AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 733 PM EDT Tue Mar 31 2026 .WHAT HAS CHANGED... Updated Aviation section. There is a marginal risk for a strong to severe thunderstorm this evening, mainly across western MA and CT. && .KEY MESSAGES... - Scattered showers and thunderstorms this evening with a strong to severe storm possible over western MA - Unsettled weather continues into Wednesday and Wednesday Night - Milder and unsettled pattern later this week brings showers from time to time along with warmer temperatures for inland locations. && .DISCUSSION... KEY MESSAGE 1...Scattered showers and thunderstorms this evening with a strong to severe storm possible over western MA Short-wave energy embedded within larger scale zonal flow aloft will help trigger showers and thunderstorms this evening over western MA/CT. The latest Convective Outlook from The Storm Prediction Center places western MA and CT in a marginal risk for severe storm with a general thunderstorm risk elsewhere in southern New England. The overall strength of synoptic forcing for ascent in the atmosphere will be on the weak side tonight. Furthermore, instability will be limited to the tune of 250-500 J/Kg of MLCAPE. While sufficient for thunderstorm development, these numbers do not present an alarming scenario for severe weather. Deep layer shear will be strong with 40-50 knots of shear in the 0-6 km layer. Thus, we have the ingredients needed for a period of convection. If we consult the latest suite of hi- resolution model guidance, we find that 00-06Z (8PM-2AM), will be the best opportunity for thunderstorms across southern New England. Hi- res guidance keeps the most robust activity mainly along and north of the I-90 corridor. CSU ML probabilities give a 5-10% chance of severe thunderstorm wind gusts or large hail for western MA. Further east, lightning and periods of heavy rainfall would be the most likely hazards. Expect thunderstorm activity to wane after midnight as instability diminishes. KEY MESSAGE 2...Unsettled weather continues into Wednesday and Wednesday Night A wind shift to the west/southwest early Wednesday will support another mild afternoon in southern New England with many locations reaching the upper 60s to low 70s. The presence of a frontal wave moving over The Northeast will continue to keep things unsettled with intermittent periods of showers expected during the day Wednesday. A lull in shower activity is expected Wednesday afternoon, but a cold front sagging south will support an additional round of showers Wednesday night into Thursday, mainly along and south of the I-90 corridor. Latest model guidance resolves the most shower activity over the south coast of MA and RI. Chillier temperatures settle in Wednesday night with lows temperatures falling to the 30s by Thursday morning. KEY MESSAGE 3...Milder and unsettled pattern later this week brings showers from time to time along with warmer temperatures for inland locations. Beyond Wednesday we`re in for a big cooldown as 1040mb high pressure moves into Nova Scotia and surface winds veer to the northeast pushing a cold front the rest of the way through the region. This, combined with stubborn low clouds will keep high temperatures very cold compared to Wednesday, in the upper 30s and low 40s. This will be a 30 degree difference in high temperatures for some locations! The roller coaster continues on Friday as the front lifts back to the north bringing warmer temps in the 60s and even some 70s by the weekend. That being said, it remains a very chaotic and dynamic pattern with SNE sandwiched between a subtropical ridge and east coast trough so confidence in the temperature forecast is low to moderate. Same with exact timing and placement of any rainfall associated with these frontal passages and passing shortwaves. A generally unsettled pattern with scattered rain showers looks to hold on through the early part of the weekend before a more appreciable front and mid level trough move through around Sunday/Sunday night. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 00Z TAF Update...Moderate confidence. Backdoor front was settling near a line from ORE-PVD this evening. MVFR/IFR ceilings with NE winds in its wake will improve overnight once front lifts back to north. VFR to west of front with S winds. Watching TSRA moving through eastern NY which should weaken as it reaches SNE, mainly bringing SHRA and an embedded TS along and north of I-90 until around midnight. LLWS expected overnight, especially near coast, with 020 winds 230-240/50-60kt. Scattered showers expected Wed morning with S/SW winds, then backdoor front once again drops S during afternoon and evening, this time to more of southern New England, with wind shift to N/NE and lowering ceilings to MVFR/IFR. Also expecting a period of showers, mainly focused near South Coast, later in day. KBOS Terminal...Moderate confidence in TAF. Timing of improvement later tonight may be too quick and there is lower confidence on whether or not IFR cigs return Wed afternoon. KBDL Terminal...Moderate confidence in TAF but low confidence in timing of any isolated t-storm risk. Outlook /Wednesday Night through Sunday/... Thursday: Mainly MVFR, with areas IFR possible. Breezy. Chance RA, FZRA likely. Thursday Night: Mainly MVFR, with areas IFR possible. Chance RA. Friday: Mainly VFR, with local IFR possible. Breezy. Friday Night through Saturday: Breezy. Slight chance RA. Saturday Night: Breezy. Chance RA. Sunday: Windy with local gusts up to 30 kt. RA likely. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Moderate southwest winds overnight between 15 and 25 knots with strongest winds over the outer south coastal waters. A few marginal gale force gusts are possible. SCY in place through tomorrow night. Seas remain elevated over the southern marine zones as well but gradually subside from 7-10 feet Wednesday morning to 4-6 feet by Wednesday evening. Winds shift to the northeast Wednesday night into Thursday but remain moderately strong with sustained winds between 15 and 20 knots. Outlook /Wednesday Night through Sunday/... Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain. Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain. Friday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Friday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Saturday: Winds less than 25 kt. Areas of seas approaching 5 ft. Saturday Night: Low risk for Small Craft Advisory winds with local gusts up to 30 kt. Seas up to 5 ft. Slight chance of rain. Sunday: Strong winds with gusts up to 30 kt. Areas of rough seas. Chance of rain. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ231- 250. Small Craft Advisory until 7 PM EDT Wednesday for ANZ232>235- 237. Small Craft Advisory until 2 PM EDT Wednesday for ANZ236. Small Craft Advisory until 6 AM EDT Thursday for ANZ254>256. && $$