Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 200832 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 432 AM EDT Wed Jun 20 2018 .SYNOPSIS...
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Dry weather is expected today as high pressure builds across New England. Showers are likely tonight south of the Mass Pike as low pressure passes south of New England. High pressure from Canada brings dry weather Thursday and Friday. A cold front them brings a chance of showers at times this weekend, followed by dry weather early next week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Clearing skies moving SE across the region at 08Z as seen on latest GOES-East IR and Nighttime Microphysics imagery. Patchy fog also lingers across Nantucket from time to time, though light W-NW winds have brought in some clearing at 08Z. High pressure across NY state will push SE during the day, so expect light W winds to shift to SW during the afternoon. May see enough mixing across E coastal areas to see gusts up to around 20 kt this afternoon, mainly from Boston north to Cape Ann. Clouds will increase during the afternoon as mid and upper level moisture starts to approach ahead of the next system. Expect seasonable temps today, up to the lower 80s across NE Mass to the CT valley, though only in the mid 70s or so along S coastal areas with the onshore wind.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
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Tonight... 00Z model suite remains in pretty good agreement with the approach of low pressure out of middle Appalachians. Noted that the models are trending a bit further S with the low pres as the H5 long wave trough across the NE U.S. into Labrador and Newfoundland tends to flatten at its base S of New England. The low moves off the NJ coast around 09Z or so with a rather sharp northern extent of the precip shield. Looks like the best chance for showers will occur across N CT/RI into S coastal Mass where likely POPs are in the forecast. The higher QPF amounts area also suppressed to the S, so expect maybe 0.1 to 0.2 inches, possibly a bit higher on the islands. Looks like conditions should remain mainly dry, but can`t rule out a few brief showers possibly as far N as the Mass Pike. Thursday... Leftover showers along S coastal areas should push offshore by midday, though there is some timing issues amongst the model suite during this timeframe. Leaned toward the somewhat faster GFS/GGEM timing. Skies should become mostly clear during the afternoon, though a few clouds may linger across Cape Cod and the islands. It will be a cooler day on Thursday along the Mass E coast as winds become E-NE by around midday or early afternoon. Temps there will only top off in the mid 60s to lower 70s, coolest on the outer Cape and Nantucket, ranging to the lower 80s across the CT Valley.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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Highlights... * Dry and seasonable on Friday * Unsettled weather for this weekend * Dry weather early next week Overview... 20/00Z guidance continues to show improved agreement in the mid level pattern from earlier cycles. This agreement still breaks down in some of the finer details Saturday night into Sunday, but not to the point where confidence is lost in the overall trends. High pressure should move offshore, opening the door for a low pressure to move through the Great Lakes into the Saint Lawrence valley. This trajectory will force both the warm and cold fronts of this system across southern New England sometime this weekend. At this time, expecting an increasing risk for showers late Friday night into Saturday, peaking about Saturday evening, then diminishing into Sunday. A secondary cold front should cause showers to linger later Sunday. This weekend still doesn`t look like a washout. Another high pressure should return with dry weather early next week. Not seeing any major deviations from normal temperatures for this period. Perhaps a bit cooler than normal Saturday, depending upon timing of a warm front and amount of sunshine.
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&& .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
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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 Thursday/... High confidence. Through 12Z...VFR. INVOF KACK, expect variable CIGS/VSBYS from VFR to IFR-LIFR in patchy low clouds/fog moving across. Light N or calm winds will become light NW by around 10Z or so. Today...VFR. May see brief MVFR VSBYS in patchy fog INVOF KACK through around 14Z. Winds shift to W-SW up to around 10 kt inland, and 10-15 kt across E MA/RI. May see gusts up to 20 kt on portions of Cape Cod after 20Z or so. Tonight...Mainly VFR. May see brief MVFR VSBYS in patchy fog along S coastal terminals around or after 04Z. Scattered -SHRA move from W-E this evening S of the Mass Pike. Best chance across central and NE CT/RI and S coastal Mass with brief local MVFR CIGS. W-SW winds gusting to 15-20 kt this evening across Cape Cod. Winds shift to light W-NW across the interior after 06Z. Thursday...VFR. Any leftover -SHRA along S coastal areas move offshore by mid morning, though may linger until midday across Cape Cod and the islands. N-NW winds shift to E-NE by around midday, with some gusts to 20 kt along E coastal terminals possible. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Thursday Night through Sunday/...Moderate confidence. Thursday Night through Friday: VFR. Friday Night: VFR. Slight chance SHRA. Saturday: Mainly VFR, with areas MVFR possible. SHRA likely. Saturday Night: Mainly VFR, with local IFR possible. Chance SHRA, isolated TSRA. Sunday: Mainly VFR, with local MVFR possible. Chance SHRA.
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&& .MARINE...
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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 Thursday/...High confidence. Through 12Z...Light N-NW winds with seas 1 to 3 ft. Today and Tonight...Light W winds early today shift to SW, up to 15-20 kt on the eastern waters late today. May see gusts up to 25 kt late this afternoon into this evening on the eastern outer waters, where seas may briefly build up to 4 ft. Small Craft Advisory has been issued. Winds may gust up to 20 kt on the lower end of Narragansett Bay into Buzzards Bay with locally choppy seas this afternoon. Reduced visibility in showers and patchy fog tonight mainly across the south coastal waters. Thursday...N-NW winds early Thu will shift to E-NE by midday Thu with gusts up to 20 kt possible. Leftover reduced visibility along S coastal waters through midday Thu, then improving. Outlook /Thursday Night through Sunday/...Moderate confidence. Thursday Night through Friday: Winds less than 25 kt. Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Rain showers likely. Saturday Night: Winds less than 25 kt. Local rough seas. Rain showers likely, with isolated thunderstorms. Sunday: Winds less than 25 kt. Areas of rough seas. Slight chance of rain showers.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 4 PM this afternoon to 10 PM EDT this evening for ANZ250. && $$ SYNOPSIS...Belk/EVT NEAR TERM...EVT SHORT TERM...EVT LONG TERM...Belk AVIATION...Belk/EVT MARINE...Belk/EVT

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