I will be on vacation next week so this will be the last forecast until Monday, January 23.

Summary and Analysis:

A trough in the upper-level wave pattern is propagating slowly eastward toward the Northeast this afternoon. A cold front at the leading edge of this trough is lifting the mild, moist air over us as it moves eastward, thus the rain this afternoon……

Just a minor digression here….. When I mention a front this time of year it is usually a surface representation of what we call the polar front, which is where the strongest temperature gradient in the Northern Hemisphere is located, separating very cold air to the north from much warmer air to the south. The jet stream forms at upper-levels along this polar front, the strong winds being generated by a steep pressure gradient created by the temperature gradient (warm air is lighter than cold air and pressure is just the weight of the air above a point). We name the surface fronts (surface representation of this polar front) either a cold or warm front depending on which way the polar front is moving. If the cold air is advancing (polar front moving south and east, at the leading edge of a trough in the wave pattern of the polar front) it is called a cold front. If warm air is advancing (polar front moving north and east, at the leading edge of a ridge in the wave pattern), we call it a warm front. When a cold front passes, the cold air within the trough, north of the polar front, moves in and temperatures drop. The opposite occurs after a warm front passes, the warm air to the south of the polar front (associated with the ridge) moves in and temperatures rise…..

……The cold front will move through this evening and temperatures will drop precipitously overnight. It will also become windy as the pressure gradient steepens. This pressure gradient is due to strong surface high pressure associated with the western side of the trough building eastward. As a result, it will turn dry but windy and much colder tonight into the weekend. As the trough propagates eastward over the weekend the surface high pressure system will build over the region. This will result in beautiful winter days with seasonable temperatures on Sunday and Monday. The only fly in the ointment is on Saturday. The southern edge of the trough, represented as a stationary front (polar front), will be located over the Middle Atlantic states. Warmer air and moisture overriding this front will be creating cloud cover, with snow and ice over southern PA, MD and NJ Saturday morning. This precipitation, in the form of snow may make it far enough north to give Berkshire County a snow shower late in the day, but I believe it is more likely that we will just have a cloudy and cold day and will stay dry.

Unfortunately, if you are either a snow or winter lover, fortunately if you don’t like cold and snow, the trough will lift out early next week and a broad ridge in the wave pattern will build over almost the entire US, with the polar front shifting north well into Canada. As a result, temperatures will again become unseasonably mild midweek, probably through next weekend. Any precipitation that falls during that time will be in the form of rain.

Berkshire County Forecast

Thursday Night

A few lingering light showers early this evening, then remaining mostly cloudy overnight. It will turn windy and much colder. There is the chance of a snow flurry or snow shower toward morning with little or no accumulation. Temperatures will be near 50 into the lower 50s this evening. Temperatures will start a precipitous drop from north to south beginning about 11 pm with temperatures falling into the upper 20s to near 30, mid 20s over the elevated terrain, by morning. Southwesterly winds at 10 – 15 mph early will shift to west-northwesterly late in the evening and increase to 10 – 20 mph, 15 -25 mph over the elevated terrain.

Friday

Mostly cloudy with the chance of a flurry or snow shower early then becoming mostly sunny. It will be windy and much colder than previous days. Probability of precipitation 30% early, little or no snow accumulation. Temperatures will hold steady in the upper 20s to near 30 in the lower elevations of central and northern Berkshire (e.g. Pittsfield, North Adams), low 30s over the lower elevations of South County (e.g. Great Barrington), mid 20s over the elevated terrain into early afternoon, then fall through the 20s during the afternoon. West-northwest winds at 15 – 25 mph. Wind chill temperatures in the teens during the afternoon.

Friday Night

Partly cloudy and cold with diminishing winds. Low temperatures in the mid to upper single digits, near 10 in South County, mid single digits over the elevated terrain. Northwesterly winds at 10 – 15 mph in the evening, becoming light after midnight.

Saturday

Mostly cloudy and cold. There is the chance of a snow shower late. Probability of precipitation 30%. Little or no accumulation. High temperatures in the mid 20s over the lower elevations of central and northern Berkshire, mid to upper 20s in South County, and low 20s over the elevated terrain. Light south-southwesterly winds.

Saturday Night

Chance of a flurry or snow shower early, then clearing skies and not as cold. Low temperatures in the mid to upper teens. Light south-southwesterly winds becoming northwesterly at 5 – 10 mph after midnight.

Sunday

Mostly sunny with seasonable temperatures and a light northwesterly breeze. High temperatures near 30, low 30s in the lower elevations of South County and mid to upper 20s over the elevated terrain. Northwesterly winds at 5 – 10 mph.

