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.