Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 161803 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 203 PM EDT Sat Sep 16 2017 .SYNOPSIS... Mainly dry and warm/humid weather is expected this weekend, but a few isolated showers or a thunderstorm can not be ruled out both days. Hurricane Jose will bring high surf and dangerous rip currents this weekend into the middle of next week. Wind and rain effects are possible, especially across Cape Cod and the Islands. But the full extent of those impacts and their timing remains dependent on the uncertain storm track. High pressure then builds over the region with drier and seasonable weather Thursday and Friday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 2 PM update... Stratus and fog has eroded for the most part with sct-bkn cu developing, but low clouds still lingering across portions of Cape Cod. There may be a short window for partial clearing on the Cape before clouds fill back in by late afternoon. Scattered showers have developed across SE NY within instability axis of SBCAPES 1000+ J/kg. Higher instability extends east into western MA and northern CT so still can`t rule out a few showers or an isold t-storm in this region. Given weak wind fields and high PWATs, there is a low risk for locally heavy rainfall. Highs should reach upper 70s to lower 80s. Sea breezes will keep it cooler along the immediate coast. Humid airmass with dewpoints in the mid/upper 60s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Tonight... Any leftover showers across N CT/W RI will dissipate by 02Z, otherwise expect dry conditions. Otherwise, expect mainly dry conditions. However, areas of fog and low clouds move into coastal areas and will likely redevelop across the normally prone inland valleys as dewpoints remain in the lower-mid 60s. May need dense fog headlines again for some areas. Another humid night with temps falling back to the upper 50s to lower 60s. Sunday... A near repeat of today as H5 W-E elongated short wave/vorticity max lingers across N CT/RI into SE Mass as it remains parallel to the upper flow. So, could see another shot for isolated showers or even a thunderstorm during the afternoon across N CT and W RI. Have kept POPs in the slight chance range. Temps will again rise to the 70s to lower 80s. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... 16/00Z guidance suite has come into better agreement with the handling of Jose through Monday. The CMC remains the fastest and farthest north, while the GFS and ECMWF are quite close. GFS remains the model keeping Jose the strongest through Monday, but still appears to be a bit too strong. Beyond Monday, 00Z guidance suite seems to have latched onto the idea of Jose eventually turning to the right, even in the ensembles. The question which remains to be answered is: how soon? That very important question is why there is low confidence in the details of the forecast Monday night into Wednesday. Southern New England still looking at the possibility of a landfalling tropical cyclone, to a near miss southeast of Nantucket. Moderate confidence in the forecast for the end of next week. Once Jose moves away from our region, we should see a high pressure build south from eastern Canada. Near to slightly below normal temperatures expected much of next week. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday night/... Through 00z...Mainly VFR, but areas of MVFR/IFR stratus lingering on Cape Cod. Stratus and fog lurking over the waters may expand across the islands toward 00z. Tonight through Sunday night...High confidence in trends. Lower confidence in timing. Expect stratus and fog to redevelop across much of SNE tonight with IFR/LIFR conditions. Improving conditions to VFR by late Sunday morning or early afternoon, then lowering back to IFR/LIFR Sunday night. Light winds with weak coastal sea breezes. KBOS Terminal...High confidence in trends. Lower confidence in timing. IFR/LIFR stratus and fog likely redevelops tonight. KBDL Terminal...High confidence in trends. Lower confidence in timing. IFR conditions likely redevelop tonight. Outlook /Monday through Wednesday/... Monday...High confidence. VFR. Patchy MVFR/IFR in fog and low clouds early Monday morning. Chance of MVFR cigs in widely scattered showers Monday afternoon. MVFR cigs/vsbys may reach the south coast Monday night, depending on the track and speed of Hurricane Jose. Tuesday-Wednesday...Low confidence. MVFR with areas of IFR in low clouds/rain/fog. Potential for NE winds at 35-40 kt. Poor visibility on Cape and Islands in rain and fog. Conditions are dependent on the track and speed of Hurricane Jose. Some improvement possible from west to east Wednesday afternoon. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday/... Through Today...High confidence. Expect light winds with seas 4 ft or less. Areas of low clouds and dense fog across most of the coastal waters with visibility at or below 1/2 mile. Conditions may slowly improve by around 12Z-14Z across the near shore waters, with reduced visibility continuing across the open waters. Tonight and Sunday...Moderate confidence. Expect light southerly winds. Visibility will again lower to 1/2 mile or less across the open waters in areas of low clouds and fog, which will move into the near shore waters tonight into early Sunday. As Jose moves north, swells will push across the southern waters. Expect seas to build to 3-6 feet, highest on the southern outer waters. Have put up small craft advisories for hazardous seas, which could reach into Block Island and RI sounds by Sunday morning. Outlook /Sunday Night through Wednesday/... Expecting to have marine headlines during much of this period, especially across the southern coastal waters. Seas expected to slowly build Sunday night into Monday night. Winds and seas should then build faster Tuesday into Tuesday night. High seas will linger into Wednesday, but will start to subside once Hurricane Jose moves off. Much of the high seas are focused along the South coasts of RI and MA, but then spread to the east coast of Cape Cod Tuesday. Much of this depends on the track of Jose, which has plenty of time to change over the next several days. Mariners are strongly urged to monitor the latest forecasts regarding Jose this weekend into early next week. && .TIDES/COASTAL FLOODING... Jose`s large wind envelope will likely produce significant seas with a large swell component; moving onshore early to mid next week. Significant wave action should occur on top of relatively high astronomical high tides and a building surge. As a result, we believe there is a high risk of moderate to severe beach erosion over a prolonged period early next week. Multiple high tide cycles of large swells breaking onshore have us concerned that we could experience a very serious beach erosion event along portions of both our south and east facing ocean- exposed shorelines next week. In addition and dependent upon how close Jose gets to our coast, there is also a risk for minor to moderate coastal flooding along portions of the coast with probably southeast and east facing shorelines most at risk. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory for hazardous seas from 6 PM this evening to 6 PM EDT Sunday for ANZ254>256. Small Craft Advisory for hazardous seas from midnight tonight to 6 PM EDT Sunday for ANZ235-237. && $$ SYNOPSIS...Belk/EVT NEAR TERM...KJC SHORT TERM...EVT LONG TERM...Belk AVIATION...Belk/KJC MARINE...Belk/EVT TIDES/COASTAL FLOODING... is the U.S. government's official web portal to all federal, state and local government web resources and services.