Summary: As the coastal storm deepens rapidly (central pressure of 965 mb!) and departs for the Canadian Maritime this afternoon, the pressure gradient between the intensifying surface low and approaching surface high pressure from southern Canada and the Great Lakes has also intensified. As a result, west-northwest winds have become strong and gusty (39 mph gust at the BCC weather station). The winds are driving very cold air for this late in the winter quite far south as the trough in the jet stream pattern has dipped all the way to the southeastern states. Temperatures dropped into the mid 20s in northern Florida this morning and are only in the 50s throughout Florida (even Miami) this afternoon.

As the trough becomes centered over us tonight, it will become quite frigid, despite the strong winds. If winds were calm, temperatures would drop well below zero tonight. As it is, with temperatures in the single digits and winds of 15-25 mph, wind chill temperatures will drop to -10 to -20 at times so if you have to go out, watch for exposed skin. On Monday, there will be plentiful sunshine but there will still be a gusty wind so it will still feel quite cold.

Monday night through Tuesday evening, the deep trough in the jet stream pattern will final lift out and a weak ridge will briefly build in. This will be followed by another trough which will not be quite as deep and so, even though it will turn colder for mid-week it will not be as frigid as our present conditions. As this next trough approaches, it is generating a surface low pressure system along its eastern edge (surface low pressure [storms]in middle latitudes are almost always in this location in the jet stream wave pattern). This low pressure system will track through the Great Lakes and drag its warm front across our region Monday night followed by its cold front Tuesday afternoon and evening. The warm front will likely come through dry, with nothing more than some cloudiness.

It will then get milder on Tuesday as we move into the “warm sector” of the Great Lakes storm system and aside from some thin mid and high-level clouds we will see a fair amount of sunshine through early afternoon. Temperatures will likely reach 40 degrees in the lower elevations and the mid to upper 30s in the elevated terrain. The cold front will move through from late afternoon into the evening with a fairly solid band of precipitation. Precipitation type is a bit of a tough call right now. It will be cold enough aloft to support snowfall. Therefore, I think that even though it may start as a little rain or mixed rain and snow in the elevated terrain and hilltowns, those areas will receive predominantly snowfall with 1-3″ of wet snow accumulating. In the lower elevations (all of the large towns and “cities”) it will be too warm at low-levels to support snow initially so rain or mixed rain and snow will likely fall for an hour or two before it turns to all snow. In these locations only a dusting to 1″ of wet snow will likely fall.

Sunday Night

Partly cloudy this evening, becoming clear after midnight, windy and very cold.

Temperatures will fall into the low to mid single digits in most locations, near zero over the elevated terrain. Wind chill temperatures as low as -10 to -20 at times.

West-northwest winds at 15-30 mph, with the strongest winds within this range over the elevated terrain, with occasional gusts over 40 mph.

Monday

Abundant sunshine but still windy and cold.

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

West-northwest winds at 15-25 mph through early afternoon, with occasional gusts to 35 mph, diminishing somewhat later in the afternoon.

Monday Night

Except for a period of cloudiness as the warm front passes through near midnight, it will be mostly clear.

It will not be nearly as cold as Sunday night. Low temperatures will occur before midnight and will likely be in the mid to upper teens in most locations, with some low teens over the elevated terrain. Temperatures will begin to rise after midnight (warm frontal passage) and reach the low to mid 20s by morning.

West-northwest winds at 5-10 mph in the evening, becoming light and shifting to south-southwesterly near midnight. Southerly winds after midnight will increase to 8-12 mph by morning.

Tuesday

Mostly sunny early, then increasing mid and high-level clouds from mid-morning through early afternoon. Becoming overcast with a period of precipitation between mid-afternoon and early evening. As discussed in the summary, this will be mostly wet snow in the elevated terrain and hilltowns although it may start as a little rain or rain and snow mixed. The rain or rain/snow mixture will last longer in the lower elevations (possibly an hour or two) before it changes to wet snow. Probability of precipitation 80%. Most likely snowfall accumulations a dusting to 1″ in the lower elevations with 1-3″ in the elevated terrain and hilltowns.

It will be much milder, with high temperatures near 40 in Pittsfield, Adams, North Adams and Williamstown, low 40s in Great Barrington and Sheffield, and mid to upper 30s over the elevated terrain and hilltowns (depending on elevation).

South-southeasterly winds at 10-15 mph.