Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 020822 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 322 AM EST Fri Dec 2 2016 .SYNOPSIS... Cooler temperatures are expected as we head into the weekend. Other than scattered light snow showers or flurries over the northern and western higher terrain areas, it should remain mainly dry through most of the weekend. A brief snow or rain shower is possible Sunday night into early Monday. High pressure will provide dry weather Monday afternoon into Tuesday. Low pressure moving from the southeast states to the Mid- Atlantic coast may produce some mixed precipitation across southern New England Tuesday night into Wednesday, but the track remains uncertain. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Downsloping westerly winds should help keep southern New England dry today. Winds may gust to or a little over 20 mph this afternoon. Temperatures will be a little cooler than yesterday thanks to some modest cold advection. High temperatures are expected to range from the mid 40s across the higher terrain to near 50 across the southeast coastal plain. A fair amount of cloudiness will probably persist today near the crest of the Berkshires but considerable sunshine everywhere to the east. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Tonight...All models depict a short wave trough and some pooling of deeper moisture passing across our area tonight. Looks to be enough there to support scattered snow showers over the Berkshires spilling onto the east slopes, especially in Franklin County. Can not rule out a very minor accumulation of say a half inch or so in the higher elevations of northwest Franklin County tonight. May also see a few flurries tonight over the northern Worcester hills. We may also experience a period of gusty winds as well tonight as the short wave trough aloft and leading edge of a pulse of cold air advection moves through. Temperatures will drop with the cold advection, but mixing from the wind and at least partial cloud cover will tend to brake the temperature drop. Saturday...Looks to be dry with mostly sunny skies across most of the area. As the surface wind becomes more northerly later in the day, ocean effect clouds may impact the outer Cape with a slight chance of showers grazing the very outer Cape. H85 temperatures dropping a few degrees celsius will translate to surface high temperatures 4 or 5 degrees cooler Saturday afternoon than Friday afternoon. Nonethess highs in the lower to mid 40s are not too far off our climatological normals, perhaps just a degree or two below average. Winds will again be fairly gusty, reaching 20 to 25 mph during much of the day. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Highlights... * A cool period with slightly below normal temperatures. * Low pressure to our south Tue night and Wed could cause some mixed precipitation this far north but track confidence is low. Sunday... High confidence. A mostly sunny and cool day is forecast with high pressure over southern New England. Highs from the upper 30s to lower 40s with diminishing winds. Sunday night and Monday morning... Moderate confidence. A band of clouds associated with a very weak short wave trough will spread across the area. Although the atmosphere is mainly dry, cannot rule out a few brief snow showers, which could perhaps leave a localized dusting. Overnight lows in the 20s except 30 to 35 Cape Cod and Islands. Rest of Monday and Tuesday... High confidence. Clear to partly cloudy conditions as a new high pressure system builds in from the west and north. Highs again both days in the upper 30s to lower 40s with lows in the 20s except lower to mid 30s Cape Cod and Islands. Tuesday night and Wednesday... Low confidence. Upper level low pressure from the southwestern U.S. will be lifting northeastward and weakening as it approaches New England in this time frame. The 12Z GFS spawns a decent low pressure system not too far to our south, but the GFS ensemble members are not as emphatic. The GFS and some GEFS members have a strong easterly low level jet that creates rain over the southeast half of our area and snow in the northwest half. It is notable that the 12Z operational run is farther southeast than previous runs, more in line with the ECMWF and Canadian models. The 12Z ECMWF is consistent with its prior runs and has precipitation knocking at our door Tuesday evening but then it shifts off the coast to our south, closer to the main low off the Mid-Atlantic coast. The Canadian model is also advertising a stronger persistent high over our region that prevents the northward advance of precipitation. As a result of the uncertainty, at this time we have forecast only 20-30 percent probabilities of mixed precipitation interior and rain in RI and eastern MA Tuesday night into Wednesday. Thursday... Low confidence. A strong cold front is forecast to approach southern New England from the west by Thursday evening. NCEP believes that the GFS is too fast with this approach. In general, continued chance PoPs for mainly showers Thu, but could end as snow showers by Thu. night. This will undoubtedly change in the next 7 days! && .AVIATION /08Z 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/... High confidence. BKN-OVC clouds at 2500-3000 ft at times near the crests of the Berkshires today through Saturday. There could also be a band of clouds near or a little under 3000 feet across the outer Cape during mid to late Saturday afternoon. Otherwise, VFR conditions should prevail. West winds today and NW winds Saturday at the surface may gust to 20 knots at times. Scattered snow showers tonight over the Berkshires could locally lower the visibility to 5 or 6 miles. KBOS TAF...High confidence in overall TAF. VFR. West wind may gust between 20 and 25 knots this afternoon into this evening. KBDL TAF...High confidence in overall TAF. Outlook /Saturday Night through Tuesday/... Saturday through Sunday...High confidence. Mainly VFR. May see some spotty light -SHRA Saturday across outer Cape Cod. NW wind gusts up to 25-30 kt Saturday into Sat night, especially in the higher terrain and along the south and east coasts. Sunday night and Monday morning...Low confidence. May see patchy MVFR conditions in spotty -SHRA/-SHSN Sunday night into Monday morning, then should be mainly VFR by Monday afternoon. Monday and Tuesday... High confidence. VFR. Increasing mid cloudiness in western sections Tuesday afternoon. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday/... Moderate confidence for this period. gusty winds will persist from the west today and northwest Saturday. Will keep Small Craft Advisories up for most waters through at least daybreak Saturday. Our mixing height tool suggests increasing gusts over Boston Harbor and Narragansett Bay as well toward evening and have Small Craft Advisories going into effect again at 3 PM today. That may be a few hours early but believe it wise to have a small buffer in the event the timing is off some. Anticipate west wind gusts between 25 and 30 knots across most of the coastal weathers this evening. Outlook /Saturday Night through Tuesday/...Moderate confidence. Saturday night...Expect NW winds gusting up to 25-30 kt across most of the waters. Seas will range up to 5-6 ft over the outer waters. Winds should diminish over Boston Harbor and Narragansett Bay after midnight Saturday night. Sunday through Monday...Seas may linger around 5 ft early Sunday, otherwise winds and seas should diminish below small craft criteria. NW to N winds may gust up to 20 kt late Mon. on the outer waters. Monday night and Tuesday... Winds and seas below small craft criteria. However, north to northeast winds will gust to 20 kt at times. Seas will build to near 5 ft over the waters south of Block Island and Marthas Vineyard toward Tuesday evening, as low pressure forms over the Mid-Atlantic region. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 7 AM EST Saturday for ANZ231>235- 237-250-251-254>256. Small Craft Advisory from 3 PM this afternoon to 7 AM EST Saturday for ANZ230-236. && $$ SYNOPSIS...EVT/Thompson NEAR TERM...Belk/GAF/Thompson SHORT TERM...Thompson LONG TERM...GAF AVIATION...GAF/Thompson MARINE...GAF/Thompson

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