Area Forecast Discussion
Issued by NWS Boston, MA

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603 FXUS61 KBOX 270829 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 428 AM EDT FRI MAY 27 2016 .SYNOPSIS...
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Very warm to hot afternoon temperatures will continue Today and Saturday away from the immediate coast. A backdoor cold front will bring cooler temperatures to eastern MA Sunday but it will remain very warm across the interior, where hit and miss showers and thunderstorms likely develop during the afternoon. The potential exists for a period of heavy rain very late Sunday night into Memorial Day. Dry weather likely follows Tuesday through Thursday, with above normal temperatures trending back to seasonable levels by late in the week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/... 11 PM Update... Still noting only a few spotty showers moving along the MA/NH border late this evening with very weak mid level short wave moving in the westerly wind flow. Not seeing any lightning with this activity, however. With lack of any precip, will be tough to get convection going at this hour so kept thunder out of forecast through the remainder of the overnight. Temps at 03Z mainly in the upper 50s to mid 60s across E MA/RI ranging to the lower-mid 70s across N central MA. Expect temps to fall back to the mid 50s to mid 60s from E-W overnight. Near term forecast pretty much on track, but did lower POPs through 06Z with lack of activity on regional radar, then blended to slight chance to low end CHC POPs during the early morning hours across N MA. Updated remainder of forecast to bring conditions current. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Friday...Mid level ridge continues to be the main influence of our weather. It will be another warm day for much of the area with southerly winds. The pressure gradient is a little tighter, so we may get away without a sea breeze developing on the east coast. The south coast will be the larger concern with southerly winds keeping temperatures along the coast cool. Expect high temperatures into the mid to upper 80s for most locations away from the south coast. A pre-frontal trough will move into southern New England during the day which could result in some convection. However, there are some limiting factors, including rising heights, that will limit this potential somewhat. There will be enough instability generated during the day as well as elevated instability for thunder to develop. Again, think this will be rather spotty and isolated for the most part. Friday night...Any isolated convection that does occur will diminish during the evening hours. Then dry weather is expected. Low temperatures are expected to be in the 60s. With dewpoints in the upper 50s to lower 60s, patchy ground fog will likely develop in the typically prone locations. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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Highlights... * Turning cooler Eastern MA coast Sunday but still very warm inland * Hit and miss showers/t-storms likely across interior southern New England Sunday afternoon/early evening * Period of heavy rain possible very late Sunday night into Memorial Day with even a small risk of localized flooding * Dry weather Tue into Thu with above normal temps trending back to seasonable levels late in the week Details... Saturday night...Isolated to widely scattered showers/t-storms may linger into the evening but should be on the downward trend with the loss of daytime heating. Otherwise, expect mainly dry weather Saturday night but it will be quite mild and muggy for late May. Low temps may only drop into the middle to upper 60s for many locations away from the cooling marine influence of the south coast. Patchy fog likely develops in the typically prone locations with dewpoints in the 60s. Sunday...Still timing differences with the backdoor cold front but appears that it will still be east of the CT River Valley by mid afternoon. So its conceivable that Sunday afternoon temps will have fallen into the 60s along the Eastern MA coast, while the Lower CT River Valley might be in the lower 90s. The morning should mainly be dry, but expect 1000 to 2000 J/KG of Cape to develop across interior southern New England. Despite upper level ridging, decent low level convergence/instability will allow low level moisture to pool a bit. The result should be hit and miss showers/thunderstorms developing across interior southern New England Sun afternoon. The extent of this activity will be determined by how fast the front moves and amount of instability that is able to develop. Highest risk for scattered activity is across western MA/northern CT but it could extend back into portions of central MA/RI if front moves slower. 