825 FXUS61 KBOX 022324 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 724 PM EDT Mon Jun 2 2025 .SYNOPSIS... High pressure brings dry and warmer weather Tuesday after a chilly start. Summertime warmth develops mid to late week, with heat peaking on Thursday with highs possibly into the lower 90s. A few thunderstorms are possible Thursday afternoon, with a better chance for storms and showers late Friday or early Saturday with a cold front passage. Temperatures trend seasonable next weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Key Messages: * Mainly dry and chilly with lows in the 40s Last northern stream shortwave will be rotating southward across SNE overnight. Shortwave will be accompanied by a pocket of 500 mb temps down to -22 to -23C. However, this will occur around 06z which is diurnally an unfavorable time to impact instability. As a result, other than a period of clouds and a low risk for a brief sprinkle/shower, expect a dry shortwave passage followed by clearing skies overnight as the upper trough and shortwave moves to the east. HRRR keeps bulk of smoke to the west tonight. Clearing skies and light winds will result in good radiational cooling overnight allowing lows to drop into the 40s for most places, except lower 50s urban centers and some coastal locations. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Key Messages: * Dry and warmer Tue Upper level trough axis quickly moves to the east with ridging building in from the west and warming temps aloft. Dry air in the column will support plenty of sunshine and while there may be some smoke aloft moving in from the west, bulk of smoke expected to remain to the west. After a chilly start temps will recover to above normal levels. Highs should reach upper 70s to near 80, but cooler along the immediate coast where seabreezes develop. High pres builds south of New Eng Tue night with mainly clear skies and light winds. However, increasing smoke aloft is forecast to spill in over the ridge as it moves into the region. Lows will be in the 50s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Key Messages: * Hot and humid conditions mid-late week with high temperatures in the mid to upper 80s and possibly low 90s Wed-Fri * Becoming more unsettled late Thursday with multiple opportunities for showers and thunderstorms through Saturday * Trending cooler/drier by Sunday and Monday Wednesday through Friday A broad upper level ridge at 500 hPa builds over New England on Wednesday. This will begin a three day stretch of warm/humid weather across southern New England. Wednesday will feature the most sunshine with surface high pressure and subsidence aloft suppressing any significant cloud cover. Southwest flow will advect a much warmer air mass over southern New England with 925 hpa temps rising to near 20 Celsius by Wednesday afternoon. With deep diurnal mixing forecast during the afternoon Wednesday, we can expect surface temps to reach the mid to upper 80s across most of the forecast area. There is even a low probability for some locations to reach the low 90s with ensembles suggesting a 30 to 50 percent chance of high temperatures exceeding 90 degrees in The CT River Valley and inbetween I-495/I-95 west of Boston. Expect locations closer to the coast to be substantially cooler with Cape/Islands in the low 70s and the remaining coastal locations in the mid to upper 70s. The three day stretch of heat and humidity peaks on Thursday. Persistent southwest flow is forecast to support a surge in dewpoint temperatures with many locations in southern New England expected to experience dewpoints in the low to mid 60s on Thursday afternoon. 925 hPa temps continue to rise as well, perhaps reaching as high as 25C on Thursday afternoon. This will likely support surface temperatures in the upper 80s to low 90s on Thursday afternoon. Expect increasing cloudiness during the second half of Thursday as a weak pulse of short-wave energy traverses over The Northeast. Modest height falls and moderate instability to the tune of 1000 J/kg of MLCAPE will likely result in a few afternoon thunderstorms/downpours. Not expecting any strong to severe storms at this time as both lapse rates and deep layer shear are not forecast to be favorable for organized storm development. CSU ML probs support a 5-15% chance of severe weather across southern New England on Thursday. Friday looks to feature more cloud cover, thus high temperatures are unlikely to reach 90 for a second consecutive day. The air mass however, will continue to support warm/muggy conditions with afternoon highs in the mid to upper 80s. The heat finally breaks late Friday as a cold front pushes through the region with another round of showers and possibly a rumble of thunder. Latest model guidance does not support impressive instability, buy a couple of hundred J/Kg of CAPE would be enough to support a few storms. We`ll have more details as we enter the window of high resolution guidance later this week. Saturday through Monday A low-pressure system moves through The Northeast on Saturday, resulting in yet another wet Saturday for most of southern New England. There is some uncertainty with respect to timing of precipitation. A few solutions support a dry first half of Saturday with a wet Saturday evening/Saturday night. Still time to iron out those details, but right now ensemble means are suggesting 0.5 to 0.75" of rain between Saturday morning and Sunday morning. By Sunday, model guidance suggests low-pressure will be exiting the region. This would be followed by a cooler/dryer end to the weekend with a similar pattern carrying into Monday. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 00Z TAF Update: High confidence. VFR through Tue night. Winds becoming light SW this evening, then light NW to calm late tonight. Sea breezes developing by midday Tue. Light SW wind Tue night. BOS TAF...High confidence in TAF. BDL TAF...High confidence in TAF. Outlook /Wednesday through Saturday/... Wednesday through Wednesday Night: VFR. Thursday: VFR. Breezy. Chance TSRA, slight chance SHRA. Thursday Night: Breezy. Slight chance SHRA. Friday: Breezy. Chance SHRA, chance TSRA. Friday Night: Breezy. Chance SHRA, slight chance TSRA. Saturday: Breezy. SHRA likely, chance TSRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tranquil boating conditions expected through Tuesday night with winds below 20 kt and seas 3 ft or less. SW flow this afternoon becoming NW after midnight, then locally onshore Tue afternoon nearshore waters as sea-breezes develop. Outlook /Wednesday through Saturday/... Wednesday through Wednesday Night: Winds less than 25 kt. Thursday through Thursday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Saturday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, slight chance of thunderstorms. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...KJC/RM NEAR TERM...KJC SHORT TERM...KJC LONG TERM...RM AVIATION...KJC/RM MARINE...KJC/RM