Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 242030 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 330 PM EST Fri Nov 24 2017 .SYNOPSIS...
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Dry and seasonably cool weather will prevail this afternoon. Milder air returns Saturday ahead of a cold front. The cold front moves through southern New England Saturday night accompanied by scattered showers. Blustery weather follows on Sunday. Milder temperatures may return for Tuesday and Wednesday of next week, then cooler weather for Thurday. We will be watching possible cold front passage for the end of next week.
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&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 1 PM update... Have made a slight upward adjustment in this afternoon`s high temperature forecast in some locations based on current conditions. Note that Fitchburg and Taunton both were up to 49 degrees already. Many areas should see readings near 50 or possibly even the lower 50s for highs. Otherwise no changes. The entire region has sunshine and light southwest winds, as high pressure to our south dominates the weather. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Southwest winds should increase slightly tonight, setting the stage for a warmup Saturday. As noted by prior shift, dewpoints also increase with the southwest flow, but not expecting fog to be an issue. Low stratus is likely across the Cape and islands late tonight. Dry conditions continue. Saturday should be above normal temperature-wise as modest southwest winds continue ahead of a cold front. Latest model suite continues to show pretty good lift and humidity within the 850-700 mb layer, but more drier air beneath it to be overcome. Envisioning a scenario where clouds increase through the day, with dry weather into mid-late afternoon. Since this is a cold frontal passage, and BUFR soundings continue to show the column saturating from the top down, will continue the idea of a slight chance for showers, becoming a greater risk towards the east coast very late in the day Saturday due to proximity to more humid low levels. && .LONG TERM /SUNDAY THROUGH FRIDAY/...
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Big Picture... Longwave trough lingers over the Eastern USA much of the period, but with a flattening trend. Shortwave pattern shows a shortwave moving through a zonal flow. One shortwave moves through New England Sunday, with lingering troffiness over the area on Monday. A ridge builds for Tuesday, then a more shallow shortwave races across on Wednesday. Another shortwave, this one a little deeper, reaches New England toward the end of next week. Model mass fields are in general agreement east of the Rockies through Wednesday. Mass and thermal fields with a shortwave moving in off the Pacific Ocean show less agreement with that feature during most of the forecast period up through the time it reaches us the end of next week. Confidence in the forecast is strong through midweek, but low-moderate on next Friday. Contour heights are lower/colder than normal Sunday and Monday, then trend above normal midweek, then trend lower/colder again by Friday. Details... Sunday-Monday... Upper trough digs over New England Sunday. Cold pool will be in place with 500-mb temps at -30C, which will destabilize the airmass. Moisture lingers below 800 mb during this time. Expect quite a few clouds to pop during the day, possibly a few flurries in the north. Mixed layer temps will support max sfc temps in the upper 30s and 40s. Winds in the mixed layer reach 20-25 knots in the ECMWF and 30- 35 knots in the GFS. Either way, expect gusty northwest winds. We took a blend of the two. The trough and cold pool move off on Monday and high pressure builds surface and aloft. Could be some lingering clouds Monday but should trend to less sky cover during the day. Expect a fair day with max sfc temps in the 40s. Tuesday through Thursday... Developing southwest flow brings milder air to the region Tuesday. Another cold front crosses New England Wednesday, but with most of the curvature and the core of the upper jet over VT/NH/ME. Expect a cold frontal passage during the day, with a few clouds and a wind shift, but otherwise dry. High pressure builds with dry weather Thursday. Temperatures cool a little from Wednesday. Friday... Cold front moves through during the day, but differences among the models upstream lead to uncertainty in the timing as well as the stability of this solution. GFS and ECMWF currently show the showers starting early Friday morning and end them toward evening.
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&& .AVIATION /21Z FRIDAY 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 Saturday Night/...High confidence. VFR most areas, however could see development of stratus around 1500 ft across southern RI and southeast MA, including Cape Cod and the islands between 08Z and 14Z. Light SW winds this afternoon increase some in speed on Saturday with gusts to 18-20 kt possible in the higher terrain and along the coast. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Sunday through Wednesday/... Sunday: VFR. Windy with local gusts to 30 kt. Sunday Night through Wednesday: VFR. Breezy Monday.
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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 Night/... High pressure in control with good boating weather through this afternoon. Small Craft Advisories are in effect for the waters off of the east coast of MA for increasing southwest winds tonight into Saturday. Seas also will likely build once more across portions of the outer coastal waters. Additional Small Craft Advisories may be needed...for southern waters...for marginal rough seas. Will hold off on that decision until later this afternoon. Outlook /Sunday through Wednesday/... Sunday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Sunday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Monday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Tuesday: Winds less than 25 kt. Tuesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft. Wednesday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 7 PM EST Saturday for ANZ250-254. Small Craft Advisory until 2 PM EST Saturday for ANZ251. Small Craft Advisory from 1 AM to 6 PM EST Sunday for ANZ255- 256.
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&& $$ SYNOPSIS...WTB/Belk NEAR TERM...GAF SHORT TERM...Belk LONG TERM...WTB AVIATION...WTB/Belk/GAF MARINE...WTB/Belk/GAF

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