Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 171142 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 742 AM EDT Tue Oct 17 2017 .SYNOPSIS... High pressure will maintain dry weather this week along with a gradual warming trend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Forecast remains on track. Only minor tweaks to bring the forecast back in line with observed trends. Previous Discussion... Shortwave has pushed offshore and clearing has set in across most of SNE in drying and subsidence behind it. Exception is near Cape Cod and Islands, where northerly flow over milder ocean was producing some ocean effect clouds (and a few showers earlier). Trend will be for clearing by mid morning, as upper flow turns more anticyclonic and northerly flow begins to back to west. Flow may weaken enough to allow sea breeze to develop around midday along eastern MA coast, but our thinking is there will be just enough mixing to prevent that from happening. Winds do turn more W/SW this afternoon. Many locations will be off to a cold start with temperatures in 30s and areas of frost. We are keeping Frost Advisory posted until 8 AM. Airmass doesn`t recover too much today but sunshine will help temperatures reach well into 50s, if not near 60 in a few locations.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... High pressure becomes centered south of New England, putting us in SW flow tonight and Wed. Clear skies and light winds will allow for radiational cooling tonight, so we undercut MOS guidance, and there is potential for patchy frost across interior once again. Frost Advisories will probably need to be re-issued later this morning, once we assess this morning`s lows and decide which zones will remain active for Frost/Freeze program. On Wed, we begin the warmup with increasing SW flow. Airmass remains very dry through column so plenty of sunshine is expected. This should boost highs into 60s and lower 70s. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... * Highlights... - Warmer than normal through this period - Dry weather through this weekend This portion of the forecast will feature a nearly zonal mid level flow evolving into a strong ridge toward this weekend. This will mean a warming trend, and above normal temperatures. Almost no moisture to work within the lowest levels of the atmosphere, so mainly clear skies expected until later this weekend. This should even be the case for a weak cold frontal passage late Thursday into Friday. Operational and ensemble guidance agree on the overall pattern, but do have some detail differences. Will continue to favor a consensus approach to smooth over the less predictable details. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/...
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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 Wednesday/...High confidence. VFR conditions today into Wed. N winds gusting to 20-25kt on Cape Cod and Islands this morning will diminish by afternoon as winds turn to W/SW areawide. KBOS Terminal...High confidence in TAF. Brief weak seabreeze possible 15z-19z, but not included in TAF since it looks marginal. KBDL Terminal...High confidence in TAF. Outlook /Wednesday Night through Saturday/...High confidence. Mainly VFR through the period except some patchy ground fog at typically prone terminals each morning.
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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 Wednesday/...High confidence. Maintaining Small Craft Advisories, mainly through this morning for lingering 25kt gusts and 5 ft seas, except on outer waters E of Cape Cod where seas will take most of day to subside. Winds diminish this afternoon and become W, before SW flow prevails tonight and Wed. Outlook /Wednesday Night through Saturday/...High confidence. Mainly tranquil boating weather expected across the coastal waters through this period. The exception should be a period late Thursday into Friday morning when a dry cold front crosses the waters. Wind gusts may reach up to 25 kt behind this front. Seas may approach 5 feet as well, especially across the outer coastal waters. Small Craft Advisories may be needed for at least a portion of the waters late Thursday into Friday. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Frost Advisory until 8 AM EDT this morning for CTZ002>004. MA...Frost Advisory until 8 AM EDT this morning for MAZ005-006- 009>014-017-018-020-021-026. RI...Frost Advisory until 8 AM EDT this morning for RIZ001-003-006. MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ231- 250-251. Small Craft Advisory until 5 PM EDT this afternoon for ANZ254- 255. Small Craft Advisory until noon EDT today for ANZ256. && $$ SYNOPSIS...Belk/JWD NEAR TERM...Belk/JWD SHORT TERM...JWD LONG TERM...Belk AVIATION...Belk/JWD MARINE...Belk/JWD

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