 

Posted 4:00 pm

Summary:

It will be unseasonably mild for the next few days with a few bouts of, mostly, rain showers. Temperatures should rise above freezing for all but the highest elevations this evening and then stay above freezing into Friday. Some snow showers, or a short period of light snow, is likely late this afternoon and this evening. Snowfall totals should be light, a dusting to as much as 1/2″ over the elevated terrain. It should then remain overcast but dry until about 1 am. There will then be a line of steadier, heavier precipitation moving through between about 1 and 3 am. This will likely be rain, about 0.20″, in all but the highest elevations. Above about 1500 feet the precipitation may fall as wet snow. If snow does fall, these higher elevations will likely receive about 1/2″ – 1″ with up to 2″ in the highest elevations.

Wednesday should see variable amounts of clouds and sun. It will be dry and unseasonably mild, with temperatures well up into the 40s. It will then turn overcast again Wednesday night and remain quite mild, with a few rain showers after midnight. It will remain cloudy and mild Thursday, with temperatures once again well up into the 40s. There will only be a little drizzle or a light shower or two during the morning with a better chance of showers during the afternoon as a stronger cold front moves through. This will set the stage for dropping temperatures but drier weather, with temperatures dropping through the 30s Thursday night with seasonably cold temperatures Friday through the weekend. There could be a little light snow Saturday night as the polar front, stalled to our south, inches back toward the region but snowfall should be light, on the order of a dusting to 2″ at most.

Analysis:

Somewhat complex but weak low pressure systems will move through over the next few days as a weak portion of the polar front moves back and forth over the region. As a result, we will see unseasonably mild weather with bouts of, mostly rain, showers. As of this afternoon, a surface low pressure system is moving northeastward through the Great Lakes. It will drag its associated warm front through this evening. There will likely be a few snow showers or a period of light snow associated with this frontal passage. Accumulations should be light, on the order of a dusting to 1/2″. This low’s trailing cool front will then move through after midnight with a steadier period of precipitation between 1 and 5 am. This will be rain in most areas but the precipitation could remain as snow above 1500 feet. Expect 1/2″ to as much as 2″ in these higher elevations. The front will then stall to our south and then move back as a warm front on Wednesday and Wednesday night. We will see a few light rain showers as it passes after midnight Wednesday night.

A deeper trough in the upper-level wave pattern will finally upropagate eastward, with a surface cold front along the leading edge moving through Thursday evening. Surface high pressure will build into the region during the day on Friday so we will likely see some sun but it will be breezy and seasonably cold. The trough then flattens out and the polar front stalls to our south on Saturday. A weak disturbance propagation along the front to our south could bring us a little light snow Saturday evening but then high pressure should build back in for Sunday, with a good amount of sun and seasonably cold temperatures.

Berkshire County Forecast:

Tuesday Night

Overcast, quite breezy, and much milder than previous nights. Snow showers or a period of light snow are likely early this evening, ending by 9 pm. A steadier period of precipitation, mostly rain, will occur between 1 and 5 am. This will likely be snow above 1500 feet or so. Probability of precipitation 60% in the early evening, near 100% after midnight. Rainfall totals between 0.20″ and 0.25″. Snowfall totals a dusting to 1/2″ in the lower elevations during the evening, 1/2″ to 2″ above 1500 feet. Temperatures rising to near 40 over the lower elevations, mid 30s over the elevated terrain. Southerly winds at 15 – 25 mph with gusts to 35 mph, particularly over the elevated terrain.

Wednesday

Mostly cloudy early then becoming partly cloudy. It will be unseasonably mild. High temperatures in the mid 40s over the lower elevations (e.g., Pittsfield, North Adams), upper 40s in the lower elevations of South County (e.g. Great Barrington), low 40s over the elevated terrain. Southwesterly winds at 5 – 15 mph early, becoming light during the afternoon.

Wednesday Night

Increasing clouds during the evening. Overcast and mild with a few light rain showers likely after midnight. Probability of precipitation 60%. Likely rainfall 0.10″. Low temperatures generally in the mid to upper 30s. Southerly winds increasing to 10 – 15 mph.

Thursday

Cloudy, breezy and unseasonably mild. There could be a little drizzle or a light rain shower in the morning. Rain showers are likely during the afternoon. Precipitation probability will increase from south to north (greatest probability in North County) and as the afternoon progresses. High temperatures near 50 in most locations. South-southwesterly winds at 10 – 15 mph.

