Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 311957 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 357 PM EDT SUN AUG 31 2014 .SYNOPSIS...
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A WARM HUMID FLOW WILL CONTINUE ACROSS NEW ENGLAND THROUGH TUESDAY WITH SCATTERED SHOWERS AND THUNDERSTORMS FROM TIME TO TIME. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT THEN WARM BUT LESS HUMID WEATHER WILL FOLLOW FOR WEDNESDAY THROUGH FRIDAY. ANOTHER COLD FRONT MAY BRING A CHANCE OF SHOWERS AND THUNDERSTORMS NEXT SATURDAY.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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CONVECTION FIRING ACROSS EASTERN PA AND NJ AND SE NY IN AXIS OF SBCAPES 1500-2000 J/KG. CLOSER TO HOME...SBCAPES 500-1000 J/KG BUT THERE ARE BREAKS DEVELOPING IN THE CLOUDS ACROSS SNE SO FURTHER DESTABILIZATION IS LIKELY. HI-RES GUIDANCE CONTINUES TO POINT TO A LATE SHOW WITH CONVECTION 21-00Z AS MID LEVEL SHORTWAVE MOVES IN FROM THE WEST. PWATS ALREADY NEAR 2" AND EXPECTED TO PEAK AROUND 2.25" TOWARD 00Z SO HEAVY RAINFALL AND LOCALIZED FLASH FLOODING OF URBAN AND POOR DRAINAGE AREAS IS THE PRIMARY THREAT. 0-6KM SHEAR APPROACHING 40 KT IN THE WEST SO POTENTIAL EXISTS FOR A FEW STRONG TO PERHAPS SEVERE TSTMS WITH DAMAGING WIND GUSTS ALSO A CONCERN IF FURTHER DESTABILIZATION OCCURS. MAIN FOCUS FOR CONVECTION WILL INITIALLY BE IN THE INTERIOR...BUT EXPECT AT LEAST A FEW SHOWERS/TSTMS IN A WEAKENED STATE TO MAKE IT TO THE COASTAL PLAIN LATER THIS EVENING AS SHORTWAVE MOVES THROUGH. WHILE INSTABILITY WANES TONIGHT...THERE IS STILL SOME SBCAPE AND HIGH KI VALUES TO SUPPORT CONVECTION. THE COLUMN WILL WILL BEGIN TO DRY FROM THE N LATE TONIGHT ACROSS N ZONES. AREAS OF STRATUS AND PATCHY FOG EXPECTED TO DEVELOP OVERNIGHT. IT WILL BE A WARM AND HUMID NIGHT WITH MINS 65 TO AROUND 70 DEGREES.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
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MONDAY... WARM AND HUMID AIRMASS CONTINUES ACROSS THE REGION WITH WEAK SFC BOUNDARY/FRONT DRAPED ACROSS FAR N NEW ENG. PWATS DECREASE BELOW 1.5" ACROSS THE N BUT TROPICAL PLUME WITH PWATS NEAR 2" WILL PERSIST IN THE SOUTH. AIRMASS DESTABILIZES AGAIN WITH SBCAPES 1000-1500 J/KG. SCT SHOWERS/TSTMS EXPECTED TO REDEVELOP...ESPECIALLY ALONG AND SOUTH OF THE MASS PIKE WHERE DEEPER MOISTURE IS PRESENT IN THE RIGHT ENTRANCE REGION OF THE UPPER JET. 0-6KM SHEAR IS CONSIDERABLY WEAKER SO SEVERE WX NOT ANTICIPATED. HEAVY RAINFALL IS THE MAIN THREAT IN HIGH PWAT AIRMASS. TEMPS WILL REACH LOW TO MID 80S AGAIN...COOLER S COAST. DEWPOINTS 70+ SO VERY HUMID. MONDAY NIGHT... COLUMN MOISTURE GRADUALLY DECREASES THROUGH THE NIGHT. SOME LINGERING CONVECTION POSSIBLE IN THE EVENING ALONG THE S COAST...OTHERWISE MAINLY DRY WEATHER. AREAS OF STRATUS AND FOG WILL LIKELY REDEVELOP OVERNIGHT. ANOTHER HUMID NIGHT.
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&& .LONG TERM /TUESDAY THROUGH SUNDAY/...
