Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 252024 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 424 PM EDT MON JUL 25 2016 .SYNOPSIS... A weak cool front may cause scattered showers and thunderstorms tonight...a few with gusty winds, especially in western and southern portions of the region. High pressure will bring dry but hot conditions Tuesday and Wednesday. A cold front approaches the area on Thursday. This front may linger in our area into this weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 415 PM update... First line of thunderstorms has sagged southeastward, with a severe portion of the line moving across southern Connecticut. Farther north, scattered showers were developing from Hartford County to Worcester County. A few other showers were on the sea breeze in northeast MA. Downdraft CAPE is 1200 but across our area the line is fighting some warm air aloft and poor mid level lapse rates. A second area of convection was occurring from central NY southward through PA. This is associated with the upper level shortwave trough and a weak cool front. Mid level lapse rates will be increasing as it approaches. Short-range models move it east- southeastward, meaning the majority of it passing across CT. Will carry 40-55 percent probabilities of showers/tstms tonight across the region...exiting eastern coastal areas around 10-11 PM. Have removed the severe wording from the grids but will add gusty winds as enhanced wording mainly in CT and areas along the CT/MA and CT/RI border into the evening hours. Boston Logan winds had turned to the southeast and within an hour or so, temperatures could shoot up above 90 degrees there. Otherwise, dwpts will be slow to decrease even as winds shift toward the W-NW. Expect some localized ground fog especially where rainfall is observed. Indications suggest Cape/Islands see a mix of marine fog/stratus. Minimum temps mainly 65 to 70. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Tuesday...Even with some cooling aloft, high temperatures still are forecast to soar to the low to mid 90s. This is courtesy of mostly sunny skies, some downsloping west-northwest flow, and 925 mb temperatures from 23C to 25C. Tuesday night...Dry with high pressure in control. Lows in the 60s to near 70 along coast. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Highlights... * Lower humidity lingers thru midweek * Hot temperatures anticipated Wednesday away from the coast * Cold front approaches the region on Thursday * Showers and thunderstorms are possible again Friday and possibly into the weekend Overview... 25/12z guidance is in decent overall agreement through mid week.However there continues to be significant differences in solutions for Thursday night and on. 12Z models seem to be in general agreement on bringing a cold front into our area Thursday or Thursday night. However, models differ on when the front pushes south of our area. Will continue to go with a consensus approach for this forecast. Details... Wednesday and Wednesday night...Dry weather with high pressure in control. Still hot, especially away from the coasts. Sea breezes are expected to develop, which should help to limit high temps along the shorelines. Thursday...We should see another day of hot conditions, however a cold front will be approaching our area from the N/NW. Moisture increasing along the front should enable isolated to scattered afteroon t-storms on Thursday/Thursday evening. Thursday night and Friday...Uncertainty increases with this portion of the forecast. Models differ on how far south cold front pushes, as well as timing on potential open wave or deeper low pressure passing near/south of our area. Will have chance pops for showers/t- storms. Friday high temps expected to be a few degrees lower than previous days. Saturday and Sunday...Lots of uncertainty remains with this portion of the forecast, leading to a low confidence forecast. ECMWF keeps frontal boundary nearby, with potential low pressure moving along the front. GFS pushes the front south of our area for much of the weekend. Will continue with a chance of showers for this timeframe. Monday...Continued significant amount of uncertainty for this timeframe, could have a drier period with frontal boundary exiting the area. Will go with only slight chance pop for this period. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/... Through this evening...Moderate confidence. Mainly VFR through the evening. Widely scattered showers or a thunderstorm late this afternoon. Then a better chance of showers or thunderstorms, mainly in CT and areas along the CT/MA and CT/RI borders this evening. Gusty winds, heavy downpours in any thunderstorms. IFR conditions possible in thunderstorms. Later Tonight...Moderate confidence. Most thunderstorms/showers exit the coast between 03Z and 04Z with VFR developing initially then late night fog especially at typically prone airports. Stratus also possible along the Cape/Islands especially. Mix of IFR/MVFR conditions. Tuesday and Tuesday night...High confidence. Mainly VFR after early morning fog/stratus dissipates. Winds mainly NW with gusts 15-20 kt during the afternoon hours. KBOS TAF...Moderate confidence in TAF. Winds shifting back to south-southwest by 21-22Z. VFR but chance of showers or thunderstorms until about 04Z. KBDL TAF...Moderate confidence in TAF. Chance of a few strong thunderstorms this evening. IFR possible in any localized heavier thunderstorm. Otherwise VFR except localized MVFR visibilities in patchy fog late tonight. Outlook /Wednesday through Saturday/...Moderate to high confidence. High confidence Wednesday. Moderate confidence Thursday through Saturday. VFR conditions expected on Wednesday. Mainly VFR conditions Thursday, except MVFR cigs/vsbys possible in scattered afternoon/eveningshowers/thunderstorms. Thursday through Saturday...Mainly VFR, except MVFR cigs/vsbys possible in periodic showers and thunderstorms. Potential for patchy low ceilings/fog at night. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/...High confidence. Seas remain below SCA, although they may build to 3 to 4 ft along the south coast on Tuesday. Winds from the W-SW tonight will shift to mainly west to northwest on Tuesday with some gusts to 15-20 kt. Scattered showers and thunderstorms, especially in the southern coastal waters tonight. Light northwest winds Tuesday night. Outlook /Wednesday through Saturday/...Moderate to high confidence. Quiet boating weather is expected for Wednesday. During Thursday into Saturday winds and seas are expected to remain below SCA criteria, but the potential exists for areas of low clouds, fog, and scattered showers and thunderstorms which would limit visibilities at times. && .FIRE WEATHER... During Tuesday, behind the departing cool front, much drier conditions are expected across southern New England. Minimum relative humidity during Tuesday is expected to range from 30 to 40 percent across much of the area. The exception is along Cape Ann and the Cape/Islands, where minimum RH values of 40 to 60 percent are forecast. Northwest winds around 10 mph may gust to 20 mph at times during Tuesday. Winds are expected to be lighter on Wednesday with nearshore sea breeze develompent. However, minimum RH will drop to 30 to around 40 percent across the interior. Along east coastal MA and southern RI, sea breezes will allow for higher minimum RH of 40 to 70 percent. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Heat Advisory until 6 PM EDT this evening for CTZ002>004. Air Quality Alert until 10 PM EDT this evening for CTZ002-003. MA...Air Quality Alert until 11 PM EDT this evening for MAZ004>016- 026. Heat Advisory until 6 PM EDT this evening for MAZ005-010>013- 017. RI...Heat Advisory until 6 PM EDT this evening for RIZ001. MARINE...None. && $$ SYNOPSIS...GAF/NMB NEAR TERM...GAF SHORT TERM...GAF LONG TERM...NMB AVIATION...GAF/NMB MARINE...GAF/NMB FIRE WEATHER...NMB is the U.S. government's official web portal to all federal, state and local government web resources and services.