Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 030613 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 113 AM EST Sat Dec 3 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 few brief snow or rain showers are possible Sunday night into early Monday. Otherwise, high pressure will provide dry weather Monday afternoon through Tuesday morning. Low pressure moving out of the Ohio valley to the mid Atlantic states may bring some mixed precipitation as far north as southern New England late Tuesday night and Wednesday, but timing and track remain uncertain. The potential for another period of unsettled weather exists for later in the next workweek. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 115 am Update... Not much change to previous forecast. Water vapor imagery continues to show a strong northern stream short wave trough exiting southern Quebec into northern New England. Forcing ahead of this feature was generating some cloudiness and a few sprinkles/flurries across the region at 1 am. Main impacts from this short wave will be a reinforcing surge of colder/drier air in its wake later this morning. As a result winds will shift from WSW to WNW with increasing gusts up to 35kt/40mph. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... Saturday...Looks to be dry with mostly sunny, at at least away from the northern MA border and the east coast. Still expecting the surface wind become more northerly during the day. This will most likely mean ocean-effect clouds, and perhaps some showers, too. Any showers would mainly impact the outer Cape, but really not expecting much of anything to develop. Winds will again be fairly gusty, reaching 20 to 25 mph during much of the day. Saturday Night...Lower clouds and spotty ocean-effect rain showers may continue across outer Cape Cod. Not expecting much in the way of QPF, as it`s a low risk. Otherwise, expect mainly dry conditions elsewhere across the region. Winds will be gusty, up to 25-30 kt across the higher inland terrain, as well as along the coast. Near seasonable temperatures. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Highlights... * Temperatures running a bit below seasonal normals through at least Tuesday * Low pressure moving out of the Ohio Valley/mid-Atlantic states may push some mixed precipitation into the region Tuesday night and Wednesday, but confidence remains low * Low confidence regarding timing of unsettled weather next Thu/Fri. Sunday...High confidence. Lower clouds and spotty ocean effect rain showers may initially continue into Sunday morning across outer Cape Cod as colder air moves across the milder waters on strong N-NW winds. Otherwise high pressure builds into the area with dry conditions and mostly clear skies. Could see wind gusts to 25 kt initially along the shoreline, but as high builds in and pressure gradient relaxes, winds will lower. Temperatures will be a few degrees cooler than normal, with highs in the 30s to low 40s. Sunday night through Monday...Moderate confidence. Continue to expect a band of clouds moving thru the area from a weak mid level short wave that pushes into/thru the region Sun night into Monday. Not much moisture to work with this feature as it pertains to our area, though 12Z ECMWF does shows some light QPF amounts during Sunday night/Monday morning, accompanied by a very weak surface low. GFS solution is drier...and with W/NW flow still looking to be in place for Monday...thinking that a mainly dry, low QPF solution looks reasonable. Will go with mainly a slight chance pop for a few showers or snow showers. Monday night...Moderate confidence. Dry conditions and mostly clear skies prevail Monday night with surface high pressure centered over southern Quebec...and upper level ridging...being the main influence on our weather. Tuesday and Wednesday...Low confidence. Models continue to differ regarding how much precipitation makes its way into southern New England during this timeframe. Low pressure system to our SW tries to bring moisture into our area. Elongated precip shield lies to the S and W of the region as high pressure shifts E of the region Tuesday and Tuesday night. Big question will be the timing as the high exits, if it does. Models still show the potential for 2 surface low pressure centers developing, one moving thru the southern Great Lakes Region and another moving off the Carolina or Mid-Atlantic coastline. Uncertainty exists on whether we end up with minimal QPF between these 2 systems. Model and ensemble solution spread lending to lower than average confidence. Will continue to lean toward a model blend at this point due to the remaining uncertainty and timing, with chance pops late Tuesday as well as Wednesday. Precip could be a wintry mix of light snow/rain. Thursday and Friday...Low confidence. While models show a deep mid level trof digging into the central and eastern US, there are significant differences in timing/placement. This in turn makes a difference in surface features, along with issues with how the sensible weather evolves. ECMWF shows a surface low approaching from the SW, while 12Z GFS shows a weaker solution for our area. Overall, low confidence continues. Will continue chance POPs at this time. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 115 am update...high confidence thru Sunday Thru 12z... Mainly VFR with marginal MVFR across the higher terrain. Other than a brief sprinkle/flurry early this morning expecting mainly dry weather to prevail. WSW winds will become WNW with gusts up to 35 kt toward daybreak...highest gusts over high terrain and Cape Cod and islands. After 12z... More of the same...VFR and dry but gusty WNW winds up to 30-35 kt. Tonight... VFR and dry with gusty WNW winds up to 25 kt or so...strongest winds across the high terrain and Cape Cod and islands. Sunday... VFR and dry along with diminishing NNW winds. KBOS TAF...High confidence in TAF. Main impacts will be gusty WNW winds today and tonight with gusts up to 35 kt at times. KBDL TAF...High confidence in TAF. Main impacts will be gusty WNW winds today and tonight with gusts up to 35 kt at times. Outlook /Sunday Night through Wednesday/... Sunday night and Monday...Moderate confidence. May see patchy MVFR conditions in spotty -SHRA/-SHSN Sunday night into Monday morning, then should be mainly VFR by Monday afternoon. Monday night...Moderate confidence. VFR. Tuesday and Wednesday...Moderate confidence for overall trends, lower on exact timing. Mainly VFR Tuesday morning. May see MVFR CIGS/VSBYS move into central and western areas Tuesday afternoon in mainly -RA, but may see mixed precipitation interior. MVFR CIGS/VSBYS possible Tue night into Wed with chance of light rain/snow. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday/... 10 pm update... Trough of low pres moves across New England tonight and then offshore late Sat morning resulting in a reinforcing surge of colder air. This will result in a renewed surge of gusty NW winds beginning Sat morning into the afternoon and night. Earlier discussion below. ==================================================================== Moderate confidence for this period. Isolated rain showers within souther coastal waters this evening. Gusty winds will persist from the west tonight, and northwest Saturday. While there will be times where winds briefly diminish below 25 kt, it is very difficult to identify precisely when, and for how long the lulls persist, before the gusty conditions return. Thus, will keep Small Craft Advisories up for most waters through Saturday night. Lower confidence on the timing of Small Craft Advisories in Boston Harbor and Narragansett Bay. Will need to monitor the trends through this weekend. Outlook /Sunday Night through Wednesday/...Moderate confidence. Sunday and Monday...Expect winds and seas to diminish below small craft criteria during Sunday, then should remain below small craft Sunday night and Monday. Monday night and Tuesday...Winds and seas remain below small craft criteria for most of the waters. N-NE winds gusting up to 25 kt and seas may build to 4-5 feet during Tuesday night along the southern coastal waters. Wednesday...Winds/seas may reach small craft criteria, especially along the southern coastal waters. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 6 AM EST Sunday for ANZ231>235-237- 250-251-254>256. Small Craft Advisory until midnight EST tonight for ANZ230. Small Craft Advisory until 1 PM EST this afternoon for ANZ236. && $$ SYNOPSIS...Belk/NMB NEAR TERM...Nocera SHORT TERM...Belk LONG TERM...NMB AVIATION...Nocera/NMB MARINE...Belk/Nocera/NMB

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