Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 160846 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 446 AM EDT Sat Sep 16 2017 .SYNOPSIS...
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Areas of dense fog across a good portion of southern New England will cause low visibility through mid morning. Some of the fog may linger near the coast through midday. Otherwise, expect generally dry and seasonable weather this weekend, but some isolated showers 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.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Dense fog continues along coastal areas and a bit further inland as well as across portions of the lower CT valley at 08Z, otherwise patchy low clouds and fog noted across the remainder of the region. The fog can be seen very well on GOES-16 non-op experimental fog product (10.3-3.9um) this morning. With few if any clouds above the low deck, the stratus should start to break up around or after sunrise, with good clearing across inland areas by around 13Z-14Z. May take a bit longer along the coast with light sea breezes kicking in late this morning or midday. Expect the lower visibility to improve by around 12Z, so continued the dense fog advisory for coastal areas. For the remainder of today, expect mainly dry conditions with weak high pressure across northern New England. However, still noting broad mid level long wave troughing lingering across S coastal areas, which may be just enough that, if the fog does break, to see some diurnal convection bubble up. Noting some decent instability where the leftover W-E weak mid level vorticity max lies, across N CT/RI into interior SE Mass. SB lifted indices around zero to -1, K indices into the lower 30s and TQ values up to 16-17, all marginal but may be enough with good low level moisture to kick some widely sct showers and a few thunderstorms during the afternoon. With light winds at the surface and aloft, the precip will be slow to move so could see locally heavy rainfall in any convection. With partly to mostly sunny skies across most areas, temps should top off from the lower-mid 70s along the immediate coast to the lower 80s across the CT valley and portions of the coastal plain.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
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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.
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&& .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
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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.
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&& .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
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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 Sunday/... Through 12Z...Moderate confidence. Areas of dense fog with LIFR conditions across most if not all coastal terminals through around 12Z. Mainly IFR-LIFR CIGS with locally MVFR-IFR VSBYS in patchy fog away from the coast, which should continue through the remainder of the night. Today...Moderate confidence. Mix of MVFR-LIFR CIGS/VSBYS early, but should slowly lift and dissipate by mid-late morning. Some IFR conditions may linger across Cape Cod and the islands through at least midday, otherwise mainly VFR through the afternoon. Low risk for some scattered showers and possibly an isolated thunderstorm mainly across N CT/N RI into S central and W Mass this afternoon. Tonight...Moderate confidence. Any leftover isold showers will dissipate by 02Z, otherwise MVFR-IFR CIGS/VSBYS return around or after 03Z-04Z inland, with areas of LIFR conditions along the immediate coast in areas of fog. Sunday...Moderate confidence. MVFR-IFR conditions through around 14Z, then should improve to mainly VFR. Some MVFR-IFR VSBYS may linger through midday INVOF KACK. Isolated showers/thunderstorms possible across N CT/W RI midday through the afternoon. KBOS Terminal...Moderate confidence in TAF. IFR-LIFR CIGS/VSBYS in areas of fog through 11Z-12Z, then should improve to VFR by around 14Z. Light sea breeze developing by 17Z-18Z through around 22Z. KBDL Terminal...Moderate confidence in TAF. May see patchy fog with local MVFR CIGS/VSBYS through 12Z-13Z, then VFR. Low risk of a few showers and a possible thunderstorm in vicinity of the terminal this afternoon. Outlook /Sunday Night through Wednesday/... Sunday night-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.
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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 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.
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&& .TIDES/COASTAL FLOODING...
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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.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...Dense Fog Advisory until 8 AM EDT this morning for MAZ006-007- 015-016-019>024. RI...Dense Fog Advisory until 8 AM EDT this morning for RIZ005>008. MARINE...Small Craft Advisory for hazardous seas from midnight tonight to 6 PM EDT Sunday for ANZ235-237. Small Craft Advisory for hazardous seas from 6 PM this evening to 6 PM EDT Sunday for ANZ254>256.
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&& $$ SYNOPSIS...Belk/EVT NEAR TERM...EVT SHORT TERM...EVT LONG TERM...Belk AVIATION...Belk/EVT MARINE...Belk/EVT TIDES/COASTAL FLOODING...Staff

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