AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 240 PM EST Sun Dec 28 2025 .WHAT HAS CHANGED... Winter Weather Advisory expanded to include SW RI, eastern Kent and SE Providence counties in RI as well as northern Bristol and northern Plymouth counties in SE MA. No change to potential strong winds late Monday night and Tuesday. Wind Advisories may be needed for at least the high terrain and Cape/Islands. && .KEY MESSAGES... - A period of freezing rain tonight will bring a tenth to a quarter inch of ice accumulation to interior MA and portions of northern CT, with a trace to a tenth of an inch elsewhere away from the south coast. - Rain tapers off late Monday, then windy and turning much colder Mon night - Strong gusty winds begin early Tuesday morning, peaking late morning through early afternoon. - Below normal temperatures continue through late week. Periods of light snow possible. && .DISCUSSION... KEY MESSAGE 1...Freezing rain tonight The stage is set for a period of icing tonight as shallow cold air will be slow to dislodge as moisture moves into the region with pretty mild temps aloft. Mid level shortwave and warm front approaches from west with a modest low level jet developing ahead of the shortwave. This will advect anomalous PWATs into SNE with strong convergence at the nose of the jet acting on this moisture to bring widespread rain to SNE, beginning 8-11 pm from west to east. Temps are expected to fall back into the 20s this evening and may wet bulb further as precip moves in given dewpoints in the teens. Soundings in the interior show a classic freezing rain situation with pronounced warm nose above 2k ft and shallow low level cold air below 2k ft as precip moves in. This will ensure a period of widespread freezing rain in the interior tonight but temps will be rising from late evening through the overnight which will allow ice to gradually transition to plain rain, but it may take until Mon morning across portions of far northern MA where shallow cold air will hang on the longest. In the coastal plain including the Boston to Providence corridor, we do expect a brief period of icing as temps will be near 32F as precip develops and even if temps are slightly above freezing rain falling on cold ground will support patchy light icing. For this reason we expanded the winter weather advisory to interior SW RI and the PVD-TAN-PYM corridor. Any icing here will be brief and not expected to be widespread as temps in the coastal plain will quickly rise through the 30s overnight and into the 40s by daybreak. Not expecting any icing along the immediate south coast and Cape and Islands. The highest ice accretion will be across interior MA and CT, mainly north and west of I-84 to I-90 to I-495 corridor where 0.10 to 0.25" of ice is possible, and we leaned toward HREF which used more reliable FRAM method. If ice accretion exceeds 0.25" there could be some localized tree damage and the best chance of 0.25" ice would be across the northern Berkshires and adjacent CT valley. Elsewhere north of PVD-TAN-PYM we are expecting a trace to less than 0.10" of ice. Any icing impacts to the morning commute would be confined to areas in far northern MA. KEY MESSAGE 2...Rain tapering off late Mon, then windy and much colder Mon night Brief dry slot moves in by daybreak which will allow rain to be more spotty in the morning. There is a low risk for brief spotty freezing rain in the morning in portions of far northern MA near the VT and NH border where low level cold air may be slow to dislodge. If there is any icing after daybreak it will transition to plain rain by mid or late morning. Otherwise, we are expecting another pulse of rain moving west to east across SNE with the cold front and mid level shortwave. Temps will warm into the 40s with potential for lower 50s RI and SE MA. The cold front will be moving through the region during the mid to late afternoon with rain tapering off after the fropa as much drier air moves in from the west. Some upslope snow showers may spill over into the east slopes of Berkshires Mon night, otherwise clearing skies. Strong advection and an increasingly mixed boundary layer will result in gusty W winds developing Mon night with 30-40 mph gusts, except potential for 40-50 mph gusts in the interior MA higher terrain and Cape/Islands where wind advisories may eventually be needed. 850 mb temps bottom out around -14 to -18C Mon morning. Lows by Mon morning will drop to mid teens to lower 20s but wind chills Mon morning will bottom out near 10F in the coastal plain, single numbers interior and zero to -5F in the Berkshires and Worcester Hills. KEY MESSAGE 3...Strong gusty winds begin early Tuesday morning, peaking late morning through early afternoon. A cold front moves through late Monday night into early Tuesday morning with considerably colder air pushing in behind it. High pressure will build in from the south on Tuesday as low pressure exits. Strong CAA paired with a tight pressure gradient and fairly strong LLJ jet raises the concern for efficient mixing of gusty winds down to the surface. Per latest model guidance, there is increasing agreement on a stronger 850mb jet (45-55 kts) compared to yesterday. Model soundings are supportive of the strong gust potential indicating mixing from around 850 mb. Ensembles continue to display a range of 35-55 mph gusts. Quite a range...however this reflects the current spread among ensemble/deterministic guidance. GFS and Canadian have leaned on the lower end while the ECMWF/ens leaned higher. The higher gusts in that range will be more likely over the higher terrain and near the Cape/Islands. NBM probabilities have been consistently in the 60-80% range for gusts greater than 45 mph (advisory criteria) for the high terrain (Berkshires, Worcester Hills) and around the Cape/Islands. Probabilities are lower elsewhere (< 35%); however, we are keeping in mind NBM has run low on gusts in previous wind events this season. Other guidance has shown higher probabilities. Both the NBM and ECMWF ens highlight potential for gusts near High Wind Warning Criteria for