AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 134 PM EST Fri Feb 20 2026 .WHAT HAS CHANGED... Winter Weather Advisories remain in effect from 10 AM today to 7 AM Saturday due to accumulating snow and ice, leading to slippery road conditions. Increasing confidence in seeing impacts from the Sunday/Monday coastal storm on the South Coast, Cape Cod, and the Islands with dangerous marine conditions on the coastal waters. Winter Storm Watches issued for the South Coast, Cape Cod, and the Islands. High Wind Watches issued for Cape Cod and the Islands. Storm Watches for all coastal waters except Boston Harbor where a Gale Watch has been issued. Coastal Flood Watch issued for the eastern Massachusetts coast. && .KEY MESSAGES... - Winter Weather Advisories remain in effect through 7AM Saturday for interior southern New England as a winter storm with a mix of rain, snow, sleet, and freezing rain is currently overspreading New England. Expecting mostly rain for areas southeast of I-95. All locations will see a change back to snow tonight with light accumulations possible. Slippery road conditions are expected. - Light snow showers continue Saturday with little additional accumulation expected. - Coastal storm likely impacts the South Coast, Cape Cod, and the Islands but we still cannot rule out a more widespread impact across the rest of southern New England. && .DISCUSSION... KEY MESSAGE 1...Winter Weather Advisories remain in effect through 7AM Saturday for interior southern New England as a winter storm with a mix of rain, snow, sleet, and freezing rain is currently overspreading New England. Expecting mostly rain for areas southeast of I-95. All locations will see a change back to snow tonight with light accumulations possible. Slippery road conditions are expected. A low pressure system continues to move northeast through the Great Lakes while another low has formed off the DelMarVa coast. The warm front ahead of the Great Lakes low is driving the mix of precipitation currently pushing through southern New England, with a warmer airmass keeping temperatures warm enough for rain to present as the predominant p-type (with some snow starting to mix in across the higher elevations). The latest suite of guidance is indicating a warm nose pushing all the way up to the Mass Pike, with global guidance nudging it as far north as northern MA. Areas north of the warm nose will likely remain solely as snow while areas under the nose will see a mix of p-types... likely sleet, rain, and snow. Patchy freezing rain is possible in the interior higher elevations, but confidence is low on exactly how far east it could spread. Winter Weather Advisories remain in effect through 7AM Saturday for interior southern New England, with the greatest accumulations of wet snow expected (3-5" with spot 6" amounts along the NH border) near and north of the Mass Pike and into the Merrimack Valley/North Shore. Areas along and south of the Mass Pike into Northern Connecticut and northwest Rhode Island are more likely to see minor wet snow of a coating to 3" as well as possible ice accretion up to 0.2". Later tonight, expecting any mixed precip to fully transition to snow, with only minor accumulations expected. While totals will be light (1-2 inches) the timing of the transition will not be ideal for the evening commute and will likely result in slick travel. Opted to not go with an advisory as confidence in snowfall and sleet totals over 2 inches remains low. Generally expecting a mostly rain event SE of I-95 with a period of light snow this afternoon/tonight. In these areas, a coating to a half inch of snow is possible mainly on grassy surfaces or side streets. KEY MESSAGE 2...Light snow showers continue Saturday with little additional accumulation expected. Light snow showers are expected to continue through mid-morning Saturday as an inverted trough remains stagnant over New England. However, the dendritic growth zone will dry out throughout the morning, leading to poor snow growth potential. Expecting very minor accumulations, if any, Saturday morning, with the North Coast/Cape Ann likely to see highest additional totals of up to 1". KEY MESSAGE 3...Coastal storm likely impacts the South Coast, Cape Cod, and the Islands but we still cannot rule out a more widespread impact across the rest of southern New England. Still seeing differences among deterministic models and ensembles regarding track of the Sunday/Monday coastal storm but those differences have begun to decrease a bit over past 24 hours. Storm track, whether it passes southeast of 40/70 benchmark or makes a closer pass, is highly dependent upon strength of downstream 500 mb ridge, which ultimately affects how deep and orientation of upper trough moving off East Coast. 12z GFS remains the strong outlier when compared to other models and brings coastal storm right over 40/70 benchmark, which if it verifies, would bring widespread heavy snow and strong winds to much of SNE. We`re also still seeing a very large spread in GFS ensemble members and Canadian/ECMWF ensembles as well, so forecast confidence in any particular solution is not very high. GFS solution is not completely supported by other guidance but we have noted more of a NW trend; consensus is for a weaker downstream ridge which results in a slightly farther offshore pass but still brings heavy snow and strong winds to Cape Cod and the Islands and South Coast. This would also bring accumulating snow to much of SNE, but not the extreme amounts as seen on some model snow maps that have been making the rounds these past few days. Since we are most confident on 6"+ totals on Cape Cod and the South Coast, we will issue a Winter Storm Watch for these areas. We considered also including more of RI and SE MA given recent trend but decided to hold off for now given spread in ensemble members. Keep in mind if we see continue to see a NW trend in guidance, the Watch will likewise need to be expanded to include more of SNE, at least into more or RI and eastern MA including Providence and Boston. We`re just not