Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 280715 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 315 AM EDT SUN AUG 28 2016 .SYNOPSIS... High pressure centered over Northern New England brings dry weather through today. A cold front moves south across New England tonight and Monday, and may bring a few showers or thunderstorms, mainly across northern Massachusetts. Weak high pressure brings dry and less humid conditions late Monday and Tuesday. The risk for thunderstorms along with warmer and more humid weather returns Wed, as yet another cold front moves across the area. Canadian high pressure brings a period of dry and fall-like weather late next week into the weekend with mild days followed by cool nights. && .NEAR TERM /THROUGH TODAY/... Not much change from previous thinking. Ridge aloft shifts east by this evening. High pressure at the surface will move out of the Maritimes and out to sea. Dry weather still expected though, as not much lift or moisture to work with during the day. Generally light south winds today. Seabreezes develop again on both coasts. Max temperatures similar to Saturday. && .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/... A mid level shortwave from the Plains moves east to Quebec tonight, then moves south across New England Monday. The best dynamics, in the form of a 100+ knot upper level jet, still looks like it will stay mainly to our north. That means most of the forcing for rainfall will be from a shortwave, a weak cold front, and whatever convective instability can be generated. Given that most of this will occur at night into the morning hours, not expecting strong thunderstorms. These attributes should also keep areal coverage of any storms isolated or widely scattered. Thus not a washout expected. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Highlights... * Temps...Very warm & humid Wed...more pleasant Tue * Precip...Isolated T-storm Mon...higher risk Wed * Fall-like weather Thu-Sat with mild days and cool nights Overview and model preferences... Northern stream becomes more dominant this period and eventually erodes the subtropical ridge. Thus trend will be not as warm and less humid beginning Thu and likely lasting into next Sat. However this transition will be marked by a very warm and humid day Wed along with potential convection. Regarding guidance...both GEFS and EPS ensembles are in very good agreement on the large scale flow including timing of frontal passage Wed. However as expected at this time range deterministic guid differing on amplitude and timing of smaller features. For example 00z EC is slower with fropa Wed ngt into Thu along with a cooler post frontal airmass Fri with 850 temps dipping down to +4C! Typical biases (slower and more amplified) for the EC at this time range. So for this portion of the forecast there is above average forecast confidence on trends and avg confidence on details. Daily details... Monday Night...Turning much less humid in post frontal airmass. Tuesday...dry and comfortable humidity as ridging lingers across New England. Seasonably warm. Seabreezes keep the shoreline slightly cooler. northern stream short wave approaches along with attending cold front. Warmer and more humid ahead of the approaching cold front. Temps should surge well into the 80s away from south coast. In fact with wsw surface winds and ensembles suggesting +17C at 850mb and +22C at 925 mb...highs of 85-90 are possible. Heavy rainers possible as PWATs surge to about +1 SD along with surface dew pts 65 to 70. Modest instability and marginal shear will yield a low risk for a few strong storms possible. Thursday thru Saturday...a touch of fall weather this period courtsey of 1025 mb Canadian high building across the Great Lakes into New England. Ensembles suggest 850 temps dropping to about +8C (about -1 SD) for a number of days. Likely see highs in the 70s and lows in the 40s and 50s! Thus the theme will be for mild days followed by cool nights. Very pleasant with dry weather and low humidity. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday/...High Confidence. Today... VFR with light winds increasing out of the south. Some increase in high thin clouds during the afternoon. Seabreezes redevelop. Tonight... VFR. Increasing mid and high clouds. Areas of 5000 foot ceiling bases with widely scattered MVFR in a shower or thunderstorm. Patchy fog with local IFR vsbys after midnight. Monday... Mainly VFR, with isolated SHRA/TSRA yielding brief MVFR which shifts into CT/RI and southeast MA during the afternoon. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Monday Night through Thursday/... Tuesday...Moderate to high confidence for VFR and dry weather. Light winds with local seabreezes likely. Wednesday...Moderate confidence. Mainly VFR but Local MVFR possible in scattered SHRA/TSRA. Thursday...Moderate to high confidence. VFR and dry weather likely. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday/...High confidence. Seabreezes will return late this morning and continue through this afternoon. Seas trend slowly higher into Monday in response to southeast swell from distant Hurricane Gaston. A widely scattered shower or thunderstorm possible late tonight into Monday as a cold front crosses the waters. Outlook /Monday Night through Thursday/... Tuesday...High pres overhead resulting in fine boating weather. Only issue will be south to southeast swells across the ocean waters from TS Gaston. Wed...Another cold front passage in the afternoon/evening along with risk for T-storms. Thu...Quiet boating weather should return as high pres builds into the Great Lakes and eventually the northeast. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Belk/Nocera NEAR TERM...Belk SHORT TERM...Belk LONG TERM...Nocera AVIATION...Belk/Nocera MARINE...Belk/Nocera is the U.S. government's official web portal to all federal, state and local government web resources and services.