Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBOX 131751 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 151 PM EDT Fri Oct 13 2017 .SYNOPSIS...
-- Changed Discussion --
High pressure centered over far southeast Canada moves eastward and offshore today. This afternoon will be dry and seasonably cool, with a gradual increase in clouds late. Warmer and more humid conditions arrive over this weekend as high pressure moves offshore and a cold front approaches from the west. This setup will also result in scattered showers at times, but a washout is not expected. This front moves offshore late Sunday night or early Monday morning, followed by drier, less humid and cooler weather next week.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
145 PM update... High pressure had become centered over Nova Scotia early this afternoon, and was continuing to move to the east. Surface winds have shifted to the E/ESE over southern New England. Low level moisture has been slower to advance into our area, though some stratocumulus had made it into a portion of east coastal/south coastal New England. It looks probable that mostly sunny skies will last thru the remainder of this afternoon for much of the area, with an increase in clouds holding off until late in the day. Temps will top off in the lower-mid 60s, with a few spots reaching the upper 60s. This is generally close to seasonal normals for mid October.
-- End Changed Discussion --
&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Tonight and Saturday... As the ridge moves further offshore, the SW wind flow becomes established as a cold front slowly works E out of the Great Lakes. The low level moisture will increase as well milder air moving in. Some question as to whether spotty light precip may start to break out after midnight, as models showing some solution spread in how far E that moisture may push in overnight. Kept slight chance POPs going for tonight. May also see patchy fog develop overnight. Low temps will be mainly in the upper 40s to mid 50s, maybe a bit milder along the S coast. Better lift and moisture feed will work in during Saturday as the high sits S of Nova Scotia and the approaching cold front remains well W of the region. With the onshore flow, should see scattered showers develop during the mid day and afternoon hours mainly near and S of the Mass Pike. It will be mild though, with highs mainly in the upper 60s to lower 70s. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Highlights... * Much warmer than normal and humid Sat night/Sunday * Scattered showers Sat into Sun morning, then again Sun night * Dry weather much of next week and chilly Mon night/Tuesday Saturday night... Anomalous 591 dam subtropical ridge over the southeast states builds into the Mid Atlc region and results in a warm front moving across southern New England. This boundary and associated moisture plume of PWATs +2 standard deviations above normal will result in a chance of showers. Very mild night for mid Oct given dew pts in the low to mid 60s! This will also yield a risk for patchy dense fog. Sunday... Chance of morning showers as warm front lifts northward across the area. Warm sector overspreads the area by late morning/early afternoon with 925 mb temps surging to +17C to +18C at 925 mb! This will support highs easily 75-80 away from the south coast with a low prob of a few interior locations getting into the low 80s, which will approach new record highs for the day. Quite anomalous when you consider the normal high temp for mid Oct is 60-65. After warm front exits late morning a period of dry weather is expected in the warm sector. It will become windy as 991 cyclone exits the northern Great lakes and intensifies to a sub 980 low as it tracks across southern Quebec during the day Sunday. This strengthening pres gradient combined with steepening low level lapse rates in the warm sector will support southwest wind gusts up to 40-45 mph, which may be strong enough for isolated wind damage given fully leaved trees. Greatest risk appears eastern MA given location of low level jet. Sunday night... Strong low level convergence along approaching cold front and robust upper level jet streak with RRQ over southern New England. This will support a deep layer of ascent accompanied by adequate deep layer moisture. This setup may provide a broken line of low top convection along and ahead of approaching cold front. Given strong wind fields a few of the heavier showers may produce gusty winds. Instability appears to be lacking but with dew pts in the mid 60s will have to monitor instability trends on later model runs. If instability is greater than what models are simulating this could be a sneaky low top convective event. Fropa occurs later Sun night with much drier/less humid post frontal airmass ovespreading the region 06z-12z Monday. Next Week... Dry and seasonably cool Monday behind initial cold front late Sun night/early Mon morning. Coolest air arrives Mon ngt/Tue morning with secondary/trailing short wave trough. Guidance has 850 mb temps cooling off to about -2C across New England. So slightly cooler than normal Mon ngt into Tue along with patchy frost possible as MOS guid offers lows in the 30s, some upper 20s possible. GFS and EC ensembles lower 850 temps to about -3C 12z Tue with deterministic guid as cool as -6C. Nonetheless a cool shot of air Mon ngt/Tue. Ensembles and deterministic guidance both indicate northern stream reloads middle of next week with new jet energy diving into the northeast mean trough. This will support a reinforcing shot of seasonably cool airmass. Regarding precip, this looks to be a rather dry pattern. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday/...High confidence thru 00Z this evening, then moderate confidence. 1745z update... This afternoon...Mainly VFR. Localized MVFR cigs possible in stratocumulus late in the day, with the better chance across RI and SE MA. Tonight...CIGS becoming MVFR, with patchy MVFR vsbys in fog after midnight. Localized IFR conditions in stratus/fog late. Saturday...MVFR CIGS. Scattered showers expected. KBOS TAF...High confidence in TAF thru 00Z, then moderate confidence. VFR thru 00Z, then CIGS becoming MVFR 00-02Z. Chance for showers late tonight and during Sat. KBDL TAF...High confidence in TAF thru 00Z, then moderate confidence. VFR thru 00Z, then CIGS becoming MVFR 00-02Z. Chance for showers late tonight and during Sat. Outlook /Saturday Night through Tuesday/... Saturday night...MVFR with IFR possible. Scattered showers and patchy fog. Sunday morning...MVFR with IFR possible in the higher terrain. Scattered showers. Moderate confidence with some uncertainty on areal coverage of IFR. Sunday afternoon...MVFR and VFR. Mainly dry but gusty SW winds up to 30 kt, possibly higher. High confidence. Sunday night...MVFR with scattered showers, a few gusty showers possible. SW winds up to 30 kt, possibly slightly higher. Moderate confidence with some uncertainty on areal coverage and intensity of showers. Mon and Tue...VFR and dry. High confidence.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday/... Today... Seas remain at or above small craft criteria across the southern outer coastal waters. Expect seas remain around 4-6 ft. Otherwise seas slowly subside across the waters during the afternoon. Tonight and Saturday... Seas around 5 ft will linger across the southern waters S of RI into early Saturday morning, then should subside. Otherwise expect E-SE winds to slowly diminish during tonight, shifting to S-SW on Saturday. Visibility may lower in patchy fog, along with spotty showers that may push across the waters during Saturday. Outlook /Saturday Night through Tuesday/...High confidence, except some uncertainty how strong southwest winds become Sun afternoon and evening. Saturday night...Poor vsbys in areas of showers/drizzle and fog. Sunday...Poor vsbys in areas of morning showers/drizzle and fog, improving by midday. SW winds become gusty especially near shore with gusts up to 30 kt, possibly higher. Cold frontal passage Sunday night. Mon and Tue...Cold front moves offshore early Mon followed by dry weather and good vsby.
-- End Changed Discussion --
&& .BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 4 PM EDT this afternoon for ANZ255. Small Craft Advisory until 11 AM EDT Saturday for ANZ256.
-- End Changed Discussion --
&& $$ SYNOPSIS...Nocera/EVT NEAR TERM...NMB SHORT TERM...EVT LONG TERM...Nocera AVIATION...Nocera/EVT/NMB MARINE...Nocera/EVT/NMB

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.