


Area Forecast Discussion
Issued by NWS Boston, MA
Issued by NWS Boston, MA
887 FXUS61 KBOX 132340 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 740 PM EDT Mon Oct 13 2025 .SYNOPSIS... A coastal storm will continue to impact coastal areas with occasional heavy rain and gusty winds through tonight. The coastal low will begin to move farther offshore Tuesday, with decreasing rains and easing northerly winds. However, an unseasonably cool airmass brings dry weather with below normal temperatures and a return of breezy northwest winds for mid to late this week. Temperatures then rebound back to above normal levels for this weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Key Messages: * Locally heavy rain focused across SE coastal MA through tonight * Isolated t-storms with heavy rain possible across RI and SE MA late afternoon through tonight * NE winds slowly diminish through tonight but remain gusty along the coast Persistent heavy rain banding has been impacting Plymouth county since the morning. Decent low level frontogenesis combined with convergence at the land sea interface at the nose of the low level jet contributing to the enhanced rainfall. Low level frontogenesis is persistent across SE MA tonight within a weakening but nearly stationary low level jet axis across SNE, with PWATs near 1.5 inches along the coast. As a result, expect locally heavy rainfall with additional amounts up to 2 inches across portions of Plymouth county. The other forecast issue through tonight will be the potential for a few heavy convective showers or t-storms developing across RI and SE MA. Elevated instability is increasing this afternoon through tonight across SE New Eng. Soundings show up to 500 J/kg of elevated CAPE above the frontal inversion. Many of the hi-res CAMs are showing numerous convective showers moving in from the ocean and impacting portions of eastern MA into RI which would enhance rainfall in this area and could produce some localized flooding if heavy rainfall occurred in a short time period. This is something that will need to be monitored through tonight. Otherwise, should see slow improvement further inland with bands of light rain tapering off and ending overnight. Regarding wind forecast, expect strongest winds with gusts 40-50 mph through the afternoon across the Cape/Islands, with 30-40 mph gusts near the coast slowly diminishing late today through tonight as persistent and nearly stationary low level jet gradually weakens. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Key Messages: * Rain gradually ending across eastern MA late morning through the afternoon * Gusty NE winds diminishing along the coast Tuesday... The morning looks wet across eastern MA as bands of showers will continue to impact the region, with a risk of thunder over the Cape/Islands as persistent low level jet acts on elevated instability. Otherwise, it will be drying out further inland with mainly dry conditions, especially western New Eng. Eventually the rain in eastern MA will end during the afternoon as the coastal low drifts offshore. NE wind gusts 25-35 mph along the immediate coast will gradually diminish through the afternoon. Highs will range from 55-60 across much of SNE with lower 60s Cape/Islands. Tuesday night... As the coastal storm continues to pull away, ridging aloft builds into the region with drier air in the column moving in form the NW with decreasing PWATs. Expect partial clearing with diminishing wind becoming light, with lows mostly in the 40s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Ensemble guidance is in good agreement for upper troughing across the region Wednesday through Friday. The previous coastal low slowly pulls offshore. This will keep an enhanced NW-SE pressure gradient across southern New England supporting "blustery" conditions through mainly Friday. A cooler airmass will be in place through late week, especially for Thursday. Residual moisture Wednesday-Thursday may support a few showers across the Cape/Islands. More forecast details below... Wednesday through Friday: Breezy, cool, and mainly dry (for most). However, the combination of a cooler airmass, residual moisture, and NW winds will bring cloudy conditions to the Cape/Islands along with some ocean-effect showers possible Weds/Thurs. A cooler, below normal airmass sinks across the region within the upper trough. Temperatures trend at to slightly below normal on Wednesday with highs in the upper 50s to low 60s. Later Wednesday into Thursday, deterministic/ensemble guidance indicates another push of cooler into the region. This will bring in a below normal airmass with 850mb temperatures -3 to -1C. This will likely yield high temperatures in the 50s for Thursday with even upper 40s possible across the high terrain locations of the interior. This is about 5-10 degrees below normal. With the added element of wind, it may feel like 40s at times. Temperatures will slowly moderate Friday as an upper ridge approaches from the west bringing gradual height