Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 301953 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 353 PM EDT THU JUL 30 2015 .SYNOPSIS... SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING WILL GIVE WAY TO DRIER WEATHER FRIDAY...BUT IT WILL REMAIN VERY WARM. WARM AND HUMID CONDITIONS WILL RETURN THIS WEEKEND...THEN WILL BECOME LESS HUMID WITH TEMPERATURES CLOSER TO NORMAL NEXT WEEK. THERE IS A LOW RISK FOR SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THIS WEEKEND INTO EARLY NEXT WEEK...HOWEVER MUCH OF THE TIME DRY WEATHER WILL PREVAIL. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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355 PM UPDATE... * LINE OF STRONG TO POSSIBLY SEVERE STORMS THRU 9 PM * * LOCALIZED WIND DAMAGE/FLOODING AND PERHAPS AN ISOLATED TORNADO MESOANALYSIS SHOWS 1500-2000 K/KG OF SB CAPE ACROSS SOUTHERN NEW ENGLAND WITH 25KT OF 0-6KM SHEAR BUT MEAGER MID LEVEL LAPSE RATES. LINE OF STORMS HAS BECOME MORE ORGANIZED FROM SW MA ACROSS CT AND INTO NYC AREA. SO FAR HEAVY RAIN HAS BEEN MAIN THREAT BUT OCCASIONALLY WE HAVE SEEN HIGHER CORES DEVELOP IN SOME OF THE STORMS...SO POTENTIAL FOR LOCALIZED WIND DAMAGE AND FLOODING WILL CONTINUE INTO THIS EVENING. FOCUS FOR STORMS LOOKS TO BE ACROSS CT...NORTHERN RI AND CENTRAL/ EASTERN MA PER HIGH-RES MODELS. IN PARTICULAR HRRR SHOWS EVOLUTION NICELY ALTHOUGH ITS TIMING IS A COUPLE OF HOURS TOO SLOW. LINE SHOULD REACH PROVIDENCE/BOSTON CORRIDOR 6-7 PM. ALTHOUGH VERY LOW PROBABILITY...STILL CANNOT RULE OUT AN ISOLATED TORNADO PRIMARILY AS FAR E AS WORCESTER HILLS. PRESENCE OF 30-35KT WINDS AT 925 MB AND LOW LCL FROM 70+ DEWPOINTS POINTS TOWARD THAT POTENTIAL. IF ONE DOES OCCUR... AND THAT IS A BIG IF...IT WOULD LIKELY BE TOWARD WEAKER SIDE GIVEN STRENGTH OF WIND FIELDS ALOFT. ACTIVITY DIMINISHES TONIGHT WITH LOSS OF DAYTIME HEATING AND PASSAGE OF COLD FRONT. EXPECT PATCHY FOG TO DEVELOP OVERNIGHT.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... FRONT WILL BE OFFSHORE FRI MORNING WITH DRIER AND MORE COMFORTABLE AIRMASS IN ITS WAKE. KEEPING FRI NIGHT DRY ALTHOUGH WE SHOULD SEE INCREASING CLOUDS AS NEXT SHORT WAVE APPROACHES. && .LONG TERM /SATURDAY THROUGH THURSDAY/... HIGHLIGHTS... * EXPECT MORE SEASONABLE TEMPS AND LOWER HUMIDITY THROUGH MOST OF THIS PERIOD * CHANCE FOR A FEW SHOWERS/ISOLATED THUNDER EACH DAY BUT MUCH OF THE TIME REMAINING DRY SYNOPTIC OVERVIEW AND MODEL PREFERENCES... MEDIUM RANGE FORECAST CONTINUES TO FEATURE ANOMALOUS H5 CUTOFF VORTEX ACROSS JAMES AND HUDSON BAYS WHICH WILL ELONGATE ACROSS QUEBEC DURING THE LONG