It still looks like Berkshire County will be on the western edge of the precipitation shield from tonight’s coastal storm. I would put the probability of light snow at 30% for northwest portions of the county up to 50% for southeast portions. Accumulations, if any occur, should only be a dusting for most of the county with up to one inch in the elevated terrain to the east, particularly southeast (e.g. Otis and Becket). It still looks like a significant snowstorm for southeastern New England. It will turn windy and cold here on Sunday, with mostly cloudy skies and some scattered snow flurries and snow showers in the afternoon. Monday (President’s Day), if you are lucky enough to have the day off, will have mostly sunny skies as surface high pressure begins to build in from Canada. It will still be fairly windy, although winds may diminish somewhat in the afternoon. It will be “warmer” than Sunday, with temperatures in the 20s. The sun will add warmth (the sun is getting quite high in the sky as we move through mid February) but the wind (wind chill) will take it away…..

Summary: The cold front is presently (2 pm) located along the eastern margin of the Catskills and Adirondacks, just to the west of Albany. Under sunny skies in advance of the front it has become quite spring-like, with temperatures rising well into the 40s in Berkshire County and even over 50 in Great Barrington (51 deg.). A very weak ripple of surface low pressure has developed along the front, to our southwest, over West Virgina, this afternoon and is associated with an area of light mixed precipitation. This low will move northeast along the front and weaken further this afternoon and this evening. It seems unlikely that we would get anything but rain from this low, with our temperatures this afternoon around 50 degrees. However, after the cold front passes later this afternoon our temperatures will drop rapidly and as the low moves along the front to our south we will likely get a period of light snow overnight. Accumulations should be light, on the order of an inch or two, with as much as three inches in a few spots over the higher terrain to the east, especially the southeast (e.g. Otis, Becket).

As mentioned in yesterday’s post, once the cold front has passed well to our east and off the coast, and the cold trough in the atmosphere begins to make its way east behind the front on Saturday, a more vigorous upper-level disturbance will rotate around the base of the trough and generate much more vigorous ascent in the atmosphere along the front off the Southeast and Mid-Atlantic coast. This will result in explosive development of a storm (represented by surface low pressure) off the coast Saturday night and Sunday as the storm makes its way to the Canadian Maritime. The scenario has not changed much from yesterday. The storm track appears to be ever so slightly to the east of its projected path yesterday. It still looks like Berkshire County will be on the western margin of the storm’s precipitation shield with a period of light snow a good bet overnight Saturday. It only looks like an inch or so for western parts of Berkshire County with more like two inches for eastern portions. I think it is unlikely that we will receive any more accumulation than that, even if the storm tracks further west than it is now projected. It is still possible that we will receive no snow at all, if the track is even slightly east of where it is now projected. It appears likely that eastern New England, particularly coastal regions, will get significant accumulations, upwards of 6 inches in some locations, such as RI and southeast MA.

As the storm deepens and moves into the Canadian Maritime on Sunday, it will drive strong, cold winds into Berkshire County (see yesterday for a more “scientific” explanation). As a result, Sunday will be an unpleasant day to be outside, with temperatures holding in the teens at best and gusty northwest winds at 15-25 mph. Wind chills will be near zero during the day and may drop to -10 to -20 Sunday night. The arctic airmass will be short-lived, however, and lift out quickly during the early week, with temperatures rising back into the 20s on Monday and 30s on Tuesday. It looks like the surface low pressure system headed our way for Tuesday will pass well to our northwest, so we should only get a little light snow or mixed snow and rain, as the low’s associated warm front and then cold front pass through.

Friday Night

Becoming overcast during the evening with a period of light snow developing around midnight and ending by morning. Probability of precipitation 80%. 1-2″ of accumulation is likely for most parts of the county. Some locations may receive less than an inch and the elevated terrain to the southeast (e.g. Otis, Becket) may receive up to 3″.

Low temperatures in the mid 20s in most locations, low 20s over the elevated terrain.

Light northwesterly winds increasing to 5-10 mph by morning.

Saturday

Mostly cloudy and colder.

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

Northwest winds at 10-15 mph.

Saturday Night

Light snow is likely. Probability of precipitation 60%. Most likely accumulations are only around 1″ in the western half of the county and 2″ in the eastern half. There is a significant possibility that there will be no accumulation.

It will become much colder with low temperatures in the low to mid teens in most locations, near 10 over the elevated terrain.

