AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 416 AM EST Sun Dec 14 2025 .SYNOPSIS... Fast moving low pressure will bring accumulating snow to the region into midday especially south of the Massachusetts turnpike. The snow will linger into the afternoon across Rhode Island and especially across far eastern Massachusetts where it may persist into this evening. A brief shot of arctic air follows tonight into Monday, with wind chill values dropping to between 0 to 10 below zero. Cold weather continues Monday night into Tuesday but with much lighter winds. A warming trend begins Wednesday and especially by Thursday when high temperatures of 50+ are possible. Unseasonably mild temperatures will be accompanied by a round of showers sometime later Thursday into early Friday with perhaps a period of strong southerly winds and heavy rain. A brief shot of much colder weather with another period of strong winds possible later Friday into Saturday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Key Messages... * Accumulating snow ends by lunchtime across western MA/CT, but persists into the afternoon especially across eastern MA * Hourly snowfall rates generally on the lighter side...but brief bursts of moderate snow possible near the south coast Trend in high res guidance has been to shift the timing of the end of the steadiest snow from mid morning to the afternoon for much of Rhode Island and Eastern Massachusetts. Model guidance, namely the HRRR and NAM3km have also begun to resolve an inverted trough and wrap around ocean effect snow extending from low pressure as it pulls away. Trough will be a good focus for vertical motion and moisture as omega increases to -10 to -15 ubar/sec. Sharply colder air filtering behind departing low pressure will introduce non-zero MLCAPE values which could help with ocean enhancement of any snowbands. Despite these favorable parameters, daytime will likely be limited by marginal sfc temps in the mid and even upper 30s. Temps may be locally lower under any ocean effect bands but its really going to take considerable rates to cool the PBL from the influence of 45-47F water temps. As a result, still think that advisory level snow totals 2-4" for RI/SE MA with localized 5-6" amounts possible near the south coast and Cape Cod. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... Key Messages... * Very cold with wind chill values near or below zero * Windy conditions with gusts up to 40 mph Sunday Night and Monday The coldest airmass of the season thus far will move in behind the snow for Sunday night as 850mb temps crash into the -15C to -20C range. This will result in overnight low temperatures bottoming out in the single digits across the interior, to the low teens near the coastal plain. A strong pressure gradient will result in gusty winds overnight, around 25-40 mph. This will bring the windchill index/feels-like temperatures down to the 0F to -5F range, with -5F to -15F in the high terrain. MONDAY High pressure helps to keep an Arctic air mass in place through the day on Monday as GFS and Euro ensembles keep temperature anomalies near 10 degrees colder than normal. Other story Monday will be a steep pressure gradient keeping a stiff NW wind in place for the region. Wind gusts between 25 and 35 mph will make high temperatures in the teens (at higher elevations) and 20s elsewhere feel more like the single digits to lower teens at their warmest. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Key Messages... * A few brief snow showers possible Mon night, otherwise diminishing winds with low temps mainly in the teens * Dry & chilly Tue...Highs mainly in the lower to middle 30s * Turning milder Wed with continued dry weather & highs into the 40s * Showers with heavy rain & potential briefly strong southerly wind gusts later Thu into early Fri with unseasonably mild temps * Brief shot of much colder temps returns behind the front later Fri into Sat with another round of strong winds possible Details... Monday night into Tuesday... A weak shortwave may bring a few brief snow showers to the region Monday night. Otherwise...still chilly Mon night into Tue but with light winds. Low temperatures Mon night will mainly be in the teens. Highs on Tue will range from the upper 20s in the highest terrain to mainly the lower to middle 30s elsewhere. Wednesday... The developing -PNA and high pressure to our south sliding further east will allow for the beginning of a pattern change and milder temperatures. While it will remain dry on Wed, gusty southwest winds developing will push high temperatures well into the 40s. Thursday into Friday morning... Strong shortwave energy over the northern plains will move eastward into the Great Lakes. As this happens...strong surface low pressure perhaps sub 980 mb will pass well to our north across Quebec. Given the potential strength of the surface low pressure system...the long range guidance is indicating a strong southerly LLJ nearly 3 standard deviations outside climatology. Not only will this bring up unseasonably mild temperatures and Pwats exceeding 1 inch. This will combined with strong forcing ahead of the cold front and bring showers with perhaps brief heavy rain sometime later Thu into Fri. In addition...given the magnitude of the southerly LLJ we will have to watch for a brief period for strong surface wind gusts if the inversion is able to mix out. It is way too early to assess that...but depending on the timing temperatures may rise well into the 50s Thu night/early Fri and may even flirt with 60 degrees. If we are able to get mild enough...the potential for a period of strong winds to be realized will increase. Again...way too early to say much more than that but something to watch in the coming days. Later Friday into Saturday... Briefly turning much colder later Friday into Saturday behind the cold front. Mainly dry weather expected, but another period of strong winds this time from the west is possible immediately behind the cold front. && .AVIATION /09Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 06Z Update Today...Moderate Confidence Expecting snow to end between 15/16z and 16/18z from northwest to southeast, but lingers to around 00z towards the southeast New England coast. Otherwise, improvement to VFR conditions expected from W to E. Light SW winds tonight shift to the NW at 5 to 10 kt then 15-25 kt after 21z. Could see some gusts up to 30 kt for the evening push. Tonight...High Confidence VFR outside the the outer-Cape/Nantucket where ocean effect snow showers may persist Sunday evening. This activity should dissipate though after midnight. Otherwise, NW wind gusts of 20 to 25 knots with a few gusts near 30 knots across the high terrain and near the coast develop Sunday night. Monday...High Confidence Mainly VFR with NW gusts of 30-35 knots. A few CU but should be above MVFR ceilings. KBOS Terminal... High confidence in trends. Moderate confidence in timing. Snow continues through much of the day with wrap-around snow showers possibly continuing as late as 21-00z. NW winds increase to 10-15 kt w/ gusts up to 30 kt after 21z. Total snow accumulations of 1-3". KBDL Terminal...Moderate confidence in TAF. Snow ends after 18z w/ NW winds increasing to 10-15 kt w/ gusts up to 25 kts after 20z. Total snow accumulations of 1-3" Outlook /Monday Night through Thursday/... Monday Night: VFR. Breezy. Slight chance SHSN. Tuesday: VFR. Tuesday Night: VFR. Breezy. Wednesday: VFR. Windy with areas of gusts up to 30 kt. Wednesday Night through Thursday: VFR. Breezy. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Today Through Monday Night ...High confidence. Light N/NW winds through the early afternoon. Winds quickly increase to gales around 21z and gales continue through 20z Monday. Strong cold advection allows for ample mixing resulting in wind gusts between 35-40kts Sunday evening through Monday afternoon. Areas of very light freezing spray possible 00z Monday - 19z Monday. Elsewhere, small craft advisory conditions expected in Narragansett Bay and Boston Harbor. Outlook /Monday Night through Thursday/... Monday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Slight chance of snow showers. 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: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Thursday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Winter Weather Advisory until 7 PM EST this evening for MAZ017>024. RI...Winter Weather Advisory until 7 PM EST this evening for RIZ001>008. MARINE...Small Craft Advisory from 4 PM this afternoon to 3 PM EST Monday for ANZ230-236. Gale Warning from 7 PM this evening to 1 PM EST Monday for ANZ231>235-237-250-251-254>256. && $$