Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 071433 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1033 AM EDT TUE JUL 7 2015 .SYNOPSIS... A WARM FRONT WILL WEAKEN AS IT MOVES NORTH ACROSS THE REGION TODAY. A COLD FRONT MOVES ACROSS THE REGION WEDNESDAY BRINGING SHOWERS AND THUNDERSTORMS...SOME WITH HEAVY DOWNPOURS. THE FRONT MOVES SOUTH OF NEW ENGLAND WEDNESDAY NIGHT AND STALLS...ALLOWING ANOTHER ROUND OF SHOWERS AND STORMS THURSDAY. HIGH PRESSURE THEN BUILDS IN WITH FAIR WEATHER FOR FRIDAY AND SATURDAY. ANOTHER WEATHER SYSTEM APPROACHES EARLY NEXT WEEK AND MAY BRING MORE WET WEATHER. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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1030 AM UPDATE... WARM FRONT IS BEGINNING TO PUSH THROUGH SOUTHERN NEW ENGLAND THIS MORNING. AS IT LIFTS NORTHWARD THAT WILL PUT THE REGION WITHIN THE WARM SECTOR. BIGGEST QUESTION IS IF THE LOW STRATUS WILL BURN OFF IN TIME TO ALLOW FOR AN INCREASE IN INSTABILITY. REGARDLESS ITS GOING TO BE A WARM...MUGGY DAY. SCT SHOWERS CONTINUE TO POP-UP ACROSS THE REGION WITH THE HEAVIEST SHOWERS SOUTH OF THE WARM FRONT. PATCHY FOG EARLY THIS MORNING HAS BURNED OFF. SOMETHING THAT WILL NEED TO BE REEVALUATED FOR THIS EVENING. OTHERWISE BULK OF THE FORECAST REMAINS ON TRACK FOR THIS AFTERNOON...WITH THE POTENTIAL FOR A FEW STRONG THUNDERSTORMS. BEST CHANCE IS ACROSS WESTERN MA AND NORTHERN CT. CANNOT RULE OUT AN ISO SEVERE BUT THE POTENTIAL IS VERY LOW AT THIS TIME. BEST TIMING FOR THE STRONG STORMS WILL BE AFTER 2 PM. PREVIOUS DISCUSSION... UPDATED THE FORECAST TO ACCOUNT FOR CURRENT CONDITIONS. PATCHY FOG ACROSS CT WILL BEGIN TO WANE AS MIXING AND DIURNAL HEATING BEGINS. OTHERWISE A FEW SCT SHOWERS HAVE DEVELOPED ACROSS SE MASS...ON THE EDGE OF THE THREAT-E ADVECTION. NOT ANTICIPATED MUCH IN TERMS OF STRONG THIS MORNING...MORE NUISANCE PASSING SHOWERS. ANTICIPATE THESE SHOWERS TO CONTINUE TO MOVE ACROSS THE SOUTHERN WATERS INTO SE MASS FOR THE NEXT FEW HOURS. BIGGEST QUESTION THIS AFTERNOON IS IF WE WILL GET ENOUGH SUNSHINE TO INCREASE THE INSTABILITY. BOTH THE GFS AND NAM INDICATE AROUND2000 J/KG OF MU CAPE WHILE THE EC IS LESS...CLOSER TO 1000 J/KG. THE SHEAR IS ALSO NOT AS IMPRESSIVE WITH AROUND 20-30 KTS OF SHEAR. HOWEVER PWATS ARE STILL HIGH SO IF ANY THUNDERSTORM DOES DEVELOP THIS AFTERNOON...THEN ANTICIPATE HEAVY DOWNPOURS. ALL THE HI-RES GUIDANCE IS HINTING AT THE WESTERN PORTION OF THE CWA SEEING THE GREATEST RISK. EVEN WITH MARGINAL...SHEAR AND INSTABILITY...STILL CANT RULE A VERY WEAK SPIN-UP WITHIN THE TROPICAL AIRMASS. BEST CHANCE IS ACROSS THE CT VALLEY WHERE WINDS COULD BACK AND HELICITY IS PROGGED TO BE NEAR 100.