Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 060159 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 959 PM EDT Thu Aug 5 2021 .SYNOPSIS... Low pressure departs this evening making way for a pleasant end to the work week. The better part of Saturday looks dry before a slight chance of showers develops Saturday evening as a low tracks south of our region. This low may generate some showers again on Sunday. High pressure returns for early next week, bringing summer like temperatures and humidity to our by Tuesday and Wednesday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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10 PM update... The last of the showers have moved offshore but still plenty of low clouds and patchy fog persisting across RI and SE MA where low level moisture is hanging tough. Clearing has developed across CT and western MA where and this drying trend will gradually spread east overnight with partial clearing developing in the east. However, expect patchy radiation fog to develop overnight across portions of the interior. Lows will settle into the upper 50s and lower 60s across much of the region with mid 60s over the Cape/Islands and urban centers.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Humid and summerlike conditions return for Friday, as rapid clearing continues its progress east on Friday morning. Seasonable 12-16C 850 mb temps suggest that we will reach highs slightly above average tomorrow, likely in the low to mid 80s across most areas. The CT River Valley will likely be the warmest spot given south/southwest flow up the valley. Clear conditions will persist through the short term period before clouds begin to creep into SNE from the West around 12Z Saturday. Temperatures will again be limited by dewpoints Friday night, with lows region wide between 60 and 70 degrees. Light southwest flow persists overnight. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Highlights... * Mostly dry and warmer on Saturday * Temperatures around average Sunday, cooler Monday, then warming back up toward mid week. Humidity slowly increasing as well, in the 60s early in the week, toward low 70s by late week. * Typical summer pattern with scattered shower chances each day but no washouts expected. Saturday... Mid level ridging with anticyclonic flow aloft with surface high pressure in the vicinity will keep things dry on Saturday with warmer temperatures to boot. Model soundings show the boundary layer mixing up to 850 mb where temperatures warm to around +17C so we can expect highs in the mid to upper 80s. Not looking like a full sun day, though; with a decent amount of mid and upper level moisture we should see a mix of clouds and sun. Can`t rule out a few scattered showers over western MA late in the day as a shallow shortwave crosses northern New England. This will bring a chance of light showers to the rest of the region during the overnight hours as well. Sunday and Monday... Caught between a northern stream shortwave dipping down from northern New England and a southern stream shortwave/surface low lifting out of the mid Atlantic, Sunday and Monday will be unsettled. Though exact details on who sees rain and when are less certain, it`s likely that we`ll see scattered showers with a mix of clouds and sun. Temperatures Sunday will be cooler than Saturday as slightly cooler air moves overhead and increased cloudcover reduced insolation. Monday onshore flow around the maritime high and low to the south will keep the east coast quite cool, in the upper 70s perhaps as far inland as Rhode Island. Tuesday through Thursday... A subtropical ridge builds in through mid week pumping up temperatures and bringing the return of highs in the mid to upper 80s along with more humid conditions; dewpoints reach the 70s once again by mid to late week. Given anticyclonic flow directing disturbances around the periphery of southern New England we should stay on the whole dry, though can`t rule out some scattered showers each afternoon/evening. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 00Z Update... Tonight...Moderate confidence. Showers have moved out, except for the Cape and islands where they should come to an end within the hour. IFR/LIFR conditions persist across eastern MA and RI terminals early this evening, improving to VFR slowly from west to east. Full clearing expected by 8-9 am on Friday, though some low clouds and fog are possible. Friday...High Confidence. VFR with light winds. Friday Night...High Confidence. VFR with light and variable winds. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Saturday through Tuesday/... Saturday: VFR. Saturday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA. Sunday: Mainly VFR, with areas MVFR possible. Chance SHRA. Sunday Night: VFR. Monday: Mainly VFR, with local MVFR possible. Slight chance SHRA. Monday Night: VFR. Tuesday: Mainly VFR, with areas MVFR possible. Slight chance SHRA. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. High confidence through Friday. Winds shift to the west/southwest overnight, but the surf may take some time to settle down on Friday. It is likely that a rip current statement will need to be hoisted for Friday off of Nantucket and Martha`s Vineyard given a high risk of rips off their southern coasts. Otherwise, winds will diminish below 15 kts through Saturday morning. Seas will drop below 5 ft across the inner waters around 18Z on Friday and across the outer waters by 00Z Saturday. /Outlook /Saturday through Tuesday/... Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Saturday Night through Sunday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Sunday Night through Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...High Rip Current Risk from 8 AM EDT Friday through Friday evening for MAZ023-024. RI...High Rip Current Risk from 8 AM EDT Friday through Friday evening for RIZ006>008. MARINE...Small Craft Advisory until 8 AM EDT Friday for ANZ235-237. Small Craft Advisory until 2 AM EDT Friday for ANZ250. Small Craft Advisory until 8 PM EDT Friday for ANZ254>256.
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&& $$ SYNOPSIS...KS NEAR TERM...KJC/BW/KS SHORT TERM...KS LONG TERM...BW AVIATION...BW/KS MARINE...KS is the U.S. government's official web portal to all federal, state and local government web resources and services.