Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 240940 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 540 AM EDT TUE MAY 24 2016 .SYNOPSIS...
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Scattered showers and few embedded thunderstorms this morning will focus primarily across Western MA and Northern CT by afternoon as low pressure slowly moves across southeastern New England. An upper level high pressure ridge will then bring very warm to borderline hot weather to most of the region Wednesday through Saturday, except for times of cooler temperatures on the immediate coast. A few showers and thunderstorms are possible Thursday night into Friday, but a better chance exists Saturday afternoon and evening ahead of the cold front.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Scattered showers and a few thunderstorms continue to rotate N-NW across the region at 09Z. Noted several reports of thunderstorms, including a tree split in two in Acushnet. Will continue to monitor those. Band of showers with embedded thunderstorms will shift into S NH over next couple of hours, while more showers continue to rotate around upper low across W MA/N CT through mid morning. Good instability still in place as well with core of H5 cold pool slowly shifting toward the region, so can not rule out more isolated convection through mid morning. Will see a brief break in the action except for a few showers lingering through mid to late morning. Then convection looks to start firing up again, with another round of sct showers/isold thunderstorms develop mainly across W MA and N CT. 00Z short range model suite continue to signal the instability remaining across the region, with total totals up to the lower to mid 50s /more robust on the NAM/, surface based LIs down to zero to -2 and K indices to the lower 30s. Also noted CAPES on order of 400-500 J/kg this afternoon across this area so, along with H5 temps down to -18C to -19C in the core of the cold pool as it crosses the region, can not rule out any small hail that could develop in any thunderstorms. Convection should begin to wane toward sunset, but will linger across N and W MA into N central CT into the evening. With the onshore winds continuing, albeit light, temps will only rise to around 60 along the immediate coast, but look to reach to the upper 60s to near 70 across the CT valley.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
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Tonight... As the H5 upper low and the associated surface reflection continue to move slowly NE tonight, will see some leftover isolated showers/thunderstorms into this evening before finally ending. With light and variable winds in place along with wet ground in many places, will likely see patchy fog redevelop overnight. Also, cooler, drier air will not rush in with light pres gradient in place, so temps will not fall back too far tonight. Expect lows in the 50-55 degree range.
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&& .LONG TERM /WEDNESDAY THROUGH MONDAY/... Highlights... * Very warm Wed/Thu/Fri with highs well up into the 80s except cooler immediate coast at times * Hot Saturday afternoon w/highs mainly upper 80s to the lower 90s * A few showers/t-storms possible Thu night/Fri but best chance Sat afternoon/evening ahead of cold front * Turning much cooler Sun and especially Mon along the coast Details... Wednesday...Closed upper level low lifts northeast of our region allowing for rising heights/warmer mid level temps. More importantly, surface winds will turn to the west which makes a huge difference in afternoon high temps this time of year. Given 850T between 13c/14c and plenty of late May sunshine, high temps should be in the mid to upper 80s for most including Boston, as any sea breezes that develop along the Eastern MA coast will be overcome by increasing gradient by afternoon. It will be a bit cooler on the south coast/Cape/Islands, but still should see highs well into the 70s to near 80. Dry weather will dominate Wednesday, but there is a low risk of a spot shower/t-storm during the afternoon/early evening across the interior. Limiting factors though will be dry mid levels and lack of low level forcing. Wednesday night...Other than a low risk for a spot shower/t-storm across the interior during the evening dry weather is expected behind a weak cold front. Low temps will only fall back into the 50s in most locations with 60 to 65 in some of the urban centers. A touch of patchy fog may develop in the typically prone locations toward daybreak. Thursday...Upper level ridging across the Southeast U.S. continues to nose into southern New England. This will result in plenty of sunshine and with warm mid level temps, highs again should reach well into the 80s in most locations. However, gradient will be weaker allowing for sea breezes to develop on the immediate Eastern MA coast including Boston by early afternoon. High temps will still likely reach well up into the 70s to near 80 in this region before sea breezes develop and temps fall a bit. Should remain dry given lack of forcing and upper level ridging nosing into this region. Thursday night and Friday...A shortwave will lift northeast into northern New England Thu night/Fri. While the best forcing will to our north, a few showers/t-storms are possible with the best chance across western and northern MA. Certainly not expecting a washout though and the majority of the Thu night/Fri will be dry. Still looks like a warm afternoon with temps into the 80s, but it may be cooler across Northeast MA depending on location of backdoor cold front. Saturday...A hot day with westerly flow and 850T near 16c. This should yield highs in the upper 80s to lower 90s for most locations. Dewpoints into the 60s will make it feel somewhat muggy. Pre-frontal trough ahead of an approaching cold front may trigger scattered showers/thunderstorms mainly Saturday afternoon and evening. Sunday and Monday...High pressure over the Canadian Maritimes will build south into New England. So despite rather high height fields, northeast low level flow will result in much cooler temps Sun and especially Mon particularly along the coast. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/...
