Area Forecast Discussion

373 FXUS61 KBOX 021800 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 100 PM EST Tue Dec 2 2025 .SYNOPSIS... A winter storm will bring accumulating snow across interior southern New England into tonight...particularly north of I-90 into the high terrain where precipitation remains mainly snow. Mainly rain is expected near I-95 and even for a time across the interior southern New England south of I-90...before a transition back to snow occurs later tonight. All precipitation should have come to an end by daybreak Wednesday. Beyond that high pressure brings dry weather to end the week except for a moisture starved front Thursday bringing a few snow showers. Arctic airmass bring well below normal temperatures Thursday night, Friday, and Friday night. && .NEAR TERM /THROUGH TONIGHT/... Key Messages... * Winter Storm continues tonight across interior southern New England especially north of I-90 and the high terrain * 1-2" per hour snowfall rates north of I-90 and especially near route 2 make for hazardous travel for the evening commute * Mid level warm layer moving northward will result in Ptype transitioning to a period of rain south of I-90 even across the interior through the mid to late afternoon hours * Narrow swath of sleet and freezing rain for a time into northern CT and possibly interior southern MA * Mainly rain along the I-95 corridor into RI that should transition to a period of snow before ending toward daybreak * Total snow accumulations of 6-10" in the highest terrain of northern MA...2-5" in the lower elevations of western/central MA...and mainly a dusting to 2" across CT/RI & eastern MA Details... This afternoon into tonight... Low pressure will be intensifying as it moves off the mid Atlantic coast and tracks just inside the Benchmark this afternoon into this evening. Thermal profiles are initially cold enough for mainly snow northwest of the I-84/I-495 interchange inland from the coastal front into mid afternoon. However...given the lack of cold high pressure across eastern Canada and the mid level centers tracking northwest of the Benchmark will allow warmer mid-level air to move northward. Therefore...an initial burst of snow through early afternoon will change to mainly rain south of I-90 by mid-late afternoon. A few inches of snow may occur in this region before the transition to rain across southwest/south central MA perhaps into far northern CT. There remains some uncertainty how far north this mid level warm layer will reach before stalling out...but we are thinking this will mainly stay south of the route 2 corridor and possibly not make it much further north than I-90. As the mid level low/s close off and result in strong mid level frontogenesis...we may see 1-2 per hour snowfall rates this afternoon into early evening where Ptype remains snow north of I-90 and especially towards route 2. This will result in significant impact to the evening commute north of I90 and especially near route 2 corridor. There also may be a narrow area of sleet and freezing rain on the edge of the mid level warmth...but should be fairly narrow swath. We did expand the Winter Weather Advisory into northern CT to account for this risk. We also may see that narrow band of sleet and freezing rain into interior parts of southern MA. Meanwhile...areas south of I-90 as well as along the I-95 should see moderate to heavy rain for the late day commute. As the mid level low/s shift east of the region...lingering moisture with temps cooling aloft should allow for many locations to transition to snow before things wind down before daybreak Wednesday. A coating to an inch of snow will be possible onto the I- 95 corridor with perhaps 2" into the lower elevations of interior eastern MA. Further northwest in the lower elevations of western/central MA...total accumulations of 2-5" seem reasonable. The highest snowfall amounts of 5-10" should be common across the northern Worcester Hills/Berks and as well as areas north of route 2. All in all...no changes planned to any of the headlines except for the expansion of the Winter Weather Advisory into northern CT. Lastly...gusty N winds will work into the region on the backside of the system later this evening and overnight. Gusts of 20-30 mph are expected overnight with some 35-40+ mph gusts possible across the outer- Cape/Nantucket. Low temps by daybreak will be in the 20s across the interior...with lower to middle 30s along the I-95 corridor and middle to upper 30s near the Cape and Islands. So not expecting many issues with roads along and southeast of I-95 corridor...but northwest of I-95 untreated roads will be slippery for the Wed am commute despite the precipitation having ended. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... Key Messages: * High pressure builds in following the exit of the coastal storm, leading to cooler, drier weather The low responsible for the active weather to start the week exits heading into Wednesday morning and high pressure moves in behind it. High temperatures are not expected to get higher than the low 40s and mid 30s for the region, with some spots in the higher elevations struggling to get above freezing. NW winds weaken and shift slightly more to the W and SW as the day progresses. && .LONG TERM /THURSDAY THROUGH MONDAY/... Key Messages: * Scattered snow showers possible Thursday. * Arctic airmass in place Thursday night-Saturday bringing well below normal temperatures. Details... After a brief period of weak high pressure, a shortwave trough moves through the region on Thursday