Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 251044 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 644 AM EDT SAT JUN 25 2016 .SYNOPSIS... Large high pressure ridge extending across the northeast U.S. into the Gulf of Maine will slowly shift down the coast, with warm and dry conditions through Monday. An approaching cold front brings showers and possibly some thunder later Monday night through Wednesday. High pressure then brings dry seasonable weather for the end of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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645 AM update High pressure overhead with generally clear skies and light wind. Dew points are 45 to 55. This is lower/drier than the long-term average for June 25th of 55 to 58, but still much higher than the extreme low values for June 25th of 33 to 36. This is your all-purpose fair weather day with the light flow allowing sea breezes along the coasts. No changes to the forecast. Previous discussion W-E high pressure ridge axis sitting from W NY state to the Gulf of Maine will slowly shift to the S coast during the day today. Expect a generally light E-SE wind, becoming more southerly across N CT and the CT valley this afternoon. With a light pressure gradient, sea breezes will kick in by midday with speeds up to around 10 kt. With a very dry airmass in place through the layer, expect excellent subsidence through the day even with fair lapse rates as H5 temps of -14C to -15C. Do note some afternoon showers trying to develop, but mainly across the Hudson Valley into the northern mountains of NH/VT as winds become more S there. Expect temps to rise to the 80s away from the coast, highest across the CT valley where a 90 degree reading may be possible, while holding in the 70s along the immediate coast. It will feel comfortable though as dewpts remain in the lower-mid 50s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Tonight... With high pressure ridge across the region, will continue to be dry and comfortable as dewpts fall back to the upper 40s to mid 50s. Light/variable winds in place, dropping off to calm across some inland areas. With continued good radiational cooling, will see temps fall back to the upper 40s to around 50 in the normally prone areas of interior E Mass to the lower Cape and the Vineyard, ranging to the mid 50s to around 60 in the urban centers. Once again, may see a few hours of patchy low clouds and fog around or after 06Z in the typically prone locations. Sunday... As the ridge begins to push S of the region, light winds will become more S-SE across the region. While dry conditions continue with dewpts in the lower-mid 50s, will start to see them creep up during the afternoon across the CT valley. Expect another warm day with highs in the 80s away from the coast, and in the lower-mid 70s near the shore. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Big Picture... A shortwave originating over the Pacific Northwest moves east across Canada and then digs over New England Tuesday and Wednesday. Above normal heights Monday diminish to near normal the rest of the week. This suggests above normal temps Monday trending to normal during mid to late week. Model forecast mass fields are similar much of the period. There are differences between GFS and ECMWF with timing on the midweek cold front. Confidence is limited as to exact timing, but potential for convection should exist for both days. Details... Sunday night through Monday... High pressure offshore moves farther away, and the surface flow turns more from the south and southwest. Expect dry weather during this time. 850 mb temps of 14-16C would support max sfc temps in the mid 80s. Monday night through Wednesday... Northern shortwave approaches from the Great Lakes. At this time the upper shortwave digs southeast toward New England and turns the upper flow more from the southwest and parallel to the cold front. With flow moving along the cold front rather than pushing it, we should see the forward progress slow until the trough axis swings overhead. Meanwhile the surface flow will bring a warm humid airmass across New England with dew points climbing into the 60s. Stability parameters will favor convection. The cold front will be the eventual focusing mechanism on Wednesday, but a pre-frontal trough may concentrate convection on Tuesday. Thursday-Friday... High pressure builds in behind the cold front but with upper contours and 850 temps near seasonal normals. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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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 Sunday/...High Confidence. Today...VFR. Light S-SE winds, becoming sea breezes along the coast up to around 10 kt by midday. Tonight and Sunday...VFR. Low risk for patchy MVFR conditions in fog late after midnight tonight in normally prone locations. KBOS TAF...High confidence. VFR. E-SE winds increasing to around 10 kt by midday today becoming light S tonight. Winds shift back to E-SE around 10 kt by midday Sunday. KBDL TAF...High confidence. VFR. Low chance for MVFR-IFR conditions in patchy fog 07Z-11Z tonight. Outlook /Sunday Night through Wednesday/... Sunday night and Monday... High confidence. VFR. Light winds. Areas of IFR/LIFR possible in late night/early morning fog. Monday night through Wednesday... Moderate confidence. Mostly VFR. Areas of IFR/LIFR in late night/early morning fog. Also brief MVFR cigs/vsbys in scattered showers/thunderstorms.
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&& .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday/...High confidence. Expect winds and seas below small craft criteria through Sunday as high pressure ridge remains across the waters. Outlook /Sunday Night through Wednesday/... Moderate confidence. Winds and seas remain below Small Craft Advisory thresholds through the period. Potential for low vsbys in fog, especially Tuesday and Wednesday early mornings. Scattered showers and thunderstorms with brief poor vsbys Tuesday and Wednesday. && .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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