the Berkshires/immediate east slope of Berkshires with even low probs in the Worcester Hills and near the Cape/Islands. This seems reasonable at least for the higher terrain. The westerly component flow may support downslope enhancement as well in the Berkshires. Wind Advisories will likely be needed with the highest confidence for the interior high terrain and Cape/Islands. A High Wind Warning is also not out of the question for at least the east slope of the Berkshires. Confidence will increase as we get in future model guidance, including from high-resolution models. Temperatures will also be below normal Tuesday in the 20s in most spots. The gusty west winds will bring wind chills in the single digits to teens during the day Tuesday. Mid-level moisture will be present on Tuesday with steep lapse rates/marginal instability. Combined with enhanced westerly flow, this should be enough bring a few streamers/showers from the Great Lakes into western MA. Can`t rule out an isolated snow shower or flurry for southern New England within the cold advective regime. KEY MESSAGE 4...Below normal temperatures continue through late week. Periods of light snow possible late week. There is good agreement among ensemble guidance for continued mid- level troughing across the northeast through late week. Accompanied by cold temperatures aloft, this will support below normal temperatures in the 20s to low 30s through the weekend. There is a signal for another shot of colder air for Thursday and Friday with highs struggling to make it out of the 20s. A few ocean-effect showers are possible Wednesday near the Cape Cod /Islands. There may be a few systems that move through the flow later in the week; however, confidence remains low for precip probabilities/timing due to model variance. First chance comes with the passage of the arctic front late Wednesday-Thursday AM. Next chance will be with an offshore system. This may bring a period or two of light snow fall late Wednesday through Friday. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 18Z TAF Update: Through 00z Monday: High confidence. VFR; lowering mid/high-level VFR cloudiness 20z Sun-00z Mon. Winds become SW under 10 kt. Tonight and Monday: High confidence in trends but moderate on timing the changeover from FZRA to RA. Conditions deteriorate between 01-03z Mon as with 3-6 SM -FZRA, MVFR ceilings/visbys develop. Best chance for icy untreated runways are away from the south coast and Cape Cod, where RA should predominate. Gradual transition from FZRA to RA takes place from south to north between 06-10z Mon; however widespread IFR ceilings/visbys develop as sites changeover to RA/BR. IFR to LIFR continues in RA/BR rest of the day Monday, with strong confidence in not much if any improvement until the cold front moves in from the west between 22z Mon-00z Tue. SW winds around 5-10 kt through tonight, with low level wind shear after 05z as SW low-level jet increases to around 45 kt. Winds Mon become S around 10 kt with gusts to 20 kt until frontal passage after 22z, which brings a windshift to WSW/W. Monday Night: High Confidence. VFR, though borderline VFR/MVFR ceilings in/around high terrain. WNW winds increase significantly to around 15-25 kt with gusts 35-50 kt, highest gusts in high terrain. KBOS Terminal...Moderate Confidence. VFR through 03z Monday. FZRA develops w/MVFR cigs/visbys around 03z Mon. Changeover to RA around 07z with mist as winds turn light SE, to go along with cigs/vis lowering to IFR with low level wind shear. These conditions stay generally steady, until frontal passage late in the day brings improvement to VFR. KBDL Terminal...Moderate Confidence. VFR through 02z Monday. FZRA develops w/MVFR cigs/visbys around 02z Mon. Changeover to RA with mist around 07z, to go along with cigs/vis lowering to IFR with low level wind shear. These conditions stay generally steady, until frontal passage around 20-22z with improvement to VFR thereafter. Outlook /Tuesday through Friday/... Tuesday: Mainly VFR, with local MVFR possible. Strong winds with gusts up to 45 kt. Tuesday Night: Mainly VFR, with local MVFR possible. Windy with gusts up to 35 kt. Wednesday: Mainly VFR, with local MVFR possible. Breezy. Wednesday Night through New Years Day: VFR. Breezy. Slight chance SN. Thursday Night: VFR. Slight chance SN. Friday: VFR. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through Monday night: High confidence. Gale warnings in effect for all waters with strongest winds Mon night. Increasing S-SW wind late tonight into Monday with gusts 25-30 kt, then wind shift to W behind the cold front late Mon-Mon evening with 35-45 kt gusts developing. Vsbys lowering tonight into Mon in areas of rain and fog, improving Mon night. Outlook /Tuesday through Friday/... Tuesday: gale force winds with gusts up to 45 kt. Rough seas up to 15 ft. Slight chance of snow. Tuesday Night: Strong winds with gusts up to 40 kt. Rough seas up to 14 ft. Wednesday: Strong winds with gusts up to 30 kt. Areas of rough seas. Slight chance of rain, slight chance of snow. Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of snow, slight chance of rain. New Years Day: Winds less than 25 kt. Local rough seas. Chance of snow. Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of snow. Friday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of snow. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory from 7 PM this evening to 6 AM EST Monday for CTZ002>004. MA...Winter Weather Advisory from 7 PM this evening to 6 AM EST Monday for MAZ002>016-026. Winter Weather Advisory from 7 PM this evening to 1 AM EST Monday for MAZ017-018. RI...Winter Weather Advisory from 7 PM this evening to 6 AM EST Monday for RIZ001-003. Winter Weather Advisory from 7 PM this evening to 1 AM EST Monday for RIZ002-004-006. MARINE...Gale Warning from 7 PM Monday to 7 PM EST Tuesday for ANZ230- 236. Gale Warning from 7 PM Monday to 7 AM EST Wednesday for ANZ231- 250-251-254. Gale Warning from 4 PM Monday to 7 AM EST Wednesday for ANZ232>235-237. Gale Warning from 1 PM Monday to 7 AM EST Wednesday for ANZ255- 256. && $$