Area Forecast Discussion
Issued by NWS Boston, MA

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591 FXUS61 KBOX 221107 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 707 AM EDT Fri Sep 22 2017 .SYNOPSIS... Jose southeast of Nantucket will slowly drift back to the southwest the next few days. This will maintain strong winds, rain and rough seas today, which then diminish. Clearing skies will move in from the west tonight and Saturday. Warmer weather arrives Sunday and Monday, before a backdoor front brings cooler weather and possibly a few showers by midweek. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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7 AM update... Bands of rain showers are rotating west across eastern New Eng. Expect occasional bands of showers to continue to move into SNE from the ocean as shortwave energy rotates around mid level low SE of Nantucket. In fact, much of the hi-res guidance is suggesting some locally heavy rain across portions of SE MA. Further west across western MA and CT valley dry weather will prevail with partial sunshine. Strong northerly winds combined with clouds and showers will result in a chilly day in eastern New Eng, with temps holding near 60 or the lower 60s, increasing to low/mid 70s western MA and CT valley where some sunshine is expected. Wind gusts up to 45 mph will be confined to SE New Eng coast and especially the Cape and Islands but still windy further inland with 30-40 mph gusts in the coastal plain decreasing to 20-25 mph in the CT valley. Winds will begin to diminish mid/late afternoon. Previous discussion... Early this morning, Jose was 135 miles southeast of Nantucket and drifting slowly west. Meanwhile high pressure has settled over the Great Lakes and Northern New England. Still a strong pressure gradient around Jose, and this extends up to south coastal Mass and RI. With the storm and its gradient moving west, we would expect the winds to linger this morning across the Islands and South Coast. Winds aloft are forecast to diminish this afternoon and evening, so we will expect the surface winds to also diminish. Farther north, the pressure gradient is less, as are observed winds. Winds above the ground at Boston are still around 40 knots, but less to the west and northwest. At best, there may be some gusts near 40 knots. But the trend is lower. We will run a Wind Advisory through midday along Plymouth County and the South Coast. Radar shows showers across Southeast Mass and parts of RI, with the heaviest showers over Cape Cod and the Vineyard. With the storm drifting west, these showers may also move farther west into the rest of RI and move or Eastern Mass. The best chance of showers remains along the Cape and Islands. Temperatures will be warmest in the CT Valley, and coolest where the flow is coming off the water. Temps in the mixed layer favor mid 70s, so this is favored for the interior with max temps in the 60s farther east.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Jose continues to weaken while not moving out of the vicinity. So we expect north-northeast winds tonight and Saturday but with speeds diminishing to 5-15 mph inland and 15-30 mph on the Islands. Clouds linger over Eastern Mass and especially SE Mass until midday Saturday, but with a west to east clearing trend farther west. Lingering chance pops in RI and Eastern Mass tonight, but the chance dissipates Saturday morning as Jose further weakens. Dew points 55 to 60 will allow min temps similar to that where the winds diminish inland, a little milder along the coast due to clouds and wind. Temps aloft around 15-16C will support max temps Saturday in the mid 80s. Southeast of the I-95 corridor the clouds and ocean influence should hold max temps in the upper 60s and 70s. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Highlights... * Return to summer warmth Sun/Mon * Showers possible by mid week * Watching Maria but latest NHC track keeps it offshore Jose continues its slow dissipation through early next week, keeping high surf and elevated risk of rip currents on south coastal beaches. Concern is for an increase in beach-goers this weekend, as building upper ridge brings return to warmer conditions. Keep in mind many area beaches are no longer staffed with lifeguards this late in September! 