Posted 3:30 pm

Summary:

A surface low pressure system will develop off the Southeast US coast overnight tonight and then move up along the coast, but offshore, during the day on Saturday. It will intensify as it moves to a position south and east of Cape Cod Saturday evening and then into the Canadian Maritime region Saturday night and Sunday. This storm will bring heavy snow to the Southeast and parts of the Mid-Atlantic, with a wide swath of 6 -12″ from northern SC through NC and into eastern VA. There could even be up to 15″ along the central coast of VA. As the storm moves by Cape Cod it is also likely to dump 6 – 12″ in southeastern New England, with up to 18″ on Cape Cod on Saturday and Saturday evening. We should be on the western edge of the snow shield during the day on Saturday. As of this afternoon it looks like snow should begin here during the afternoon and end during the evening. The snow should be generally light. Most likely accumulations are 1 – 3″, with the least in northwestern parts of the county and the most in southeastern portions. Since we are projected to be at the western edge of the precipitation, any shift in the projected track of the storm will have a significant impact on accumulations. If the storm tracks 50 miles to the east, we will only get a dusting, or no snow at all. If the storm tracks further west we could get 3 – 5″.

Analysis:

The broad trough in the jet stream wave pattern, and its associated cold weather, continues to cover the entire northern tier of states. This trough will finally begin to propagate slowly eastward this weekend. As this occurs, the nadir of the trough, and thus the coldest air will become centered over New England on Sunday. This will result in significantly below normal temperatures for Berkshire County through Monday. As the coastal storm rides northeastward along the eastern edge of this trough we will likely see some light snow Saturday afternoon and evening (see summary). Once the surface low moves into the Canadian Maritime on Sunday, moist flow circulating around the low, will be enhanced by the Great Lakes and lifted by our elevated terrain. As a result, we are likely to see scattered snow showers here on Sunday as well.

The trough then lifts to the northeast as the wave pattern flattens out (becomes zonally [west-east] oriented) for mid to late week. As a result, milder air will move back in to the county and temperatures will rise to above average, well into the 30s and possibly even the 40s Wednesday through Friday. The advance of this warmer air will be represented by a surface warm front to our south on Tuesday. This warm front will be extending eastward from a surface low moving into the Great Lakes along the eastern edge of the next ripple (trough) in the jet stream. As the warmer air overrides colder air at the surface on Tuesday and Tuesday night, light snow will likely break out late Tuesday but should change to sleet, freezing rain, and eventually rain Thursday evening and overnight.

Berkshire County Forecast:

Friday Night

Partly cloudy this evening, then increasing clouds after midnight, becoming overcast by morning. It will be quite cold, with low temperatures in the upper single digits in most of the lower elevations, near 10 in South County (e.g. Great Barrington) and mid single digits over the elevated terrain. Wind chill temperatures dropping to near zero. West-northwest winds at 5 – 10 mph, becoming light by morning.

Saturday

Overcast and cold. Light snow likely developing during the afternoon, ending during the evening. Probability of precipitation 60% in North County, 70% in central Berkshire and southwestern portions and 80% in southeastern portions (e.g. Otis, Becket). Most likely accumulations by the time the snow tapers off in the evening, a dusting to 1″ in the lower elevations of North County, including Williamstown, Adams and North Adams; 1 – 2″ over the elevated terrain to the east (e.g. Savoy and Florida); 1 – 2″ in the lower elevations of central and southwestern Berkshire, including Pittsfield, Great Barrington, Stockbridge, Lee, Lenox and Sheffield; 1 – 3″ in the elevated terrain of central and southern Berkshire, including Windsor, Peru, Otis, Becket and Sandisfield, with the greatest amounts most likely in the southeastern corner of the county. High temperatures in the mid to upper teens in the lower elevations of central Berkshire and North County, near 20 in South County and mid teens over the elevated terrain. Northerly winds at 5 – 10 mph.

Saturday Night

Any light snow ending in the evening. Remaining mostly cloudy and cold with scattered snow flurries or snow showers overnight. Low temperatures in the upper single digits in the lower elevations, near 10 in South County and mid single digits over the elevated terrain. Wind chill temperatures dropping to near zero. West-northwesterly winds at 5 – 10 mph.

Sunday

Mostly cloudy and cold with scattered snow flurries and snow showers. Becoming breezy in the afternoon. A dusting to 1/2″ accumulation possible in some locations. High temperatures in the mid teens in the lower elevations of central and northern portions, upper teens in the lower elevations to the south and low teens over the elevated terrain. West-northwest winds at 5 – 10 mph in the morning, increasing to 10 – 20 mph in the afternoon.