North-northwest winds at 10-15 mph in the evening, increasing to 15-20 mph after midnight.

Sunday

Mostly cloudy, windy and very cold. There is the chance of an afternoon snow flurry or snow shower. Probability of precipitation 40%. Nothing more than a dusting is expected.

Temperatures will rise very little as the cold, arctic airmass moves in. Expect high temperatures in the mid teens in Pittsfield, Adams, North Adams and Williamstown, upper teens in Great Barrington and Sheffield, and low teens over the elevated terrain and hilltowns, it might not rise above 10 in some of the higher elevations. Wind chill temperatures should hover near zero.

Northwest winds at 15-25 mph, with the strongest winds in the elevated terrain. There will be some gusts approaching 40 mph, over 40 in the elevated terrain, particularly during the afternoon.

Summary: Our weak, zonally oriented jet stream for the past several days has started to become more amplified with a strong, warm ridge in the jet stream developing over the western U.S. and a deep, cold trough in the jet stream plunging southward over the central and eastern U.S.. As this wave in the jet stream propagates slowly eastward as it amplifies, the cold trough will move over our region this weekend (with the leading edge of the trough represented as a cold front passage on Friday), bringing us much colder weather, particularly on Sunday, when the coldest part of the trough will be centered over our region.

It now looks as though the trough will progress a little more slowly eastward than it appeared a few days ago. As a disturbance in the jet stream rotates around the base of the trough it will create an area of divergence (diverging jet stream winds) aloft along the eastern edge of the trough. As a result, upward motion in the atmosphere will be generated and surface low pressure will develop off the Mid-Atlantic Coast during the day on Saturday. The trough will become negatively tilted (tilted backwards from the east to the west) overnight Saturday and Sunday, which will enhance the divergence aloft markedly. As a result, the surface low will deepen rapidly (we call this a “bomb”) as it is directed northeastward by the flow aloft, become a very deep low as it moves into the Canadian Maritime (970 mb in the ECMWF, 960 in the GFS! [equivalent to a Category 3 Hurricane]) Sunday evening. Fortunately (unless you are in a boat in the North Atlantic, or live in the Canadian Maritime region), this will all be happening well off the coast. Right now it looks like we will likely be on the westernmost edge of the precipitation shield from this storm. However, even though this should not be a big snowstorm for Berkshire County, I think that there is a good possibility that Berkshire County will get a few inches of accumulation overnight Saturday. In eastern New England, where they certainly don’t need it, they are likely to get more. This is NOT likely to be a repeat of last Friday, as the storm will be developing much farther away from the coastline, and much farther north along its track.

This will be a rapidly developing situation on Saturday and a change in the projected track of the low by even a small amount to the west or east, or a change in the timing of the storm development process, could result in us getting no snow at all (still a likely event) or a more significant accumulation. I will update this tomorrow afternoon.

After the low departs on Sunday, it will turn very windy and much colder as the pressure gradient force resulting from the deepening coastal low will generate strong northwest winds that will drive cold air from Canada southward over our region. After that, it looks like the jet stream wave pattern will become quite “wavy” (active) and progressive (waves in the jet stream propagating fairly rapidly eastward). As a result, there will be a series of storms moving from west to east across the country during the work week, likely effecting Berkshire County on Tuesday and again on Friday. It is unclear if these storms will bring all snow or a mixture of precipitation types. Right now I am leaning towards a mixture.

Thursday Night

Increasing cloudiness this evening, becoming mostly cloudy overnight. There is the slight chance of a snow shower or flurry, predominantly in North County. Probability of precipitation 20%. No accumulation is expected.

Temperatures will not fall much with a cloud cover and a persistent southerly breeze. Low temperatures will likely be in the upper 20s to near 30 in most locations.

Southerly winds light early, increasing to 5-10 mph by midnight and 10-15 mph by morning.

Friday

Mostly sunny and quite mild in the morning. Clouds will begin to increase late in the morning, becoming partly sunny (50-75% cloud cover) in the afternoon as the cold front moves through. Temperatures will begin to drop mid-afternoon following the cold front passage.

High temperatures will occur from late morning to early afternoon with highs near 40 in Pittsfield, near 40 to low 40s in Adams, North Adams and Williamstown, low 40s in Great Barrington and Sheffield, and mid to upper 30s over the elevated terrain and hilltowns. Temperatures will drop through the 30s over the course of the afternoon.