quite ready to buy into that just yet. Onset of the snow looks to be Sunday night, with the peak of the snowfall rates later Sunday night into Monday, before snow tapers off Monday evening. It`s possible dry air at onset could cause snow to hold off until Monday, something depicted toward end of 12km NAM run, so it`s also not out of the question that the bulk of the snow could fall during the day Monday. In addition to the snow, there is increasing confidence in seeing widespread 50-60 mph gusts on Cape Cod and the Islands and most of the coastal waters. Even with a more offshore track, coastal storm should deepen rapidly down into 970-mb range, producing a wide envelope of high winds as well as moisture on the cold conveyer belt. High Wind Watches have been issued for Cape Cod and the Islands, with Storm Watches for the coastal waters. This will be a dangerous storm for mariners with potential for at least 25 foot seas offshore. Finally, high astronomical tides Monday into Tuesday brings the potential for minor to moderate coastal flooding along eastern MA coast, depending upon timing of highest surge. Surge guidance and pattern recognition suggests a 3 foot surge around high tide early Monday morning and again early Tuesday morning, which could bring the water level to over 6 feet in Nantucket Harbor and to 13.5 feet in Boston, although wave impacts along the coastline would result in greater impacts (likely Moderate) as well as coastal erosion. Keep in mind large pressure falls would also add to the water level, so even a more offshore track could still result in significant coastal flooding. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 18Z TAF Update: Moderate confidence due to uncertainty in precip type and timing of lowest conditions. Precip continues to move east with Ptype starting as snow then turning to sleet/freezing rain/rain. Freezing rain is most likely in western portions of western MA and CT with sleet/snow more likely in eastern MA. Rain/sleet most likely in RI and SE MA with rain most likely over the Cape and Islands. Mixed precip will continue through about 00z-03z tonight before switching back to snow/snow showers as the system exits. The only area not anticipated to switch back to snow is the South Coast and Cape/Islands. CIGS are quickly dropping to IFR/LIFR across the region, within 30 mins of precip starting. CIGS remain IFR/LIFR overnight even as precip begins to taper off. Saturday: Moderate Confidence CIGS gradually improve to MVFR/VFR late morning to early afternoon. Snow showers may linger into the afternoon esspically across western MA/CT, although confidence in any snow that falls Saturday will be light, under a half inch. KBOS Terminal...Moderate confidence in TAF. Snow should begin around 19z this afternoon and could become moderate briefly before becoming mixed with sleet after 22z. Not anticipating ptype to switch to rain at this point. ptype should become all snow again this evening after 02z with snow lingering into Saturday morning. CIGS will quickly drop to IFR/LIFR as snow begins this afternoon and remain there into Saturday morning before becoming MVFR. KBDL Terminal...Moderate confidence in TAF. Light snow should become more of a mixed precip this afternoon with sleet and freezing rain possible. ptype switches back to snow later this evening before tapering off overnight. CIGS remaining IFR this evening, improving to MVFR later overnight. Outlook /Sunday through Wednesday/... Sunday: Mainly VFR, with areas MVFR possible. Breezy. Chance SN. Sunday Night: MVFR/IFR conditions possible. Windy with areas of gusts up to 35 kt. Chance SN. Monday: Mainly VFR, with local IFR possible. Strong winds with areas of gusts up to 40 kt. Chance SN. Monday Night: VFR. Windy with local gusts up to 35 kt. Slight chance SN. Tuesday: VFR. Breezy. Tuesday Night: VFR. Wednesday: Breezy. Chance RA, slight chance SN. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. High confidence through the end of this week. Low pressure passing SE of New England will bring increasing E/NE winds through this evening, before winds back to N/NW and diminish later tonight and Sat. Rough seas will linger awhile longer offshore, then the developing coastal low as outlined above is expected to bring dangerous marine conditions later Sunday night and into Monday night. Outlook /Sunday through Wednesday/... Sunday: Winds less than 25 kt. Seas up to 5 ft. Slight chance of snow. Sunday Night: Strong winds with gusts up to 40 kt. Rough seas up to 16 ft. Chance of snow. Local visibility 1 nm or less. Monday: gale force winds with gusts up to 45 kt. Rough seas up to 23 ft. Chance of snow. Areas of visibility 1 nm or less. Monday Night: Low risk for gale force winds with gusts up to 40 kt. Rough seas up to 22 ft. Chance of snow. Tuesday: Winds less than 25 kt. Rough seas up to 13 ft. Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory until 7 AM EST Saturday for CTZ002>004. MA...Winter Weather Advisory until 7 AM EST Saturday for MAZ002>014- 026. Coastal Flood Watch from Monday evening through Tuesday morning for MAZ007-015-016-019-022>024. Winter Storm Watch from late Sunday night through Monday evening for MAZ020>024. High Wind Watch from Monday morning through Monday evening for MAZ022>024. RI...Winter Weather Advisory until 7 AM EST Saturday for RIZ001-003. Winter Storm Watch from late Sunday night through Monday evening for RIZ006>008. High Wind Watch from Monday morning through Monday evening for RIZ008. MARINE...Gale Watch from late Sunday night through Monday evening for ANZ230. Storm Watch from Monday morning through Monday evening for ANZ231. Storm Watch from late Sunday night through Monday evening for ANZ232>234. Storm Watch from late Sunday night through Monday afternoon for ANZ235-237. Storm Watch from Monday morning through Monday afternoon for ANZ236. Small Craft Advisory from 7 AM to 1 PM EST Saturday for ANZ250- 254>256. Storm Watch from Monday morning through Monday evening for ANZ250-251. Storm Watch from late Sunday night through Monday evening for ANZ254>256. && $$