AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 137 PM EST Sun Jan 25 2026 .WHAT HAS CHANGED... - Higher confidence in 12-24 inch snowfall totals for the Berkshire and eastern Massachusetts. Higher confidence is driven by a more significant period of wraparound snow and snow showers Monday. Otherwise, a high impact storm continues to impact southern New England. && .KEY MESSAGES... - Major winter storm underway this afternoon into much of the day Monday. Heavy snowfall rates and most difficult travel conditions continue this evening through 12-2am. - Lingering moisutre leads to periods of light snow/snow showers through much of the day Monday && .DISCUSSION... KEY MESSAGE 1...Major winter storm continues this evening and overnight. Difficult to impossible travel conditions persist through 12-2am with 1-3" per hour snowfall rates. After a bit of an early start, snowfall rates have increased to 1 inch per hour across much of the CWA this afternoon. These dangerous travel conditions continue well into the overnight as low pressure deepens offshore helping to increase mid level frontogenesis. The bulk of the snow falls through about 06z with gradual improvement into Monday morning as a dry slot works its way into the region. Storm totals are still holding steady as of the 18z update with totals expected to be in the 12"-18" range across the majority of southern New England, with 8"-12" expected on the Cape, Islands, and immediate southern coast. The higher elevations and northeastern MA will likely see 18"-24" for much of the 495 corridor including the Boston metro area. Coastal low takes shape off the Del Marva Peninsula this afternoon helping to further increase mid-level frontogenesis. In response, a deep and robust layer of lift will extend through much of the column including the dendritic growth zone (DGZ). BUFKIT soundings even show the potential for 2 favorable layers for dendritic growth, one in the mid to upper levels, and another closer to the surface with the deep and substantial near surface cold pool. Attention turns from mid level frontogenesis to lower level frontogenesis (925- 850mb) as a steep low level temperature gradient associated with an incoming coastal front approaches from the south. Coastal front initially races north across the ocean then slows to a crawl this evening as it encounters the wedge of low level cold air on land. Warm front aloft still continues north overnight, so expecting +SN to slowly transition to heavy sleet along the south coast and move inland between 00-05z Furthest inland extent looks to be along west to east corridor extending from Providence RI to Plymouth MA. In these locations the mid level warm nose increases to +1-2C. Perhaps a bit more exciting for us weather lovers is the non-zero chance for +TSSN as the mid levels warm enough for some elevated instability this evening into the overnight. Northeasterly LLJ increases to 30-40kts this evening as the low center passes just S of Nantucket. Thus, could see a period of gusty winds and blowing snow especially over the southern waters, Cape and Islands. HREF blizzard probs remain around 20%-30%, between 22 and 05z. The limiting factors for blizzard conditions along the south coast will be sleet and lower snow ratios as well as the short lived nature of the gustiest winds. Further inland, the mid level warm front stops short of changing the precip type to sleet and instead brings a lower ratio snow that that will help to cap totals between 12 and 18 inches for much of the interior. Impressive temperature gradient develops overnight with surface temps rising to near 32 as far inland as PVD but staying in the lower teens at ORH on the other side of the surface warm front! Prolific snow winds down from SW to NE as a mid level dry slot pushes into southern New England as 500-700mb RH values fall to 40- 60%. RH values like these are hostile to snow crystal growth and instead favor a period of "snizzle" or flurries. Any lingering snow eventually tapers to light flurries. Last hold out for light to moderate snow will be northeastern Massachusetts as northeasterly flow on Monday will allow for ocean-driven snow showers to persist into Monday afternoon. The next key message will better focus on Monday`s snowfall. KEY MESSAGE 2...Periods of light to moderate snow continue behind low pressure as it pulls offshore Monday. Warm advection driven snow moves well N of the CWA but low pressure will still be in vicinity Monday morning. Most of the frontal lift is well away from the CWA between 12 and 16z Monday so expecting decent clean up weather for the first half of the day. Snow chances increase Monday afternoon as continued NE flow around elongated low pressure maintains ample low level moisture. Frontal