South-southwest winds at 10-15 mph in the morning, shifting to westerly and then diminishing somewhat over the course of the afternoon.

Friday Night

Variable amounts of cloudiness over the course of the night. It will average out partly to mostly cloudy.

Colder than Thursday night, with low temperatures near 20 to the low 20s in most locations, mid to upper teens over the elevated terrain.

Northwest winds at 5-10 mph.

Saturday

Becoming mostly cloudy to overcast. Much colder than Friday. There is a chance of snow late in the afternoon. Probability of precipitation 40%. Nothing more than a dusting to an inch or so is expected during the afternoon, although there could be more accumulation overnight (see summary above).

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

North-northwest winds at 5-10 mph.

Summary: Our weather should remain relatively quiet for the next several days as the jet stream pattern is rather weak, disorganized and zonally (west to east) oriented. As a result, surface systems will remain relatively weak.

Lots of low level moisture streaming off the Great Lakes kept us rather overcast today and these low clouds should persist overnight, which will keep temperatures relatively mild for this time of year. There is only the outside shot at a lake-effect snow flurry. We will finally see some sunshine tomorrow (its been a few days) as very weak surface high pressure builds in.

A weak low pressure system will move by to our south and rapidly off the Mid-Atlantic Coast Wednesday night. This weak storm (I suspect the Weather Channel will give it a name anyway) will drop several inches of snow (some locations could get as much as 4-6 inches) in parts of the Mid-Atlantic (Maryland, Delaware, Southern New Jersey) as well as eastern Long Island and southeast New England. This storm will essentially miss us and only give us some cloudiness overnight Wednesday. There is a chance that the southernmost parts of the county could see a brief period of snow around midnight, as the northern fringe of the precipitation shield skirts by to the south, but I do not expect any accumulation.

As the storm departs on Thursday, weak high pressure will again build in and give us plenty of sunshine and temperatures will approach, and could even surpass 40 degrees in some parts of the county (do I hear songbirds singing? No, forget that darn groundhog). It still appears that much colder air will move in for the weekend as the jet stream pattern becomes more amplified and a cold trough digs over the region, ushered in by the passage of a cold front on Friday. It should remain relatively dry, however. A storm (surface low pressure system) will develop along the eastern margin of this trough on Sunday but it will be WELL out to sea and will not impact us (maybe the Weather Channel will name it anyway……they are already up to “P”, wonder what they’ll do when they run out of letters, they are naming every surface low pressure system so they are handing out about 3 names/week).

Tuesday Night

Mostly cloudy (75-95% cloud cover). There will be occasional breaks in the cloud cover but the low clouds will be pretty persistent. There is the slight chance of a lake-effect snow flurry. Probability of precipitation 20%. No accumulation.

Temperatures will not fall much with the persistent cloud cover and will remain relatively mild for mid-February. Low temperatures in the mid 20s in most locations, with some upper 20s in South County and low 20s in a few spots over the elevated terrain.

West-northwest winds at 10-15 mph this evening will begin to decrease after midnight, decreasing to 5-10 mph by morning.

Wednesday

It will average out partly cloudy (25-50% cloud cover) with seasonable temperatures and light winds. It should start out mostly cloudy everywhere except South County but become partly cloudy everywhere by mid to late morning. There may be an increase in high clouds late in the afternoon.

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

West-northwest winds at 5-10 mph in the morning, becoming light and variable in the afternoon.

Wednesday Night

Increasing clouds in the evening. Becoming overcast by midnight. Breaks in the overcast may persist over North County. There is the chance of a brief period of snow in southernmost portions of the county near midnight. Probability of precipitation 30% in those locations. No accumulation expected. There will be partial clearing after midnight as the storm to our south moves rapidly out to sea.

Cloud cover will again prevent temperatures from dropping too much, but some clearing after midnight will permit temperatures to drop a few degrees lower than Tuesday night. Low temperatures in the low 20s in most locations, mid 20s in South County, upper teens to near 20 over the elevated terrain and hilltowns.

Light (0-5 mph) northerly winds in the evening shifting to northwest after midnight.

Thursday

Mostly sunny (5-25% cloud cover) to partly cloudy (25-50% cloud cover) for most of the day. There may be an increase in clouds late in the afternoon. Winds will be light and temperatures will be above average.

