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

Summary: An arctic airmass has settled over the region and will be with us through Friday. As the coastal storm moved out to sea overnight, clear skies and lightening winds combined with a snow cover enabled air temperatures (not windchill) to plummet, reaching -10°F in Pittsfield, -5 to -10 in most other locations, and -13 on Florida mountain and -30 in parts of the Adirondacks.  Air temperatures this afternoon are in the single digits across the county with wind chill temperatures in the teens to 20s below zero at times. This air mass will begin to moderate and shift to our northeast on Saturday, with temperatures rising into the 20s (woohoo!), only to be replaced by another air mass of arctic origin plunging south into the “standing” wave trough over our region on Sunday behind an arctic cold front. As a result, our temperatures will again be frigid for a good part of next week.

The arctic frontal passage will generate snow showers and squalls on Saturday. The front will be quite strong and, despite the fact that the air in advance of the front will be dry, the lifting motion of the front will squeeze out whatever moisture is available and it is likely that we will see some light accumulation of an inch or two during the day on Saturday as the front passes through. An “Alberta Clipper” surface low pressure system will descend out of Alberta, Canada and rotate through the base of the jet stream wave trough, moving through here on Sunday night with another light snowfall of an inch or two.

Wednesday Night

Mostly clear this evening, with increasing, thin high clouds after midnight. It will be brutally cold.

Low temperatures generally -5° to -10°F. Wind chill temperatures in the minus teens to minus 20s at times.

Northwesterly winds at 10-15 mph this evening, decreasing to 5-10 mph after midnight.

Thursday

Mostly cloudy, becoming breezy in the afternoon and remaining very cold. There is the slight chance of a snow flurry in the afternoon. Probability of precipitation 20%. No accumulation expected.

High temperatures near 10 in Pittsfield, Adams, NorthAdams and Williamstown; low teens in Lee, Stockbridge, Great Barrington and Sheffield and; mid to upper single digits over the elevated terrain. Wind chill temperatures in the teens to 20s below zero early, single digits below zero in the afternoon

West-northwesterly winds at 5-10 mph in the morning, increasing to 10-15 mph in the afternoon.

Thursday Night

Partly to mostly cloudy, breezy and extremely cold.

Low temperatures around -5°F, as low as -10°F over the elevated terrain. Wind chill temperatures in the teens to 20s below zero.

West-northwesterly wind at 10-15 mph.

Friday

Partly cloudy, breezy and very cold.

High temperatures near 10 in Pittsfield, Adams, NorthAdams and Williamstown; low teens in Lee, Stockbridge, Great Barrington and Sheffield and; mid to upper single digits over the elevated terrain. Wind chill temperatures in the teens to 20s below zero early, single digits below zero in the afternoon.

West-northwesterly winds at 10-15 mph, shifting to southwest late.

The very cold and dry air associated with the arctic air mass moving southward is suppressing the attempts of the moisture associated with the storm system to our south from making much northward progress. Therefore, I am decreasing my snow accumulation forecast a bit from yesterday. It looks like there will be a sharp line to the northern extent of the snow shield with those to the north of that line receiving little if any snow. This line will likely set up somewhere between central and northern Berkshire. It still looks like snowfall totals will increase as one moves from northwest to southeast in the county with a dusting at most in Williamstown, to about 0.5″-1″ in Pittsfield,  1″ or so in Lee and 2-3″ in the extreme southeast (e.g. Otis, Sandisfield, New Marlborough). After that the forecast can be summed up with one word….COLD!

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

Summary: An arctic front moved through this afternoon with a line of snow squalls. Cold, dense arctic air is sinking southward behind the front. As of 5 pm, temperatures had already fallen into the single digits in central and northern VT and the Adirondacks. This cold, arctic air is descending into the base of the trough in the jet stream wave pattern which has set up shop over the eastern U.S. and will serve to deepen the trough and nudge it somewhat eastward. Meanwhile, a disturbance in the jet stream flow pattern is rotating through the base of this trough and has generated a weak area of surface low pressure over the Midwest and is generating snow showers over Iowa, Wisconsin and Illinois. This surface low pressure system will intensify as it moves east tonight, reaching the Mid-Atlantic coast Tuesday (tomorrow). We will be along the northwestern margin of the snow shield associated with this low Tuesday evening. The computer model guidance is still fairly divergent as to where this margin will be. Therefore, even a slight shift will affect accumulation totals. Right now it looks like southeastern portions of the county will receive the most snowfall and northwestern locations the least. I would estimate a dusting to 2″ is most likely in the northwest (e.g. Williamstown) with 1-3″ in most other locations and 2-4″ possible in the southeast (e.g. Otis, Sandisfield). This storm could still be a complete miss (note that I have a 60% chance [likely] of precipitation for tomorrow night) but I think that is unlikely given the trend this winter with these types of storms. I will update this forecast tomorrow afternoon…

Light snow will likely develop around dinner time Tuesday and then taper off after midnight. It will be cold tomorrow but once the storm departs it will become windy and even colder, with dangerous wind chills for the remainder of the work week, right through Friday. There is no end to the cold weather in sight either. Temperatures may moderate a little on Saturday but then take another nose dive on Sunday as another arctic front dives into the trough.

