Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 091904 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 204 PM EST Fri Dec 9 2016 .SYNOPSIS...
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* Near- and Short-term forecast updates only... Mainly dry, but unseasonably cold temperatures are on tap for our region through Saturday. Some mixed wintry precipitation is looking more likely Sunday evening into the day on Monday, but uncertainty remains. Cooler conditions return by the middle of next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Rest of today... NW winds persisting with gusts up to 35 mph beneath a deck of scattered cumulus, subsequent of deep layer mixing of residual moisture and fetch off the Great Lakes region. Also seeing some flurry activity get as far E as western and central portions of Southern New England, but given how dry the atmospheric column is, only expect flurries across the east slopes of the Berkshires into the CT River Valley. Low risk of accumulation and/or visibility restrictions. Temperatures lowering back down to the 20s towards sunset. Couple the winds, going to feel 10 degrees colder. Only 193 days left till summer! Tonight... NW flow continues but beginning to relax as surface high pressure builds in from the W coincident with weak ridging aloft and drier air. Cold air advection slows with H85 temperatures bottoming out around -15C by Saturday morning. Scattered clouds dissipating, overall mostly clear except some ocean-effect activity across the Outer Cape, looking at lows dropping into the teens. Tack on the winds, looking at wind chill values down into the single digits.
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&& .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
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Saturday into Saturday night... One more piece of mid-level energy through the prevailing cyclonic flow across the region. Some low to mid level decks and perhaps some flurry activity over the W portions of CT and MA. Otherwise thereafter a ridge of high pressure builds into the region yielding an increasing presence of surface high pressure. NW winds becoming light and variable late Saturday into Saturday night as conditions turn mostly clear. Highs barely getting above freezing, more than likely feeling like the teens and 20s given the NW breeze. Lows back down into the teens, possibly single digits, considering the light and variable flow, mostly clear conditions. Decent signs of radiational cooling and thus leaning with the coldest MOS guidance. Wicked cold.
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&& .LONG TERM /SUNDAY THROUGH FRIDAY/... */ Highlights... * Wintry precipitation likely Sunday evening into Monday * Another system may bring precip sometime Tuesday or Wednesday * Another round of unseasonably cold weather late in the week */ Overview... Models and ensemble members are in generally good agreement on much of the long term, particularly with the synoptic pattern. After starting the period with below normal temperatures, two systems may bring precipitation to southern New England. The first one moves through the region Sunday into Monday, bringing a period of mainly snow to much of the area, changing to rain along the coastal plain. The second one, a coastal system, may bring another round of snow/rain to the region sometime Tuesday or Wednesday. Or it may stay far enough to the south that there may not be much, if any, precipitation. An arctic front will bring below normal temperatures back to the region late next week. */ Daily Discussion... Sunday and Monday... Much of the day Sunday should be fairly dry as weak upper ridging moves over southern New England and high pressure moves slowly offshore. Then a shortwave moves through the upper level flow over the area early Monday. There is still some uncertainty with the track of the associated low pressure system and the potential development and location of a secondary low pressure system. Expect the models to start coming into better agreement later today as the energy responsible for the system moves onshore and is better sampled. The track of the primary low and any secondary low development will affect thermal profiles. So this is leading to a bit of uncertainty with the p-type through the event. At this time, believe it will be a mainly snow or rain scenario, but there is a low probability of a period of ice during the transition as the warmer air moves in aloft. While it is still a bit too early to detail exact snow amounts, confidence is high that a portion of the area could have accumulations in the 3 to 6 inch range. Most of the area should see at least a dusting of snow, with the possible exception being the Islands. Monday night and Tuesday... The 00Z runs of the models/ensembles indicate high pressure will build into the region and be the dominant feature during this time. However, this is a change from previous runs which had a bit more activity, especially during Tuesday. So this period remains a bit uncertain and unsettled. Wednesday and Thursday... Confidence remains rather low for this period. A broad upper level trough in the Great Lakes moves eastward over southeastern Canada and the northeastern U.S. A strong shortwave will rotate through this trough bringing another period of unsettled weather to southern New England. The low pressure system associated with this shortwave looks to be a coastal low at this point, but there is significant spread in the ensembles as to how close this system comes to southern New England. Beyond the potential precipitation event, another shot of arctic air is expected to move into the region. && .AVIATION /19Z FRIDAY 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 Saturday Night/...High confidence. 18z update... VFR. NW winds sustained around 10 to 15 kts, gusting up to 35 kts. SCT-BKN low-end VFR cigs with the chance of a flurry and slight restrictions in visibility especially over W MA and CT. Snow and wind activity diminish overnight into Saturday. Winds becoming light and VRB into Saturday night. KBOS TAF...W/NW flow. Gusts up to 35 kts. KBDL TAF...W/NW flow. Gusts up to 30 kts. Outlook /Sunday through Wednesday/... Saturday night through Sunday...High confidence. Mainly VFR conditions expected. Lowering clouds and approaching precipitation may result in a trend towards MVFR after noon on Sunday. Sunday evening through Monday...Moderate confidence. MVFR/IFR develop in snow Sunday night. Snow may change to rain across portions of the coastal plain Monday. Accumulating snow is likely across the interior. Some improvement is possible late Monday as precipitation comes to an end. Tuesday...Low confidence. Improving conditions. Mainly VFR.
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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 Saturday Night/...High confidence. NW winds with gale force gusts continuing into the evening hours. With the gradual increasing presence of high pressure, building across the region tonight towards late Saturday into Saturday night, should see NW winds taper allowing wave activity to relax. Gale warnings dropping off during the evening hours with follow-up small craft advisories concluding through Saturday. Initial wave heights 5 to 8 feet diminishing. Outlook /Sunday through Wednesday/... Sunday...High confidence. Good boating weather with winds and seas below small craft advisory thresholds. Monday...Moderate confidence. Seas below 5 feet will slowly increase once again from the south as low pressure approaches the waters. Winds increase as well and small craft advisories will be necessary. There is a moderate probability of N-NW gales. Tuesday...Moderate confidence. NW winds and seas slowly diminish. Small craft advisories will likely continue through much of Tuesday. In addition, there is a moderate probability of N-NW gales during the morning.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 10 AM EST Saturday for ANZ231>234. Small Craft Advisory until 4 AM EST Saturday for ANZ230. Small Craft Advisory until 1 AM EST Saturday for ANZ236. Small Craft Advisory until 7 AM EST Saturday for ANZ235-237. Gale Warning until 10 PM EST this evening for ANZ250-254. Gale Warning until 8 PM EST this evening for ANZ251-255-256.
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&& $$ SYNOPSIS...RLG/Sipprell NEAR TERM...Sipprell SHORT TERM...Sipprell LONG TERM...RLG AVIATION...RLG/Sipprell MARINE...RLG/Sipprell

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