accompanied by a strong cold front. The wave is fairly moisture starved with precipitable water values 0.4-0.6". There should be a brief window with some mid-level moisture advecting into the region. With the help of the approaching front, this will provide lift for a few snow showers during the day Thursday. Ensembles show low-moderate probabilities for light QPF amounts. With marginal instability present and approaching arctic front/airmass, global guidance also hint at snow squall potential. Given limited moisture and uncertainty in the details of the frontal passage, this will be lower probability for now. A few convective showers/segments that may be capable of a localized brief "burst" of higher snow rates. Overall deterministic/ensemble guidance keeps totals trace to light if anything given the localized nature of the showers. An arctic airmass will push in behind the front Thursday night. 850mb temperatures range -15 to -20C with mainly clear skies. Despite breezy conditions (at least to start the night), temperatures will likely plummet into the single digits for the interior and teens along the coast. These are the coldest temperatures of the season so far. As mentioned, winds may be elevated to start the night which will bring wind chill values into the negative single digits for the higher terrain and single digits elsewhere. The arctic airmass remains in place for Friday support high temperatures 10-15 degrees below normal. Highs struggle to reach 30 degrees, with the exception of SE MA and the south coast in the mid 30s. Ensemble guidance shows a consensus for a transition to a more active pattern heading into the weekend. There is a signal for a coastal system to brush the region sometime late Friday-Saturday. Details still less certain this far out, but this could bring another round of precipitation to southern New England. Once timing and track become more clear, we will get a better idea of precip type (snow or mix/rain event). && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 18Z update... Today...Moderate Confidence. MVFR ceilings drop to IFR-LIFR as precip overspreads the region this afternoon, 18-21z. Ptype rain for coastal terminals. SN to start for BDL,BAF, BED, and ORH, with chance for RA to mix in the afternoon 19z-21z. Lower confidence for precipitation type due to uncertainty in location of rain-snow line. E-NE wind 5-15 kt. Minor accumulations for BDL, BAF, BED, and ORH. 2-6" possible depending on where RA- SN line positions. Snowfall rates less than 0.5"/hour for terminals. Tonight...Moderate confidence. Widespread IFR-LIFR improving to VFR late from west to east after 06Z. Light SN for interior terminals in evening. Change over to a period of light RA/SN or light SN possible along the I-95 corridor, including BOS and PVD for a short period. Timing of change over is lower confidence, but would be after 03Z. Minor accum (Trace-0.5") possible at BOS. NE wind becoming N-NNW with gusts to 25 kt developing, with 30-40 kt gusts possible for Cape/Islands. Wednesday...High Confidence. VFR. NW winds with gusts up to 22 kts (up to 25 kts for Cape/Islands) in the morning decreasing in the afternoon. KBOS Terminal...Moderate confidence in TAF. Changeover to -RASN or -SN possible Tuesday night. Exact timing lower confidence, more likely between 03-07z. KBDL Terminal...Moderate confidence in TAF. Lower confidence in timing of ptype changes. Outlook /Thursday through Saturday/... Thursday: VFR. Windy with areas of gusts up to 30 kt. Slight chance SN. Thursday Night: VFR. Windy with gusts up to 30 kt. Friday: VFR. Friday Night: VFR. Slight chance SN. Saturday: VFR. Chance RA, slight chance SN. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Today through Tuesday Night... High confidence. Rain overspreads the waters and SSE winds early increase and turn out of the east then northeast late as a low pressure system crosses the southern waters. Gusts to 30-35 kts become possible tonight over the eastern waters, and around 25- 30 kts for the southern waters. Seas become rough as well, approaching 8-9 ft. Gale Warning starting 7 PM tonight through the overnight hours for the eastern waters, while a Small Craft Advisory is issued for the southern waters. Seas and winds begin to diminish heading into Wednesday as high pressure moves in over the waters. Outlook /Thursday through Saturday/... Thursday: Low risk for gale force winds with gusts up to 35 kt. Areas of rough seas. Thursday Night: Low risk for gale force winds with gusts up to 40 kt. Rough seas up to 10 ft. Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Friday Night: Winds less than 25 kt. Slight chance of rain. Saturday: Winds less than 25 kt. Chance of rain. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory until 7 AM EST Wednesday for CTZ002- 003. MA...Winter Weather Advisory until 7 AM EST Wednesday for MAZ005- 006-010>012. Winter Storm Warning until 7 AM EST Wednesday for MAZ002>004- 008-009-026. RI...None. MARINE...Gale Warning from 7 PM this evening to 7 AM EST Wednesday for ANZ230. Gale Warning from 7 PM this evening to 1 PM EST Wednesday for ANZ231-232-250-251-254-255. Small Craft Advisory from 4 PM this afternoon to 7 PM EST Wednesday for ANZ233>235-237. Small Craft Advisory from 4 PM this afternoon to 7 AM EST Wednesday for ANZ236. Small Craft Advisory from 4 PM this afternoon to 1 AM EST Thursday for ANZ256. && $$ SYNOPSIS...Frank/Mensch NEAR TERM...Frank SHORT TERM...Hrencecin LONG TERM...Mensch AVIATION...Frank/Dooley MARINE...Hrencecin/Mensch NWS BOX Office Area Forecast Discussion