This is an update on the previous entry, adjustments needed for this update include an increase in the wind forecast for today and tonight, and a posting of forecast snowfall amounts for Monday night & Tuesday. Otherwise, there are no major changes, and this will all be updated again this evening with the posting of The Week Ahead.
Today / Tonight … The transition from very mild air (for January), with temperatures probably reaching 50 during the day, to arctic cold, with temperatures falling into the teens overnight. This will be announced by big winds (gusting as high as 45 to 50 MPH) shifting from WSW to WNW (not a huge shift but you’ll notice a huge difference in temperature between noon today and midnight tonight – up to a 30-degree drop and even a few more by the time the lows are reached early Monday morning. With a line of snow squalls moving into Vermont early this morning, including thunder, one would think we’d be seeing a heavy shower or thunderstorm (rain due to the mild air) ahead of this front some time today, but that activity is likely to weaken considerably and only a few showers may survive the trip across southern NH and eastern MA early or mid afternoon. There is even a more remote chance of an isolated snow shower coming along with a secondary trough line that has to push through here early this evening around the time of the kick off of the NFL AFC Championship game between the New England Patriots and Baltimore Ravens at Foxboro MA. Expect the temperature to be in the middle 40s during the afternoon tailgate, dropping to the middle 30s by kick off time, and the upper or even middle 20s by the end of the game. The big story will be the strong westerly winds which will gust beyond 40 MPH, playing havoc with tailgate activities (beware of flying paper and plastic cups and plates and maybe a few burger rolls!). The wind will also likely have an impact on the game itself as it swirls around the stadium.
Monday / Tuesday … The winds will have dropped off by Monday but the cold air will be in, not yet in full force (see Wednesday / Thursday), but enough that you will sure notice a big difference from what we had this weekend. Of more importance is a disturbance coming out of the Great Lakes region that is going to transfer its energy to a new low pressure area just south of New England, which will then strengthen as it tracks northeastward into the waters just east of New England. Even though this low track is close enough to throw snow into the region, in most cases it would be a light snowfall, but there are 3 things working to enhance the snowfall in some locations, especially closer to the eastern coastal areas of NH & MA and probably the southern coastal areas of MA & RI. These are 1) very cold temperatures which will lead to snow to water ratios on the order of 20 or more to 1, allowing very fluffy snow to pile up easily, 2) ocean enhancement where wind comes off the ocean water and picks up additional moisture (this would be most likely on the outer part of Cape Ann and across Cape Cod in areas exposed to a northerly wind), and 3) an inverted trough, or Norlun trough setup, in which an elongated or stretched out low pressure trough extends back from the main low pressure area, in this case into southeastern New England, and results in added convergence or instability in the atmosphere. NOTE that the forecast snowfall amounts below are trickier than usual with these factors in place, and can potentially bust quite easily, so please check back in the comments section below as the day and evening goes on for any changes before the full update later tonight. For the timing of the snow, though flakes may begin in some areas late Monday afternoon, the majority of the snow will fall late Monday night into Tuesday morning before tapering off in the afternoon and pulling away to the southeast.
Wednesday / Thursday … Still looking at a pure arctic outbreak, the coldest in 2 years. Not expecting any big record low temperatures though. A weak upper level disturbance may bring some clouds later Wednesday to early Thursday but dry weather is expected.
Friday / Saturday … Not a whole lot to add yet about the winter storm potential here. Starting to see hints that it may be a double-barrel system with a shot of snow Friday with one wave of low pressure, and another low moving up the coast or just offshore on Saturday, being a secondary hit or a close call. It’s still far away, so all I can say still is that there is the potential for another significant snowfall.
Updated forecast for eastern MA, southern NH, and RI…
TODAY: Sunshine & high clouds this morning. Variably cloudy this afternoon with a slight chance of a passing rain shower. Highs around 50. Wind WSW to W 15-30 MPH with gusts 40-50 MPH.
TONIGHT: Variably cloudy with a very slight chance of a passing snow shower early. Partly to mostly clear later. Lows 14-19. Wind W to WNW 15-30 MPH gusting over 40 MPH early, shifting to NW then slowly diminishing later.
MONDAY – MLK JR DAY: Increasing clouds. A few light snow showers possible late. Highs 24-49. Wind light variable, mostly N to NNE under 10 MPH.
MONDAY NIGHT: Overcast. Widespread snow developing, with embedded heavier snow showers developing overnight especially coastal NH and eastern MA including Cape Cod. Lows 13-18. Wind NE to N 5-15 MPH.
TUESDAY: Overcast with snow and snow showers in the morning, with a few areas bands of heavier snow very possible especially coastal NH and eastern MA – accumulation a general 2 to 6 inches in areas without enhancement and 6 to 12 inches in areas that see enhanced snowfall. Mostly cloudy with any snow and snow showers ending northwest to southeast in the afternoon. Highs 18-23. Wind N to NW increasing to 10-20 MPH. Some blowing snow.
WEDNESDAY: AM sun / PM clouds. Low 0. High 15.
THURSDAY: AM clouds / PM sun. Low 3. High 20.
FRIDAY: Cloudy. Chance of snow. Low 10. High 25.
SATURDAY: Cloudy. Chance of snow. Low 18. High 28.