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OVERVIEW AND MODEL PREFERENCES... BROAD RIDGING REMAINS THE DOMINATE FEATURE ACROSS THE EASTERN USA THROUGH MOST OF THIS FORECAST PERIOD. THIS IS MORE TYPICAL FOR THE MIDDLE OF SUMMER RATHER THAN EARLY SEPTEMBER. EARLY IN THIS PERIOD...THERE WILL BE A COUPLE OF FAST MOVING SYSTEMS IN THE BROAD NORTHERN STREAM THAT WILL AFFECT OUR REGION. THIS STRONG RIDGE FINALLY BECOMES ESTABLISHED AROUND MID WEEK ACROSS THE SOUTHERN USA...WITH WARM BUT DRY CONDITIONS THROUGH THE END OF THIS WEEK. SOME QUESTIONS AS TO WHEN THE RIDGING MAY BREAK DOWN...AS MODEL SOLUTIONS LATE IN THE RUN TRY TO BREAK DOWN THE RIDGE WHILE BRINGING A MID-LEVEL CUTOFF LOW ACROSS NORTH CENTRAL CANADA INTO NORTHERN QUEBEC. OVERALL...HAVE FAIRLY GOOD CONFIDENCE WITH MOST OF THIS FORECAST... THOUGH SOME QUESTIONS WITH POSSIBLE CHANGES IN THE STEERING PATTERN OVER THE NORTHERN TIER LATE THIS WEEK. HAVE LEANED TOWARD A BLEND OF AVAILABLE GUIDANCE INTO FRIDAY...THEN PUSHED TOWARD A BLEND OF THE ECENS AND GEFS MEANS WHICH SHOWED A SLOWER BREAKDOWN OF THE RIDGING ACROSS THE REGION...WITH LOWER CONFIDENCE IN THE DETAILS OF THIS FORECAST FOR THIS WEEKEND. DAILIES... TUESDAY... ANOTHER FRONTAL SYSTEM STEADILY WORKS ITS WAY ACROSS OUT OF NY STATE...THOUGH SOME TIMING ISSUES IN PLACE AMONGST THE OPERATIONAL MODEL SUITE. KEPT CHANCE POPS ACROSS SOUTHWEST NH/WESTERN MA AROUND MIDDAY. THEN PUSHED THIS FRONT....AND THE CORRESPONDING INCREASED RAINFALL CHANCES...EAST THROUGH THE EVENING AND OVERNIGHT HOURS. THIS TIMING MAY STILL BE TOO FAST. WEDNESDAY...EXPECTING DRIER AIR TO SLOWLY ARRIVE DURING THE DAY ON LIGHT WEST WINDS. HIGH PRESSURE WILL BUILD OUT OF THE APPALACHIANS. TEMPERATURES WILL REMAIN WARM FOR THIS TIME OF YEAR...WITH A GENERAL WEST WIND FLOW THROUGHOUT THE LAYER. COULD SEE SOME SHOWERS LINGER ACROSS CAPE COD AND THE ISLANDS DURING THE EARLY MORNING HOURS. THURSDAY AND FRIDAY...EXPECTING DRY AND MILD CONDITIONS CONTINUING WITH DEWPOINTS FALLING INTO THE 50S...THOUGH AROUND 60 ALONG THE IMMEDIATE COAST. CENTER OF HIGH PRESSURE SHIFTS OFFSHORE...RESULTING AND LIGHT SOUTHWEST WINDS. THIS SHOULD MEAN SLIGHT ABOVE NORMAL TEMPERATURES AWAY FROM THE IMMEDIATE COASTS. SATURDAY AND SUNDAY...LOTS OF QUESTIONS DURING THIS TIMEFRAME... MAINLY DUE TO TIMING ISSUES OF A COLD FRONT. KEPT MENTION OF CHANCE POPS AS A COLD FRONT TRIES TO CROSS SOUTHERN NEW ENGLAND THIS WEEKEND. LOW CONFIDENCE WITH THIS FEATURE. HIGH PRESSURE SHOULD EVENTUALLY RETURN LATER SUNDAY.
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&& .AVIATION /19Z SUNDAY THROUGH FRIDAY/...