 

Posted at 4:30 pm

The forecast looks fairly similar to yesterday so I will give a quick update today and a more detailed weekend forecast tomorrow afternoon. It still looks like snow showers or light snow, associated with a coastal low developing and sliding by to our south and east, will be likely after midnight. Any accumulations should be on the order of a dusting to 1″. Any snow should end by morning as the low slides off the Southern New England coast and out to sea.

All of the models have the next low developing along the eastern edge of our upper-level trough hugging the coast more than previous runs, just as occurred with tonights storm. Right now the larger-scale global models, both the GFS (US) and ECMWF (European) models still have the low tracking far enough offshore to only give us a dusting to 1″, if anything, Saturday afternoon and night. However, the high resolution models running this afternoon are giving us on the order of 2 – 4″. We will have to see how things progress over the next 24 hours. I will give an update with my more detailed forecast tomorrow afternoon.

It still looks like below normal temperatures into Tuesday morning, with the coldest days being Sunday and Monday. More details to come tomorrow…..

Posted at 4:00 pm

Summary:

Just a quick update, since there is little change from yesterday. The high resolution models are indicating a few snow showers and squalls will move through the county between 5 and 6 pm today, leaving a dusting to 1/2″ in the lower elevations, with up to an inch over the elevated terrain. However, I am not seeing much on radar at this point, so I think the models are overdoing it a bit. In any case, this shower activity represents the leading edge of much colder air. With and after the squall activity winds should increase and become gusty and temperatures should drop rapidly, into the 20s, just after dark. It will then be breezy and colder for the next several days. It still appears that the coastal storms developing along the eastern edge of the upper-level trough should stay to our south and east, even though it appears that the surface low on Thursday night and Friday will hug the coast a bit more than it looked yesterday, bringing a few inches to southeastern-most New England. Berkshire County could see a quick burst of light snow late Thursday night into Friday morning as the storm develops but any accumulations will be quite light, a dusting to an inch. It will become quite cold on Sunday and Monday as the center of the trough moves over New England and temperatures will likely drop to near, or even below zero, with wind chills well below zero on Sunday night and Monday morning.

Berkshire County Forecast

Wednesday Night

A brief burst of early evening snow shower and squall activity is possible, ending by 6 or 7 pm. Some off and on lake-effect snow shower activity could persist through the evening in North County. It will turn breezy and much colder. Skies will remain mostly cloudy in central and northern Berkshire, with partial clearing in South County. Skies should clear county wide by morning. Probability of precipitation during the evening 50% in North County, 40% in the remainder of the county. Any snow accumulation should be limited to a dusting to 1/2″ in the lower elevations with up to 1″ over the elevated terrain, particularly in North County. Low temperatures in the mid to upper teens in the lower elevations, low to mid teens over the elevated terrain. West winds at 10 – 20 mph with gusts to 25 mph. Wind chill temperatures in the single digits by morning.

Thursday

Early morning sunshine followed by increasing clouds. Mostly cloudy in the afternoon. Breezy and colder. High temperatures in the mid 20s in the lower elevations of central and northern Berkshire, upper 20s in South County, low 20s over the elevated terrain. Westerly winds at 10 – 20 mph, diminishing late. Wind chill temperatures in the single digits to teens.

Thursday Night

Overcast and cold with lighter winds. There is the chance of snow showers or a little light snow developing after midnight, particularly in South County. Probability of precipitation 50% in South County, 40% elsewhere. Any accumulations should be on the order of a dusting to 1″. Low temperatures in the upper teens in the lower elevations, mid teens over the elevated terrain. West-southwesterly winds at 5 – 10 mph during the evening, becoming light after midnight.

Friday

Any early light snow should end by mid to late morning. Partial clearing in the afternoon. Remaining cold. High temperatures in the low to mid 20s in the lower elevations, mid 20s in South County, low 20s over the elevated terrain. West-northwesterly winds at 5 – 10 mph.

Posted at 3:50 pm

Summary and Analysis:

A complex, but relatively weak area of surface low pressure is moving through the Northeast this afternoon and evening, with one low centered over western PA and a second off the NJ coast. A broad and dominant trough in the jet stream wave pattern is centered over western Canada and the northern Great Plains, with the eastern edge of this trough located over the western Great Lakes. As the trough moved south from Canada the past few days, a concurrent ridge in the upper-level wave pattern developed over the Eastern US, with mild air surging northward into eastern portions of the Midwest and the East Coast with temperatures now above freezing in most of the Midwest, the entire Great Lakes, and virtually all of the East Coast except for northern Maine and the highest elevations of the elevated terrain.  As a result, virtually all of the precipitation associated with this broad area of surface low pressure is falling in the form of rain. As of 3 pm, all reporting stations in Berkshire County are above freezing, except for Savoy, where the temperature is 32 ºF.   Therefore, any threat for frozen precipitation for Berkshire County for the next 24 hours should be limited to the highest elevations of North County, where there could still be some freezing rain.