Monday Night

Partly cloudy, breezy and turning sharply colder.

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

West-northwesterly winds at 10-15 mph with gusts to 25 mph, diminishing to 5-10 mph after midnight.

Tuesday

Increasing clouds during the morning, overcast with light snow likely developing towards evening.

High temperatures in the low teens in Pittsfield, Adams, NorthAdams and Williamstown; low to mid teens in Lee and Stockbridge; mid teens in Great Barrington and Sheffield and; upper single digits to around 10 over the elevated terrain.

Northwesterly winds at 5-10 mph in the morning, shifting to northerly in the afternoon.

Tuesday Night

Light snow likely, tapering off after midnight. Becoming breezy and very cold, with dangerously low wind chills by morning. Probability of precipitation 60%. Most likely snowfall totals a dusting to 2″ in the northwest (e.g. Williamstown), 1-3″ most other locations, 2-4″ in the southeast (e.g. Otis).

Low temperatures in the low single digits below zero, near zero in South County and mid single digits below zero in the elevated terrain and parts of North County. Wind chill temperatures in the teens below zero at times by morning.

Northerly winds at 5-10 mph, shifting to northwesterly and increasing to 10-15 mph with gusts to 25-30 mph after midnight.

Wednesday

Mostly cloudy in the morning, becoming partly cloudy in the afternoon. Windy and brutally cold.

High temperatures in the low to mid single digits in Pittsfield, Adams, NorthAdams, Williamstown, mid single digits in Lee and Stockbridge; mid to upper single digits in Great Barrington and Sheffield and: near zero to low single digits over the elevated terrain. Wind chill temperatures occasionally in the teens below zero.

Northwesterly winds at 10-20 mph with gusts to 30-35 mph.

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

Summary: The weak surface low pressure system moving through tomorrow looks like it may intensify a little more than it appeared yesterday when it hits the coast. Therefore, snowfall totals look to be slightly higher than yesterday’s estimate. By the time the snow winds down during the evening, likely accumulations should be in the 1-3″ range for most areas, with the lesser amounts in that range in the lower elevations of South County and the greater amounts in the higher elevations and in North County. There may even be a few isolated 4″ or 5″ amounts in the elevated terrain to the north and east (e.g. Savoy, Florida, Peru). The models have been trending toward higher amounts of liquid equivalent precipitation with each model run, with this afternoon’s runs suggesting a 2-4″ accumulation, so I would not be surprised to see slightly higher amounts than the forecast 1-3″. However, I am always wary of these rapidly moving, intensifying coastal lows since they frequently scoot just to our east before they can really get going. I will try to update my snowfall estimates after more information becomes available later tonight. In any case, the timing looks like this: Light snow or snow showers will likely develop toward morning with only a dusting or so by daybreak. Snow will then continue off and on for the daylight hours and may be moderate at times. There may be a pause in the snow during the early to mid afternoon. The bulk of the snow will occur during the day with 1-3″ totals by evening. However, it looks like light snow may linger well into the evening so an additional 0.5″ or so could fall before midnight.

Snow showers and flurries are also likely on Sunday with some lake-effect early and then the approaching arctic front late in the day. Snow showers/squalls are still possible on Monday as the front moves through. Additional snowfall totals for Sunday and Monday should be in the dusting to 1″ range although if a line of heavier snow squalls develops on Monday there may be 1-2″ totals in a few spots. After the arctic front passes, temperatures will plummet and may get no higher than the single digits for both Tuesday and Wednesday.

The long-range models are suggesting we could get another little coastal low, similar to tomorrow, on Thursday or Friday and then, possibly, a larger storm late in the weekend which will usher in the next arctic air mass. So it looks like our January thaw is finished and that we are returning to winter weather for the foreseeable future….

Friday Night

Increasing cloudiness with light snow or snow showers likely developing by daybreak. Probability of precipitation 60%. Likely snowfall totals a dusting.

Low temperatures in the mid 20s.

Calm winds.

Saturday

Intermittent snow. Snow may be moderate at times. There may be a pause in the snowfall during the early to mid afternoon. Probability of precipitation 80%. Likely snowfall totals 1-3″ by evening, with the lesser amounts in that range in the lower elevations in South County and the higher amounts in the elevated terrain and in North County. A few spots over the elevated terrain to the north (e.g. Savoy, Florida, Peru) may see as much as 4″ or 5″.

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

Easterly winds at 5-10 mph, shifting to northwesterly late.

Saturday Night

Light snow or snow showers likely until midnight. Breezy. Remaining mostly cloudy after midnight. Probability of precipitation 60%. Additional snowfall accumulations of a dusting to 0.5″ possible.

