Area Forecast Discussion
Issued by NWS Boston, MA
Issued by NWS Boston, MA
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538 FXUS61 KBOX 240740 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 340 AM EDT Fri Jul 24 2026 .WHAT HAS CHANGED... No significant changes to the forecast. && .KEY MESSAGES... - Mainly dry conditions expected through the weekend with seasonable temperatures. - Periodic chances for showers and thunderstorms late Monday through mid-week, potentially lingering into Thursday. && .DISCUSSION... KEY MESSAGE 1...Mainly dry conditions expected through the weekend with seasonable temperatures. Surface high pressure builds further over the region today with flow aloft becoming more zonal. High pressure overhead will result in light and generally variable wind patterns today allowing for local sea breezes in the coastal areas. Temperatures will be in seasonable ranges with highs in the low to mid 80s. Another clear night will support radiational cooler allowing temperatures to fall into the 50s to around 60 overnight. The center of the surface high pushes offshore on Saturday shifting winds to the east. With weak high pressure still in place, expect another dry day with mainly sunny skies. Highs across the interior likely range in the low to mid 80s while the onshore flow will keep temperatures slightly cool (mid-upper 70s) along the immediate eastern coastal areas. By Sunday, mid-level troughing arrives from west. Most guidance also indicates a low pressure system passing offshore. As the NAM/RRFS are starting to come into range, they have been leaning more aggressive with bringing in a push of moisture from offshore later Sunday, particularly for the eastern portion of southern New England(Cape/Islands). Model soundings indicate a shallow layer of moisture in the lower levels supported by the easterly surface flow with drier mid-level air. This could potentially point to a layer of low clouds and even some patchy drizzle in areas of eastern MA developing through the day on Sunday. Other model guidance is less aggressive, but still shows a signal for moisture, although more faint. Due to the spread, this is lower confidence at this time. Details will become more clear as we sit more solidly in the high-res guidance window. KEY MESSAGE 2...Periodic chances for showers and thunderstorms late Monday through mid-week, potentially lingering into Thursday. There is a good consensus across model guidance on a mid-level trough positioning across the region for a good through at least late-week next week. A series of shortwaves embedded in the flow are expected to progress across the region through the week supporting periodic chances for showers and thunderstorms. Flow becomes more southerly Monday with moisture gradually advecting into the region ahead of the first shortwave. By Tuesday, precipitable water values rise to 1.50 to 2". This will set up the region for periodic chances for showers and thunderstorms, especially in the late Monday through mid-week timeframe. There is potential for the unsettled conditions to linger through Thursday if the trough tracks slower. There is a fair amount of agreement among guidance that this won`t be a complete wash-out with support for more diurnally driven development of showers and thunderstorms in the afternoon/evenings. Given above normal precipitable water amounts, localized heavy rainfall will be a possibility within any thunderstorms. There is a signal for potentially strong to severe thunderstorms highlighted in the NSSL ML probabilities Tue/Wed, given the higher instability and sufficient shear. Sometimes to keep an eye on for now. Temperatures will likely hover between normal to just below normal for the first half of the week. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 06z TAF Update: Today and Tonight...High Confidence. VFR conditions today and tonight. Generally calm to light S winds for interior terminals. Diurnally driven sea breezes along the immediate coast starting ESE then shifting to SE/SSE later in the after 8-12 kts. Sea breezes kick out 00-02Z shifting winds back to light S/SSW. Saturday...High Confidence. VFR. Easterly winds for all terminals. Less than 10 kts for the interior and 8-12 kts for the coastal areas. KBOS Terminal...High confidence in TAF. Sea breeze likely develops 14-16Z and kicks back out to S/SSW 01-03Z. KBDL Terminal...High confidence in TAF. Outlook /Saturday through Tuesday/... Saturday through Saturday Night: VFR. Sunday: VFR. Slight chance SHRA. Sunday Night through Monday: VFR. Monday Night: VFR. Slight chance SHRA. Tuesday: Mainly VFR, with areas MVFR possible. Breezy. Chance SHRA, chance TSRA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through Saturday...High confidence. Light winds and seas 1-4 ft today and tonight. Moderate risk for rip currents over the weekend. Outlook /Saturday through Tuesday/... Saturday: Winds less than 25 kt. Areas of seas approaching 5 ft. Saturday Night through Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Sunday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Monday: Winds less than 25 kt. Seas locally approaching 5 ft. Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Tuesday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers, slight chance of thunderstorms. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ DISCUSSION...Mensch AVIATION...Mensch MARINE...Mensch