AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 144 AM EDT Sun Mar 29 2026 .WHAT HAS CHANGED... Increased confidence in mild temperatures Tuesday and Wednesday. Still tracking the potential for much colder conditions late week, but uncertainty remains high. The latest NBM has trended somewhat warmer, but still shows highs in the 30s and 40s Thursday and Friday. && .KEY MESSAGES... - Mainly dry weather with a warming trend through Monday. - Risk for showers Monday night into Tuesday with above normal temperatures. - A stretch of well-above average temperatures peaks midweek with highs 15-20 degrees above normal by Wednesday. It will also be breezy with of showers and a rumble of thunder along and ahead of a cold front Wednesday evening. - Turning abruptly colder for the end of the workweek behind the front. Chance for a wintry mix across elevated areas of the interior Thursday and Thursday night but details remain uncertain at this time. && .DISCUSSION... KEY MESSAGE 1...Mainly dry weather with a warming trend through Monday. High pressure moves over the North Atlantic from the Mid Atlantic coast today. Winds become southwest and increase this afternoon. The primary impact of this will be a warming trend with dry weather that lasts through Monday. Despite the increasing SW winds today, humidity will not be quite as quick to respond. Throw in the lack of significant recent rainfall, and that combination will lead to fire weather concerns later today. In consultation with the various state fire weather agencies, will continue the Special Weather Statement to highlight these concerns. KEY MESSAGE 2...Risk for showers Monday night into Tuesday with above normal temperatures. Our weather pattern starts to shift Monday night into Tuesday. The aforementioned high pressure continues to move farther offshore over the North Atlantic as a low pressure approaches the Great Lakes. Southwest winds should continue, but not be quite as strong. This could permit a front to possibly move far enough south to trigger some showers late Monday night into Tuesday. There are no concerns for anything other than rainfall. Even then, it would be just a chance. Much of southern New England could remain dry through early Tuesday morning. KEY MESSAGE 3...A stretch of well-above average temperatures peaks midweek with highs 15-20 degrees above normal by Wednesday. It will also be breezy with of showers and a rumble of thunder along and ahead of a cold front Wednesday evening. Unseasonably mild airmass peaks on Wed with pre-frontal low level winds increasing to 40-45 kts. The elevated southwest flow advects much warmer air with 925mb temps rising to +15 to +20C. Potential cap on temperatures will be the presence of increasing mid and high level cloud cover around, which opens the door for questions on how much diurnal insolation we can realize. Even still, with 925 mb temps on the order of +14 to +16C and 850 mb temps in the +10 to +12C range, even some cloud cover should offer highs at least in the 60s, with a conditional shot at 70s if we can generate any persistent breaks in cloudiness. Will see increasing POPs along and ahead of a cold front which moves in Wed afternoon and into Wed evening. Could see some isolated thunderstorms as CAPE values increase to 300-500 J/kg Wednesday afternoon in the warm and moist prefrontal environment. Front then moves more slowly moving offshore overnight to early Thurs. Will have to watch how slowly this front pushes offshore as recent ECMWF guidance showing a possible secondary low forming along the slowing frontal zone into early Thurs, which would mean lingering rain into the early morning hours Thurs along the southern roughly third of Southern New England. KEY MESSAGE 4...Turning abruptly colder for the end of the workweek behind the front. Chance for a wintry mix across elevated areas of the interior Thursday and Thursday night but details remain uncertain at this time. Much cooler and more unsettled weather for late in the week. Cold front moves well offshore by Thursday as strong >1040 mb high builds south across SE Canada. Shallow wedge of cold air moves in on NE allowing for 925 mb temps to drop from around +14-16C from Wed afternoon to a chilly 0 to -2C by Thurs. Highest confidence in colder temperatures will be found across northern MA closer to the center of high pressure. There is some uncertainty as to the magnitude of cold as the eventual southward extent of high pressure likely changes run to run. The closer the high center generally the colder it will be. As a reference, 00z guidance has trended a bit further N with the high and has slightly warmer temps. Think the latest NBM is reasonable as it keeps highs in the mid 30s to mid 40s at best Thursday and Friday. Best chance for below freezing temps would be across northeastern MA and the Worcester Hills. Still some considerable differences in the timing of a frontal wave late week. GFS/GEFS has become more amplified with the shortwave and has slowed down somewhat since the last run and brings the wave Thursday night into Friday. ECMWF/EPS is still closer to Friday. That`ll be important because the potential exists for some wintry precip at onset in at least interior Southern New England pending surface temps. So some potential for wintry precip again as we close out the month of March, but at this day-6/day-7 timeframe it`s unclear if it ends up being Thurs or Fri. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through Monday...High Confidence. VFR. Diminishing wind this morning becoming SW by daybreak then gusts to 25 kt developing this afternoon. S-SW wind 5-15 kt tonight. Areas of LLWS possible overnight into Monday morning with a strengthening low level jet. Monday Night and Tuesday...Moderate Confidence. VFR for most. Areas MVFR possible in scattered showers late Monday night into Tuesday, with the greatest risk towards the northern MA border and towards the Berkshires. Breezy. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Tuesday Night through Thursday/... Tuesday Night through Wednesday: Mainly VFR, with local MVFR possible. Windy with gusts up to 35 kt. Chance RA, isolated TSRA. Wednesday Night: Mainly VFR, with areas MVFR possible. Breezy. RA likely. Thursday: Mainly VFR, with local MVFR possible. Breezy. Chance RA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. High pressure moving offshore will lead to increasing SW winds across the coastal waters into Monday. Gusty winds develop later today into tonight, which will eventually build seas across the southern coastal waters. Small Craft Advisories extended into Monday, but there could be brief lulls in gusts below 25 kt tonight. Decided to keep the headlining simple, rather than trying to pinpoint those lulls exactly. Not enough confidence to extend the Small Craft Advisories beyond Monday just yet. However, expecting another surge in SW winds Tuesday which may need further advisories. Outlook /Tuesday Night through Thursday/... Tuesday Night through Wednesday: Strong winds with gusts up to 35 kt. Rough seas up to 14 ft. Slight chance of rain, isolated thunderstorms. Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Rain likely. Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from noon today to 7 PM EDT Monday for ANZ230>237-250-251-254>256. && $$