High temperatures in the upper 30s in Pittsfield, near 40 in Adams, North Adams and Williamstown, lower 40s in Great Barrington and Sheffield, and mid 30s over the elevated terrain and hilltowns.

Light northwest winds early, shifting to westerly and then southwesterly.

Summary: A storm system (surface low pressure system) tracking through the upper Great Plains and Great Lakes will drag first its warm front and then its cold front (following close behind) across our region tomorrow. This will result in a brief period of mixed precipitation, turning rapidly to freezing rain and then rain tomorrow morning, continuing as all rain into the afternoon. Temperatures behind the cold front are still relatively mild so we will not have a return to the very cold temperatures we have been experiencing in recent weeks and will have near normal to above normal temperatures for the rest of the work week. We will be between weather systems for a few days (Tuesday and Wednesday) without any storms or strong high pressure systems. However, scattered lake-effect snow showers are a good bet Monday night into Tuesday as strong west-northwesterly breezes blow across the lakes after the cold front passes. A weak low pressure system will scoot by to our south Wednesday night and Thursday. Right now it looks like it will miss us. A strong cold front will likely come through Friday and Friday night and put us back in the deep freeze next weekend.

Sunday Night

Clear in the evening with increasing clouds after midnight, becoming overcast by morning.

Temperatures will fall into the low to mid 20s in most locations this evening and then begin to rise after midnight as the clouds move in. Temperatures will likely reach the mid to upper 20s in most locations by morning. Temperatures could hit 30 in some parts of South County.

Light south-southeast winds increasing to 5-10 mph by morning.

Monday

Precipitation will likely begin between 7 and 9 am as a brief period of mixed precipitation that turns rapidly to freezing rain. Temperatures will be close to freezing and will rise above freezing in most locations within an hour or two after the rain begins, turning the precipitation to just plain rain by mid to late morning. The freezing rain could linger a little longer in some locations within the elevated terrain and hilltowns. However, temperatures should be above freezing everywhere by noon. Ice accumulations of 0.10″ at most will likely not cause any real problems as most roads have been treated during our recent snowfall. Rain will continue into the afternoon and should end by mid to late afternoon. Probability of precipitation near 100%. Rainfall totals around 0.25″.

High temperatures in the upper 30s in Pittsfield, Adams, North Adams and Williamstown, near 40 in Great Barrington and Sheffield, and mid to upper 30s over the elevated terrain and hilltowns.

South-southeast winds shifting to southerly and then southwesterly over the course of the day, increasing from 5-10 mph in the morning to 10-15 mph during the late morning to early afternoon, then decreasing to 5-10 mph late.

Monday Night

Mostly cloudy with scattered snow showers likely. Snow showers are most likely in central and northern Berkshire, particularly in the elevated terrain. Probability of precipitation 60% in these locations. There may be a dusting of snow in some locations. There is just a chance of snow showers in South County, with the probability of precipitation 40%.

Low temperatures in the upper 20s in most locations, mid 20s over the elevated terrain and hilltowns.

West-southwest winds at 5-10 mph in the evening, shifting to westerly and increasing to 10-20 mph after midnight.

Tuesday

Mostly cloudy and quite breezy, although it may be only partly cloudy at times, mostly in South County. There is still the chance of a snow shower, predominantly in the morning over central and northern Berkshire. Probability of precipitation is 30%. No accumulation more than a light dusting is expected.

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

West-northwesterly winds at 15-20 mph with some gusts over 30, particularly in the elevated terrain.

Summary: Now that I have been discovered I feel compelled to say something intelligent like……it’s going to snow. Oh, more intelligent than that? Ok, I’ll try…..

The coastal surface low is deepening rapidly off the Virginia coast this afternoon with the central pressure dropping to 989 mb at 1 pm. The low will continue to deepen as it moves northeast, reaching just east of Cape Cod by Saturday morning. The central pressure will have dropped to between 970-980 mb by then, which is fairly low for a winter coastal storm. However, that is not unusually low. For example, the 1993 “Superstorm” had a central pressure of 962 mb. What distinguishes this storm is that it will be fairly compact, creating a strong pressure gradient, particularly with strong surface high pressure to the north, and therefore, very strong winds. In addition, this storm is carrying very large amounts of moisture (water vapor) from its origin in the Gulf of Mexico and from the Gulf Stream as well. Therefore, even though the duration of the storm will not be notable (it will move out to sea with its snowfall fairly early on Saturday), accumulation totals in southeastern New England could possibly be historic (27.3″ is the record for Boston) due to very high snowfall rates during the peak of the storm tonight. I think Berkshire County will see rates of 1″ per hour but southeastern NE could see 3″ per hour at times, generating white-out conditions. In addition, this storm is developing large amounts of environmental instability for a snowstorm as the two disturbances in the jet stream merge (discussed in previous forecasts) with the northern branch disturbance bringing in very cold air aloft above the warm ocean waters at the surface. Environmental instability is what generates accelerated upward motion in the atmosphere that is responsible for severe thunderstorms and it is likely that there will be “thundersnow” during some of these heavy bursts of snow in southeastern NE tonight.

