DAYS 1-5 (DECEMBER 3-7)
A westerly air flow aloft and high pressure south of New England combine for a very nice early December day today with relatively mild air and plenty of sun, but some high cloudiness will make an appearance in the sky only to increase the chances of a photogenic sunset in the 4 p.m. hour. 🙂 Tonight, more of those high clouds will steam in ahead of an approaching trough and cold front, which will bring even more cloudiness on Friday. Previously, I thought that some rain showers may accompany the passage of this front during the day on Friday but right now it looks like the front will come through dry, but moisture streaming northeastward ahead of our weekend storm threat may mean that some rainfall arrives by the end of the day or Friday evening, shortly after the front has gone by the area. And now onto the storm threat for the weekend – something we’ve been eyeing with great uncertainty for days. I wish I had a clearer picture of how this will unfold for today’s update, given that it’s not that far away, but there are still some questions to be answered. It does look like we’ll be looking at a system that impacts us throughout the day Saturday, making an exit Sunday. It will be a system that starts as rain through the entire WHW forecast area (southern NH, central and eastern MA, eastern CT, & RI). But there is going to be cold air available just to the northwest, as well as aloft, and we’re very likely to end up with a rain/snow line as this system moves through. The big question is how quickly and how far south and east does this rain/snow line get. I can say that the greatest threat for accumulating snow will be across interior southern NH and central MA based on current information, and the least of the threat will be across the South Coast and Cape Cod. But what happens between these areas? Further refining of this forecast is obviously needed, but my initial feeling is that these areas will at least mix with if not turn to snow at some point Saturday night or early Sunday, before precipitation departs, with some accumulation possible… Other impacts of the system not to be forgotten will be some strong wind and coastal flooding potential. More on that in the next update. Regardless of the details of the storm, behind it comes a period of windy and colder weather with a few lingering snow showers possible Sunday afternoon, and continued breezy and chilly but mainly dry weather Monday, with just a possibility of a few snow flurries migrating southeastward from the hills and mountains to the northwest.
TODAY: Mostly sunny. Highs 47-54. Wind W to SW 5-15 MPH.
TONIGHT: Increasing high clouds. Lows 35-42. Wind SW 5-15 MPH.
FRIDAY: Thickening high to middle overcast. Light rain possible by late-day mainly southwest of Boston. Highs 45-52. Wind SW up to 10 MPH shifting to NW.
FRIDAY NIGHT: Cloudy. Periods of rain. Lows 38-45. Wind N to NE up to 10 MPH.
SATURDAY: Overcast. Rain likely, with some mix/snow possible higher elevations of southwestern NH and north central MA by later in the day. Temperatures steady 38-45 then slowly falling. Wind NE 5-15 MPH inland and 15-25 MPH coastal areas with higher gusts especially in coastal areas and higher elevations.
SATURDAY NIGHT: Overcast. Rain southeast, rain/mix I-95 corridor, mix/snow to the northwest with accumulation possible. Lows 28-35 except 35-42 South Coast. Wind NE to N 15-25 MPH, higher gusts.
SUNDAY: Overcast with rain/mix/snow ending from west to east early – additional snow accumulation possible I-95 belt north and west. Becoming partly sunny with a few lingering snow showers thereafter. Temperatures generally steady mainly in the 30s. Wind N to NW 15-25 MPH, higher gusts.
SUNDAY NIGHT: Partly cloudy. Chance of passing snow flurries. Lows 18-25. Wind NW 15-25 MPH, higher gusts possible.
MONDAY: Partly sunny. Chance of passing snow flurries. Highs 30-37. Wind W 10-20 MPH, higher gusts possible.
DAYS 6-10 (DECEMBER 8-12)
Keeping an eye on a possible offshore storm December 8 – should stay offshore with dry/chilly weather here. Fair, cold start then a little milder December 9. Disturbance from the northwest brings a rain and/or snow shower risk December 10 then a shot of colder air with dry weather through December 11. Next jet stream disturbance may threaten the region with rain/mix/snow by the end of the period.
DAYS 11-15 (DECEMBER 13-17)
Precipitation threats early and again late in the period. Obviously with recent model performance and typical uncertainty this far in advance anyway, can’t elaborate on much at this point. Temperatures near to below normal.