AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 607 AM EST Wed Mar 4 2026 .WHAT HAS CHANGED... No significant changes made to the forecast with the greatest concerns being black ice early this morning and another wintry mix Thursday night and Friday. && .KEY MESSAGES... - Areas of black ice early this morning, otherwise dry and milder this afternoon. Highs will be in 40s or 50s with the higher temps dependent on how quick low clouds/fog dissipate. Patchy fog develops late tonight with lows mainly in the upper teens and 20s. - Another round of rain and freezing rain late Thursday into early Friday. Wintry weather generally along and north of the Mass pike. - Pattern change towards milder weather this weekend and looking more likely for very warm temps next week. && .DISCUSSION... KEY MESSAGE 1...Areas of black ice early this morning, otherwise dry and milder this afternoon. Highs will be in 40s or 50s with the higher temps dependent on how quick low clouds/fog dissipate. Patchy fog develops late tonight with lows mainly in the upper teens and 20s. The wintry mix should depart our region toward daybreak as the shortwave moves off the coast. The concern will then turn to the formation of black ice and areas of fog for the early morning commute. Residual moisture, light winds and cold ground will make for a very favorable environment for black ice to develop...perhaps with some freezing fog too. We have gone ahead and issued a special weather statement to highlight this concern. Otherwise...high pressure builds over the region today. The uncertainty revolves around very weak mixing and how long the low clouds/fog linger. The guidance is quite aggressive in scouring the low clouds out quickly. If that happens...925T in the +5C/+6C range would support highs into the lower to middle 50s. However...there is concern that the low clouds/fog will be slower to dissipate especially in those typical low-lying valley locations especially the CT River Valley. If this occurs...these locations will be held in the 40s. This will be more of a nowcast situation...but may have the cooler readings in parts of the lower CT River Valley and perhaps the immediate coast too if sea breezes develop. We should see temps drop quickly after sunset given light/calm winds and still plenty of snowpack across the region. Low temps should mainly be in the upper teens and 20s tonight. This will likely lead to the formation of patchy fog late tonight. KEY MESSAGE 2...Another round of rain and freezing rain late Thursday into early Friday. Wintry weather generally along and north of the Mass pike. Zonal flow continues into Thursday when our next system arrives: a mid level shortwave that slides through New England late Thursday into Friday. A mid level warm front will initially bring rain to most of the region Thursday afternoon, but another freezing rain, sleet, and rain mixed precipitation event is expected similar to what we experienced tonight. The main cause of this is the high pressure sitting over southeast Quebec directing cold NE flow into the region at the surface. Model soundings show this this evolution well, with surface temps dropping below freezing by Thursday evening and especially overnight while a warm nose remains at 850 mb (all night or part of the night, depending on location). This will lead to a messy mix of precipitation. The best chance of frozen precipitation is along and north of the MA pike where ensemble guidance shows a 15% (lower elevations) to 60% (highest elevations) chance of at least 0.01" of ice. Precipitation then comes to an end on Friday morning leaving a cloudy and chilly day in its wake with highs likely not escaping the 30s. KEY MESSAGE 3...Pattern change towards milder weather this weekend and looking more likely for very warm temps next week. Our warm-up begins in earnest this weekend and especially next week as we fall under the influence of a building western Atlantic ridge. This directs anomolously warm air into the region with 850 mb temps potentially pushing up to ~13C by Saturday before dipping on Sunday. A weak front on Saturday night may bring some scattered showers, but these would all fall as rain given expected temperature profiles. Still, ensemble probabilities have backed off in the last several runs on even seeing 50F on Saturday; confidence in seeing much above normal temps goes up, though, for Monday into Tuesday when probabilities of temps over 50F are 90%+ likely reaching into the 60s. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 12z TAF Update... Today...Moderate confidence. IFR-LIFR conditions in areas of low clouds and fog linger into early this morning in spots. While we do eventually expect improvement to VFR conditions...timing is uncertain and given weak boundary layer winds this could be a slow process especially in low- lying locations such as the CT River Valley. Most locations should be VFR by afternoon except perhaps parts of the lower CT River Valley. Winds becoming light WSW...but we may see some localized sea breezes along portions of the immediate coast this afternoon. Tonight...Moderate confidence. VFR conditions in the evening...but areas of low clouds and fog may develop late resulting in MVFR-IFR conditions with even localized LIFR cigs/vsbys. While low clouds and fog patches are possible anywhere late tonight...guidance seems to be indicating greatest risk for it being most widespread across CT/RI and southeast MA. Light/calm winds. Thursday...Moderate confidence. The initial morning low clouds/fog patches may briefly burn off. However...widespread MVFR to localized IFR conditions to overspread the region from southwest to northeast along with a shield of rain that may be mixed with sleet especially north of the MA turnpike. Light NE winds. KBOS Terminal...Moderate confidence in TAF. The main uncertainty is if winds may be weak enough for localized sea breezes to develop for several hours this afternoon. KBDL Terminal...Moderate confidence in TAF. The main uncertainty is how long it takes the low clouds and fog to burn off this morning. Low risk this may even take until sometime this afternoon. Outlook /Thursday Night through Sunday/... Thursday Night: Mainly IFR, with areas MVFR possible. Breezy. RA, FZRA. Friday: MVFR/IFR conditions possible. Breezy. Chance RA, FZRA likely. Friday Night: MVFR/IFR conditions possible. Slight chance RA. Saturday: Mainly VFR, with areas IFR possible. Breezy. Slight chance RA. Saturday Night: Mainly VFR, with local IFR possible. Breezy. Chance RA. Sunday: VFR. Breezy. Slight chance RA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Today through Thursday...High confidence. Lingering southerly swell will result in small craft seas lingering across our southern waters into the first half of the evening before dropping below criteria. Otherwise...high pressure building over the waters today and tonight will keep sustained winds generally 10 knots or less through tonight. Low pressure approaching from the west will allow NE winds to increase to between 10 and 20 knots on Thu. Outlook /Thursday Night through Sunday/... Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain. Local visibility 1 to 3 nm. Friday: Winds less than 25 kt. Areas of rough seas. Chance of rain. Friday Night: Winds less than 25 kt. Areas of rough seas. Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Saturday Night: Moderate risk for Small Craft Advisory winds with local gusts up to 30 kt. Areas of rough seas. Chance of rain, isolated thunderstorms. Sunday: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 10 PM EST this evening for ANZ254>256. && $$