0 to 6 km shear is weak, so overall severe weather threat is low. However, given decent instability can not rule out a strong thunderstorm or two. Any storms that develop will be slow moving and capable of producing very localized heavy rain. So to sum up Sunday, dry weather expected for much of the day but scattered showers/t-storms likely develop in the afternoon across the interior. While activity should be hit and miss, very localized heavy rainfall and lightning will be the biggest concern with any storm. Sunday night and Memorial Day... Hit and miss convection across the interior should diminish Sunday evening with the loss of daytime heating. Mainly dry weather expected for the first part of the night. Things then become very interesting very late Sunday night into Memorial day. The National Hurricane Center is expecting low pressure between the Bahamas and Bermuda to develop into a tropical or sub tropical cyclone in the next 48 hours. While a direct impact will not occur, an approaching cold front will likely pull a plume of its tropical moisture northward. PWATS may rise to around 2 inches in southern New England. Still plenty of uncertainty on how this unfolds, but a period of heavy rain showers and a few embedded thunderstorms are possible across the region. Fortunately, this appears to be a progressive event but given tropical connection there is a small risk of some localized flooding. Something will have to watch closely, especially given it will be on the end of a Holiday Weekend and a big travel day. Tuesday through Thursday... Looks like dry and warm weather follows behind the cold front on Tuesday with highs mainly in the 80s. It is a long way off, but current guidance favors dry weather Wed into Thu as high pressure builds down from the Canadian Maritimes. This would also generate an easterly low level component to the wind with temperatures likely returning to seasonable normals by Thursday.
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&& .AVIATION /09Z FRIDAY THROUGH TUESDAY/...
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Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Overnight...High confidence. VFR conditions likely for much of the period. Low probability of brief MVFR conditions in ISOLD -SHRA/-TSRA mainly across W MA/N central CT. Friday...High confidence. Mainly VFR. Low probability of brief MVFR conditions in SCT -SHRA/-TSRA mainly across the interior. Friday night...High confidence. Mainly VFR. Patchy ground fog develops resulting in patchy MVFR/IFR conditions. KBOS TAF...High confidence in TAF. KBDL TAF...High confidence in TAF. Outlook /Saturday night through Tuesday/... Saturday night...Moderate to high confidence. Any isolated convection diminishes early in the evening. Mainly VFR conditions but a period of MVFR to even localized IFR condition may develop late in patchy fog and perhaps a touch of low clouds. Sunday...Moderate confidence. VFR conditions may lower to MVFR thresholds across Eastern New England behind backdoor cold front. Otherwise, mainly VFR across the interior but briefly lower conditions possible in hit and miss showers/t-storms during the afternoon. Sunday night and Memorial Day...Moderate confidence. MVFR-IFR conditions may develop late Sunday night into Memorial Day in a period of rain showers which may be locally heavy. Monday night and Tuesday...Moderate to high confidence in mainly VFR conditions.
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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/...High confidence. High confidence. Quiet boating weather is expected through the short term. There is a low probability of seas reaching 5 feet on the outer waters Friday night. Winds will generally be out of the south. Fog may develop over the waters Friday night, limiting visibilities. Outlook /Saturday night through Tuesday/...High confidence. Winds and seas will generally remain below small craft advisory through the period with a relatively weak pressure gradient. Biggest concern for Mariners will be late Sunday night into Memorial Day, when a period of heavy rain showers/isolated thunderstorms are possible.
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&& .CLIMATE... Warmest day of the week appears to be Saturday and some record highs may be challenged. Record highs for Saturday May 28... Boston...92 set in 1931 Providence...91 set in 1931 Hartford...93 set in 1977 Worcester...88 set in 1911 and 1929 Milton/Blue Hill...90 set in 1929 && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...Air Quality Alert from 11 AM this morning to 11 PM EDT this evening for CTZ002>004. MA...None. RI...None. MARINE...None.
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&& $$ SYNOPSIS...EVT/Frank NEAR TERM...EVT - Coming soon SHORT TERM...EVT - Coming soon LONG TERM...Frank AVIATION...EVT/Frank MARINE...EVT/Frank CLIMATE...Staff

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