Being towards the western edge, Berkshire County will miss the worst of this storm. In fact, the storm appears to be moving a little faster and will move slightly to the east of yesterday’s projected track. Therefore, the only changes I would make to the forecast is to subtract a couple of inches from the snowfall totals and to have the snowfall end earlier on Saturday. Snowfall totals should be in the 10-16″ range for most of the county, with northern and western locations closer to 10″ and southern and eastern locations closer to 16″. I still think that the elevated terrain and hilltowns to the east could receive up to 2 feet, with even more in a few “favored” spots. This is particularly likely to occur in the southeastern hilltowns (e.g. Otis, Becket).

The steady snow has begun across most of the county (as of 2 pm). The intensity of the snowfall should gradually increase from south to north this afternoon, I still think we will have 3-6″ (3 to the north, 6 to the south) by early evening, and become heavy at times this evening. The snowfall should reach peak intensity late evening to near midnight with snowfall rates of 1″ per hour at times.  It is already fairly windy, with east-northeasterly winds gusting to near 30 mph (at BCC weather station) and these winds will continue to increase, with gusts near 40 mph overnight. Temperatures have begun to drop with the steady snow, and will continue to drop into the teens this evening, with windchills below zero at times. As a result, blizzard, or near blizzard conditions may occur late this evening, making travel, or even lingering (malingering?) outdoors, dangerous.

I do not see much in the way of banding features in the radar so I think the snowfall should remain steady across the county for most of the duration of the event. The snowfall should begin to diminish after midnight and it appears that most of the accumulating snow should have ended by 4-6 am, with only light snow lingering into the morning hours. Snow should end by late morning and it now looks like skies will clear in the afternoon, although it will remain windy and cold. Sunday looks like a beautiful winter day to get out and enjoy the snowfall (if you are so inclined) as surface high pressure crests over the region with plenty of sunshine, much lighter winds and temperatures rising into the 20s in most locations.

Friday Night

Snow, heavy at times this evening. Windy and quite cold. Blizzard, or near blizzard conditions at times, with markedly reduced visibility and dangerous travel conditions, particularly over the elevated terrain. Snowfall rates in some locations 1-2″ per hour at times. Snowfall rates will likely peak during the late evening to near midnight and then begin to diminish after midnight, becoming light by morning. Probability of precipitation 100%.

Temperatures will fall to the low teens by morning, upper single digits in the elevated terrain. Windchill temperatures in the single digits below zero.

Northeasterly winds in the early evening shifting to northerly in the late evening and then north-northwesterly after midnight. Wind speeds of 15-20 mph, 20-25 mph over the elevated terrain with wind gusts 30-40 mph.

Saturday

Light snow likely in the early morning, ending over the course of the morning, persisting the longest along the western slopes (upslope). Clearing during the early afternoon. Becoming mostly sunny by mid-afternoon. Remaining windy and cold. Probability of precipitation 60%. Storm snowfall totals as stated in the “summary” above.

Temperatures will not rise much, only reaching the mid teens in most locations, upper teens in Great Barrington and Sheffield and near 10 to low teens over the elevated terrain and hilltowns. Windchill temperatures in the single digits below zero at times.

North-northwest winds becoming northwesterly in the afternoon at 15-20 mph, 20-25 mph over the elevated terrain, with gusts 30-40 mph.

Saturday Night

Clear and very cold.

With clear skies and a deep, fresh snow cover, if winds were calm we would have ideal radiational cooling conditions and temperatures would likely plummet to well below zero. However, it should remain breezy until well after midnight. It will still be quite cold, with low temperatures near zero in most locations. It may reach the single digits below zero in locations sheltered from the wind over the elevated terrain.

