Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 231431 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 1031 AM EDT SAT JUL 23 2016 .SYNOPSIS... Hot conditions continue today, along with another risk for thunderstorms this afternoon, some of which may become severe. An approaching cold front will bring another round of scattered showers and thunderstorms from Monday into early Tuesday. More warm weather follows midweek. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1030 am update... Another hot day today with highs reaching the low to mid 90s across eastern MA/CT/RI although a bit cooler along immediate south coast where sw winds expected. Some of the hi-res guidance also hinting at a weak seabreeze across the immediate coast in eastern MA. Dewpoints to mix out this afternoon and likely drop into the upper 50s to lower 60s away from the immediate south coast. Main concern for this afternoon is the potential for another round of strong to possibly severe t-storms as rather potent shortwave moves into New Eng later today. Very good mid level cooling with this shortwave as 500 mb temps drop to -12 to -14C by evening which is impressive with temps into the 90s. Mid level lapse rates expected to increase to around 6.5 C/km associated with the cooling temps aloft which will allow MLCAPES to increase to around 1000 J/kg. The instability will be tempered by the decreasing dewpoints this afternoon so do not expect MLCAPES to get much higher. Hi-res guidance suggesting showers and t-storms will develop in northern New Eng and spill south into the region after 3 pm with focus across northern and eastern MA where core of cold pool moves. Currently, 0-6km shear is around 40 kt which is more than enough to support organized severe convection. However, guidance is indicating deep layer shear decreasing from the north mid to late afternoon and may drop below 30 kt which would limit organization of storms. However, very large T/Td spread and inverted V sounding profile support gusty winds and cant rule out isolated wind damage with the stronger storms. Hail is also a concern with cooling temps aloft. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... Thunderstorms/showers should end earlier than Friday night thanks to faster movement of the forcing shortwave. Drier air will lead to some drying during the overnight but leftover convective debris cloudiness will likely keep temps from dropping too far. Expect mins mainly in the 60s. A few spots of fog possible, especially where late day rainfall is observed. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Overview... Not much change from the previous model cycle. High pressure covers much of the southern USA for most of next week. This will mean any fronts will struggle to get very far south of our region next week. Mid level flow transitions to a near zonal flow by early next week, then to a broad trough by mid week. Temperatures should generally be above seasonable levels most of this portion of the forecast. Details... Sunday... High pressure in place through the day. Winds appear to be light enough where seabreezes may develop along both coasts. Moderate confidence in seabreezes. Above normal temperatures continue for most of southern New England. Monday... A mid level shortwave moves across our region late Monday into Monday night. Most of the day should be rain-free. Some signs of marginal instability crossing during the morning, which may be a warm front with a couple of light showers. Greater instability moves in from the west during the afternoon and evening, in the warm sector ahead of a cold front. Precipitable water values remain high, so locally heavy rainfall is still possible in stronger thunderstorms. Scattered showers and thunderstorms should continue into Monday night as a cold front passes by. Tuesday and Wednesday... High pressure takes control and brings fair weather. Above normal temperatures continue. Thursday and Friday... Latest operational guidance continues to indicate some potential for showers, largely due to a stalled front to our south, and another cold front approaching from the north. Still have low confidence in the details. Will continue to mention a chance of showers and thunderstorms due to the presence of these boundaries. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tonight/... Today...moderate confidence. VFR through at least 18Z. Then another risk for sct TSRA possible mainly E of a line from kEEN-kORH-kWST. Some strong winds possible once again in some of these storms. Otherwise, winds mainly W-SW 10-15 kt. Tonight...High confidence. Mainly VFR after any storms/showers end through the overnight hours. KBOS TAF...Moderate confidence. Another round of thunderstorms is likely this afternoon to early evening. Some of those storms could produce strong wind gusts. Low prob of a brief seabreeze developing this afternoon but it will likely remain just to the east. KBDL TAF...High confidence of VFR prevailing. There could be some patchy fog with MVFR visibility through 12Z. Outlook /Sunday through Wednesday/... Sunday...High confidence mostly VFR. Possible areas of IFR in early morning fog. Monday...Moderate confidence. Mostly VFR. Possible IFR in early morning fog. Brief MVFR/IFR cigs/vsbys in afternoon and early night showers/thunderstorms. Tuesday and Wednesday...High confidence VFR. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tonight/...High confidence. Seas will continue to dissipate through the morning as winds outside of thunderstorms have already dropped to or below 20 kt. Seas will also gradually dissipate this morning allowing the remaining small craft advisories to be dropped. Otherwise, another round of showers and thunderstorms are possible over the waters this afternoon and evening which could contain localized strong wind gusts. Outlook /Sunday through Wednesday/...Moderate confidence. Winds less than 20 knots and seas less than 5 feet through this period. A cold front will bring scattered showers/thunderstorms Monday afternoon and night, with potential for strong wind gusts and brief poor vsbys in heavy downpours. && .EQUIPMENT... The KBOX radar is down for maintenance. Technicians will try to return the radar into service by no later than 3 PM this afternoon. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ255- 256. && $$ SYNOPSIS...Belk/Doody NEAR TERM...KJC SHORT TERM...Doody LONG TERM...Belk AVIATION...Belk/Doody MARINE...Belk/Doody EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.