Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 241051 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 651 AM EDT FRI JUN 24 2016 .SYNOPSIS... Large high pressure will slowly move across the northeast U.S. into early next week, keeping dry conditions across the region. Warm to hot temperatures will move in Sunday and Monday, with showers and thunderstorms possible Tuesday. More seasonable weather is expected late in the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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7 am update Patches of fog in SE Mass and Ct Valley are burning off. Generally fair skies over the region, and the fair weather will continue through the day. No changes planned for the forecast. Previous discussion High pressure ridge stretching from the Great Lakes into northern New England early this morning will slowly shift into the region this afternoon. With the position of this high, expect N-NE winds to veer to E-NE during the day but, with a low pressure gradient in place, winds will generally be at 10 mph or less. Will see some gusts up to around 15 mph this morning along the immediate S coast and the islands. H85 temps start off in the +9C to +12C range this morning, but should recover to +12C to +14 during the afternoon. With nearly full summer sunshine, expect temps to recover to the mid 70s to lower 80s away from the coast, but will remain cooler especially along the E coast with the onshore winds.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Tonight... As the ridge axis slowly settles across the region, it will gradually shift E. Expect mainly clear conditions with light E-SE winds. Will need to monitor the normally susceptible areas for radiational cooling, especially interior E Mass, the northern CT valley and even Martha`s Vineyard where they radiate very well with calm winds. For now, have lows mainly in the 50s, though a few spots could drop below 50. Could also see patchy low clouds and fog redevelop after midnight in the normally prone spots. Saturday... High pressure continues to slowly shift E, while low pressure lingers off the mid Atlantic coast. This will keep mainly E winds in place, and may pick up along the S coast during the afternoon with gusts possibly up to around 20 mph. Should be another mainly sunny, warm summer`s day. Highs will range in the lower-mid 80s away from the coast, mildest across the lower CT valley, but holding mainly in the 70s along the immediate coast. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... 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 to near 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 for Monday 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 Wednesday. 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. && .AVIATION /12Z 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. Today...VFR. Light N-NE winds becoming E-SE up to around 10 kt during the day. Any leftover IFR conditions improve by 14Z. Tonight...Mainly VFR. Local MVFR-LIFR conditions in patchy fog after midnight, mainly across lower CT River Valley, interior non- urban locations, perhaps along the S-coast. Light winds. Saturday...VFR. Light E-SE winds, may gust up to 15 kt during the afternoon along the S coast. KBOS TAF...High confidence. VFR. Light N-NE winds becoming E-SE today through Saturday. KBDL TAF...High confidence. Mainly VFR. Low chance for MVFR-IFR conditions in patchy fog after midnight through 11Z-12Z Saturday. 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. Today...Light N-NE winds early, becoming E-SE during the day. Gusts up to 15 kt possible along southern near shore waters this afternoon. Seas build up to 4 ft on the southern waters during the afternoon. Tonight...E-NE winds continue, gusting up to 15 kt on the southern outer waters. Seas up to 4 feet continue over the S waters. Friday...E-NE winds gradually increase over the southern waters up to E of Cape Cod during the day with gusts up to 20 kt. Seas continue at around 4 ft, but may see a few reach to 5 ft well offshore during the afternoon. 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...WTB/EVT SHORT TERM...EVT LONG TERM...WTB AVIATION...WTB/EVT MARINE...WTB/EVT

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