Area Forecast Discussion
Issued by NWS Boston, MA

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953 FXUS61 KBOX 281928 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 328 PM EDT TUE JUN 28 2016 .SYNOPSIS... A slow moving cold front will bring scattered showers and a few thunderstorms into Wednesday, with the bulk of the activity occurring tonight. This front will push offshore Wednesday night. High pressure then brings dry seasonable weather for Thursday. Another cold front may bring more showers and thunderstorms Friday or Saturday. Dry weather returns for the remainder of the holiday weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Instability remains the primary limitation for showers and thunderstorms across southern New England this afternoon. Latest mesoanalysis showing CAPE values starting to increase to around 500 J/kg. This is in response to some breaks in the clouds across western MA and northern CT. Both low level and mid level lapse rates remain poor this afternoon. As a result, have low confidence for any strong thunderstorms across southern New England this evening. A cold front will slowly approach our region tonight, with a mid level shortwave arriving late tonight. Plenty of moisture available, so it all comes down to generating enough lift for showers. Precipitable water values still 1.5-2.0 inches, so locally heavy rainfall a possibility. Will mention only isolated thunderstorms at most, owing to poor instability and time of day. South winds continue through much of the night. Thus, looking for more stratus and patchy fog to develop once more. This should be most prevalent toward the south coast of MA and RI, but could very well encompass just about all of southern New England. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... Wednesday...A surface cold front will sweep across the region later in the day. While the vast majority of the day will be dry for most locations, there is a low risk for a few strong thunderstorms developing in the afternoon ahead of this front. Strong thunderstorms will be dependent upon getting enough sunshine to increase instability, and having enough mid level moisture lingering to permit storms to develop. While thunderstorms remain uncertain, the highest risk will be across Eastern MA/RI where moisture will be a bit deeper. Wednesday night...Drier weather develops behind a departing cool front. Humidity drops to more comfortable levels, but not by a lot. Seasonable temperatures through this period. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Highlights... * High pressure brings dry weather Thursday * A cold front brings showers and thunderstorms Friday/Saturday * High pressure brings dry weather for the remainder of the holiday weekend Overview...Relatively quiet pattern continues with broad upper level ridge over the western U.S. and broad upper troughing over the eastern U.S. The ridging pushes into the center of the country by early next week. Models are in good agreement on the synoptic pattern and will use a blend of available guidance for this forecast. A cold front will move offshore Wednesday night bringing in slightly cooler but quiet weather for Thursday. Another cold front will move through southern New England Friday or Saturday (ECMWF is a bit faster than the GFS), bringing showers and potentially thunderstorms to the area. High pressure builds into New England from the Great Lakes for the remainder of the holiday weekend. Temperatures...After slightly cooler temperatures Thursday, temperatures will warm into the weekend. The cold front will bring another slightly cooler day Sunday before temperatures warm once again. Overall, temperatures will be right around to a few degrees above normal with highs generally in the 80s and lows in the upper 50s to lower 60s. Precipitation...The only shot of rain in the long term forecast is showers and possibly thunderstorms with the cold front Friday or Saturday. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday/... Through 00z...Moderate confidence. Mix of VFR and MVFR conditions. Scattered showers and thunderstorms remain main to the west of southern New England, but could get as far east as KORE-KBDL by 29/00Z. Tonight...Moderate confidence. Conditions lower to MVFR-IFR thresholds as boundary layer cools with an abundance of low level moisture. Scattered showers and thunderstorms also expected with main risk between 01z and 09z. Wednesday...Moderate confidence. MVFR-IFR conditions should improve to mainly VFR by afternoon as low clouds/fog patches dissipate. Low risk for a few strong thunderstorms Wed afternoon, mainly Eastern MA/RI. Wednesday night...High confidence. Mainly VFR conditions. Low risk for MVFR conditions in patchy fog. Light and variable winds. KBOS TAF...High confidence in TAF trends. Moderate confidence in timing. KBDL TAF...High confidence in TAF trends. Moderate confidence in timing. Outlook /Thursday through Saturday/... Thursday...High confidence. Mainly VFR conditions. Any lingering MVFR conditions will improve quickly to VFR. Light and variable winds. Friday and Saturday...Moderate confidence. Mainly VFR conditions and dry weather. Scattered showers and thunderstorms may result in brief periods of MVFR conditions. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday Night/...High confidence. Winds and seas will generally remain below small craft advisory thresholds through this portion of the forecast. South to southwest wind gusts of 20 knots are expected at times with 2 to 4 foot seas across the open waters. Southeast swell may increase seas to near 5 feet Wednesday night across the outermost coastal waters south and east of Nantucket. Low confidence in this happening. Main concern is for areas of fog tonight into Wed morning across the southern waters. May also see a few thunderstorms with brief heavy rain overnight tonight. Outlook /Thursday through Saturday/... High confidence. Mainly quiet boating weather expected. Winds and seas remain below SCA criteria throughout the period. However, they will increase as a cold front approaches and then crosses over the coastal waters sometime late Friday to Saturday. This will result in showers and thunderstorms, which will reduce visibilities at times. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Belk/RLG NEAR TERM...Belk SHORT TERM...Belk LONG TERM...RLG AVIATION...Belk/RLG MARINE...Belk/RLG is the U.S. government's official web portal to all federal, state and local government web resources and services.