rises. An enhanced NW-SE pressure gradient stay intact across the region bringing breezy NW winds. Gusts 20-30 mph are possible on Wednesday over land with gusts nearing gale force possible over the waters. Stronger winds are possible on Thursday as a push of cooler air drops southward late Wednesday into Thursday with NW downslope flow. Cool advection should support a well-mixed boundary layer bringing down gusty NW winds. Ensembles show gusts 25-35 mph with the higher gusts more likely for the Cape/Islands. Can`t rule out a gust up to 40 mph across the Berkshires. The waters will likely be gale force Thursday. Winds trend lighter for Friday as the gradient relaxes, but may stay elevated over the waters. Next Weekend: Ensemble guidance shows a good consensus for a pattern change developing Saturday into Sunday as a strong 500mb ridge pushes across the northeast. This will advect in higher heights, warmer temperatures aloft and keep conditions dry. There is potential for 850mb temperatures to rise to +12-14C by Sunday. Quite a difference from Thursday! Overall this will favor a warming trend for the weekend with temperatures closer to normal Saturday and potentially above normal Sunday with ensemble members showing a range of upper 60s to low 70s at this time. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 00Z TAF Update: Tonight: High confidence. Little change to ongoing conditions this period. IFR with MVFR/IFR visby rains for TAF sites east and south of ORH. This area will have the most degraded flight categories. Low chance for a rumble or two of thunder along the south-coast/southeast New England terminals. NE winds around 15-20 kt with gusts 25-30 kt, slowly easing by Tue AM. Further inland (BAF/BDL), mainly MVFR with more intermittent/light rain showers, with NE/N winds around 10-13 kt with gusts to 20 kt. Tuesday: High confidence in trends but lower confidence in timing improvement. Beginning Tue AM with IFR ceilings/MVFR visby rain for TAFs near and east/south of ORH, and MVFR ceilings for BAF/BDL. Very slow improvement in both flight categories and rainy conditions through the mid morning to early evening, occurring soonest in interior and later in the day (after 18z at soonest) for BOS, PVD and the Cape airports. NE winds gradually ease; by early evening, NE winds become NW around 5-10 kt, and still northerly around 10-15 kt over the Cape and Islands. Tuesday Night: High confidence. MVFR ceilings becoming VFR. Decreasing N to NW winds. KBOS Terminal...High confidence in TAF trends. Moderate confidence in timing. IFR visbys/ceilings in steady rain most of the overnight; while visbys in rain gradually improve, IFR ceilings likely to continue into Tue early- aftn, before improving up to MVFR levels late in the day. NE gusts around 25-30 kt early tonight but slowly decrease and become N during Tue. KBDL Terminal...High confidence in TAF trends. Moderate confidence in timing. MVFR with intermittent rain tonight, trends dry early Tue with MVFR improving to VFR by aftn. N winds around 10 kt. Outlook /Wednesday through Saturday/... Wednesday: VFR. Breezy. Wednesday Night: VFR. Windy with local gusts up to 30 kt. Slight chance SHRA. Thursday through Thursday Night: VFR. Windy with gusts up to 35 kt. Slight chance SHRA. Friday: VFR. Windy with local gusts up to 30 kt. Friday Night: VFR. Saturday: && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Gale warnings continue across the coastal waters into this evening before winds gradually diminish overnight through Tuesday. Small craft advisory winds and rough seas will persist through Tuesday before diminishing Tue night. Visibility reduced at times in rain and fog into Tuesday. Outlook /Wednesday through Saturday/... Wednesday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Slight chance of rain showers. Wednesday Night: Strong winds with gusts up to 30 kt. Rough seas up to 9 ft. Chance of rain showers. Thursday: Strong winds with gusts up to 40 kt. Rough seas up to 10 ft. Chance of rain showers. Thursday Night: Strong winds with gusts up to 35 kt. Rough seas up to 11 ft. Chance of rain showers. Friday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 11 ft. Chance of rain showers. Friday Night through Saturday: Winds less than 25 kt. Local rough seas. && .TIDES/COASTAL FLOODING... Minor splashover possible for late afternoon high tide across eastern MA coast from combination of 1-1.5 ft surge and up to 15 ft seas offshore. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Wind Advisory until 8 PM EDT this evening for MAZ022>024. RI...Wind Advisory until 8 PM EDT this evening for RIZ008. MARINE...Gale Warning until 11 PM EDT this evening for ANZ230. Gale Warning until 2 AM EDT Tuesday for ANZ231-233>235-237-251. Gale Warning until 4 AM EDT Tuesday for ANZ232-250-254>256. Small Craft Advisory until 7 PM EDT Tuesday for ANZ236. && $$ SYNOPSIS...KJC/Mensch NEAR TERM...KJC SHORT TERM...KJC LONG TERM...Mensch AVIATION...Loconto/Dooley/Mensch MARINE...KJC/Mensch TIDES/COASTAL FLOODING...