Low temperatures near 20, upper teens over the elevated terrain.

West-northwesterly winds at 10-15 mph, with gusts 25-30mph during the evening, diminishing after midnight.

Sunday

Mostly cloudy, breezy and colder, with snow showers or flurries likely. Probability of precipitation 60%. A dusting is likely in some locations.

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

Southwesterly winds at 10-15 mph with gusts to 25-30 mph.

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

Summary: Not much has changed since yesterday’s post. It still looks like another small shot of snow on Saturday as another weak surface low pressure system forming along the eastern edge of the jet stream trough moves quickly through and out to sea. We will likely get a similar amount of snow to what we received today although we may get a bit more, on the order of 1-2″.

On Sunday, a piece of the arctic air mass sitting over, of all places, the Arctic, will break off and begin its descent into the trough. The arctic front at the leading edge of this airmass will generate snow showers and snow squalls late on Sunday or Sunday night. Another 1″ or so is possible from this event as well. The front will temporarily stall over our region but then begin to slowly sink southward on Monday and Tuesday as the core of that piece of arctic air moves directly over our region. Temperatures will take a corresponding nosedive and we are likely to peak in the teens on Monday and Tuesday and struggle to get out of the single-digits on Wednesday and Thursday.

The long-range models suggest no significant let up from the cold as a reinforcing push of frigid, arctic air sinks into the “standing wave” trough for the following week. With the trough axis just to our west, any storms that form along its eastern margin should remain well out to sea. Therefore, at this time there is no evidence that we will receive any significant snow storms for the foreseeable future.

Thursday Night

Mostly cloudy with the chance of a snow flurry or two. Probability of precipitation 30%. No additional snow accumulation expected.

Low temperatures generally in the low to mid 20s.

Winds light and variable to calm.

Friday

Mostly cloudy in the morning. Becoming partly cloudy and not as cold in the afternoon.

High temperatures in the mid to upper 30s in Pittsfield; mid to upper 30s in Adams, NorthAdams, Williamstown, Lee and Stockbridge; near 40 in Great Barrington and Sheffield and; low to mid 30s over the elevated terrain.

South-southwesterly winds at 8-12 mph.

Friday Night

Partly cloudy.

Low temperatures generally in the low to mid 20s.

Light south-southwesterly winds in the evening, becoming calm overnight.

Saturday

Mostly cloudy with light snow likely. Probability of precipitation 70%. Likely accumulations a dusting to 2″. Becoming breezy in the afternoon.

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

Easterly winds at 5-10 mph in the morning, shifting to northwesterly and increasing to 10-15 mph, with higher gusts in the afternoon.

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

Summary: We are likely to get a light coating of snow tomorrow and again on Saturday as we are brushed by weak coastal surface low pressure systems forming along the eastern edge of the trough in the jet stream wave pattern that is setting up over the eastern half of the U.S.. We also will likely get some snow showers/squalls late Sunday or Sunday night as we are brushed by an arctic cold front diving down into the trough. Each of these three events have the potential to leave a dusting to 1″ or so of snow accumulation, although some areas may see little or no snow.

Temperatures will gradually decline through the weekend and next week as the trough essentially becomes a “standing wave” as a series of disturbances in the jet stream flow rotating through the base of the trough act to deepen and re-establish the trough in place. This standing wave pattern is becoming bad news for the western U.S. as, with a trough over the eastern U.S., the other half of the wave is a ridge over the western U.S.. This means the storm track, which follows the jet stream, is way to the north over western Canada. California, including the Sierra Nevada mountains from which snow melt provides much of the drinking water for the northern half of the state, has gotten very little precipitation. With this standing wave remaining in place, which long-range models suggest will be the case for the next few weeks, the drought in California looks to continue. Since their rainy season usually ends by March, they are running out of time to build up the reservoirs before 7 months of dryness (April-October) sets in.

Wednesday Night

Mostly cloudy with the chance of snow flurries or wet snow showers. Any snow showers will likely be mixed with rain during the evening in the lower elevations. Probability of precipitation 40%. There may be a dusting of snow in a few locations.

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

Light southerly winds in the evening, shifting to northwesterly and increasing to 5-10 mph by midnight.

Thursday

Mostly cloudy with a few snow showers and flurries likely. There may even be a period of light snow during the afternoon. Probability of precipitation 60%. Likely snowfall accumulations a dusting to 0.5″. There could be up to an inch in a few spots over the elevated terrain.

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

Northwesterly winds at 5-10 mph.

Thursday Night

Partly to mostly cloudy and a little colder.

Low temperatures generally in the low 20s, near 20 over the elevated terrain.

Winds light and variable to calm.

Friday

Mostly cloudy. Slight chance of a snow shower or flurry late. Probability of precipitation 20%. No 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.

Southerly winds at 5-10 mph.

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.