Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 011934 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 234 PM EST Thu Dec 1 2016 .SYNOPSIS...
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Dry, breezy and unseasonably mild conditions this afternoon. Other than the risk of a few snow showers or flurries Friday night, expecting mainly dry conditions through much of this weekend, with a trend toward cooler temperatures. Weak low pressure may bring spotty light rain and/or snow showers Sunday night into Monday. Into the middle of next week, there is some potential for wintry precipitation Tuesday night into Wednesday, but timing and track remain uncertain.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Drier air continues to shift east overnight. West winds will continue to bring in more humid air from the Great Lakes. Variable clouds, with more clouds more likely to linger across the western half of southern New England. Temperatures expected to be 5-10 degrees lower than last night, but still above seasonable normals.
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&& .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
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Gusty west winds continue through this period. While this should result in periods of clouds for most of the region, the possibility of showers is no so clear-cut. More clouds across northern MA, with partial sunshine expected over CT/RI and southeast MA. There should be enough of a cold pool aloft where scattered showers would be more favorable. However, west winds typically do not favor lake-effect showers very far east, as there is a decent downslope component in the CT River Valley. West winds also do not favor ocean-effect showers across the outer Cape and islands. Otherwise, expecting typical early December weather.
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&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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Highlights... * Mainly dry conditions with cooling temperatures through the weekend * Low confidence in wintry precip Sunday night into Monday * Another low may approach sometime Tuesday night or Wednesday, but low confidence on timing and track continue Overview... 00Z models and ensembles were in fairly good agreement through this weekend in keeping mainly dry conditions in place, though will see temperatures cool through this timeframe as the cutoff H5 low spins across Atlantic Canada. Should see mainly dry conditions through Sunday. From Sunday night onward, uncertainty continues with regards to how the models handle the ejection of cutoff mid level low pressure out of the SW U.S. as high amplitude H5 ridge builds across the eastern U.S. into eastern Canada. Noting wide model solution spread as next system works its way across the midwest and Ohio Valley early next week. One weak low looks to approach Sunday night into Monday, but not a lot of moisture with this system. The surface system associated with the progressive cutoff mid level system may approach around the late Tuesday into Wednesday timeframe, but with low consistency with the track and timing of this system, low confidence at this time, but could see a wintry mix depending upon the temperature regime as the system approaches. Details... Saturday through Sunday...Moderate to high confidence. Cutoff upper level low over Quebec will shift into the Maritimes, but broad troughing extends westward across northern New England into N NY state through Saturday. May see some widely sct snow showers across the E slopes of the Berkshires early Sat morning. There has been model consistency over the last couple of nights in the development of ocean effect showers over the eastern waters as colder air works across the warmer waters. They have been trying to bring some isolated showers into outer Cape Cod Sat into Sat night, though some question whether they will get in with a mainly NW flow in place. Usually need a more northerly flow to get the moisture to work across the arm of the Cape. Kept only slight chance POPs going for this aspect. Noting a fairly tight pressure gradient across the region during this timeframe between the exiting low and strong high pressure building out of the Ohio River valley to the mid Atlantic states. Will see gusty winds especially along the coast, up to 30-35 mph at times mainly Saturday into Saturday night. Temperatures on Saturday will be close to seasonal normals for early December, then will be cooler as mid level heights lower. Sunday night through Wednesday...Low confidence. High pressure will build across the region early Sunday night. May see as weak low approach Sunday night into Monday morning. Lack of good support or moisture should mean spotty light precip if that. Still uncertain on the evolution of this system as it approaches. At this point, have slight chance POPs in the forecast. Beyond this, H5 ridge looks to build over the northeast U.S. into eastern Canada, while SW U.S. cutoff low becomes captured by this building ridge in the developing SW flow aloft. This may approach the region around the Tuesday to Wednesday timeframe, but very uncertain on this track and timing. With the building ridge, temperatures should moderate somewhat but will need to monitor for possible cold air damming that may set up as any precip approaches. Will continue to monitor.
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&& .AVIATION /19Z THURSDAY THROUGH TUESDAY/...
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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 Friday Night/... Through 00Z...High confidence. Diurnal clouds have developed, mainly across the western half of southern New England. Expecting these clouds to begin dissipating toward and after sunset. Mainly VFR ceilings, with the possibility for MVFR ceilings across the higher terrain of central and western MA, and northern CT. Tonight...High confidence. VFR, areas of MVFR cigs across the higher terrain. West winds 5 to 10 kt, except 15 to 25 mph along the coast, and especially Cape Cod and the Islands. Friday and Friday Night...Moderate confidence. Some uncertainty on extent of lake effect snow/rain showers entering MA/CT during this time. Wind direction is not very favorable for ocean-effect showers across the outer Cape and islands. Temperatures would favor mostly rain showers across southern New England, where they develop. The exception would be across the east slopes of the Berkshires, where some light snow showers are possible. Will need to monitor the trends over the next 12-24 hours. KBOS TAF...High confidence in overall TAF. Lower confidence in lower VFR CIGS developing. KBDL TAF...High confidence in overall TAF. Outlook /Saturday through Monday/... Saturday through Sunday...High confidence. Mainly VFR. May see some spotty light -SHRA Saturday across outer Cape Cod. W-NW wind gusts up to 25-30 kt Saturday into Sat night, mainly along the S coast. Sunday night and Monday...Low confidence. May see patchy MVFR conditions in spotty -SHRA/-SHSN Sunday night into Monday morning, then should be mainly VFR. Timing is uncertain, though.
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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 Friday Night/... Gusty west winds persist through the period. While there may be brief lulls in the winds, rough seas should not diminish as quickly. Overall, thinking Small Craft Advisory conditions will be met on most waters through Friday night. Some of the nearshore waters, like Boston Harbor and Narragansett Bay, may fall below advisory levels for a time. Still trying to work out if there will be a significant enough window where no advisory would be in effect. Outlook /Saturday through Monday/...Moderate confidence. Saturday through Saturday night...Expect NW winds gusting up to 25-30 kt across most of the waters /except Boston Harbor and Narragansett Bay/. Seas will range up to 5-6 ft over the outer waters. Winds should diminish after midnight Sat night. Sunday through Monday...Seas may linger around 5 ft early Sunday, otherwise winds and seas should diminish below small craft criteria. N winds may gust up to 20 kt late Mon on the outer waters.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 6 PM EST Friday for ANZ231>235-237- 250-251-254>256. Small Craft Advisory until 7 PM EST this evening for ANZ230- 236. && $$ SYNOPSIS...Belk/EVT NEAR TERM...Belk SHORT TERM...Belk LONG TERM...EVT AVIATION...Belk/EVT MARINE...Belk/EVT

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