Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 240822 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 422 AM EDT FRI JUN 24 2016 .SYNOPSIS... High pressure remains influential over New England through the weekend. Expect a warming trend which will continue into Monday with showers and thunderstorms possible Tuesday. More seasonable weather is expected late in the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1110 PM Update... Noting a few bands of cirrus clouds crossing the region on latest IR satellite imagery at 03Z, otherwise noting mainly clear skies. 03Z observations sowing some low clouds moving into central and eastern Long Island which will be monitored to see if they work into portions of the immediate S coast, Cape Cod and the islands overnight. As high pressure slowly pushes into the region from the NW, will see light/variable or calm winds. Temps running mainly in the 60s, though noting a few upper 50s across the northern CT valley, and up to around 70 in the urban centers. Forecast is pretty much on track except for some minor adjustments on temps/dewpts to bring conditions current. Previous discussion... More widespread clearing across SRN New England this evening partially as shearing vort max shifts S of the region. This will tend toward clearing skies but noted temps running a bit warmer than previously forecast. Therefore, only changes were to bring in more widespread clear skies later tonight and raise mins just a shade. Still think it will be cool overall, with many places dropping into the lower 50s before rising again. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Friday... High pressure in control. Light winds. Beneath cooler air aloft with H85 temperatures around +10C. But considering the high angle of the sun, should easily warm back up into the upper-70s to low-80s. Cooler along the coasts with expected sea-breezes. Dry and comfortable as dewpoints will range in the 40s to low-50s. Friday night... High pressure pushes E. Begin to see return E/SE flow albeit remaining light. Mostly clear, an opportunity for radiational cooling and will need to watch those areas with sandy soils in particular. Leaned cooler of the forecast guidance, mainly towards MOS. Of greater attention is interior Southeast MA and Marthas Vineyard which could fall into the 40s. Progged presently in the low-50s. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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Big Picture... Longwave pattern continues to show ridge west/trough east through next week. Shortwave scale shows a ridge over New England Sunday moving east of us on Monday. A shortwave originating over the Pacific Northwest moves east across Canada over the weekend and then digs over New England Tuesday and Wednesday. Above normal heights with the ridge Sunday-Monday, diminishing tonear normal Tuesday-Wednesday. This suggests above normal temps Sunday-Monday returning to near normal midweek. Model forecast mass fields are similar through Monday, then diverge a little starting Tuesday. Even with the divergence, the forecast scenarios are similar. This encourages confidence in the forecast through midweek. Details... Saturday night through Monday... High pressure in control with dry weather. Light flow on Sunday will support sea breezes along the coasts which will buffer daytime max temps in those areas while the interior heats up. The top of the mixed layer Sunday and Monday will be between 800 mb and 850 mb, with temps supporting max surface temps 85 to 90. Model temps forMonday actually looked a few degrees too cool. Suspect sunshine will allow for deeper mixing and warmer temps. We bumped values up 3 degrees F. Monday night through Thursday... Northern shortwave pushes a cold front through the Great Lakes early week and across New England Tuesday or Wednesday. The GFS shows the faster timing with passage on Tuesday, while the ECMWF is slower with cold fropa Wedensday. As the shortwave digs over the Northeast USA the upper flow turns more southwest and parallel to the front. This would work to slow down forward progress until the shortwave axis sweeps through. Thus we favor the slower EC scenario, but with enough uncertainty to mention chance pops later Monday night and Tuesday. Stability parameters show potential for thunder. Weak high pressure builds dry weather in for 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. Short Term /through Saturday/...High Confidence. No major changes with 03Z TAF update... Overnight...VFR for all terminals. Low chance for low clouds and patchy fog across portions of the immediate S coast, Cape and Islands. IFR-LIFR cigs mainly with potential for fog over ACK. Anticipating a near repeat of conditions the previous night over ACK. Cigs 300 to 500 ft agl. Friday...VFR. Light winds. Sea-breezes developing along the coasts towards mid-morning. Friday night...Patchy MVFR-LIFR conditions with fog. Lower CT River Valley, interior non-urban locations, perhaps along the S-coast. Light winds. KBOS TAF...VFR. Light N-NE winds overnight before becoming E again through Friday. KBDL TAF...Concern with respect to Friday night into Saturday morning with potential fog issues. Otherwise VFR and light winds. Outlook /Saturday night through Tuesday/... Moderate to High confidence. Saturday night through Monday...Areas of IFR and LIFR in late night/early morning fog. Otherwise VFR. Sea Breezes expected Sunday. Potential for local MVFR cigs/vsbys in showers and t-storms Tuesday.
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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. Overnight... Low clouds and fog issues. N-NE winds increasing as a weak frontal boundary pushes offshore. Gusts up to 20 kt possible. Friday... NE winds initially with gusts up to 20 kt diminishing while turning E-SE as high pressure pushes across New England into the Gulf of Maine. Waves begin to build of 4 feet on the outer waters but much of this looks to be the result of swell subsequent of storm activity emerging off the Mid-Atlantic. Friday Night... Light winds overall out of the E-NE with high pressure situated over the Gulf of Maine. Seas of 4 feet continue over the S waters mainly due to swell from continued storm activity off the Mid- Atlantic. Outlook /Saturday night through Tuesday/... Moderate to high confidence. Winds and seas remain below Small Craft thresholds through Monday. On Tuesday a steady wind from South-Southwest will bring gusts to 25 knots as well as 5 foot seas on the outer waters. A Small Craft advisory may be needed Tuesday.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...WTB/EVT NEAR TERM...EVT SHORT TERM...EVT LONG TERM...WTB AVIATION...WTB/EVT MARINE...WTB/EVT

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