Area Forecast Discussion
Issued by NWS Boston, MA

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631 FXUS61 KBOX 220710 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 310 AM EDT Sun Oct 22 2017 .SYNOPSIS... High pressure south of New England will provide very warm and dry weather into Monday. Seabreezes along both coasts today will make it a little cooler there. A cold front with possibly waves of low pressure will bring gusty showers to the area Tuesday afternoon into Wednesday. Drier and seasonably cool weather is expected behind the front for late in the week. && .NEAR TERM /THROUGH TODAY/... High pressure will remain in control of our weather, but will be centered more to our northeast today. The resulting light winds will set the stage for a seabreezes along both coasts, which in turn will mean lower max temperatures today. That said, above normal warmth will continue, with portions of the Connecticut River valley approaching 80 degrees once more. && .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/... Seabreezes diminish early this evening, to be replaced with a light south synoptic flow. Another mild night in store, with slowly increasing dew points. Dry weather continues. Still some concern for low clouds and patchy fog across portions of southeast MA, as dew points may get close to the water temperatures just offshore. Just don`t have much confidence in that outcome, yet. Monday is still expected to be mostly dry. Overrunning lift should get underway by the afternoon. The main limitation for rainfall will by the abundant relatively dry air near the ground. Many members of the 22/00Z guidance suite bring light rainfall into southern New England during the daytime Monday. Thinking this is likely a bit overdone, especially across the eastern half of southern New England. Will continue to have a chance of showers during the afternoon into evening hours across the western half of southern New England, owing to the proximity to the approaching cold front. There should be better low level moisture convergence to help overcome the drier air a little quicker. Temperatures should be a little lower with increasing clouds, but still well above normal. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Highlights... * Period of strong to damaging wind gusts possible Tue into early Wed * Heavy rain will result in an urban/street flooding threat Tue-Wed * More seasonable temps Thu/Fri although some showers may linger Thu Details... Monday night... Upper level ridging will gradually lose its grip on our region as low level jet increases ahead of low pressure lifting northeast towards the Great Lakes. While just a few spot showers are possible Monday evening, the threat for scattered showers will increase after midnight across the interior. Increasing low level moisture/lower clouds will hold overnight low temps in the upper 50s to lower 60s which may actually rise a bit toward daybreak. Tuesday and Wednesday... The two main concerns will be revolve around the potential for heavy rain/localized urban/street flooding threat along with a period of strong to damaging winds. Anomalous digging trough to our west will induce meridional upper level flow into southern New England ahead of an approaching cold front. The result will be a southerly low level jet/Pwats both increasing to 3+ standard deviations above normal. Timing of the cold front still uncertain in this time range, but strong LLJ/high Pwats coupled with strong forcing will bring periods of showers some of which will contain heavy rainfall Tue into Wed. The front will be slow moving, and both the GEFS/EPS showing decent probabilities of 2+ inches of rain with even some low probs of exceeding 4 inches. Therefore, an urban/street flooding threat will exist. The other concern will be the potential for a period of strong to damaging wind gusts Tue into early Wed. Most of the guidance indicates a 925 mb southerly LLJ on the order of 45 to 60 kt. While some of this wind will remain aloft given an inversion in place, surface temps well up into the 60s to the lower 70s are expected Tue into Wed. This may allow some more of the wind to mix down than we normally might expect. In addition, the potential exists for a fine line with embedded thunder given we may see a few hundred J/KG of Cape with dewpoints in the 60s coupled with strong forcing. While timing is uncertain, the potential exists for a period of southerly wind gusts of 40 to 50 mph especially along the coastal plain. If a fine line or any convection develops ahead of the front, a few gusts up to 55 or 60 mph would be possible. Given most trees are fully leafed, these potential wind gusts will bring an enhanced risk for tree damage/isolated to scattered power outages. There is a pretty good bet that some wind headlines will likely be needed. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday/.... Through 12Z...High confidence. Mainly VFR. Could be a few spots of ground fog at typically prone airports. Today...High confidence. VFR, dry weather and light winds. Seabreezes develop by mid morning along both coasts. Tonight...Moderate confidence. Uncertainty on how quickly MVFR-IFR conditions overspread the area from the south. Mainly dry conditions prevail along with light south winds. Monday...High confidence. Mainly VFR, although with a low risk for early AM fog and lower clouds with isolated IFR conditions possible. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Monday Night through Thursday/... Mon night into Wed...Moderate confidence. Mainly a mix of IFR/MVFR in low CIGS, fog and rainfall. Occasional strong S wind gusts. LLWS likely, especially during the day on Tue and Wed. Thu...Moderate confidence. Some improvement to VFR, although lingering IFR/MVFR possible. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday/...High confidence. Very tranquil boating weather for late Oct continues this period with light winds, dry weather and good vsby. Local seabreezes develop today by mid morning. Light south winds tonight into Monday. Outlook /Monday Night through Thursday/...Moderate confidence. Tue into Wed...Occasional Southerly Gales with wind gusts 35-40 kt possible. Seas, building 8-10 ft mainly S and SE waters. Even in periods where Gales not experienced, high end small craft advisories likely. Rain/fog lead to vsby restrictions. Some thunderstorms possible over the waters. Thu... Gradual improvement with winds shifting around to the W. A few gusts still to 25 kt at least, along with lingering seas/swells. Small craft advisories likely to follow Gales. && .FIRE WEATHER... Dry weather continues through at least tonight with minimum RH values 25 to 35 percent today, lowest values over CT and western MA. However, with high pressure nearby winds will be very light. Thus fire weather parameters remaining below Red Flag Warning criteria. && .CLIMATE... All the record max temperatures for October 22 were set in 1979. While being well above normal today, most of these records appear to be safe Here are the records for today Hartford 85 in 1979 Boston 83 in 1979 Worcester 82 in 1979 Providence 86 in 1979 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Belk/Doody NEAR TERM...Belk SHORT TERM...Belk LONG TERM...Doody AVIATION...Belk/Doody MARINE...Belk/Doody FIRE WEATHER...Staff CLIMATE...Belk is the U.S. government's official web portal to all federal, state and local government web resources and services.