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Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through 12Z...Moderate confidence. Mainly VFR across central and western areas, except locally MVFR in any heavier showers and isolated TSRA. Across eastern MA/RI, MVFR- IFR CIGS/local IFR VSBYS in locally +SHRA and isolated TSRA. Areas of LIFR across SE MA, Cape Cod and the Islands in -SHRA and fog. Today...Moderate confidence. General MVFR-IFR CIGS through midday, then slow improvement but may linger through the afternoon along E coastal MA. Areas of MVFR-IFR VSBY across central and eastern areas should improve by midday. Isolated TSRA with locally heavy rainfall. Low risk of small hail across CT valley during the midday and afternoon. Light E-NE winds back to N-NW during the afternoon. Tonight...Moderate confidence. Isolated SHRA/TSRA lingers across central and N MA through this evening, then ending. Patchy fog lingers along E coastal MA with MVFR-IFR VSBYS, while fog redevelops away from the coast with areas of MVFR VSBYS. Light/vrbl winds. KBOS TAF...Moderate confidence. MVFR CIGS may become briefly IFR through 13Z-14Z. VFR VSBYS may become locally MVFR in any showers through mid morning. Low risk for TSRA through 14Z, then again after 18Z today. CIGS improve to VFR by 22Z. Mainly VFR tonight. Low chance of MVFR VSBYS in patchy fog after 05Z. Light NE winds become Light/vrbl tonight. KBDL TAF...Moderate confidence. Mainly VFR conditions. Local MVFR in any showers through the day. Low risk of TSRA. Mainly VFR tonight, though VSBYS may lower to MVFR in patchy fog after 05Z. Outlook /Wednesday through Saturday/... Wednesday and Thursday...High confidence. VFR conditions other than a few hours of patchy ground fog possible toward daybreak Thu in the typically prone locations. Thursday night and Friday...Moderate confidence. VFR conditions likely dominate but some brief MVFR conditions possible in a few showers/t-storms mainly across the interior. Saturday...Moderate confidence. Mainly VFR conditions but brief MVFR- IFR conditions possible Saturday afternoon/evening in scattered showers and thunderstorms.
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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. Through 12Z...Moderate confidence. Expect E-NE winds less than 15 kt and seas below 5 ft. Visibility reductions in showers, widely scattered thunderstorms and patchy fog. Today...Moderate Confidence. E-NE winds less than 15 kt. Seas will build up to 5-6 ft across the outer waters from Cape Cod southward, mainly in S-SE swells this afternoon. Local visibility restrictions in scattered showers, isolated thunderstorms and patchy fog. Winds will back to N during the afternoon. Small crafts have been issued for portions of the outer waters. Tonight...Moderate Confidence. N-NW winds as low pressure moves offshore, but remaining light. E-SE swells will remain at 5-6 ft through around midnight, then will slowly subside toward daybreak. Small crafts will continue for portions of the outer waters. May see local visibility restrictions in patchy fog. Low risk of isolated showers early. Outlook /Wednesday through Saturday/...High Confidence. Winds and seas will remain below Small Craft Advisory thresholds the majority of the period with the exception being Wednesday night. Some brief near shore southwest wind gusts of 20 to 25 knots are likely Wed afternoon...which will result in some choppy seas. In addition, long southwest fetch may bring a period of 5 foot seas across our southern waters Wednesday night which may require headlines.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory for hazardous seas from 1 PM this afternoon to 4 AM EDT Wednesday for ANZ254-255. Small Craft Advisory for hazardous seas from 3 PM this afternoon to 1 AM EDT Wednesday for ANZ256. && $$ SYNOPSIS...Frank/EVT NEAR TERM...EVT SHORT TERM...EVT LONG TERM...Frank AVIATION...Frank/EVT MARINE...Frank/EVT

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