Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 310539 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 139 AM EDT TUE MAY 31 2016 .SYNOPSIS... A cold front over New York will swing across Southern New England tonight. Scattered thunderstorms over Eastern New York will affect Western MA and CT before weakening. Another batch of showers moving up the front may graze the South Coast overnight. High pressure then builds over New England with dry weather for the middle of this week. Another cold front may bring unsettled weather by the end of this week. A low pressure may move through early next week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 10 pm update... Convection is weakening across western MA and hi-res guidance continues this trend this evening as it drifts east. Still seeing SBCAPES of 500-1000 J/kg so will continue to mention chc thunder next few hours. Otherwise...watching area of rain lifting north from south of long island. Deeper moisture and omega remains mostly to the south but is expected to clip the cape/islands where best chance for a period of light rain. Adjusted PoPs accordingly. The other concern this evening will be areas of fog along the south coast. With southerly winds increasing ahead of a cold front, these areas of fog will likely move farther north into southeast MA and RI this evening. The front will move through western MA overnight with notable drop in dewpoints. However, it will remain humid in the coastal plain. Min temps in the 60s, except upper 50s Berkshires. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... There may be some lingering showers along the South Coast early Tuesday. But with high pressure building in, the trend will be for showers tapering off and sky cover diminishing. Drier air will work into New England with dew points falling through the 50s. A weak cold front dips south over the region late Tuesday. The main effect of this front will be to turn winds out of the north Tuesday night. This may bring dew points a little lower, roughly upper 40s to mid 50s. Sunshine Tuesday will create mixing to at least 850 mb, possibly higher. Temps at the top of the mixed layer will support max surface temps in the low to mid 80s. The lower dew points will allow min temps to be a little lower than tonight, generally in the 50s. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Highlights... * Mainly dry with above normal temperatures Wednesday * Unsettled weather may return toward the end of this week * A low pressure may move through early next week Medium range models are in good agreement with the overall synoptic pattern. A mid-level ridge will move offshore Wednesday. Mid-level troughing then moves into Quebec towards the end of this work week, and starts influencing our weather with several shortwaves working around the base of this trough. This will result in more unsettled weather towards the end of this week. The latest operational GFS was much more aggressive in developing a mid-level cutoff late in this forecast period. Favored a solution closer to the ECMWF, which also had support from the GFS ensemble mean solution. Wednesday...A back door cold front arrives. Despite that, temperatures will still be above normal across the interior. More seasonable temperatures toward the coastal plain, mainly east of II-95, due to the onshore flow. Thursday through Sunday...Mid-level trough moves into Quebec, allowing several shortwaves rotating through the base of this trough to move through southern New England. This will result in periods of showers, particularly Friday into Saturday. Due to the difficulty in nailing down the timing at this time range, have kept chance PoPs in the forecast for much of this period. However, not expecting rain to be widespread, nor for the entire period. Temperatures will be seasonable for much of this time. Monday...Potential for an occluded low pressure to move into the Great Lakes early next week. Not confident in the timing just yet. Some hints in the GFS of a secondary low pressure developing more toward the coast early Monday. The GFS is more aggressive in developing a stronger, more southern, mid-level cutoff than the ECMWF. This is leading the GFS to a slower timing as well. Will keep a chance of showers in the forecast until these differences can be resolved. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday/... Through 12z...areas of IFR cigs near the south coast with occasional light showers and patchy fog. Mainly VFR elsewhere, but patchy MVFR cigs/vsbys possible. Today...High confidence. areas of morning IFR cape/islands. otherwise VFR. Tonight and Wednesday...High confidence. VFR. Easterly winds developing Wednesday. KBOS TAF...May see a brief period of MVFR cigs through 12z. Moderate confidence. KBDL TAF...High confidence in TAF. Outlook /Wednesday Night through Saturday/... Thursday...Moderate confidence. Mainly VFR conditions expected. Increasing clouds with diminishing conditions through the night, particularly along the south coast. Friday and Saturday...Moderate confidence. Mainly VFR conditions expected. Brief MVFR conditions are possible in SCT -SHRA at times. && .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. Tonight...Moderate confidence. Poor visibility due to dense fog, mainly across the southern waters from Block Island to Nantucket. Winds will remain below 20 knots. Seas will remain below 5 feet. Tuesday and Tuesday night...Moderate confidence. A south swell builds into the southern waters Tuesday. Expect the swell to reach 4 feet during the day, with potential for 4-5 foot swell Tuesday night. Southwest wind Tuesday shifts from the North Tuesday night, but remains below 20 knots. Outlook /Wednesday Night through Saturday/... Wednesday...Moderate confidence. Northeasterly winds and seas will remain below Small Craft Advisory criteria. Thursday...Moderate confidence. Easterly winds and seas increase. Seas may rise above 5 feet, especially on the outer waters. Friday...Moderate confidence. Easterly winds are expected to remain below 15 kts. Seas decrease through this period. Saturday...Moderate confidence. Southeasterly winds are expected to remain below 15 kts. Seas continue to decrease through this period. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...WTB/Belk NEAR TERM...KJC SHORT TERM...WTB LONG TERM...Belk AVIATION...Belk/KJC MARINE...WTB/Belk is the U.S. government's official web portal to all federal, state and local government web resources and services.