boundary approaching from the west brings a wind shift to the W and so the low level convergence and frontogenesis allows for another period of light to even moderate snow through much of Monday afternoon. Additional snow accums from this feature will range from 1-4 inches, with areas W of the CT river closer to 1" and eastern MA closer to 4". This additional snowfall gives us greater confidence in 12-24 inch storm totals across the Berkshires where upslope will locally enhance totals as well as northeastern Massachusetts including Boston where the wraparound moisture lingers the longest. Lingering snow showers wind down after 00z Tues. Key Message 3...Abnormally cold and mostly dry with a low probability of another storm off the coast next weekend. Overall benign weather is expected to follow this weekend`s snowstorm. Dry, cold NW flow persists through at least the start of next weekend keeping precipitation out of the forecast for the most part while temperatures remain well below normal each day. Normal highs/lows for late January are in the mid 30s and low 20s respectively; we are forecasting highs in the teens and 20s with lows in the single digits thanks to an anomalously cold airmass overhead. A few shortwaves rounding the broader trough could bring some flurries off and on but on the whole things look dry. We`ll continue to monitor a potential storm off the coast toward next weekend but odds are still favorable that it would pass harmlessly offshore. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 18z Update Today and Tonight: High Confidence. Heavy snow, widespread LIFR conditions through 08z. Snowfall rates of 1-3" per hour are likely. Snow lessens in intensity overnight into Monday but there should be a change to rain for a time on the Islands and possibly Cape Cod, with some sleet possible along the South Coast. Snow totals Monday morning range from 8-12" along the South Coast, Cape Cod, and Islands to 14-20" elsewhere, with 20-24" possible in the higher elevations and northeastern coast, including BOS. Much of this will fall from later Sunday afternoon through midnight Monday. Monday: High Confidence in treads. Moderate Confidence in timing. Snow begins to lighten up Monday morning. Prolonged northeasterly flow brings ocean enhanced snow to the northeastern coastal plain, including Boston, through midday. Winds shift to north westerlies Monday afternoon and flurries finally move offshore. Monday Night: High Confidence. MVFR, becoming VFR. Sky cover becoming clear. NW wind 10 knots with gusts 20 knots. KBOS Terminal...High Confidence in TAF. KBDL Terminal...High Confidence in TAF. Outlook /Monday Night through Friday/... Tuesday through Wednesday: VFR. Breezy. Wednesday Night: VFR. Thursday: VFR. Breezy. Slight chance SN. Thursday Night through Friday: VFR. Breezy. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight through Monday Night: High confidence. Moderate to heavy snow through this evening as a coastal storm arrives and brings gale-foce wind from the northeast 20-35 knots through this afternoon and gusting 30-40 knots tonight. Somewhat warmer air noses north, changing to rain or sleet on most of south coastal waters overnight. Wind shifts northwest Monday afternoon with gusts less than 20 knots. With the shift in wind, snow showers are possible Monday afternoon, followed by drying conditions Monday night. Outlook /Monday Night through Friday/... Tuesday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 14 ft. Tuesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Slight chance of snow. Wednesday: Winds less than 25 kt. Seas up to 5 ft. Chance of freezing spray. Wednesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Chance of snow, chance of freezing spray. Thursday Night: Strong winds with local gusts up to 30 kt. Local rough seas. Chance of freezing spray, slight chance of snow. Friday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of freezing spray, slight chance of snow. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Storm Warning until 8 PM EST Monday for CTZ002>004. MA...Winter Storm Warning until 8 PM EST Monday for MAZ002>024-026. RI...Winter Storm Warning until 8 PM EST Monday for RIZ001>008. MARINE...Gale Warning from 10 PM this evening to 5 AM EST Monday for ANZ230. Gale Warning from 10 PM this evening to 6 AM EST Monday for ANZ231. Gale Warning from 7 PM this evening to 1 AM EST Monday for ANZ232>234. Gale Warning from 6 PM this evening to 1 AM EST Monday for ANZ235-237. Gale Warning from 10 PM this evening to 1 AM EST Monday for ANZ236. Gale Warning from 10 PM this evening to 7 AM EST Monday for ANZ250-251. Gale Warning from 7 PM this evening to 7 AM EST Monday for ANZ254. Gale Warning until 1 AM EST Monday for ANZ255-256. && $$