A very interesting set-up, coming out of unseasonable warmth to the threat of significant snow (for some areas) on what is essentially and somewhat arguably the busiest travel day of the year (Wednesday). You’re going to either hear or take part in great analysis over the next 24-36 hours so I’m going to take the streamlined route in the discussion here and expand upon it with you all in the comments.
First, today, another very mild day by November standards, though sun will be limited for a while due to lots of high cloudiness streaming northward, it should shine brighter a little later as clouds thin out. But these clouds will thicken back up tonight in advance of a low pressure area developing along a frontal boundary just offshore. This system will be propelled northeastward rather rapidly. With departing warm and moist air to feed the system, and arriving cold air to set up contrast, we have a short-lived by volatile set-up, complicated further by the fact that its passage by southeastern New England will take place on the eve of Thanksgiving, presenting all kinds of complexities regarding both air and road travel. As for the storm itself, it will be moving very rapidly, arriving precipitation-wise during the morning and midday and departing by around midnight. It’s what happens in that 12+ hour period that is critical. We know that it should start as rain in most areas except probably mix to immediate snow in higher elevations of central MA. And in this area it will remain generally snow, where it is likely that the most will fall, which is over 6 inches of snow. This will likely include the tricky I-90/I-84 area which is elevated, and congested on a dry weekend day outside of the holidays at times. Potential for major traffic nightmare here. It’s also quite likely that the immediate coast and down across southeastern MA, coastal RI, and Cape Cod and the Islands will remain as mostly rain, possibly mixing later in the storm as steadiest precipitation is ready to depart. It’s the whole middle section, from Boston through Metro West down into RI and up into southeastern NH and interior northeastern MA that is the most tricky. The most reliable guidance suggest marginal temperatures for the majority of the event, which means at any given time it can be raining, snowing, or both. A cop out? Not at all. It’s that marginal. We’ll just have to see how the event unfolds. There is the potential for some heavier banding features associated with the storm during its passage which would tilt the balance more toward snow where they set up. So the forecast amounts are highly subject to change in this belt. See below for those amounts…
Once the storm gets out of here, and that will happen fairly rapidly from southwest to northeast in the later evening of Wednesday. By Thanksgiving morning, it’s gone, and that day itself is going to feature a gusty breeze, lots of clouds, intervals of sun, and a few spotty snow showers with some lingering low level moisture, at least through midday.
Friday looks fair, breezy, and cold as high pressure moves in. Saturday will feature increasing clouds as a warm front approaches, and this front may produce a touch of light snow Saturday night (uncertain depending on movement of its associated disturbance and available moisture). For now it looks like a cold front will follow this up later Sunday, allowing Sunday to be milder ahead of the front. Again, timing is a little uncertain this far out. The front may still be in the vicinity Monday which may keep clouds and some threat of precipitation in the region. Plenty of time to look at that.
SOUTHEASTERN NEW ENGLAND FORECAST…
TODAY: Limited sun with lots of high clouds morning. More sun with less high clouds this afternoon. Highs in the 60s through midday cooling into the 50s this afternoon. Wind W 5-15 MPH.
TONIGHT: Increasing clouds. Lows upper 30s to middle 40s from southern NH to Cape Cod. Wind light W.
WEDNESDAY: Overcast. Rain develops south to north morning-midday, except mix/snow in highest elevations well west and northwest of Boston. Rain/snow line moves slowly eastward but mix/snow may also develop spontaneously closer to I-95 later in the day. Temperatures cooling through 30s northwest of Boston, from lower 40s into 30s Boston southeastward. Wind NE to N 10-20 MPH with higher gusts.
WEDNESDAY NIGHT: Cloudy. Snow northwest of Boston, mix or snow immediate Boston area southward to interior RI, mix or rain interior southeastern MA and coastal RI, and mostly rain coastal southeastern MA to Cape Cod, all ending from southwest to northeast by or shortly after midnight. Snow accumulation 6 inches or more in higher elevations central MA into southwestern NH, 3-6 inches most other interior locations west of the I-95 belt but also into interior RI with the potential for spotty higher amounts, 1-3 inches on the east side of the I-95 belt ranging down to little or nothing in coastal locations. Lows upper 20s higher elevations well inland to middle 30s Cape Cod. Wind N 10-20 MPH, higher gusts especially coastal areas.
THURSDAY – THANKSGIVING: Lots of clouds, intervals of sun. Spotty light snow showers through midday. Highs upper 30s to lower 40s. Wind NW 10-20 MPH, higher gusts.
FRIDAY: Mostly sunny. Low 25. High 35.
SATURDAY: Increasing clouds. Touch of light snow at night? Low 20. High 40.
SUNDAY: Partly cloudy. Low 30. High 50.
MONDAY: Variably cloudy. Chance of rain/snow showers. Low 35. High 45.