Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 221939 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 339 PM EDT MON AUG 22 2016 .SYNOPSIS... High pressure will bring beautiful late summer weather through Tuesday with low humidity. Warmer and more humid weather is expected Wednesday through Friday along with a low risk of showers and thunderstorms Thu night into Friday. Dry and less humid weather may return next weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Secondary mid level shortwave swings through northern New England this evening then offshore tonight, with main effect being another pulse of gusty winds along the coast and adjacent E MA waters. Otherwise, high pres builds in from the west with clear skies and diminishing winds. With dry airmass in place, ideal radiational cooling will allow low temps to drop into the mid/upper 40s in the colder spots in the CT valley and interior E MA, with 50s elsewhere. The mildest spot will be the urban heat island in Boston and also Nantucket with lows around 60. Patchy late night radiation fog possible. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Tuesday... High pres in control will bring sunny skies and lighter winds. Despite a chilly start to the day, moderating 850 mb temps to 11-12C will result in highs reaching the upper 70s to lower 80s, a bit cooler higher terrain. Weak seabreezes may develop in the afternoon. Low humidity levels with dewpoints in the upper 40s to lower 50s. Tuesday night... High pres remains in control. Clear skies and light winds will result in another chilly night although probably not as cool as tonight as airmass moderates. Lows will be mostly in the 50s. Patchy late night radiation fog possible again. && .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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Highlights... * Warmer and more humid Wed thru Fri * Dry much of this week except a risk of T-storms Thu ngt/Fri * Dry and less humid weather may return next weekend Overview and model preferences... Strong signal for gradual re-admittance of the subtropical ridge into the region through the latter half of the week. Therefore, after this roughly 48 hr taste of fall, a return to much more summer-like and above normal temperatures are expected to cap off the week. This regained influence is thanks to digging trof across the W CONUS, which will eventually eject weak energy E in the form of a shortwave arrival for Fri. Following this weak passage, there is not enough of a significant shift in the pattern, such that ridging will once again regain control by the weekend. Given there continues to be very good agreement on these overall themes, a consensus blend of latest operational guidance and persistence will be used for this update. Details... Wed and Thu... The gradual warming trend begins thanks to H85 temps reaching +12C by wed afternoon, and +15C by Thu. This suggests mainly 80s for highs on Wed then mid-upper 80s by Thu. Dwpts will be on the rebound as well, increasing from the low 50s to near 60 by Thu afternoon. Breezy SW winds on Thu as high pres center moves E of the region. Fri... Shortwave will eject to the E across the NE on Fri. While the bulk of it/s associated dynamics and moisture will actual shift to the N as the wave opens in response to the ridging influence. Still with increasing dwpts and slight dip in upper lvl temps do note about 500-1000j/kg of MU CAPE to work with as the attendant front arrives by the afternoon. PWATS and lapse rates are both quite modest, the former around 1.75 inches and the latter between 30-40 kt unidirectional in the 0-6km layer. Therefore, although TS is possible, they look to be relatively modest at this point in time. Will continue to monitor the risk as we approach. Otherwise, with enough sunshine temps will make a run toward 90F in some spots. Sat and Sun... Temperatures drop off a bit closer to normal, but with H85 temps between +12C and +15C, note that highs in the 80s are still likely either day. However, a weak backdoor front may bring in some air off the waters off the Gulf of Maine which may limit temps particularly for E MA. Mon... Assuming high pres remains a strong as progged (mainly near 1025hpa) this could be enough to hold off a second front moving in from Canada, until later next work week, suggesting a continuation of drier weather.
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&& .AVIATION /20Z MONDAY THROUGH SATURDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/... Through 00z. VFR. NW gusts to 25 kt. Tonight through Tuesday night...High confidence. Winds diminish this evening and VFR conditions persist. Some patchy late night and early morning radiation fog possible in typical fog prone locations. KBOS Terminal...High confidence in TAF. Seabreeze should develop Tue afternoon. KBDL Terminal...High confidence in TAF. Outlook /Wednesday through Saturday/... High confidence in a stretch of mainly dry VFR weather. Sea breezes most likely mid-late week. && .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 Tuesday Night/... Tonight...Moderate confidence. Expect another pulse of gusty NW winds this evening, mainly eastern waters as shortwave passes to the north. Expect a period of G25kt eastern MA waters and have expanded the SCA to Nantucket Sound and Cape Cod Bay. Seas will build to near 5 ft over outer eastern waters. Winds will diminish after midnight. Tuesday...High confidence. High pressure building in from the west will result in light NW winds which will become locally onshore up to 15 kt nearshore waters in the afternoon as seabreezes develop. Subsiding seas. Tuesday night...High confidence. Tranquil boating weather. Outlook /Wednesday through Saturday/...High confidence. Wed... Mainly quiet boating weather with high pres overhead. Thu and Fri... Afternoon S-SW wind gusts may reach near 25 kt close to shore, particularly around the Cape/Islands. Small craft advisories may be needed. Although swells will build out of the S-SW anything above 5 ft should remain well outside of the New England coastal waters. Sat... A return to mainly quiet boating weather as high pres once again settles across the waters.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 2 AM EDT Tuesday for ANZ231-232. Small Craft Advisory until 8 PM EDT this evening for ANZ230- 236. Small Craft Advisory until 2 AM EDT Tuesday for ANZ250-251-254. && $$ SYNOPSIS...KJC/Doody NEAR TERM...KJC SHORT TERM...KJC LONG TERM...Doody AVIATION...KJC/Doody MARINE...KJC/Doody is the U.S. government's official web portal to all federal, state and local government web resources and services.