635 FXUS61 KBOX 031906 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 306 PM EDT Tue Jun 3 2025 .SYNOPSIS... Summer warmth arrives Wednesday through Friday with heat peaking on Thursday with highs possibly into the lower 90s. Rain and thunderstorm chances increase again for Friday into the weekend. Drying out again for Monday with temperatures around seasonable levels. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Key Messages... * Dry tonight with lows mainly upper 40s & 50s Mid level ridge builds east into New Eng as surface high sets up south of New Eng. Some high clouds will move into the region but overall looking at mainly clear skies with light SW wind developing. Decent radiational cooling will allow low temps to drop into the 50s with some upper 40s in the coldest locations. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Key Messages... * Summer warmth arrives Wed with highs mid-upper 80s away from the south coast but low humidity * Some smoke/haze moves in aloft Mid level ridge continue to build across New Eng. Surface high moving offshore will result in a SW flow which will bring warmer low level temps into New Eng. 850 mb temps increase to 16-17C by late Wed with 925 mb temps 20-22C in the interior. This will result in highs reaching mid-upper 80s away from the south coast with a few locations in the CT valley and NE MA possibly reaching 90. Cooler upper 70s along the immediate south coast. Dewpoints will mix out into the low-mid 50s during peak heating so comfortable humidity levels. As mid level ridge moves into New Eng, expect smoke aloft to the west to move into the region. This will start tonight and continue into Wed before moving to the east late Wed-Wed night. This will result in a hazy sky at times. Another quiet night Wed night with mainly clear skies and light SW winds. Lows will drop into the upper 50s and lower 60s. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Key Messages: * Hot temperatures expected Thurs with temps in the lower 90s away from the coast with some humidity, and in the mid to upper 80s Fri. * Several chances for showers/t-storms Fri into Sun, better chances north. Heavy rain possible but details on timing and placement is still uncertain. * Brief dry weather for Monday. Details: Thursday: Thursday still projects as the warmest day in the spell of very warm temperatures, with 850 mb temps warming to around +16 to +18C and full sunshine supporting high temperatures well into the 80s to lower 90s. Some mid-90s could be achievable in areas such as the CT and Merrimack Valleys when factoring in a modest southwest wind. Dewpoints in the mid 60s support heat indices in the mid 90s, although these dewpoints could mix out a little lower. Regardless, although this will be the first really noticeable very warm and humid day and some areas could get near traditional heat advisory thresholds, we probably will fall short of meeting the time-based criterion (two or more days). Convective potential looks very limited with model forecasts of a capping inversion and subsidence aloft. Other than a limited (under 20 percent chance) at a t-storm in northwest MA closer to the leading edge of broader 500 mb height falls but anticipating drier weather for the vast majority of the time. Friday into the Weekend: Although temperatures will begin to cool off for Fri into the weekend, it`s also a potentially more active period weatherwise as broad southwest flow aloft with rather weak low-level winds associated with a broad upper trough over northeast North America interacts with subtropical moisture. This should (again) set the stage for several opportunities for showers/t-storms in this period. While the GFS and its GEFS parent ensemble are quite a bit drier, both the EPS/ECMWF and the Canadian GEM and its ensemble show some rather notable QPF amts with these international ensembles showing moderate (40-60%) probs of 24-hr rain over 1" and very low to low (10-20%) chances of 24-hr rainfall exceeding 2" near/north of the Mass Pike. The weaker flow aloft and lower instability may lead to less of a severe-weather risk, but instead potential for heavy downpours/training of rain into Fri and Sat; while the better potential for downpours based on current ensembles looks to be in the northern third of Southern New England, the exact placement is still in question. With regard to temps, Fri is still quite warm with highs in the mid 80s, although temps then cool off for Sat and Sun with readings in the mid 70s. Monday: Monday looks to be a brief break in the shower/t-storm activity as weak high pressure builds in. Expect drier weather but temps around seasonable levels before southeast flow returns and brings increased cloud cover for Mon night. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 18z TAF Update... Through Wednesday night...High Confidence. VFR conditions continue through the period. Light SW winds tonight and Wed night, with SW 10-15 kt Wed. BOS TAF...High confidence in TAF. BDL TAF...High confidence in TAF. Outlook /Thursday through Sunday/... Wednesday Night: VFR. Thursday: VFR. Breezy. Thursday Night: VFR. Slight chance SHRA. Friday: VFR. Chance SHRA, chance TSRA. Friday Night: Mainly VFR, with local MVFR possible. Chance SHRA, slight chance TSRA. Saturday: Mainly VFR, with areas MVFR possible. Breezy. SHRA likely, slight chance TSRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Through Wednesday night...High confidence. High pres over the waters will result in winds and seas below SCA thresholds through the period. Generally SW flow through the period with gusts up to 20 kt developing during Wed. Outlook /Thursday through Sunday/... Wednesday Night through Thursday Night: Winds less than 25 kt. Friday: Winds less than 25 kt. Slight chance of rain showers, slight chance of thunderstorms. Friday Night: Winds less than 25 kt. Chance of rain showers, slight chance of thunderstorms. Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...KJC NEAR TERM...KJC SHORT TERM...KJC LONG TERM...BW AVIATION...KJC/McMinn MARINE...KJC/McMinn