Steady rain will continue across the county through the evening, although rain should lighten up for a few hours during the late evening, ending by the early morning hours, around 2 am or so. As the low pressure system moves into eastern Canada and intensifies, the counter-clockwise circulation around the low will have a number of impacts for us. First of all, the eastern edge of the previously described upper-level trough will surge eastward and the cold front (polar front) associated with it will move across the county tomorrow. As a result, temperatures will start out fairly mild, but begin to drop during the afternoon, and particularly tomorrow (Wednesday) night. In addition, the pressure gradient will increase as the low deepens, so it will become quite breezy with wind chills dropping into the single digits by Thursday morning. Also, moisture circulating around the low, being lifted by the advancing cold front and our elevated terrain will result in scattered snow showers, and even a few squalls, Wednesday afternoon and evening. There will be some lake-effect snow but with winds more out of the west-southwest any snow showers should be limited to southern VT on Thursday.

The upper-level trough will continue to broaden, with the polar front along its southern edge displaced well to our south, and be reinforced by cold disturbances moving out of Canada, so that the cold air associated with this feature will cover the entire northern tier of the US for several days, right through the weekend and into early next week. Therefore, temperatures will be below normal in Berkshire County right into early next week, with the coldest temperatures over the weekend. In fact we likely will not see above freezing temperatures until mid-week next week. Unfortunately for snow lovers, and all of the businesses in the county which depend upon it, there is unlikely to be much natural snow, as all of the surface lows which develop along the eastern edge of the trough, one on Friday, and a few over the weekend, should track out to sea to our south and east. At least it will be cold enough for the ski areas to make snow…..

Berkshire County Forecast

Tuesday Night

Steady rain early this evening, will likely lighten up and become more intermittent mid to late evening and end by 2 am or so. There may still be a few pockets of freezing rain over the highest terrain of North County. Remaining overcast once the rain ends. Probability of precipitation near 100%. Rainfall totals around 0.50″ this afternoon and evening. Temperatures holding steady in the mid 30s, low 30s over the highest terrain. Northeasterly winds at 5 – 10 mph this evening, becoming light westerly after midnight.

Wednesday

Mostly cloudy and cool. A few, widely scattered, light flurries or sprinkles are possible. Late afternoon it will become breezy and colder with a snow shower or squall more likely toward evening. Little or no accumulation for most locations with a quick dusting possible in any squalls that develop. Probability of precipitation 40%. Temperatures will rise only slightly with highs in the late morning to early afternoon in the mid to upper 30s in most locations, near 40 in the lower elevations of South County, and low to mid 30s over the elevated terrain. Light west-southwesterly winds in the morning becoming westerly at 10 – 15 mph in the afternoon, with a few higher gusts in any snow squalls which develop.

Wednesday Night

Variably cloudy, breezy and much colder. Low temperatures in the mid to upper teens, low teens over the elevated terrain. West-southwesterly winds at 10 – 20 mph with gusts to 25 mph. Wind chills dropping into the single digits.

Thursday

Some early morning sunshine, otherwise mostly cloudy, breezy and cold. High temperatures in the mid 20s in the lower elevations of central and northern Berkshire, upper 20s in the lower elevations of South County and low 20s over the elevated terrain. West-southwesterly winds at 10 – 20 mph, diminishing later in the afternoon.

 

Posted at 2:30 pm, Friday 12/30

Summary and Analysis:

Yesterday’s storm has moved into the Canadian Maritime and the surface low has become quite deep, with central pressure around 965 mb. This is creating a strong pressure gradient which is generating strong west-northwesterly winds across our region. As these cold winds blow across the mild, unfrozen Great Lakes numerous bands of lake-effect snow have developed across New York state and into Berkshire County. A few of these bands contain fairly heavy snow and, in fact, one of these moved across central Berkshire near noon today and dropped a quick inch of snow. These will continue to wave back and forth, north to south and then back to the north again tonight as the snow within them diminishes. An Alberta Clipper type low will move across the Great Lakes and to our north Saturday and Saturday night. The low may be close enough to give Berkshire County a quick dusting of snow Saturday evening, with the greatest likelihood in northern portions. Our weather should be quiet Sunday into Monday as surface high pressure develops over the Northeast.

