Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 291739 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 139 PM EDT Thu Sep 29 2016 .SYNOPSIS... A low pressure wave will pass south of the region, bringing cloudy, cool conditions with showers Friday through Saturday which may linger into Sunday. Conditions will improve somewhat early next week, but still can not rule out a period of showers. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 140 PM Update...MSAS is showing high pressure building down the east coast as of 17Z. This is allowing cloud cover to erode a bit across northeastern MA. Much of the western part of the area remains mostly clear though there are some patchy clouds. Otherwise, not much has changed since the last update. There is still enough of a gradient to result in gusty northeasterly winds across much of the area. Due to the persistent and strong NE winds, have issued a High Surf Advisory for east facing coastlines of Cape Ann, outer Cape Cod and Nantucket through 6 PM today. High risk of rip currents as well as some possible splashover around the time of high tide late this morning to midday. Also near a new moon phase so somewhat higher astronomical tides. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Tonight and Friday... Any breaks in the clouds early tonight across northern areas will be short lived as mid and high level moisture works N-NW especially after midnight. Persistent NE winds will keep raw conditions in place, though gusts will tend to drop off late. Overnight lows will be close to this morning`s lows, ranging from the upper 40s across the higher inland terrain to the mid and upper 50s along the immediate coast. On Friday, a wave of low pressure will try to push NE, but will stay offshore. However, a plume of moisture will work northward in the mid level wind flow. PWATs will increase to 1.9 to 2 inches across S coastal areas by late in the day. Slug of precip also looks to shift N, with the best shot for precip across N CT/RI and SE Mass. QPF amounts could reach 0.3 to 0.5 inches during Friday, highest along the immediate S coast. The fight between drier low level air and the higher moisture aloft will make it tough to get appreciable rainfall north of the Mass Pike, where a tenth of an inch or less is forecast at this point. Have carried likely POPs near and south of the Mass Pike for most of Friday. Expect highs in the mid to upper 50s across the inland terrain ranging to the lower-mid 60s elsewhere. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... Highlights... * Periods of showers and drizzle into Sat with cool afternoons * Some showers and drizzle may linger into Sunday * Drier weather Mon-Wed but a period of showers remain possible Details... Friday Night and Saturday... Strong high pressure across eastern Canada will combine with a low pressure emerging off the mid Atlantic coast to produce a period of wet weather across most of southern New England. Although this surface low is not too strong, expecting gusty northeast winds along the coast, especially across the Cape and islands. While measurable rainfall will occur, its uncertain if 1+ inch amounts will make it into any of our region, or remain to our south where better low level forcing resides. The most likely areas to get heavier rainfall should be the Cape and islands, which will be closer to the low circulation. Onshore flow, clouds and periods of showers will keep high temperatures below normal for late September. Sunday... The Mid Atlantic low pressure moves farther east, allowing the pressure gradient to weaken. However, high pressure over the Maritimes will still still generate a moist, northeast flow. Depending on the exact timing, some showers and drizzle will probably linger into Sunday, especially along the eastern MA coast. High temperatures will likely remain below normal given lingering low clouds. Monday through Wednesday... Another high pressure will build down into eastern Canada and northern New England early next week. While a shortwave may bring a period of showers, a good shot at dry weather for a decent portion of this time frame. Northeast winds at the surface much of the time will probably continue to hold high temperatures near to below seasonable levels. We also will have to keep a close eye on what is expected to become Hurricane Matthew over the Caribbean. Most model guidance suggests this system will remain south of our region through Wednesday of next week. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday/... Through 00Z...Moderate confidence. A mix of conditions will continue through the rest of the day with a mix of MVFR and low end VFR conditions across eastern MA and a mix of VFR to clear skies across the western zones. NE winds gusting to 25-30 kt across E MA/RI. Tonight...Moderate confidence. Mainly VFR tonight near and N of the Mass Pike. Low end VFR-MVFR CIGS move into southern areas. Gusty NE winds to 25-30 kt continue along the east coast. Friday and Friday night...Low confidence, mainly for timing. Will see MVFR- IFR CIGS and/or VSBYS as -SHRA and patchy fog move in from S-N during the day. NE wind gusts up to 25 kt continue along the coast. KBOS TAF...High confidence in trends, moderate confidence in timing. KBDL TAF...High confidence in trends, moderate confidence in timing. Outlook /Saturday through Tuesday/... Saturday through Sunday...High confidence. Mainly MVFR to IFR conditions in low clouds, periods of showers/drizzle and patchy fog. Northeast wind gusts of 20 to 30 knots expected along the coast, and perhaps a bit stronger across Nantucket. Monday...Low confidence. May see improvement to mainly MVFR conditions. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday/...High confidence. Gale warnings issued for portions of the south coastal waters as winds gust up to 35 kt late tonight through midday Friday. Small crafts remain in effect for remaining waters. Expect NE winds to continue, with general gusts up to 25-30 kt most waters. Seas up to 8-10 feet, highest over the eastern open waters. Winds will gradually diminish during Friday, but will still see gusts to around 25 kt along with seas up to 7-9 ft. Outlook /Friday Night through Tuesday/... Friday Night into Saturday Night...High confidence. Rough seas expected to continue across the outer coastal waters. Seas gradually subside as winds diminish Saturday night. Small craft advisories needed at a minimum during this time. Still a possibility of gale warnings continuing for some of the southern coastal waters Friday Night. Sunday and Monday...Moderate confidence. Pressure gradient weakens, so expecting winds and seas to remain below small craft advisory thresholds. Some risk for rough seas to linger across the outermost eastern coastal waters. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...High Surf Advisory until 6 PM EDT this evening for MAZ007-022- 024. RI...None. MARINE...Small Craft Advisory until 6 PM EDT Friday for ANZ231>236-250- 251-254. Small Craft Advisory until 6 PM EDT this evening for ANZ230. Gale Warning from 2 AM to 8 PM EDT Friday for ANZ237-256. Gale Warning from 8 AM to 8 PM EDT Friday for ANZ255. && $$ SYNOPSIS...Belk/EVT NEAR TERM...RLG/EVT SHORT TERM...EVT LONG TERM...Belk AVIATION...Belk/RLG MARINE...Belk/EVT is the U.S. government's official web portal to all federal, state and local government web resources and services.