TERM PERIOD. WILL STILL SEE LONG WAVE TROUGH ACROSS THE EASTERN GREAT LAKES AND DOWN THE APPALACHIANS WHICH WILL TEND TO FLATTEN...THOUGH SHORT WAVES WILL ROTATE AROUND THE BASE OF THE CUTOFF LOW INTO THE MEAN TROUGH. THIS WILL BRING PERIODS OF SHOWERS/THUNDERSTORMS ACROSS THE REGION FROM TIME TO TIME. NOT EXPECTED A TOTAL WASHOUT AT ANY TIME...THOUGH MODELS LOOK LIKE THEY MAY HAVE SOME CONTINUITY WILL BE AROUND THE LATE MON/MON NIGHT AND TUE NIGHT TIMEFRAMES. HOWEVER...OPERATIONAL MODEL SOLUTION SPREAD DOES WIDENS OVER TIME AS ONE WOULD EXPECT ESPECIALLY THIS TIME OF THE YEAR...SO CONFIDENCE IN SPECIFIC TIMING OF CONVECTION AND ANY SHORT WAVE PASSAGE LOWERS. USED A BLEND OF AVAILABLE GUIDANCE INTO MONDAY...THEN TRANSITIONED OVER TO THE GFS AND EC ENS MEANS WHICH GAVE A BIT MORE CONTINUITY WITH PREVIOUS FORECASTS. DETAILS... SATURDAY...MODELS CONTINUE TO PAINT A WEAK H5 SHORT WAVE IN THE MEAN UPPER FLOW FOR LATER SAT INTO SAT NIGHT. LOOKS LIKE BEST INSTABILITY AND MOISTURE...WHAT THERE IS OF IT...WILL BE ACROSS CENTRAL AND WESTERN AREAS. ANOTHER QUESTION WILL BE WHETHER THERE WILL BE SOME NOCTURNAL INSTABILITY SHOWERS/TSTMS ALONG THE S COAST WHERE HIGHEST HUMIDITIES ARE IN PLACE. HAVE LEFT OUT FOR NOW...BUT IT IS SIGNALED ON THE GFS MODEL. HAVE GENERALLY SLIGHT CHANCE POPS GOING...BUT MAY SEE A LINE OF SCT SHOWERS/TSTMS ACROSS CT VALLEY INTO CENTRAL MA/NE CT POSSIBLE DURING THE LATE AFTERNOON/EARLY EVENING. EXPECT THE SHORT WAVE TO SHIFT E AND WEAKEN SO PRECIP SHOULD ALSO WEAKEN OVERNIGHT. HIGHS WILL GENERALLY BE IN THE 80S. IT WILL BE COOLER WELL INLAND LATE SAT NIGHT WITH LOWS AROUND 60...RANGING TO AROUND 70 ALONG THE S COAST...CAPE COD AND THE ISLANDS. SUNDAY...WEAK SURFACE RIDGE BUILDS ACROSS SO EXPECT A MAINLY DRY DAY. H85 TEMPS WILL BE FROM +15C TO +16C...WHICH WILL TRANSLATE TO THE 80S FOR MOST AREAS...A BIT COOLER ALONG THE S COAST WITH THE S- SW WINDS IN PLACE. MONDAY...SOUTHWEST WIND FLOW REMAINS IN PLACE. MODELS SIGNALING A POSSIBLE PRE FRONTAL TROUGH APPROACHING LATE MON OR MON NIGHT /TIMING IN QUESTION/. MAY SEE WIDELY SCT SHOWERS/ISOLD TSTMS ACROSS CENTRAL AND WESTERN AREAS...WITH THE BEST CHANCE ACROSS W MA AND W HARTFORD COUNTY. WITH THE MILDER S-SW FLOW IN PLACE...EXPECT HIGHS MAINLY IN THE 80S. TUESDAY...W-SW FLOW ALOFT AS QUEBEC VORTEX BROADENS. ANOTHER SHORT WAVE AND ASSOCIATED COLD FRONT LOOKS TO APPROACH LATE TUE INTO TUE EVENING. GFS MOST AGGRESSIVE IN DIGGING H5 TROUGH TO THE W WHICH WILL KEEP WARM AND HUMID AIR IN PLACE. HAVE CARRIED CHANCE POPS ACROSS THE REGION...THEN SHOULD PUSH OFFSHORE TUE NIGHT. WEDNESDAY-THURSDAY...A LOT OF QUESTIONS AS TO WHETHER FRONT WILL STALL S OF NEW ENGLAND DURING THIS TIMEFRAME AND IF WAVES WILL MOVE ALONG THIS FRONT. FOR NOW...HAVE CHANCE POPS MOVING ACROSS WED NIGHT/THU...BUT TIMING IS STILL VERY MUCH IN QUESTION. LOW CONFIDENCE DURING THIS TIMEFRAME DUE TO TIMING DIFFERENCES. