Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 290650 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 250 AM EDT WED JUN 29 2016 .SYNOPSIS...
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Scattered showers will come to an end early this morning, followed by a warm and humid afternoon with the low risk of a few strong thunderstorms across eastern New England. Dry and seasonable weather follows tonight and Thursday. Another cold front may bring scattered showers and thunderstorms to the region Friday and Friday night. There is a low risk this activity lingers into Saturday, otherwise a beautiful holiday weekend is expected with dry weather and low humidity.
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&& .NEAR TERM /THROUGH TODAY/...
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***Low risk for a few strong thunderstorms across eastern New England this afternoon*** Scattered showers with brief very localized heavy rainfall was moving across the region very early this morning. Still can not rule out an isolated thunderstorm or two. This in response to a 25 knot southerly low level jet, marginal elevated instability and Pwats greater than 1.5 inches. Bulk of this activity should come to an end early this morning, as the low level jet weakens and deeper moisture lifts northeast of the region. For the rest of the morning and into this afternoon, mainly dry weather will prevail. Surface winds turning west southwest should allow skies to become partly sunny allowing highs to recover into the lower to middle 80s away from the immediate coast. Dewpoints in the 60s will also make it feel rather humid today, so a summerlike day is on tap. While the vast majority of the day will be dry, the main uncertainty is if we are able to generate a few thunderstorms this afternoon across eastern New England as a cold front crosses the region. The highest risk for this will be across eastern MA, where sea breeze interaction might assist in development. We should see 1000+ j/kg of Cape develop across eastern New England with mid level lapse rates increasing to between 6 and 6.5 c/km. In addition, 0 to 6 km shear values will be on the order of 40 knots. These are all favorable parameters for a few strong to marginally severe thunderstorms. However, there is one big negative factor which is an abundance of mid level dry air. This may prevent any convection from developing and its possible we end up with just low topped showers. So to sum up, there is a low risk for a few strong to marginally severe thunderstorms across eastern New England this afternoon, but too much mid level dry air may prevent this from occurring. Highest risk might be on a subtle sea breeze front, which may allow for a bit better moisture to pool. Something will certainly have to keep a close eye on today.
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&& .SHORT TERM /TONIGHT/...
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Tonight... If any isolated showers/t-storms are able to develop across eastern New England this afternoon, they should quickly diminish early this evening with the loss of daytime heating. Skies should become mostly clear allowing low temps to drop into the upper 50s to lower 60s in most locations. Light winds will likely allow for patchy ground fog to develop in the typically prone locations overnight, which may be locally dense.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/... HIGHLIGHTS... * Dry with seasonable conditions on Thursday * Scattered showers and thunder Friday/Saturday from passing front * Cooler and less humid for Sunday into July 4th Holiday OVERVIEW... The 12Z guidance is in good agreement for both the medium and long range. Still a few minor issues because of timing but overall have a high confidence in forecast trends. Upper level trough will remain the dominate features across the Northeast as a subtropical ridge builds across the Southeast, while a moderate upper ridge continues over the West. Trended the overall pattern towards a blend of the guidance as well as the ensemble means, which has remained consistent over the past few runs. DAILIES... Thursday... Cold front will move offshore on Thursday resulting in high pressure pushing into the region. A few sct cu will develop as there will be some left over mid-level moisture but overall a pleasant day is on tap. Sea breeze development will keep coastal conditions cooler but temps will be in the 80s across the interior. Friday into Saturday... Cold frontal system will approach from the west late Friday into Saturday. Return flow across will help pool in higher dewpoints, especially Friday night. So cannot rule out the potential for fog development. Otherwise sct showers with isolated thunderstorms are possible on Friday. The attention is more towards Friday night into Saturday. Still a timing difference as the GFS is faster pushing the front through by 12z Saturday. However the EC is about 12 hours slower, which could result in more widespread thunderstorms. In fact, the conservative EC show surface based CAPEs around 1000 j/kg, with increasing 0-6km shear and steepening mid-level lapse rates. This may result in a few strong storms Sat morning. Something to continue to watch in case guidance slows down the timing of the frontal passage. Sunday and beyond... Cold frontal system will be offshore by Saturday night allowing a pleasant Sunday. Potent shortwave will move through the flow on Sunday which will keep upper level trough over the region and cool down temps aloft. 700 mb temps are near 1 to 2 standard deviations below normal, indicating the cooler air aloft. Stationary front will stall across the Ohio valley and into the Mid-Atlantic keeping Southern New England on the dry, relatively cooler side. Less muggy conditions will prevail as the hot, muggy conditions will stay south of the front. These conditions will prevail into Tuesday. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
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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 Tonight/... Today...Moderate to high confidence. MVFR-IFR conditions should improve to VFR by afternoon in most locations, but lower Cigs/Vsbys may linger across the islands. Sct showers should come to an end early this morning. This will be followed by mainly dry weather, but there is the low risk for a few strong thunderstorms this afternoon across eastern MA. Tonight...Moderate to high confidence. Mainly VFR early this evening except for this risk for low clouds/fog patches across the Cape/Islands. Across the rest of the region, will likely see localized patchy ground fog develop late in the typically prone locations. Meanwhile, other locations may see conditions remain VFR. KBOS Terminal...Moderate confidence. A period of MVFR CIGS through mid morning otherwise, mainly VFR. May see a sea breeze for a few hours later this morning and into the afternoon, but timing and duration is uncertain. Lastly, there is a low risk of a t-storm in the vicinity of the terminal this afternoon. KBDL Terminal...Moderate to high confidence. MVFR-IFR conditions improve to VFR by late morning. Outlook /Thursday through Sunday/... Thursday...High confidence. Mainly VFR conditions. Sea breeze for the coastlines. Friday and Saturday...Moderate confidence. Mainly VFR conditions and dry weather. Scattered showers and thunderstorms may result in brief periods of MVFR conditions especially Fri night into Sat. Sunday...High confidence. VFR conditions will prevail.
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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 Tonight/...High confidence. Winds and seas will remain below small craft advisory thresholds. Main concern will be for areas of fog, which may be locally dense at times this morning and again this evening across our southern waters. Also, there is a low risk for an isolated strong thunderstorm this afternoon near the adjacent coastal waters. Outlook /Thursday through Sunday/... High confidence. Quiet boating weather expected. Winds and seas remain below SCA criteria throughout the period. Could see a few gusts near 20 kts on friday ahead of an approaching cold front. This front should cross waters by Saturday. This will result in showers and thunderstorms, which will reduce visibilities at times.
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&& .FIRE WEATHER... This Weekend into Next Week... Hit or miss showers and thunderstorms will occur tonight into Wednesday, with another shot for thunderstorms on Friday night. However, widespread perception looks to be nil over the next 7 days. High pressure and dry conditions appear to take hold of the region late Saturday lasting into next week. Specifics are still to hard to nail down, but it looks like the area will be less humid and a bit cooler but dry during this time frame. RH values could drop close to 30 percent between Sun into Wed. Winds overall appear to be light during this period. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...Air Quality Alert from 11 AM this morning to 11 PM EDT this evening for RIZ006>008. MARINE...None.
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&& $$ SYNOPSIS...Frank NEAR TERM...Frank SHORT TERM...Frank LONG TERM...Dunten AVIATION...Frank/Dunten MARINE...Frank/Dunten FIRE WEATHER...Dunten

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