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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 MONDAY NIGHT/...HIGH CONFIDENCE IN TRENDS BUT LOWER CONFIDENCE IN PRECISE DETAILS AND TIMING. THROUGH THIS EVENING...AREAS OF MVFR CIGS WILL LINGER THIS AFTERNOON. SW GUSTS TO 25 KT ALONG THE COAST. SCT TSTMS EXPECTED TO DEVELOP 20-00Z ACROSS THE INTERIOR WITH BRIEF IFR CONDITIONS POSSIBLE ALONG WITH HEAVY DOWNPOURS AND GUSTY WIND. TONIGHT...CONVECTION MAY LINGER TONIGHT AND MOVE ACROSS THE COASTAL PLAIN BEFORE DIMINISHING. AREAS OF STRATUS AND PATCHY FOG EXPECTED TO DEVELOP AND EXPAND ACROSS THE REGION...BUT HIGHEST PROBABILITY NEAR THE S COAST. EXACT TIMING UNCERTAIN. MONDAY...MVFR/IFR CIGS/VSBYS MAY LINGER MOST OF THE DAY ALONG THE SOUTH COAST...BUT IMPROVING TO VFR IN THE INTERIOR AND ESPECIALLY FAR N AREAS AS DRIER AIR MOVES IN FROM THE N. SCT SHOWERS/TSTMS EXPECTED TO DEVELOP WITH BRIEF MVFR/IFR POSSIBLE IN ANY TSTMS. MONDAY NIGHT...AREAS OF IFR STRATUS AND FOG EXPECTED TO REDEVELOP BUT UNCERTAINTY ON AREAL EXTENT. A FEW SHOWERS/TSTM MAY LINGER INTO THE EVENING ALONG THE SOUTH COAST. KBOS TERMINAL...HIGH CONFIDENCE IN TAF REGARDING TRENDS BUT LOWER CONFIDENCE ON PRECISE DETAILS AND TIMING. KBDL TERMINAL...HIGH CONFIDENCE IN TAF REGARDING TRENDS BUT LOWER CONFIDENCE ON PRECISE DETAILS AND TIMING. OUTLOOK...TUESDAY THROUGH FRIDAY... TUESDAY...MODERATE CONFIDENCE. MVFR-IFR VSBYS THROUGH AROUND 14Z IN PATCHY FOG...THEN BRIEF PERIOD OF VFR. MAY SEE PERIODS OF MVFR IN SCT SHOWERS/TSTMS ESPECIALLY INLAND DURING THE AFTERNOON/EVENING. PRECIP SHOULD TAPER OFF AFTER MIDNIGHT. PATCHY FOG RETURNS AFTER 05Z-06Z WITH MVFR-IFR VSBYS IN NORMALLY PRONE INLAND LOCATIONS. WEDNESDAY THROUGH FRIDAY...MODERATE CONFIDENCE. EXPECTING MAINLY VFR CONDITIONS AS HIGH PRESSURE BUILDS IN. LOCAL MVFR-IFR VSBYS AND CIGS IN LATE NIGHT PATCHY FOG AND STRATUS. MAIN AREAS OF CONCERN WILL BE THE TYPICALLY PRONE LOCATIONS ACROSS THE FAR INTERIOR /SOUTHWEST NH AND NORTH CENTRAL AND WESTERN MA/.
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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. MODERATE CONFIDENCE THROUGH MONDAY NIGHT. MODEST LOW LEVEL JET WILL HELP TO SUPPORT SOME SW GUSTS TO 25 KT INTO THE EVENING ALONG THE SOUTH COASTAL NEARSHORE WATERS SO SCA WILL CONTINUE. OVER THE OUTER WATERS...EXPECT WINDS TO REMAIN BELOW SCA BUT BUILDING SEAS TO NEAR 5 FT SO SCA HERE AS WELL. THE LOW LEVEL JET MOVES OFF THE COAST OVERNIGHT WITH DECREASING WINDS. WINDS AND SEAS WILL BE BELOW SCA THRESHOLDS MONDAY INTO MONDAY NIGHT. A FEW SHOWERS/TSTMS POSSIBLE TONIGHT AND AGAIN MONDAY INTO MONDAY EVENING. OTHERWISE...AREAS OF FOG WILL LIKELY REDUCE VSBYS LATER TONIGHT INTO MONDAY...AND AGAIN MONDAY NIGHT. OUTLOOK...TUESDAY THROUGH FRIDAY... MODERATE CONFIDENCE. EXPECTING WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT CRITERIA THROUGH THIS PERIOD. MAY SEE SOME SOUTHWEST WIND GUSTS UP TO 20 KT TUE NIGHT...BEFORE SHIFTING TO W-NW AND DIMINISHING BY WED MORNING.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ231>235-237. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 11 AM EDT MONDAY FOR ANZ254>256.
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&& $$ SYNOPSIS...KJC NEAR TERM...KJC SHORT TERM...KJC LONG TERM...BELK AVIATION...KJC/BELK MARINE...KJC/BELK

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