North-northwest winds at 10-20 mph in the evening, diminishing to 5-10 mph after midnight.

Sunday

Scattered, thin, mid and high level clouds will occasionally dim the sun. Otherwise, mostly sunny (you can call it partly cloudy if you want) and milder.

High temperatures in the low to mid 20s in Pittsfield, mid 20s in Adams, North Adams and Williamstown, mid to upper 20s in Great Barrington and Sheffield, and upper teens to low 20s over the elevated terrain and hilltowns (depending on elevation).

Northwest winds at 5-10 mph in the morning, becoming light and variable in the afternoon.

Summary: Its pretty much just watch and wait at this point……

I have increased my estimated snowfall totals somewhat as the trend in the track of the coastal surface low in the models is a little closer to the coast than it looked yesterday. It now appears that the low will be centered right over Cape Cod early Saturday morning which is an ideal location for us to receive heavy snowfall.

Most of the county should receive in the 12-18″ range by the time the storm winds down Saturday morning. There will be a bit of a southeast to northwest bias with this storm so that northwestern parts of the county are more likely to get the lower amounts within that range and southeastern portions in the higher end of that range. However, as with all of these rapidly developing coastal storms, there will likely be great variability in the intensity of the snow between locations as there is frequently “banding” in the precipitation shield. Therefore, it is still possible that Williamstown could get 18″ while Great Barrington gets 12″. The elevated terrain and hilltowns to the east will likely get 18-24″ and a few favored east facing slopes could receive more than 2 feet.

The timeline for the storm looks similar to yesterday except it now appears that things will progress a little more slowly….

Intermittent light snow or snow showers should develop in the early morning hours, near daybreak, with the snow remaining light and intermittent throughout the morning. Accumulations should not be more than 1-2″ by noon. The snow will become steadier and more moderate during the afternoon, and even heavy at times late. Accumulations will likely be in the 3-6″ range by 6 or 7 pm. A gravity wave may develop tomorrow afternoon as the coastal low develops rapidly. This would result in a burst of heavy snow followed by a few hours of very light snow but these features are not forecast by the models so we will just have to watch the radar tomorrow to see if that occurs. If so, snowfall totals will be less than 3-6″ by evening. The snow will likely become quite heavy as the evening progresses and continue heavy at times past midnight. Depending on where the heavy precipitation bands set up snowfall rates could be as much as 1-3″ per hour at times. Winds will also be brisk out of the north-northeast so visibility will become quite poor and temperatures will begin to drop, with very low wind chill temperatures. Conditions could even meet “blizzard” criteria at times (visibility less than 1/4 mile with wind gusts to 35 mph and temperatures in the teens or below), particularly over the elevated terrain. Travel will likely become quite dangerous and is not advisable unless absolutely necessary. The snow will decrease in intensity toward morning but will remain steady until it winds down sometime during Saturday morning. It will remain windy and quite cold on Saturday, with snow continuing in eastern New England.

I plan to update this forecast again tomorrow afternoon. I may add a brief update late tonight if I see any significant changes as new information comes in…..

Thursday Night

Mostly cloudy. Becoming overcast toward morning with a good chance of a little light snow or a snow shower developing near daybreak. Probability of precipitation 50%. No accumulation expected.

Low temperatures in the mid to upper teens.

Easterly winds at 5-10 mph, increasing to 10-15 mph by morning.

Friday

Intermittent light snow in the morning, becoming steadier and more moderate during the afternoon. Snow may become heavy at times toward evening. If a gravity wave develops, there could be a pause in the precipitation for a few hours. Probability of precipitation 100%. Accumulations no more than 1-2″ by noon, around 3-6″ by evening.

High temperatures should occur in the early afternoon, rising into the mid 20s in Pittsfield, mid to upper 20s in Adams, North Adams and Williamstown, upper 20s in Great Barrington and Sheffield, and near 20 to low 20s over the elevated terrain and hilltowns. Temperatures will begin to drop in the afternoon as the steady snow develops, dropping into the upper teens in most locations, except low to mid teens in the elevated terrain and low 20s in Great Barrington and Sheffield by dark. Wind chill temperatures falling into the single digits, to near zero later in the afternoon.

Northeast winds at 10-15 mph in the morning, increasing to 15-20 mph, 20-25 over the elevated terrain during the afternoon. Gusts over 30 mph are likely.