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. HIGH CONFIDENCE THROUGH FRI NIGHT. LINE OF SHOWERS/TSTMS WITH MVFR/IFR ARRIVE IN W NEW ENGLAND 18Z- 20Z AND SHOULD WEAKEN BEFORE REACHING COAST 21Z- 00Z. HEAVY RAIN MAIN THREAT BUT POTENTIAL FOR 40-50KT GUSTS IN STRONGER STORMS. SW WINDS GUST TO 25KT ESPECIALLY NEAR S COAST. MVFR/IFR CIGS SHOULD RETURN TO PARTS OF A COAST...CAPE COD AND ISLANDS THIS EVENING. COULD ALSO SEE PATCHY IFR DUE TO VALLEY FOG INLAND. VFR FRI AND FRI NIGHT WITH W/SW WINDS...MAY HAVE LOCAL SEA BREEZES DURING AFTERNOON NEAR COAST. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. MAIN WINDOW FOR TSTMS 22Z-00Z. HEAVY RAIN/LIGHTNING MAIN HAZARDS. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. MAIN WINDOW FOR TSTMS THRU 21Z. 40KT GUSTS POSSIBLE IN STRONGER STORMS. OUTLOOK /SATURDAY THROUGH TUESDAY/...MODERATE CONFIDENCE. EXPECT GENERALLY VFR MOST OF THE TIME. LOW CHANCE OF SCT SHOWERS/ ISOLD THUNDERSTORMS SAT AFTERNOON/EARLY SAT NIGHT AND AGAIN MON-TUE. BRIEF LOCAL MVFR IN ANY PRECIP.
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. HIGH CONFIDENCE THROUGH FRI NIGHT. SCA REMAINS POSTED FOR 20-30KT GUSTS THIS AFTERNOON NEAR SHORE AS GRADIENT TIGHTENS AHEAD OF COLD FRONT. IN ADDITION...LONG SOUTHWEST FETCH WILL ALLOW FOR SEAS TO BUILD TO BETWEEN 3 TO 5 FEET ACROSS MOST OPEN WATERS. WINDS DIMINISH THIS EVENING...BUT KEEPING SCA THROUGH TONIGHT FOR THE OUTER WATERS DUE TO LEFTOVER SWELL. HIGH PRESSURE WILL BUILD OVER REGION FRI AND FRI NIGHT WITH LIGHT WINDS AND DIMINISHING SEAS. OUTLOOK /SATURDAY THROUGH TUESDAY/... SATURDAY-SUNDAY...SW WINDS MAY GUST UP TO 20 KT SAT/SAT NIGHT THEN DIMINISH. WITH LONG S-SW FETCH...SEAS FORECAST UP TO 5 FT MAINLY ON THE SOUTHERN OUTER WATERS. MONDAY-TUESDAY...CONTINUED SW WINDS IN PLACE...WHICH MAY GUST TO 20 KT AT TIMES. SEAS UP TO 5-7 FT ON THE SOUTHERN OUTER WATERS. MAY SEE SCT SHOWERS/THUNDERSTORMS MON NIGHT/TUE. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ230>234-236-251. SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ235- 237. SMALL CRAFT ADVISORY UNTIL 8 AM EDT FRIDAY FOR ANZ250-254>256. && $$ SYNOPSIS...EVT/JWD NEAR TERM...JWD SHORT TERM...JWD LONG TERM...EVT AVIATION...EVT/JWD MARINE...EVT/JWD

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