850 mb temperatures warm significantly, to nearly 20C Sun/Mon, which translates to highs well into 80s across interior. It`s even possible we see a 90-degree reading in CT Valley Mon (BDL). It`s also not out of question parts of CT Valley experience late-season heat wave, though highs should fall just short of 90 both Sun and Tue. Warmth won`t last too long as backdoor front should drop south across region Tue and Wed, bringing somewhat cooler (seasonable) E/NE flow as well as scattered showers. Later next week, we still need to monitor track of Maria. Latest forecast is for it to pass offshore, but close enough to bring another round of high surf with renewed threat of rip currents and beach erosion. It`s still much to early to confidently say that will happen, since we need to assess interaction with approaching Great Lakes trough/surface cold front. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday/... Today... Gusty North-northeast winds continue today, with gusts to 40 knots along the south coast and islands and gusts in the 30s farther north. These winds will diminish this afternoon and evening. Observed cigs at MVFR/IFR levels in Eastern Mass. This may spread back to the northwest a little, covering RI and parts of Central Mass for a few hours. Vsbys may also briefly lower to around 4 miles in showers. Tonight and Saturday... MVFR cigs linger across Eastern Mass and RI tonight, then lift to VFR Saturday. Winds will diminish through the period, with gusts 20- 30 knots mainly along the South Coast. KBOS TAF...Moderate confidence. Cigs will lower through the day, but linger at MVFR levels. A few showers may move through with brief MVFR vsbys. Winds at 2000 ft AGL are around 40 knots, so gusts 35 to 40 knots are possible today, then diminishing. KBDL TAF...High confidence in TAF. Outlook /Saturday Night through Tuesday/... High confidence. Sun and Mon... VFR. Light winds with sea breezes possible. Tue... MVFR possible in scattered showers, especially eastern MA.
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&& .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Today... Jose continues to drift west, but well south of the waters. Still expect winds from the north-northeast, gusting 35 to 40 knots on the southern waters and 25 to 35 knots in the east. Seas will remain rough at 10-15 foot offshore, while rough but lower closer to shore. Showers continue, especially over the southern and southeast waters. Tonight and Saturday... Gusty north winds will diminish tonight and Saturday. Winds above 25 knots will linger on the southern and southeast waters Saturday. Seas will also diminish through the period, but with 5 foot seas lingering on the outer waters Saturday. Outlook /Saturday Night through Tuesday/... Moderate confidence. Light winds expected Sun with local sea breezes as high pressure remains over waters. Backdoor cold front is expected to drop S across waters Mon into Tue with light E/NE winds and scattered showers. Seas will gradually subside Sun and should finally drop below 5 ft on outer waters. Lingering swells from Jose, combined with increasing swells from Maria may lead to seas building over 5 ft again on waters S and E of Nantucket by Mon or Tue. && .TIDES/COASTAL FLOODING... Another round of minor coastal flooding is expected with this afternoon`s high tide on Nantucket with expected 1 ft storm surge. Along Plymouth County coast, we will not extend the Coastal Flood Advisory since the combination of 1 ft surge and seas of 12 ft offshore does not even yield minor flooding. High surf will continue into at least Saturday along the east side of Cape Cod and Nantucket with lingering beach erosion. Some beach erosion may also persist along south facing ocean exposures. Swells from Maria may re-increase the surf and associated rip current risk across our ocean exposed south coast sometime during the first half of next week, even though Maria may eventually recurve out to sea before getting too close to New England. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Tropical Storm Warning for MAZ022>024. High Surf Advisory until 6 AM EDT Saturday for MAZ007-019-020. Wind Advisory until noon EDT today for MAZ018>021. RI...Tropical Storm Warning for RIZ008. High Surf Advisory until 6 AM EDT Saturday for RIZ006-007. Wind Advisory until noon EDT today for RIZ005>007. MARINE...Tropical Storm Warning for ANZ231>235-237-250-254>256. Small Craft Advisory until 4 PM EDT this afternoon for ANZ230- 236-251. && $$ SYNOPSIS...WTB/JWD NEAR TERM...WTB/KJC SHORT TERM...WTB LONG TERM...JWD AVIATION...WTB/JWD MARINE...WTB/JWD TIDES/COASTAL FLOODING...

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