973 FXUS61 KBOX 062352 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 752 PM EDT Sun Jul 6 2025 .SYNOPSIS... Higher than normal heat and humidity expected Monday with a Heat Advisory in place. Unsettled weather makes a return Monday into Monday night, continuing off and on through much of next week. Cooler weather expected middle to late next week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Key Messages... * Mild with low clouds/patchy fog for the south coast and Cape/Islands. Still thinking low clouds and fog push onto the south coast of New England overnight. Still tough to pin down the timing, as the stratus and fog is not yet visible via satellite over the ocean. The best estimate is just before midnight towards Nantucket, and between to 2-5 AM for the south coast of RI and MA. Previous Discussion... Mild temperatures and dry conditions expected tonight. Deeper moisture moves in from the south overnight, which may in aid in some development of lower clouds. Most high- res guidance shows lower clouds extending from the south mainly south of the Mass Pike, but there are a few models that show potential for lower clouds further north. Can`t rule out some patchy fog for the immediate south coast and Cape/Islands overnight. The warm temperatures from Sunday and limited radiational cooling will keep lows warmer in the upper 60s to low 70s. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Key Messages: * Warmer than normal and humid. Heat Advisory in effect. * Isolated showers and thunderstorms in afternoon, mainly for western CT and MA. Monday: Mid-level ridging continues over southern New England on Monday. Southerly jet should help transport a plume of above normal moisture (150-180% of normal) into the region. This will keep more humid air around for Monday. Temperatures will lean above normal as well with highs in the upper 80s to low 90s, although a bit cooler for the immediate south coast and Cape/Islands in the low-mid 80s. With the humidity it will feel more like low to mid 90s which has lead to a Heat Advisory being in effect Monday. Breezy SW winds. A weak shortwave approaches in the flow aloft later in the day. An approaching wave/cold front combined with instability (MLCAPE 500- 1,000 J/kg) should support isolated to scattered showers and thunderstorms developing in the afternoon as the front moves eastward. Highest chances will be in western MA and CT where the better instability is. 0-6km bulk shear values are low and mid level lapse rates are weak, so not expecting a severe risk. Model soundings do exhibit deeper warm cloud layers, skinny CAPE, and above normal PWATs, so any storm may be capable of heavy downpours. There is potential for a shower or storm to move further eastward, although a lower probability. HREF PMMs show isolated 6 hour QPF amounts up to a half inch while the ensemble max is closer to an inch. So overall, very isolated risk for a storm with a heavy downpour. Monday Night: Another mild night with temperatures hanging in the upper 60s and lower 70s. A cold front slowly works across the region into early Tuesday. Showers are possible overnight with higher chances of the Cape and Islands and SE MA. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Key Messages... * Marginal risk of flash flooding and severe thunderstorms Tuesday * Unsettled weather continues through the workweek * Below average temperatures late week TUESDAY The region will be in the right entrance region of a weak jet on Tuesday. At the same time, a cold front will move south, slowing and weakening as it does so. The remnant circulation of TS Chantal will likely partially interact with this boundary resulting in a period of rain Tuesday morning. After a brief lull in rainfall late Tuesday morning, attention turns to the possibility for widespread showers and scattered thunderstorms Tuesday afternoon. The WPC has placed the region in a marginal risk for excessive rainfall and flash flooding Tuesday. NAEFS ensemble tables indicate the chance for PWAT values to rise as high as 1.9-2.1" (+2.5 STD above climatology!) by Tuesday afternoon. The tropical airmass will also bring deep warm cloud depths approaching 13K feet and weak steering currents. BUFKIT model soundings show winds < 30kts all the way up to 300mb! The other risk Tuesday will be the chance for isolated severe thunderstorms. Dewpoint values in the 65-70 degree range will allow for MLCAPE values to easily climb to the 1500-2000 j/kg range. Despite sufficient instability levels effective shear values < 20kts will likely limit coverage and intensity of any severe storms. The SPC has placed areas of western and central Connecticut and Massachusetts in a marginal risk of severe storms with the primary risk being damaging winds. The NBM blend shows temperatures rising into the upper 80s and lower 90s on Tuesday. Heat index