening as jet stream energy shifts to the coast and the coastal surface low begins to deepen. Accumulations should be on the order of 2-4″ by Thursday morning with an additional 1-3″ falling during the day. The lesser amounts will fall over South County and the greater amounts over North County during this period. Snow should be heaviest overnight Thursday with an additional 5-9″ of accumulation. Snow will wind down fairly quickly on Friday morning as the coastal low moves out to sea.

Wednesday Night

Overcast with snow developing around midnight. Fairly continuous light to moderate snow after midnight. Probability of precipitation 90%. Likely accumulations 2-4″.

Low temperatures near 10 in the lower elevations, single digits over the elevated terrain.

Light northwesterly winds in the evening, shifting to northeasterly at 5-10 mph after midnight.

Thursday

Snow early, decreasing in intensity and becoming more intermittent, and even stopping for a time, mid-morning through most of the afternoon. The snow will diminish in South County first, but snow should be spotty or have ended everywhere by noon. Snow will then pick-up in intensity toward evening. Probability of precipitation 80%. Likely accumulations 1-3″ with the least amounts in South County.

It will be cold, with temperatures holding near 10 degrees, single digits over the elevated terrain.

Becoming breezy, with northeasterly winds at 10-15 mph, with gusts to 25 mph.

Thursday Night

Snowy, breezy and very cold. Probability of precipitation near 100%. Likely additional accumulations of 5-9″.

Low temperatures near zero.

Northeasterly winds at 10-20 mph in the evening, shifting to northerly after midnight. Gusts to 25-30 mph.

Friday

Snow ending early. Remaining mostly cloudy with some clearing late. Breezy and very cold. Total storm snow accumulations 8-14″.

High temperatures in the low single digits in most locations, mid single digits in South County and near zero over the elevated terrain.

Northwesterly winds at 10-20 mph with gusts to 25-30 mph.