Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 241915 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 315 PM EDT FRI JUN 24 2016 .SYNOPSIS...
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Large high pressure remains over the northeast U.S. into early next week keeping dry conditions across the region. Warm days and cool nights will continue into Sunday morning...then turning hot beginning Sunday afternoon into Monday with highest temperatures inland. A frontal boundary may bring showers and thunderstorms to the area Tuesday and Wednesday.
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&& .NEAR TERM /THROUGH TONIGHT/...
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3 pm update ... This evening ... Weak high pressure over the region and accompanied by a dry airmass with dew pts in the 40s inland...50s along the coast is providing splendid weather by late June standards. Dry column only yielding some scattered strato-cu with a focus for the clouds across CT into RI as seabreeze moving inland provides some convergence. Also some additional diurnal clouds over the higher terrain but nevertheless mostly sunny skies. Given the dry airmass with dew pts in the 40s temps will fall noticeably with sunset given mostly clear skies and light winds. Diurnal clouds will also erode with sunset as well. Other than cooling temps with sunset a very pleasant evening ahead. Overnight ... Another comfortable night with lows in the 50s regionwide except around 60 in the city of Boston. Given the ideal radiational cooling conditions followed by cooler MET and MAV guidance as 2m temps too warm in this pattern for overnight mins. Could be a few hours of patchy fog toward daybreak in the typical prone locations. Could be some mid to high cloudiness on the southern horizon across the Islands and Cape Cod as short wave energy in the WNW flow aloft induces a weak frontal wave off the Mid Atlc coast and traces eastward...south of 40N.
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&& .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
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Saturday ... High pressure overhead providing light winds and promoting afternoon seabreezes. However with mean mid level trough axis just offshore cold temps aloft linger across southern New England with H5 temps about -14C. This provides modest mid level lapse rates however should be enough deep layer dry air within the column to offset any shower potential. NAM offers a risk of isolated afternoon showers high terrain however this is a result of it`s dew pts climbing into the 60s. Not happening with surface ridge over the area and other model guidance limit dew pts to the 50s. Thus have discounted the NAM and will continue with a dry forecast. Very similar day tomorrow to today with comfortable humidity and warm temps with afternoon highs in the 80s inland away from the cooling afternoon seabreezes. Highs in the 70s along the coast. Given the recent dry weather /dry soil, etc/ temps have been overachieving. Thus have added a few degs to a model blend. Sat night ... High pressure remains over the area providing dry weather. Another comfortable cool night with low dew pts...light winds and mostly clear skies. Followed a blend of the MOS guid which yielded lows in the 50s to near 60 in the city of Boston. Could be a few hours of patchy fog toward daybreak in the typical prone locations.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/... Big Picture... Longwave pattern continues to show ridge west/trough east through next week. Shortwave scale shows a ridge over New England Sunday moving east of us on Monday. A shortwave originating over the Pacific Northwest moves east across Canada over the weekend and then digs over New England Tuesday and Wednesday. Above normal heights with the ridge Sunday-Monday, diminishing to near normal Tuesday-Wednesday. This suggests above normal temps Sunday-Monday returning to near normal midweek. Model forecast mass fields are similar through Monday, then diverge a little starting Tuesday. Even with the divergence, the forecast scenarios are similar. This encourages confidence in the forecast through midweek. Details... Saturday night through Monday... High pressure in control with dry weather. Light flow on Sunday will support sea breezes along the coasts which will buffer daytime max temps in those areas while the interior heats up. The top of the mixed layer Sunday and Monday will be between 800 mb and 850 mb, with temps supporting max surface temps 85 to 90. Model temps for Monday actually looked a few degrees too cool. Suspect sunshine will allow for deeper mixing and warmer temps. We bumped values up 3 degrees F. Monday night through Thursday... Northern shortwave pushes a cold front through the Great Lakes early week and across New England Tuesday or Wednesday. The GFS shows the faster timing with passage on Tuesday, while the ECMWF is slower with cold fropa Wednesday. As the shortwave digs over the Northeast USA the upper flow turns more southwest and parallel to the front. This would work to slow down forward progress until the shortwave axis sweeps through. Thus we favor the slower EC scenario, but with enough uncertainty to mention chance pops later Monday night and Tuesday. Stability parameters show potential for thunder. Weak high pressure builds dry weather in for Thursday. && .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. VFR with light and variable winds inland...then seabreezes along the coast by midday or earlier. Low risk for patchy fog/MVFR toward daybreak for a few hours in the typically prone locations. KBOS TAF...High confidence. VFR. East winds late Fri will bend to the SE and then S later this evening. Winds then settle back to SE Sat morning. KBDL TAF...High confidence. VFR. Low chance for MVFR-IFR conditions in patchy fog 07Z-11Z tonight and again Sat night. Outlook /Sunday through Tuesday/... Moderate to High confidence. Sunday through Monday...Areas of IFR and LIFR in late night/early morning fog. Otherwise VFR. Sea Breezes expected Sunday. Potential for local MVFR cigs/vsbys in showers and t-storms Tuesday.
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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. Ridge of high pres over southern New England thru Sat night yielding light and variable winds. Weak low pres will track southeast of 40N/70W Saturday. Outlook /Sunday through Tuesday/...Moderate to high confidence. Winds and seas remain below Small Craft thresholds through Monday. On Tuesday a steady wind from South-Southwest will bring gusts to 25 knots as well as 5 foot seas on the outer waters. A Small Craft advisory may be needed Tuesday.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Nocera NEAR TERM...Nocera SHORT TERM...Nocera LONG TERM...WTB AVIATION...WTB/Nocera MARINE...WTB/Nocera

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