Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 110745 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 345 AM EDT Fri Aug 11 2017 .SYNOPSIS...
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Low pressure from the Great Lakes will move east today and spread rain showers into southern New England tonight. A warm front will linger along the south coast Saturday, as waves of low pressure move along it. A cold front moves through early Sunday and stalls south of the region. High pressure follows later Sunday through Monday. Low pressure, possibly of tropical origin, will ride along this front, well south of New England around Tuesday. High pressure may finally push far enough into the region for dry and seasonable conditions by midweek.
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&& .NEAR TERM /THROUGH TODAY/...
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Low pressure well southeast of Nantucket will move farther offshore through today. Another low pressure will move into the Great Lakes, which will push its warm front toward southern New England late this afternoon. Looking at increasing clouds and a risk for showers across western MA and northern CT. Thinking most of southern New England remains dry through much of today, though. Near normal temperatures today. Light south winds will permit seabreezes along the coast, meaning lower temperatures from mid morning into afternoon along the coasts.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/...
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Mid level flow will steer a series of shortwaves across our region tonight into Saturday. These shortwaves, along with a nearly stationary front near the south coast, should provide enough lift to generate showers. It will likely take a while for the atmosphere to become sufficiently saturated for showers to become widespread. Thinking the most likely period for showers will be late evening into Saturday morning. The greatest risk for showers will be along the stationary front toward the south coast. Low level lapse rates should be poor tonight and Saturday, but mid level lapse rates become increasingly favorable enough where the possibility of isolated thunderstorms cannot be dismissed out of hand. Not thinking any risk of severe weather, and that any thunderstorms will be few and far between. Total rainfall amounts tonight and Saturday should generally range between one quarter to one half inch, with the greatest amounts toward the south coast, including the Cape and islands. Near normal temperatures tonight, with below normal temperatures Saturday.
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&& .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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Saturday night...Low pressure pulls away from the coast and a cold front swings through the region, with drying conditions. Major dry air moves in aloft, as indicated by rapidly falling K Indices late at night. The front eventually settles south of the region. Sunday...High pressure builds into New England. Very dry air aloft. Expecting a mostly sunny day. West to southwest downsloping winds should lead to warm temperatures...reaching the mid 80s, warmest in interior eastern MA per 925 mb temperatures around 21C. Could have a few 87 or 88 degree readings in the east. Monday...High pressure slowly moves eastward and we get into more of a southerly flow. Clouds will be increasing from the south during the day, but expect it to remain mainly dry due to very dry air aloft. Seasonable highs mainly 80 to 85. Monday night into Tuesday... For several days, several models have indicated the potential for low pressure, possibly tropical, to be developing off the coast of the Carolinas. If this happens, a plume of moisture may work its way northward enough to cause a chance of showers, especially in southeastern sections overnight and into a portion of Tuesday. The system itself, if it forms, would likely travel northeastward along the frontal system, passing out to sea well to our south. Wednesday and Thursday... Mainly sunny weather as high pressure builds back into the region. Could have a warmup back into the mid 80s...possibly some upper 80s.
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&& .AVIATION /07Z 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/... Today...High confidence. VFR. Low risk for a period of IFR clouds and showers clipping Nantucket first thing this morning. Light south winds, possibly turning from southeast in a seabreeze along the eastern MA coast. Tonight...Moderate confidence. Mainly VFR, but trending toward IFR cigs/MVFR vsbys after midnight in showers and fog. Saturday...Moderate confidence. Mainly MVFR ceilings with local IFR along the south coast in showers and isolated thunderstorms. Mainly VFR elsewhere, except local MVFR conditions in scattered showers. KBOS Terminal...High confidence in TAF. Sea breeze lingers through evening, then turns from the south and southwest during the night. KBDL Terminal...High confidence in TAF. Outlook /Saturday Night through Tuesday/...Moderate confidence. Sunday...VFR. Patchy late night/early morning fog with local MVFR vsbys late Sunday night. Monday...VFR. Monday night and Tuesday...VFR except areas of MVFR in scattered showers south of the Mass Pike. Patchy late night/early morning fog with local MVFR-IFR 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. Winds and seas remain less than Small Craft Advisory thresholds through Saturday. Low pressure moving into the Great Lakes will push a nearly stationary front close to the south coast tonight into Saturday. Developing showers and patchy fog should reduce visibility, especially across the southern coastal waters. Outlook /Saturday Night through Tuesday/...Moderate Confidence. Expect winds and seas below small craft criteria through the period. Winds shifting to SW Saturday night and Sunday, then to the NW Sunday night and Monday. Winds shifting to the S-SE again on Monday night and NE on Tuesday, as low pressure passes south of the region. Capped seas at 4 ft or less, due to models overdoing seas in southwest flow. Showers likely and possibly some thunderstorms over the southeast waters Saturday into Saturday evening, and again on Monday night into Tuesday. Also, some visibility restrictions in patchy fog at times nearshore during late nights and early mornings through the period.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Belk/GAF NEAR TERM...Belk/GAF SHORT TERM...Belk LONG TERM...GAF AVIATION...Belk/GAF MARINE...Belk/GAF

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