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... TONIGHT... EXPECT COLD FRONT TO SLOWLY APPROACH THE REGION OUT OF NY STATE. SHOULD REMAIN DRY...EXCEPT FOR SOME WIDELY SCT SHOWERS POSSIBLE ACROSS NW MA EARLY TONIGHT. HAVE INCREASED CHANCE POPS AFTER MIDNIGHT FROM W-E. SOME SHORT RANGE MODEL DIFFERENCES IN HANDLING MOISTURE WITH AND AHEAD OF THE FRONT...THOUGH SOUPY AIRMASS REMAINS IN PLACE SO COULD SEE SCT PRECIP. ALSO HELD OFF MENTION OF THUNDER AS BEST INSTABILITY REMAINS CLOSER TO THE FRONT. WILL ALSO SEE FOG RETURN ESPECIALLY ACROSS S COASTAL AREAS ESPECIALLY THE CAPE AND ISLANDS AS TEMPS ONLY DROP TO AROUND 70. WEDNESDAY... COLD FRONT SLOWLY CROSSES THE REGION. BEST INSTABILITY ALSO MOVES IN BY MIDDAY...WITH K INDICES IN THE LOW-MID 30S...CAPES RISING TO 1000-1200 J/KG BY MIDDAY ESPECIALLY ACROSS CENTRAL AND EASTERN AREAS ALONG WITH TQ VALUES IN THE UPPER TEENS SIGNALING SOME ELEVATED CONVECTION.BIG CONCERN THOUGH IS THE INCREASING PWATS... UP TO 2 TO 2.2 INCHES WITH GOOD LOW LEVEL MOISTURE CONVERGENCE. COULD SEE A FEW STRONG STORMS THOUGH CHANCE LIMITED WITH CLOUD COVER...BUT BETTER SHOT FOR HEAVY DOWNPOURS WHICH COULD CAUSE LOCALIZED URBAN AND POOR DRAINAGE FLOODING. EXPECT THREAT FOR THUNDER TO WIND DOWN ACROSS ROUTE 2 AREA AROUND OR AFTER 18Z...WITH BEST SHOT FOR PRECIP SHIFTING TO NEAR AND S OF THE MASS PIKE THROUGH THE REMAINDER OF THE DAY. FRONT LOOKS TO BE SLOWING AS IT MOVES S DURING THE AFTERNOON AS WELL. MAY SEE IMPULSE MOVE ALONG THE FRONT WHICH COULD CAUSE TRAINING OF SHOWERS AND CONVECTION...ANOTHER PROBLEM FOR POSSIBLE FLOODING. EXPECT A WARM AND MUGGY DAY WITH DEWPTS IN THE MID 60S TO NEAR 70 AS HIGHS REACH INTO THE MID AND UPPER 80S ACROSS THE LOWER CT VALLEY AND INTERIOR E MA...EVEN REACHING THE LOWER 80S ON THE CAPE. TEMPS LOOK TO HOLD IN THE UPPER 70S ON THE ISLANDS. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... BIG PICTURE... UPPER HIGH PRESSURE REMAINS IN CONTROL OVER THE ATLANTIC COAST WHILE LOW PRESSURE DIGS OVER THE WESTERN USA. JET FLOW FROM WESTERN CANADA RIDES ALONG THE US/CANADIAN BORDER. THE RIDGE SHIFTS TO THE MIDWEST AND PLAINS OVER THE WEEKEND MAKING ROOM FOR A TROUGH TO DIG OVER THE CANADIAN MARITIMES. UPPER HEIGHTS REMAIN AT OR ABOVE SEASONAL NORMALS THROUGH THE PERIOD. THIS SUGGESTS NORMAL SUMMER TEMPERATURES...ALTHOUGH DAYTIME HIGHS WILL OF COURSE BE HELD BACK ON DAYS OF HEAVY SKY COVER OR STRONG EAST FLOW. THE DAILIES... WEDNESDAY NIGHT-THURSDAY...MODERATE CONFIDENCE. COLD FRONT IN SOUTHEAST NEW ENGLAND DURING THE EVENING MOVES OFFSHORE BEFORE MIDNIGHT. THE FRONT THEN BECOMES ALIGNED WITH THE UPPER FLOW AND STALLS SOUTH OF THE REGION. SHORTWAVE IN THE UPPER FLOW MOVES THROUGH DURING THURSDAY...GENERATING A WAVE ALONG THE FRONT AND MAINTAINING A RISK OF SHOWERS THURSDAY. THE BEST CHANCE WILL BE SOUTH OF THE MASS PIKE NEAREST THE WAVE AND THE FRONT. PRECIPITABLE WATER VALUES REMAIN HIGH NEAR THE SOUTH COAST...SO LOCALLY HEAVY DOWNPOURS WILL CONTINUE TO BE A CONCERN IN SOUTHERN AREAS. CLOUDS AND A LIGHT EAST FLOW SHOULD KEEP DAYTIME TEMPS IN THE 70S. FRIDAY-SATURDAY...MODERATE TO HIGH CONFIDENCE. HIGH PRESSURE BUILDS OVER THE REGION WITH CLEARING SKIES AND LIGHT WINDS. MIXING SHOULD REACH TO AT LEAST 850 MB AND POSSIBLY TO 800 MB. TEMPS AT THESE LEVELS WOULD SUPPORT MAX TEMPS OF 80-85 FRIDAY AND MID 80S SATURDAY. DEW POINTS 55 TO 65 AND LIGHT WINDS SUGGEST MIN TEMPS IN THE SAME RANGE AS WELL AS PATCHY FOG. SUNDAY-MONDAY...LOW CONFIDENCE. CHANGES IN THE OPERATIONAL MODEL SOLUTIONS REGARDING MOISTURE IN THE VERTICAL ACTS TO SUPPRESS PCPN IN SOUTHERN NEW ENGLAND DURING THIS PERIOD. MEANWHILE A SHORTWAVE SWINGS ACROSS NORTHERN NEW ENGLAND INTO THE MARITIMES...PUSHING A COLD FRONT THROUGH OUR AREA. IT IS HARD TO TOTALLY KILL OFF POPS WHILE SUCH A MECHANISM IS IN PLACE. WE WILL MAINTAIN CHANCE POPS FOR THE MOMENT AND AWAIT FUTURE MODEL RUNS. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY/... TODAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR VSBYS DURING THE MORNING...THEN PATCHY MVFR CIGS MAINLY ALONG THE S COAST. BRIEF MVFR CONDITIONS IN SCT SHOWERS. LOW PROB OF ISOLD AFTERNOON THUNDERSTORMS. S-SE WIND GUSTS UP TO 20-25 KT ALONG COAST THIS AFTERNOON...HIGHEST ALONG E COAST. TONIGHT...MODERATE CONFIDENCE. CONDITIONS LOWER TO MAINLY MVFR BY 04Z-05Z IN PATCHY FOG. CHANCE OF SHOWERS ACROSS W MA/N CENTRAL CT THROUGH MOST OF THE NIGHT WITH CHANCE OF ISOLD THUNDERSTORMS THROUGH 04Z. MAY SEE IFR VSBYS ACROSS E MA/RI/N CT AFTER 06Z-07Z. WEDNESDAY...MODERATE CONFIDENCE. EXPECT MVFR TO LOCAL IFR CONDITIONS IN SCT SHOWERS AS COLD FRONT SLOWLY CROSSES THE REGION. CHANCE OF AFTERNOON THUNDERSTORMS... SOME WITH HEAVY DOWNPOURS. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY... WEDNESDAY NIGHT-THURSDAY...MODERATE CONFIDENCE. A COLD FRONT OVER SOUTHEAST MASS/RI IN THE EVENING MOVES OFFSHORE WITH WINDS BECOMING NORTH OVERNIGHT AND NORTHEAST THURSDAY BUT WITH SPEEDS BELOW 15 KNOTS. SHOWERS MOVING UP THE FRONT THURSDAY WILL BRING AREAS OF MVFR CIGS/VSBYS WITH THE BEST CHANCE IN CT-RI AND SOUTHEAST MASS. FRIDAY-SATURDAY...MODERATE-HIGH CONFIDENCE. HIGH PRESSURE BRINGS CLEARING SKIES. VFR. AREAS OF IFR POSSIBLE IN EARLY MORNING FOG. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY/...HIGH CONFIDENCE. TODAY...EXPECT LIGHT/VRBL WINDS BECOMING S-SE BY MIDDAY...THEN SHIFT TO S AS WARM FRONT LIFTS N. MAY SEE GUSTS UP TO 20-25 KT ACROSS THE NEAR SHORE WATERS...HIGHEST ON THE EASTERN WATERS. SEAS BUILD UP TO 4 FT...MAINLY ACROSS THE SOUTHERN WATERS. TONIGHT...MAY SEE LEFTOVER 20-25 KT GUSTS THIS EVENING THEN WILL DIMINISH. PATCHY FOG DEVELOPS WITH REDUCED VSBYS...BELOW 3 MILES AFTER MIDNIGHT. WEDNESDAY...SW WINDS WILL INCREASE...WITH GUSTS UP TO 20 KT ON THE SOUTHERN OUTER WATERS. EXPECT SEAS TO REMAIN BELOW 5 FT...THOUGH MAY BRIEFLY REACH 5 FT AT TIMES. CHANCE OF SHOWERS/THUNDERSTORMS SOME WITH HEAVY RAINFALL. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY... WINDS AND SEAS REMAIN BELOW SMALL CRAFT THRESHOLDS THROUGH THE PERIOD. A COLD FRONT MOVES OFFSHORE WEDNESDAY NIGHT AND STALLS OVER THE SOUTHERN WATERS. A DISTURBANCE MOVING ALONG THE FRONT WILL BRING SHOWERS AND SCATTERED TSTMS WEDNESDAY NIGHT/THURSDAY WITH REDUCED VSBYS IN ANY HEAVY DOWNPOURS. HIGH PRESSURE BRINGS FAIR WEATHER FRIDAY AND SATURDAY. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ250. SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ231- 251. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ230.
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&& $$ SYNOPSIS...WTB/EVT NEAR TERM...DUNTEN SHORT TERM...DUNTEN LONG TERM...WTB/EVT AVIATION...WTB/EVT MARINE...WTB/EVT

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