As evening approaches on Monday there could be some travel issues and this will need to be watched closely over the next few days. Warm air aloft well in advance of an approaching warm front will begin to override cold air near the surface, possibly generating a little light precipitation Monday evening into Tuesday morning. Any precipitation should be quite light but will fall in the form of sleet or freezing rain/drizzle. As the warm front, associated with a surface low moving northward into the Great Lakes. As the warm front moves through on Tuesday afternoon and evening the precipitation will increase in intensity but surface temperatures will likely have moved above freezing by that point so, hopefully, we will see just plain rain.

As the surface low over the Great Lakes moves northeastward it will drag its trailing cold front through our area overnight Tuesday. As a result, it will be colder but dry on Wednesday and Thursday. However, it is beginning to look like the cold front, at the leading edge of a broad trough in the jet stream wave pattern, will stall to our south. One or two surface lows may develop along the front in the Southeast and move northeastward off the Mid-Atlantic coast, the first on Friday and the second over the weekend. If this does occur we could see another snow event (or two). However, this situation is still a week away…..

Berkshire County Forecast:

Friday Night

Partly to mostly cloudy breezy and colder. Scattered snow flurries and snow showers are still possible. Probability of precipitation 50%. Little or no additional snow accumulation. Low temperatures near 20, mid to upper teens over the elevated terrain and low 20s in the lower elevations of South County. Westerly winds at 10 – 15 mph this evening, diminishing after midnight, becoming southwesterly at 5 – 10 mph by morning.

Saturday

Cloudy and seasonably cold, becoming breezy in the afternoon. There is the chance of a snow shower toward evening, particularly in North County. Probability of precipitation 30%. High temperature near 30 in the lower elevations of central and northern Berkshire (including Pittsfield, Adams, North Adams and Williamstown), low 30s in the lower elevations of South County (including Great Barrington and Sheffield) and upper 20s over the elevated terrain. Light southwesterly winds becoming southerly and increasing to 10 – 15 mph in the afternoon.

Saturday Night

A quick burst of light snow or snow showers is likely during the evening, with increasing likelihood as one moves further north in the county. Probability of precipitation 70% in North County, 60% in central Berkshire, and 50% in South County. Any accumulations should be light, on the order of a dusting to 2″. Otherwise, mostly cloudy with near steady temperatures overnight. Low temperatures in the upper 20s, mid 20s over the elevated terrain and near 30 in South County. South-southwesterly winds at 10 – 15 mph in the evening, becoming westerly at 5 – 10 mph toward morning.

Sunday

Mostly cloudy in the morning, clearing skies during the afternoon. High temperature in the low 30s in the lower elevations of central and northern Berkshire, mid 30s in South County, and upper 20s over the elevated terrain.

Summary:

A weak surface low pressure system located off the New Jersey coast will intensify rapidly as it moves north/northeastward this afternoon and tonight across Cape Cod and into the Gulf of Maine. As of early afternoon, it is snowing moderately across the county with approximately 2″ of accumulated snow (Richmond). It appears that the storm will move more rapidly and track slightly to the east of the forecast from yesterday. In addition, the low pressure center should be slightly less intense. Therefore, although we will still receive significant accumulations, totals should be a bit less than forecast yesterday, the snow should taper off a few hours earlier this evening, winds won’t be quite as strong tonight and Friday, and there will likely be less in the way of “wrap around” snow showers.

Analysis (General):

As the surface low pressure system moves rapidly into the Canadian Maritime tonight and Friday, the trough in the jet stream wave pattern which generated the surface storm will move over us Friday and Friday night, giving Berkshire County a brief period of colder and windy weather, although temperatures will still be near normal for the date. Strong west-northwesterly winds circulating around the departing surface low will flow across the still unfrozen Great Lakes and generate some significant lake-effect snow later tonight and during the day on Friday across western and central NY state. Some of this snow will reach Berkshire County in diminished form, scattered off and on snow showers and flurries.

The jet stream wave pattern then begins to flatten out (zonally [west to east] oriented) on Saturday and remains that way into early next week. A weak Alberta Clipper type low will move to our north Saturday night but may be close enough to give the county a little light snow or snow showers overnight Saturday. However, accumulations should be only on the order of 1 – 2″ at most. A deep trough in the jet stream wave pattern will develop over the western US on Monday with concurrent “ridging” over the eastern US. As a result, it will become unseasonably mild here Monday night into Wednesday. In addition, a surface low will develop along the easter edge of the trough and move northeastward into the Great Lakes on Tuesday. The low will drag is attached warm front across Berkshire County and generate a pretty large dose of rain here during the day on Tuesday. This will, unfortunately for winter sports lovers, destroy any powder we accumulate today.  The trough will then propagate eastward and then “broaden out”, resulting in much colder temperatures through next weekend. A storm in the southeast may make a run at us next Friday……

Berkshire County Analysis:

Snow will be moderate to occasionally heavy through the afternoon, tapering off and ending from west to east between 5 and 7 pm. It will become windy overnight with scattered snow showers developing after midnight. It will be windy and chilly Friday, with temperatures holding steady. Off and on lake-effect snow showers will be around for most of the day Friday. It will remain cloudy and turn colder Friday night, with a few lingering snow showers or flurries and diminishing winds. It will remain cloudy on Saturday as the Clipper low approaches from the west. Light snow or snow showers will likely develop Saturday evening.

