AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 709 AM EDT Wed Oct 29 2025 .SYNOPSIS... Canadian high pressure will result in cool temperatures through tomorrow night with widely scattered ocean-effect showers possible, mainly near and southeast of I-95. A strong low pressure system will bring a period of moderate-heavy windswept rain for southern New England later Thursday and Thursday night. Gradual drying early Friday morning followed by a period of gusty winds Friday into Saturday. Temperatures at or slightly below normal. && .NEAR TERM /THROUGH TONIGHT/... Key Messages: * Cooler temperatures continue with scattered ocean-effect showers mainly near/southeast I-95. Details... Another day of surface high pressure in southern New England with a surface high positioned over Quebec. This will support similar conditions to Tuesday as steady, cool northeast flow will keep a persistent cloud deck over the region today. Can`t rule out a few ocean-effect showers, mainly near/southeast of I-95. Moisture subtly increases over the region toward the afternoon, but any showers are more likely to be widely scattered in coverage with light accumulation if any. It will still remain breezy across east/southeast southern New England with gusts up to 20 mph in eastern MA and closer to 20-30 mph for the Cape/Islands. High temperatures will likely range in the low to mid 50s with a few upper 40s for the higher elevation spots of the interior. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... Key Messages: * A system will bring a period of moderate to heavy rainfall and gusty winds later Thursday and Thursday night. * Some isolated nuisance street flooding possible, exacerbated by abundance of fallen leaves. Details... Tonight: Overall quiet overnight period. Northeast winds/gusts gradually decrease into the early evening, slower to weaken in southeast MA. Moisture increases through the night as a plume of above normal (150-200%) advects in from the south overnight. This will deepen moisture through the night. Model guidance doesn`t indicate any substantial chances for showers, but can`t rule out a few showers especially by Thursday AM. Low temperatures drop into the mid-30s to low 40s for the interior and mid-40s for coastal/near-coastal areas. Thursday-Thursday Night: No major changes among ensemble/deterministic guidance in regards to a storm system that will bring a period of moderate to brief heavy rainfall across southern New England Thursday/Thursday night. Guidance still depicts a digging mid- level trough with an associated upper low becoming negatively tiled, lifting northward across the mid-Atlantic and into the eastern Great Lakes. An associated surface low should also deepen as it tracks northward. Although, the envelope of ensemble members show that there is still some uncertainty in the low track with also question in if there will be secondary low development. The incoming trough and accompanying upper jet will provide large-scale lift across the region with a plume of above normal moisture advecting into the region within the SW flow aloft. This will support widespread moderate rainfall across the region, potentially heavy at times. For timing, confidence is moderate as there is some variation among model guidance on exact timing. Most guidance has the main bulk of rain arriving in the mid afternoon to early evening Thursday timeframe. A few showers are possible during the day. Rain continues Thursday night with pockets of heavy rainfall possible. Ensembles show a range of most likely amounts from 0.75-2.0", with some higher members showing localized 2.5-3.0". The location of the heavier amounts will depend on the track of the low, with guidance highlight the Cape/Islands as more likely to receive amounts 1-2"+ amounts. Given the progressive nature of this system, flash flooding is not likely, although some localized nuisance flooding in poor drainage/low lying areas is possible. Fallen leaves this time of year may potentially exacerbate the nuisance flooding due to clogging of storm drains. It will be fairly breezy with east/northeast winds expected with gusts 20-35 mph, potentially up to 40 mph for the Cape/Islands. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Details... Key Messages... * Gusty winds develop Friday with gusts potentially up to 40 mph for higher terrain and coastal areas. Details... The dry slot associated with the system pushes into the region early Friday morning decreasing showers. Things won`t completely dry out as there will likely be wrap around moisture around the low shifting across the region Friday. It should stay mainly dry with only a pop up shower or two with the cold pool overhead. The biggest concern for impacts will be the gusty winds. The exiting deep low will supply a sufficient pressure differential/gradient across southern New England. A 45-55 kt LLJ positions across the region with cold advection which will help provide more efficient means of mixing down the stronger winds to the surface. Ensembles show potential for gusts 30-40 mph Friday afternoon and evening. This seems to match what model soundings show. The max gusts will be a matter of how deep we can mix and likely stemming from the strength of the cold advection. The east slope of the Berkshires will be favored for higher gusts with westerly component flow even providing downslope enhancements as well. Coastal areas such as the Cape may also be at risk for higher gusts 35-40 mph. Wind headlines may be needed Friday and/or Friday night. The pressure gradient relaxes a bit Saturday reducing the risk for strong winds/gusts; however, it will still be windy on Saturday. Winds become lighter Sunday as the pressure gradient relaxes even further. Dry conditions are expected with temperatures slightly below normal with highs in the low to mid 50s. Weak mid-level ridging continues into early next week keeping conditions mainly dry. Confidence decreases in the pattern toward mid-week with regard to a weak system moving through sometime Tue/Wed bringing the next shot for showers. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 12Z TAF Update: Wednesday...High Confidence. MVFR ceilings and steady northeast winds 8-12 kts with gusts around 20 kts for BOS and stronger (20+kts) for the Cape and Islands. A few light showers may develop near the east coast, Cape, and Islands by early to mid afternoon. Gusts decrease in the late afternoon for BOS and gradually weaken for Cape/Islands in the evening. Wednesday Night... High Confidence. MVFR ceilings and steady northeast winds around 10 knots. Isolated brief shower/sprinkle possible for east/southeast terminals. Thursday...High Confidence. Moderate for exact timing of rain. MVFR ceilings with IFR developing as the rain arrives with an incoming system. Rain arrives generally from west to east Thursday afternoon/early evening continuing Thursday night. KBOS Terminal... High confidence in TAF. Brief VFR possible with ceilings above 3000 feet at times, but MVFR ceilings from 2000-3000 feet should prevail for most of the TAF period. KBDL Terminal... High confidence in TAF. Outlook /Friday through Sunday/... Friday: Mainly VFR, with local IFR possible. Strong winds with local gusts up to 40 kt. Chance SHRA. Friday Night: Mainly VFR, with local MVFR possible. Strong winds with local gusts up to 40 kt. Saturday: VFR. Strong winds with local gusts up to 40 kt. Saturday Night: VFR. Breezy. Sunday: VFR. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Today and Tonight: The pressure gradient relaxes relative to Tuesday night. This will gradually diminish northeast winds throughout the day. Despite declining wind speeds, we`re still expecting 20 to 30 knot northeast gusts throughout the day with ocean-effect showers possible. Seas gradually subside by a foot or two as well, but remain elevated between 5 and 9 feet over the outer marine zones. These conditions will persist through tomorrow night. Outlook /Friday through Sunday/... Friday: Moderate risk for gale force winds with local gusts up to 45 kt. Rough seas up to 17 ft. Slight chance of rain showers. Friday Night: gale force winds with gusts up to 45 kt. Rough seas up to 18 ft. Saturday: Moderate risk for gale force winds with gusts up to 40 kt. Rough seas up to 16 ft. Saturday Night: Low risk for Small Craft Advisory winds with local gusts up to 30 kt. Local rough seas. Sunday: Winds less than 25 kt. Seas locally approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 AM EDT Thursday for ANZ231>235- 237-250-251-254. Gale Warning until 8 AM EDT Thursday for ANZ255-256. && $$