Friday Night

Snow, heavy at times. Windy and quite cold. Blizzard conditions at times, with markedly reduced visibility and dangerous travel conditions, particularly over the elevated terrain. Snowfall rates in some locations 1-3″ per hour at times. Snowfall rates will likely peak during the late evening and early morning hours and then diminish toward morning. Probability of precipitation 100%.

Temperatures will fall to near 10 by morning, single digits in the elevated terrain. Windchill temperatures in the single digits below zero.

Northeasterly winds in the early evening shifting to northerly in the late evening and then north-northwesterly by morning. Wind speeds of 15-20 mph, 20-25 mph over the elevated terrain with wind gusts 30-40 mph.

Saturday

Steady snow likely ending by noon, remaining mostly cloudy with snow showers during the afternoon. Probability of precipitation 80%. Storm snowfall totals as in the “summary” above. Windy and cold.

Temperatures will not rise much, only reaching the mid teens in most locations, low teens over the elevated terrain. Windchill temperatures in the single digits below zero at times.

North-northwesterly winds becoming northwesterly in the afternoon at 15-20 mph, 20-25 mph over the elevated terrain, with gusts 30-40 mph.

I will give a synopsis of what I expect from Friday’s storm today and give a more complete forecast tomorrow….

So you don’t hold your breath through all the scientific mumbo jumbo, it looks like Berkshire County will get at least 8-12″ of snow and as much as 2 feet in the east facing slopes of the elevated terrain (watch out Savoy, Windsor, Peru, Otis and Becket) beginning early Friday morning, probably near daybreak, and winding down sometime early Saturday morning. Because of the strong northeast winds associated with this storm I think there may be some “downsloping” effect so that western portions of the county should get less than the elevated eastern terrain.

There will be two disturbances in the jet stream, one in the northern, polar front branch and one in the southern, subtropical branch which will merge over the Mid-Atlantic coast Friday and Friday night to create prodigious upward motion in the atmosphere and generate deep surface low pressure just off the coast. In addition, the southern disturbance will bring large amounts of moisture (water vapor) to the storm off the Gulf of Mexico and Gulf Stream. There will also be considerable environmental instability due to the warm Gulf Stream at the surface and cold air moving in aloft associated with the northern branch disturbance. There will also be a strong, cold anticyclone (surface high pressure) over eastern Canada. This will serve to increase the pressure gradient between the high and low so that northeast winds will become quite strong. It will also provide a plentiful supply of cold air near the surface so the precipitation should stay snow in most locations in New England. These are all the ingredients necessary for a very strong “Nor’easter”. Of course, this is based upon the presumption that all of these ingredients will come together at just the right time. With the coastal storm still 48 hours away there is still some uncertainty, however, I have a fairly high confidence level given the trends in the models, that this will be a big storm for New England. In particular, the European model (ECMWF), which has done the best with these coastal storms, has been consistent with its solution of a very deep coastal surface low located just off the east coast. The other models are now beginning to coalesce around this same solution. Snowfall totals could even be historic, between 2 and 3 feet in some portions of eastern New England, particularly in southeastern areas. There may be a mixture of precipitation types in the immediate coastal areas, but most places should stay all snow.

The timeline will look something like this…..A weak surface low pressure system will develop along the North Carolina coast in response to the southern jet stream disturbance while a weak surface low forming in response to the northern disturbance moves eastward across the Midwest in the early morning hours of Friday. It appears that the snow should begin in Berkshire County sometime near daybreak Friday but should be light through the morning hours. I expect only on the order of 1-3″ by early afternoon Friday. During Friday afternoon the jet stream disturbances will begin to merge and the coastal low will take over and intensify rapidly as it moves north-northeast up the coast, centered east of the Del Marva Peninsula during the afternoon and just south of Cape Cod Friday evening. The snow should become moderate to heavy as Friday afternoon wears on. By dinnertime my best guess is that most places will have accumulated in the 6-10″ range. The heaviest snow should be late Friday afternoon through Friday evening. The snow should begin to lessen sometime after midnight on Friday and end sometime Saturday morning as the surface low drifts eastward off the coast.

My best “guess” at this point (believe me, it is still a guess this early with a complicated coastal storm) is that total accumulations will be between 8-16″ for most locations, with 1-2 feet in the elevated terrain to the east. It is likely that there will be some “jackpot” locations (you know who you are) that will receive over 2 feet.

I will update this forecast tomorrow afternoon…