Revised total snow accumulation forecast (by end of the day Friday):

South County: Generally 3 – 6″, with the lowest amounts in the lower elevations near the Connecticut border and highest amounts in the hill towns to the east. There could be as much as 8″ in a few spots in the hill towns to the east (i.e., Otis, Becket). Expect 4 or 5″ in Great Barrington.

Central Berkshire: Generally 4 – 8″, with the lowest amounts in the lower elevations to the west and highest amounts in the eastern hill towns. There could be as much as 10″ in a few spots over the elevated terrain to the east. Expect 5 – 7″ in Pittsfield.

North County: Generally 5 – 9″, with lowest amounts in the lower elevations and highest amounts in the hill towns to the east. Expect 5 – 7″ in Adams, North Adams and Williamstown. A few spots over the elevated terrain to the east could see up to 10″.

Berkshire County Forecast:

Thursday Night

Snow tapering off during the evening and ending by 6 or 7 pm. It will remain cloudy and become breezy/windy overnight with scattered snow showers developing after midnight. Low temperature in the mid 20s, upper 20s in the lower elevations of South County and low 20s over the elevated terrain. West-northwesterly winds at 10 – 20 mph.

Friday

Mostly cloudy and breezy/windy and seasonably cold, with scattered snow showers and flurries. Snow accumulations a dusting to as much as 1″. There could be as much as 1 – 2″ if a persistent band sets up, particularly over the elevated terrain. Temperatures holding fairly steady in the upper 20s in the lower elevations of central and northern Berkshire (i.e., Pittsfield, North Adams), low 30s in the lower elevations of South County (i.e., Great Barrington) and mid 20s over the elevated terrain. Westerly winds at 15 -20 mph with gusts up to 30 mph.

Friday Night

Mostly cloudy and turning colder, breezy in the evening with diminishing winds after midnight. Scattered flurries and snow showers are still possible with little or no additional accumulation. Low temperatures in the mid to upper teens. Westerly winds at 10 – 20 mph in the evening, diminishing after midnight to 5 – 10 mph by morning.

Saturday

Mostly cloudy and seasonably cold. There is the chance of a snow shower toward nightfall. High temperatures near 30, low 30s in South County, upper 20s over the elevated terrain. Winds shifting to southerly and increasing to 10 – 15 mph during the afternoon.

As I had feared (this has happened to Berkshire County before, you would think I would learn, haha), the storm appears to be moving faster and developing slightly further to the east than it appeared yesterday. Therefore, snowfall totals will likely be a bit less than originally forecast. Still expect a plowable snowfall, with a range of 4 – 10″, with the lowest amounts in that range in southern and western portions and the highest amounts in the hilltowns to the east. I will give a more detailed snowfall forecast later this morning as more data becomes available.

Summary:

A midlatitude cyclone (storm/low pressure system) will develop along the Mid-Atlantic coast tomorrow (Thursday) morning and then deepen rapidly during the afternoon and particularly Thursday night as it moves north/northeastward across eastern New England and into the Canadian Maritime region. Snowfall rates to the northwest of the surface low will likely reach 1-2″ hour and, as a result, snow accumulations will total 1 – 2 feet across inland New Hampshire and Maine. Berkshire County will be at the western edge of the heavy snow shield of this rapidly moving storm and will likely receive a plowable, heavy wet snowfall. As of early this afternoon the most likely snowfall totals for us appear to be in the 6-12″ range with least amounts in the southern and western parts of the county and the greatest amounts in the northern and eastern parts of the county. However, due to multiple variables, this is not a particularly high confidence forecast as this time. More on this ahead…..

