Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 151403 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 1003 AM EDT Fri Sep 15 2017 .SYNOPSIS...
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Scattered showers and a few isolated thunderstorms are possible today into this evening. Generally dry and seasonable weather is expected this weekend. Hurricane Jose will likely bring high surf and dangerous rip currents this weekend into the middle of next week. Some wind and rain effects are possible, especially across Cape Cod and the Islands. But the full extent of those impacts remains dependent on the uncertain storm track.
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10 am update... Weak surface low circulation was centered off of the southeast ME shoreline at 10 am. Radar shows isolated to widely scattered showers associated with this feature, mainly to our NE but some scattered showers/t-storms were also located SE of Nantucket. Low clouds and fog are in the process of lifting and dissipating. Will likely take another couple of hours to dissipated along the east coastal shoreline, but we did have breaks of sunshine developing over the interior. Ultimately we will develop diurnal cumulus which will allow for partly to mostly cloudy skies. With broad mid level trough lingering across the region, and cyclonic flow and cold pool aloft, should see some convection fire up during the afternoon. CAPE values to reach up to around 1000 j/kg across inland areas but will be in a window from mid to late afternoon. PWATs will be about 1.5 to 1.6 inches, not extraordinarily high but could see a few brief downpours in any convection that develops. Will also be rather sultry with dewpts in the mid- upper 60s across most areas. Depending upon the amount of cloudiness will reflect how high temps get. Temps should max out in the 70s to lower 80s, warmest across E interior Mass and the lower CT valley, rather close to where the higher CAPE values are forecast. Something to keep an eye on.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Tonight... Some leftover showers/isolated thunderstorms should diminish this evening around or after sunset. Light/variable or calm winds continue so will see set up for development of areas of fog, some of which could be dense especially if there are any breaks in the cloud deck. Saturday... The last of the mid level long wave trough lingers across S coastal areas during the day. May see another round of scattered showers/isolated thunderstorms once again during the afternoon. This will again be dependent upon how quickly the fog and low clouds breaks during the morning. Noting a suppressed area of instability in the vicinity of the leftover mid level trough, with CAPE up to around 800 or so j/kg across N CT into W RI possibly a bit further S. Still have light surface winds. PWATs are forecasted to be lower, however, so not quite as much of a threat for heavy rainfall at this point. Temps look to be a bit milder, mainly in the lower 80s away from the upper 70s to lower 80s away from the S coast. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... 15/00Z guidance suite continues the trend of a more westward track with Jose, even with the ensembles. Still lots of disagreement regarding the timing and strength of Jose among the deterministic runs, especially after Sunday. With the westward shift in track, the threat of a more direct impact from Jose is increasing. Prudence dictates that people in southern New England should pay close attention to later forecasts regarding Jose this weekend. Confidence is high through this weekend, falling to low by Monday night due to uncertainty in the track of Jose. High pressure Sunday starts to break down across our region Sunday night into Monday morning. This could permit some showers to develop Monday afternoon into Monday night. The most likely period of any wind and precipitation impacts from Jose, as of this writing, looks to be sometime Tuesday into Wednesday. These sorts of details will likely change with time through this weekend. Have low confidence in the forecast for next Thursday, which will greatly depend on the exact track and timing of Jose. One thing is known with certainty: our region will be at a moderate to high risk for dangerous rip currents later this weekend into early next week. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday/... Through Today...Moderate confidence. MVFR-IFR conditions this morning should improve to mainly VFR by midday. May see some low clouds, patchy fog and MVFR conditions linger along the S coast into the afternoon. Will also see briefly lower conditions in scattered showers/isolated thunderstorms with brief heavy rainfall possible. Tonight...Moderate confidence. Any leftover showers end this evening. Otherwise, will see return of MVFR-IFR conditions in low clouds and fog. Local LIFR CIGS/VSBYS are also possible if fog becomes dense around or after 06Z. Saturday...Moderate confidence. Again, will see MVFR-IFR conditions in low clouds/fog early, then dissipating by around mid morning to midday, except may linger along the immediate S coast into the afternoon. Low risk for scattered showers/isolated thunderstorms mainly across N CT/RI possibly into S coastal Mass Sat afternoon. KBOS Terminal...Moderate confidence in TAF. KBDL Terminal...Moderate confidence in TAF. Scattered showers and perhaps an isolated thunderstorm approach the terminal this afternoon into early evening. Outlook /Saturday Night through Tuesday/... Sunday and Monday...High confidence. VFR. Patchy MVFR/IFR in fog and low clouds each early morning. Chance of MVFR cigs reaching the South Coast late Monday, depending on the track and speed of Jose. Tuesday...Low confidence. MVFR with areas of IFR in low clouds/rain/fog. Northeast winds with potential for 35 knot speeds. Poor visibility on Cape and Islands in rain and fog. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday/... Today through Saturday...High confidence. Expect winds to remain below 15 kt through the period. Seas 4 ft or less. Visibility will be reduced in areas of fog, locally dense at times, mainly during the nighttime and early morning hours each day. Chance of a few near shore thunderstorms this afternoon/evening. Outlook /Saturday Night through Tuesday/... As Jose moves north, increasing swell also moves northward into the southern New England waters this weekend and early next week. Much of this is focused along the South coasts of RI and MA, but spreads to the east coast of Cape Cod Tuesday. Mariners are strongly urged to monitor the latest forecasts regarding Jose this weekend into early next week. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Belk/EVT NEAR TERM...Belk/EVT/NMB SHORT TERM...EVT LONG TERM...Belk AVIATION...Belk/EVT MARINE...Belk/EVT is the U.S. government's official web portal to all federal, state and local government web resources and services.