values climb further, with a few areas rising to as high as 95-100 degrees. Future shifts will decide on extending the Heat Advisory as the spatial and temporal extent of the hot conditions Tuesday afternoon comes into better focus. WEDNESDAY THROUGH SATURDAY Clockwise flow around a Bermuda ridge will maintain a steady stream of moisture into the region Wednesday through Friday. Guidance shows PWAT values between 200-250% above normal throughout the middle of the week. A series of disturbances arrive on near zonal flow starting early Wednesday. The flow becomes more meridional Thursday in response to a building ridge across far northern Canada. At the surface, models are hinting at a weak area of low pressure passing through the region on Thursday. NBM guidance currently shows low probs of 24-hour rainfall totals exceeding 1" on Thurs but this could change as model guidance irons things out going forward. Finally, temperatures will fall quite a bit by Thursday and Friday with an easterly onshore flow developing. Ensemble guidance shows surface temperature anomalies falling to between 5 and 10 degrees below climatology Thursday afternoon. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight...Moderate confidence. VFR early evening. Areas of MVFR/IFR develop mainly south of I-90 after 05z. Patchy fog develops across the south coast. Gusty winds gradually decrease between 23-03z. SSW to SW winds at 8-14 kts tonight, less than 10 kts for the interior terminals. Monday...Moderate confidence. MVFR to IFR along the south coast of RI and MA in the morning. South coast may scatter after 12z. Confidence is moderate in whether it scatters or stays BKN. Cape/Islands slower to improve in the AM gradually improving into the early afternoon. SSW to SW winds 10-15 kts, gusts 20-24 kts by early afternoon. Isolated showers and few thunderstorms develop after 16z in western CT and MA. Notated as PROB30 -TSRA for now. There is a low chance (< 30%) that a stray shower/storm makes it further east, but too low to include in TAF right now. KBOS Terminal...High confidence this afternoon. Moderate Monday. Low clouds develop to the south overnight, but are unlikely to reach the terminal. BKN mid-level ceilings Monday with SW winds with gusts around 20 kts in the afternoon. Low chance for an isolated shower/storm makes it east to to BOS after 18z. More likely to be later in the evening before showers are a concern. KBDL Terminal...High confidence. Moderate Monday. Forecast confidence is moderate beyond 10z Monday with the potential for lower ceilings. Isolated -SHRA/-TSRA possible after 16z. Low chance given isolated nature, so included as a PROB30 -TSRA through 23z. Outlook /Tuesday through Friday/... Tuesday: Mainly VFR, with local MVFR possible. Breezy. Chance SHRA, chance TSRA. Tuesday Night: Mainly VFR, with local IFR possible. Chance SHRA, slight chance TSRA. Wednesday: Mainly VFR, with local IFR possible. Slight chance SHRA. Wednesday Night: Mainly VFR, with local IFR possible. Chance SHRA. Thursday: Mainly VFR, with areas IFR possible. Chance SHRA, slight chance TSRA. Thursday Night: MVFR/IFR conditions possible. Chance SHRA, slight chance TSRA. Friday: Chance SHRA, slight chance TSRA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Through tonight: High confidence. SW winds this evening, gusting 20-25 kts, as high as 30 kts on eastern waters. Seas 3-5 ft. Most zones will stay shy of SCA criteria except the northern outer waters with gusts 25-30 kts in the afternoon and sea 4-5 ft. SCA will be in effect for that zone through 06z Monday. Monday-Monday Night: High confidence. After a brief lull Monday morning, SW winds increase Monday afternoon to 10-15 kts with gusts 20-25 kts on southern waters, 25-30 kts on the eastern waters. May need a SCA for the north outer waters zone. Seas 2-3 ft, increasing to 2-4 ft on the outer waters late in the day. Seas increase to 5 ft for the southern outer waters after overnight into Tuesday. Outlook /Tuesday through Friday/... Tuesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Chance of rain showers, chance of thunderstorms. Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, slight chance of thunderstorms. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Wednesday Night through Thursday: Winds less than 25 kt. Chance of rain showers. Thursday Night through Friday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, slight chance of thunderstorms. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Heat Advisory until 8 PM EDT Monday for CTZ002>004. MA...Heat Advisory until 8 PM EDT Monday for MAZ003>007-010>019-026. RI...Heat Advisory until 8 PM EDT Monday for RIZ001>004. MARINE...Small Craft Advisory until 2 AM EDT Monday for ANZ250. && $$ SYNOPSIS...Mensch/FT NEAR TERM...Belk/Mensch SHORT TERM...Mensch LONG TERM...FT AVIATION...Belk/Mensch/FT MARINE...Mensch/FT