Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 210154 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 954 PM EDT FRI MAY 20 2016 .SYNOPSIS... High pressure over the northeast USA will bring dry, mild weather through much of Saturday. Coastal low pressure then passes south of New England Saturday night and Sunday. It then stalls in the Gulf Of Maine Sunday, with rain transitioning to showers. The unsettled conditions continue Monday and Tuesday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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Satellite imagery shows some cirrus moving across the region. The airmass closer to the ground is quite dry with dew points mostly in the 40s. High pressure centered south of New England extends up across our area. The high will shift a little more offshore overnight but still command dry weather for us. Mostly clear skies and light wind will maintain radiational cooling for at least a part of the night. Based on the dew points we will continue to expect min temps in the 40s to lower 50s.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Saturday... High pressure moves off to the east, but remains close enough to maintain dry air over New England below 10 thousand feet. Meanwhile moisture increases above 10 thousand feet bringing increasing and thickening sky cover. The big question remains how quickly the lower levels saturate, and if there will be enough lift to produce some light rain during the afternoon. Consensus timing would place the earliest risk along and west of the CT River late morning. The more likely scenario is rainfall holds off until late afternoon, mainly across northern CT and southern RI. This timing will need to be refined over the next day. Saturday night... Low pressure intensifies and passes by southern New England close to the 40N/70W benchmark. 20/12z guidance has the deepest moisture axis and lift right across much of southern New England. Increased PoPs to categorical across northern CT, RI and southeast MA. rain is likely all the way to the MA/VT and MA/NH border. 20/18Z GFS has deviated significantly from its prior run, taking the track of this low pressure farther southeast. Meanwhile, the 20/18Z NAM has remain consistent with its prior run. Not ready to jump on this development, but it will be something to keep in mind if the other guidance sources start to trend farther offshore. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Highlights... * A coastal low pressure system will bring rain Sunday * Unsettled weather continues through early next week * Temperatures warm up the middle of next week Models are in fairly good agreement through much of the long term period. There remain some discrepancies out towards the end of next week, but that`s to be expected that far out. The main story continues to be the coastal storm expected to affect southern New England Saturday night into Sunday. The accompanying upper level trough will hang around the area into Tuesday bringing unsettled weather to the region through the early part of next week. As the trough moves offshore Tuesday, upper level ridging builds into southern New England for the middle of the week. The end of the week has a bit of an unsettled pattern with upper level troughiness moving back into the region. How amplified this pattern gets and what ultimately ends up happening depends on the model, could be a relatively dry period with warming temperatures or there could be unsettled weather with showers and possibly thunderstorms. A coastal low will pass by the region Sunday morning. The main problem with it is it actually doesn`t pass by but instead meanders around the Gulf of Maine and New England through Monday when it finally moves off into the Maritimes. Therefore, we will have unsettled weather with periods of rain and showers with cooler than normal temperatures for Sunday and Monday. The pressure gradient increases Sunday, coupled with a rather strong low level jet aloft. May need some wind headlines, probably advisories, for portions of eastern Massachusetts and Rhode Island for Sunday afternoon. As the low pressure/upper level trough moves into the Maritimes, upper level ridging builds into southern New England. Southwesterly winds will bring much warmer air into the region and temperatures will soar a good 10 degrees above normal. There is still quite a bit of uncertainty for Thursday and Friday. As mentioned above, the models are struggling with the overall pattern. Could see periods of showers or it could be dry. Temperatures continue to increase, particularly through the Connecticut River valley. Should be a nice taste of summer. && .AVIATION /02Z 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 Saturday Night/... Tonight...High confidence. VFR in dry weather and light winds. Saturday...High confidence. VFR conditions through the day, with a light south-southwest wind. Increasing sky cover through the day. There is a low potential for MVFR cigs/vsbys developing in the late afternoon/evening in light rain. Saturday night...Moderate Confidence. Mix of MVFR/IFR likely as rain, fog and low clouds build from south to north over the region. KBOS TAF...High confidence in TAF. KBDL TAF...High confidence in TAF. Outlook /Sunday through Wednesday/... Sunday...Moderate confidence. MVFR/IFR conditions will continue through much of the day, particularly across E MA/RI. Monday...Moderate confidence. MVFR/IFR conditions expected with low clouds lingering from a coastal low pressure system. Tuesday...Moderate confidence. Conditions improve all around as low pressure finally pulls away from southern New England. Wednesday...High confidence. VFR.
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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. Tonight...High confidence. High pressure moves farther offshore. Light winds/dry weather and good vsby. Seas remain below 5 feet. Saturday...High Confidence. Low pressure develops along the Mid Atlantic coast. Winds will increase from the south but remain below 25 knots. Low risk for winds to become easterly across the southern outer coastal waters of MA and RI late in the day. Seas will remain below 5 feet. Saturday night...Moderate confidence. Low pressure intensifies as it moves past New England near the 40N/70W benchmark. Winds will become east to northeast across all the waters and increase. Some potential for gale force gusts, especially after midnight Sunday. Outlook /Sunday through Wednesday/... Sunday and Monday...Low pressure meanders around just east of the coastal waters. This will allow seas and winds to remain elevated through much of the time period. Small craft advisories are likely and there`s a low probability of gales on the outer waters early Sunday. Therefore we have issued a gale watch for late Saturday night into Sunday morning. Monday night through Wednesday...Low pressure starts to move away from the waters. This will allow winds and seas to subside below small craft levels.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Gale Watch from late Saturday night through Sunday morning for ANZ231>235-237-250-251-254>256. && $$ SYNOPSIS...Belk/RLG NEAR TERM...WTB/Belk SHORT TERM...Belk LONG TERM...RLG AVIATION...Belk/RLG MARINE...Belk/RLG

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