Analysis (General):

A trough in the jet stream wave pattern located over the western US this afternoon will propagate rapidly eastward and amplify overnight and will be centered over the Midwest by Thursday morning. A strong mid/upper-level disturbance (spin/vorticity) will rotate through the base of this trough, helping to amplify and tilt the trough, resulting in strong forcing for upward movement (upper-level divergence) in the atmosphere along the leading edge of this trough. This upward motion will be enhanced as the disturbance moves over the warmer ocean waters (atmosphere destabilizes). As a result, a surface low pressure system will develop along the Mid-Atlantic coast Thursday morning and then deepen “explosively” as it moves over eastern Long Island to Cape Cod by Thursday evening and then across Maine Thursday night. In fact, models are predicting a drop in surface atmospheric pressure (mean sea-level pressure [MSLP]) from 1004 millibars (mb) Thursday morning to 976 mb around midnight when the surface low is located along the Maine coast.

Berkshire County Analysis:

Snow should develop in Berkshire County during the mid morning tomorrow. The snow should be light to moderate at first with only an inch or two accumulating by noon. Snow will likely intensify during the afternoon and could be quite heavy for a time during the mid to late afternoon, with snowfall rates possibly reaching 1″ per hour, as the surface low along the coast begins to deepen rapidly. Snow should taper off during the evening and be mostly over by midnight, although off and on snow showers are likely to continue into the day Friday as moisture wrapping around the deepening low is lifted by our elevated terrain. Although the precipitation should be predominantly snow, there is a chance that rain could mix in for a time in the southernmost parts of the county as mild maritime air is driven inland by the southeast winds circulating around the surface low. Likely snowfall totals for most of the county should be in the 6-12″ range by the time the snow winds down Friday, with most of that falling during Thursday afternoon and evening. It will become windy as well overnight Thursday and during the day Friday as the storm intensifies. I will delineate more detailed snowfall forecasts for the county below but first a few caveats….

First and foremost, this storm will be moving away from us as it intensifies so if the track of the storm is slightly east of presently forecast the heavy snow may miss us or be brief. In fact, this happened once last winter (or was it the winter before….I am getting old, haha). The models were forecasting over 1 foot of snow for Berkshire County with similar scenario with a rapidly developing coastal storm. Fortunately (or unfortunately) the storm did not intensify as far to the west as forecast and we ended up with only a couple of inches. Also, rain could mix in for a time in southern parts of the county when precipitation is the heaviest and this could keep snowfall totals down there. However, even though the high-resolution models are suggesting this could happen, I think that this is unlikely.

Important to note: The snow will be fairly wet, with temperatures near freezing. Although the wind will be relatively light during the afternoon, winds will pick up overnight as the pressure gradient strengthens around the intensifying surface low. If the snow is wet, and accumulates on tree branches during the afternoon, there could be tree damage and power outages. However, a few degrees can make a big difference. If the temperature is 31 or 32 there could be problems but if it is 29 or 30 we will be in much better shape.

Detailed Snowfall forecast:

South County: Generally 4 – 8″ with the lowest amounts within that range near the Connecticut border. Great Barrington most likely will receive in the 6 – 8″ range. The hill towns to the east, such as Otis and Becket will likely get a bit more, likely 8 – 10″.

Central Berkshire: Generally 6 – 10″, 6 – 8″ in western portions, including Pittsfield, with 8 – 10″ in eastern portions but the hill towns to the east, including Windsor and Peru will likely receive 10 – 12″, with up to 14″ in a few of the higher elevations.

North County: Highest accumulations should be here with generally 8 – 12″, including Adams, North Adams and Williamstown. The hill towns to the east, including Florida and Savory will likely see 10 – 14″, with up to 16″ in a few isolated spots.

Berkshire County Forecast:

Wednesday Night

Partly cloudy and seasonably cold with low temperatures in the low to mid 20s county wide. Upper teens are possible over the elevated terrain. Light westerly winds during the evening, shifting to southeasterly and increasing to 5 – 10 mph by morning.

Thursday

Snow developing during the morning, becoming heavy at times during the afternoon. Heaviest snow should fall from mid afternoon until early evening. Most of the snowfall totals listed above will have occurred by 8 or 9 pm. High temperatures in the upper 20s over the elevated terrain, near 30 to low 30s in the lower elevations. Southeast winds at 5 – 10 mph during the morning, increasing to 10 – 15 mph during the afternoon.

Thursday Night

Snow tapering off from southwest to northeast during the evening. Snow will generally end by midnight, although off and on snow showers will develop after midnight. It will become windy with winds 15 – 20 mph in the lower elevations and 20 – 25 mph in the elevated terrain. Wind gusts 25 – 35 mph. Low temperatures in the mid to upper 20s.

Friday

Mostly cloudy and windy with off and on snow flurries and snow showers. A dusting to an inch accumulation is likely in spots, particularly over the elevated terrain to the west. Temperatures holding steady in the upper 20s in the lower elevations of central and northern Berkshire, low 30s in South County, mid 20s over the elevated terrain.