AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 407 PM EST Sun Dec 14 2025 .SYNOPSIS... A brief shot of arctic air follows a departing low pressure tonight into Monday, with wind chill values dropping to between 0 to 10 below. Cold weather continues Monday night into Tuesday but with much lighter winds. A warming trend in temperatures is expected Wednesday and especially by Thursday with high temperatures of 50+ possible. A round of rainfall is looking likely later Thursday into Friday accompanied by a period of strong southerly winds. A brief shot of much colder weather with another period of strong winds possible Friday into early Saturday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Key Messages... * Accumulating snow ends into this evening, confined mostly to southeast MA this afternoon. * Turning colder tonight. Lows in the single digits and teens. Minimum wind chill values between 0 to 10 below. A few locations towards NW MA could see wind chill values as low as 20 below. Accumulating snow had largely ended across most of RI and portions of southeast MA. As such, canceled a portion of the Winter Weather Advisory already. Will monitor the progress of the snowfall this afternoon, and perhaps cancel more of the remaining Advisory towards 4 PM. Otherwise, it will still expire at 7 PM this evening. As of this writing, the heaviest snow band extended from between the Vineyard and Nantucket northeast across the outer Cape. The outer Cape is where additional accumulating snow is possible. Still expecting snowfall to diminish from NW to SE this afternoon. Will continue the Winter Weather Advisories as they are for now. Will likely be able to cancel some of these advisories prior to the 7 PM expiration time. Once the snowfall ends, just turning colder with clearing skies and gusts WNW winds overnight. Considered a Cold Weather Advisory towards the Berkshires, but thinking the colder conditions will not be widespread enough to warrant a headline. This will need to be monitored this evening. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Key Messages... * Gusty WNW winds through Monday * Dry weather with below normal temperatures A sprawling high pressure over the central USA will maintain dry and cold conditions across southern New England into Monday night. Some sunshine to start the day, with increasing clouds during the afternoon. Mostly cloudy skies expected Monday night, but not much in the way of precipitation. There is a low chance for a stray snow shower from the Great Lakes to make it into the Berkshires Monday Night. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Key Messages... * Rain, potentially heavy at times, likely later Thursday into Friday. * Period of strong winds possible Friday into early Saturday. Details... Tuesday: Extended period will start off with continued below normal temperatures on Tuesday. 850mb temperatures aloft warm slightly as the mid-level pattern moderates a bit from Monday, this will likely bring highs in the upper 20s to mid 30s. Surface high pressure positioned to the south will support mainly dry conditions and light southwesterly winds. Wednesday through Friday: Wednesday into Thursday, there is a good consensus among ensemble guidance for a change in the pattern aloft. A more zonal pattern is favored for Wednesday and by Thursday higher heights advect into the region ahead of our next system. This will start a trend in warming temperatures as warmer temperatures aloft move in also accompanied by breezier southwest winds. High temperatures Thursday rise into the 40s for most areas. Thursday, a mid-level shortwave trough approaches with strong WAA ahead of it. A strong 850mb temperature anomaly overhead should support a mild day with high temperatures in the 40s to near 50 in spots. Models keep things dry despite the warm and moist advection through the day Thursday ahead of the approaching system. Can`t rule out a stray shower later in the day Thursday. Ensemble guidance favors the bulk of the system to move through sometime Thursday evening into Friday, although there are some timing differences among individual members. There will be a good amount of synoptic support for soaking rain event with a strong southerly LLJ transporting in a plume of above normal moisture (170- 220% of normal) combined with broad ascent & frontal forcing. This may also support a period of moderate to heavy rainfall. With plenty of WAA ahead of the system, this system will be simply rain for everyone. Ensembles generally show a range of 0.25 to 0.80" for rain amounts. Rain should decrease from west to east Friday AM to Friday afternoon with a cold front pushing in behind it. If the front moves through during the day, it may end up being a non-diurnal type day with the high temperatures occurring at in the morning (40s/50s), especially further west. Another concern with this system will be the potential for strong winds. The suite of deterministic and ensemble guidance has shown good agreement with a strong LLJ over the region. NAEFS and ECMWF EFI highlights this jet and potential gusts to be anomalously high. The LLJ orients generally SW to NE eventually shifting over southeast MA Friday night with 925mb winds 50-70 kts. The challenge will be the degree of mixing we will get under the inversion and what locations will have the higher potential. There is also second period favored gusty winds behind the cold front on Friday. We are still pretty far out, so details are still fuzzy. Models are still struggling with the timing of the system and cold front which will influence timing/magnitude of gusts. So for now, there is a signal worth monitoring for a period of stronger winds in the Thursday night to Friday timeframe. Trending colder behind the cold front Friday night and Saturday with temperatures returning to below normal. && .AVIATION /21Z SUNDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight...High Confidence MVFR-IFR and even brief LIFR conditions are expected in areas towards the Cape and Islands in ocean effect snow showers. This activity should dissipate just after midnight. Otherwise, WNW wind gusts of 20 to 25 knots with a few gusts near 30 knots across the high terrain and near the coast develop. Monday...High Confidence Mainly VFR with NW gusts up to 30 knots. A few fair-weather clouds early, but should be VFR. VFR CIGS developing during the afternoon. Monday Night...High Confidence. VFR CIGS. Lighter W winds. KBOS Terminal...High confidence in trends. Moderate confidence in timing. Little additional accumulation, although some very light snow possible before 21Z. KBDL Terminal...High confidence in TAF. Outlook /Tuesday through Friday/... Tuesday: VFR. Tuesday Night through Thursday: VFR. Breezy. Thursday Night: Mainly MVFR, with local IFR possible. Strong winds with local gusts up to 40 kt. RA likely. Friday: Mainly VFR, with local MVFR possible. Strong winds with local gusts up to 40 kt. RA likely. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through Monday Night...High confidence. Winds quickly increase to gales this evening as colder air arrives and continues into Monday. Expecting wind gusts between 35-40 kt later this evening into Monday afternoon. Areas of very light freezing spray possible tonight and Monday. Elsewhere, Small Craft Advisory conditions expected in Narragansett Bay and Boston Harbor. Outlook /Tuesday through Friday/... Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. Tuesday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Seas locally approaching 5 ft. Wednesday: Strong winds with gusts up to 30 kt. Areas of rough seas. Wednesday Night: Winds less than 25 kt. Areas of rough seas. Thursday: Winds less than 25 kt. Areas of seas approaching 5 ft. Thursday Night: Moderate risk for gale force winds with gusts up to 45 kt. Areas of rough seas. Rain likely. Friday: gale force winds with areas of gusts up to 45 kt. Rough seas up to 12 ft. Chance of rain. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Winter Weather Advisory until 7 PM EST this evening for MAZ022>024. RI...None. MARINE...Small Craft Advisory until 3 PM EST Monday for ANZ230-236. Gale Warning until 1 PM EST Monday for ANZ231>235-237-250-251- 254>256. Freezing Spray Advisory from 1 AM to 10 AM EST Monday for ANZ232>234. && $$