Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 252330 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 730 PM EDT MON MAY 25 2015 .SYNOPSIS... WARM AND MUGGY CONDITIONS START TO BUILD IN ALONG WITH AN INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH THE END OF THE WEEK. THE THREAT FOR SCATTERED SHOWERS AND THUNDERSTORMS WILL INCREASE FROM LATE WEDNESDAY THROUGH THURSDAY AND AGAIN OVER THE UPCOMING WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 720 PM UPDATE... NOTING AREA OF MID AND HIGH CLOUDS SHIFTING E-SE OUT OF NY STATE WHILE ANOTHER AREA MOVES ACROSS ON LATEST IR SATELLITE IMAGERY. A BAND OF LOWER CLOUDS LOOKS TO BE DEVELOPING ACROSS N CENTRAL AND W MA OVER THE LAST HOUR OR SO...ALONG WITH A COUPLE OF LIGHT SHOWERS ON THE S END OF AN AREA MOVING ACROSS CENTRAL AND N VT/NH. WITH SOMEWHAT DRIER AIR ACROSS THE REGION...THE SMALL SHOWERS LOOK TO DISSIPATE...BUT COULD SEE A FEW MORE TRY TO SNEAK INTO N MA THROUGH AROUND MIDNIGHT BEFORE LIFTING NE WITH THE WARM FRONT. HAVE UPDATED NEAR TERM FORECAST TO BRING CONDITIONS CURRENT. PREVIOUS DISCUSSION... EXPECT CLOUDS TO LINGER AS DEWPTS INCREASE BEHIND THE WARM FRONT. EXPECT THE FRONT TO MOVE NORTH OF THE AREA AFTER MIDNIGHT TONIGHT. THE FRONT WILL KEEP DEWPOINTS IN THE 50S OVERNIGHT WHICH IN TURN WILL KEEP OVERNIGHT TEMPERATURES IN THE UPPER 50S TO LOWER 60S. THERE IS A LOW PROBABILITY OF SHOWERS AND SPRINKLES ALONG THE MA/NH BORDER LATE TONIGHT AS THE WARM FRONT MOVES THROUGH. HOWEVER...MOST OF THE ENERGY AVAILABLE TO PRODUCE SHOWERS REMAINS FARTHER NORTH. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... TUESDAY...A REAL SUMMER-LIKE DAY IS EXPECTED WITH THE WARM FRONT THROUGH THE AREA. EXPECT WARM...MUGGY CONDITIONS WITH TEMPERATURES CLIMBING INTO THE MID TO UPPER 80S ACROSS MUCH OF SOUTHERN NEW ENGLAND. SOUTHWESTERLY WINDS WILL KEEP THE SOUTH COAST OF RI AND MA AS WELL AS THE SOUTHERN SIDE OF CAPE ANN SIGNIFICANTLY COOLER WITH HIGHS IN THE UPPER 60S TO LOWER 70S. MODELS ARE INDICATING SOME INSTABILITY IN THE AFTERNOON. THIS MAY BE ENOUGH TO POP A FEW SCATTERED THUNDERSTORMS IN NORTHWEST CT AND WESTERN MA. SO KEPT THE SLIGHT CHANCE TO CHANCE POPS THERE. NOT EXPECTING ANYTHING IN THE WAY OF PRECIP ACROSS EASTERN MA/RI. TUESDAY NIGHT...THE UPPER RIDGE THAT HAS BEEN IN PLACE ALONG THE EASTERN SEABOARD STARTS TO BREAK DOWN...SHIFTING TO THE EAST. THIS WILL ALLOW BETTER INSTABILITY TO SLOWLY FILTER INTO SOUTHERN NEW ENGLAND. SHOWERS AND THUNDERSTORMS THAT DEVELOP OVER NYS COULD MOVE INTO THE WESTERN PORTIONS OF SOUTHERN NEW ENGLAND OVERNIGHT. HAVE SLIGHT CHANCE TO CHANCE POPS IN PLACE FOR THESE AREAS DURING THE OVERNIGHT PERIOD. CONTINUED SOUTHWESTERLY FLOW WILL KEEP THINGS WARM AND MUGGY. IT/LL BE ANOTHER NIGHT WITH LOWS IN THE 60S. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... OVERVIEW AND MODEL PREFERENCES... OVERALL SURFACE AND UPPER LEVEL PATTERN LOOKING MORE AND MORE LIKE SUMMER WITH H5 RIDGE BUILDING ACROSS EASTERN SEABOARD THROUGH LATE THIS WEEK. WILL SEE WARM AND HUMID CONDITIONS INTO THIS WEEKEND AT LEAST. MODELS AND ENSEMBLES THEN DIVERGE ON HOW QUICKLY THIS RIDGE WILL BREAK DOWN...ALLOWING FRONTAL SYSTEMS TO TRY AND PUSH S OUT OF QUEBEC AND NORTHERN NEW ENGLAND. WITH THESE FRONTS MOVING INTO A NEARLY PARALLEL UPPER FLOW...WILL TEND TO SLOW DOWN AND WEAKEN AS THEY SHIFT TOWARD THE REGION. WILL SEE SOME RELIEF TO THE EXTENDED DRY CONDITIONS ESPECIALLY DURING THE WED-FRI TIMEFRAME WHEN BEST SHOT FOR DEEP MOISTURE PLUME MOVING NE OUT OF THE CENTRAL U.S...WHERE THE RECORD FLOODING RAINS HAVE BEEN OCCURRING OVER THE LAST FEW WEEKS. TIMING ISSUES COME INTO PLAY THIS WEEKEND AS ANOTHER FRONT TRIES TO APPROACH AND WHETHER IT WILL MOVE OFFSHORE OR SLOW DOWN ACROSS THE REGION. LEANED TOWARD AVAILABLE GUIDANCE THROUGH THE REMAINDER OF THE WORK WEEK...THEN TRANSITIONED OVER TO THE 00Z ECMWF AND ECENS MEANS WHICH WERE SLOWER IN BRINGING THE WEEKEND FRONT INTO THE REGION AS ONE WOULD EXPECT WITH HOW MODELS HANDLE LONG WAVE PATTERN TRANSITIONS. DETAILS... WEDNESDAY...H5 RIDGING SHIFTS E DURING WED WITH SW WIND FLOW AT SURFACE AND ALOFT IN PLACE. WILL SEE FIRST IN SERIES OF COLD FRONTS WILL SLOWLY PUSH SE TOWARD THE REGION. GOOD INSTABILITY OUT AHEAD OF THIS FRONT. MODEL CAPES RISING TO AROUND 1000 J/KG /NAM IS HIGHER/...K INDICES RISING TO THE LOWER-MID 30S AND LI/S FALLING BELOW ZERO. LOWEST PARAMETERS LOOK TO MOVE INTO CENTRAL AND WESTERN AREAS DURING THE AFTERNOON AND CONTINUE THROUGH WED NIGHT. ALSO NOTING INCREASING PWATS...UP TO 1.8 TO 1.9 INCHES...SO COULD SEE SOME DOWNPOURS WITH ANY CONVECTION. HAVE CHANCE POPS GOING...WITH HIGHEST FROM NE...CENTRAL AND WESTERN MASS INTO N CENTRAL CT WHERE BEST SHOT FOR ANY STRONG OR EVEN POSSIBLY SEVERE STORMS COULD OCCUR. SPC HAS MARGINAL SHOT FOR SEVERE STORMS IN THESE AREAS. EXPECT HIGHS IN THE 80S...WITH A COUPLE OF SPOTS APPROACHING 90 WELL INLAND. MAY SEE AREAS OF FOG...WHICH COULD BE LOCALLY DENSE ALONG THE IMMEDIATE S AND SE COASTS...DEVELOP DURING WED NIGHT AS DEWPTS CONTINUE TO SLOWLY RISE. THURSDAY...FRONTAL BOUNDARY WASHES OUT BUT STILL SOME INSTABILITY LINGERING WITH SOUPY AIRMASS ACROSS THE REGION. INSTABILITY PARAMETERS NOT QUITE AS STRONG AS ON WED BUT STILL DECENT SO COULD SEE A FEW STRONG STORMS AS MID LAYER STARTS TO COOL A BIT LENDING TO ELEVATED INSTABILITY. SOMEWHAT LOWER PWATS...AROUND 1.5 INCHES BUT STILL ENOUGH WITH THE HIGH DEWPTS FOR HEAVY RAINFALL FROM ANY CONVECTION. EXPECT AREAS OF FOG TO REDEVELOP ALONG S COASTAL AREAS THU NIGHT INTO FRI MORNING. FRIDAY...WHILE ANOTHER BOUNDARY TENDS TO WEAKEN OVER THE REGION... NOT A WHOLE LOT OF FORCING IN BETWEEN SYSTEMS DURING THIS TIMEFRAME. ALSO NOTING SOMEWHAT DRIER AIR ALOFT WHICH DOES NOT HELP IN DEVELOPING CONVECTION. HOWEVER...STILL CAN NOT RULE OUT CHANCE FOR DIURNAL SHOWERS/TSTMS TO DEVELOP MAINLY FROM NE MASS ACROSS CENTRAL AND WESTERN AREAS INTO N CENTRAL CT WITH DEWPTS IN THE 60S. ONE MORE ROUND OF FOG LOOKS TO DEVELOP ALONG THE COAST MAINLY FROM COASTAL PLYMOUTH COUNTY SOUTHWARD. SATURDAY...MODELS BEGIN TO DIVERGE ON THEIR SOLUTIONS AS ANOTHER FRONT TRIES TO SLIP SE OUT OF SOUTHERN QUEBEC. LOOKS LIKE MORE DIURNAL SHOWERS/TSTMS DURING THE AFTERNOON/EVENING ACROSS INLAND AREAS. SUNDAY-MONDAY...TIMING DIFFERENCES WITH THE APPROACHING FRONT LEND TO LOW CONFIDENCE DURING THIS TIMEFRAME. WENT WITH THE SLOWER ECMWF GUIDANCE...WHICH TENDS TO BE THE CASE WITH UPPER LEVEL BLOCKING PATTERNS TRYING TO BREAK DOWN. IN ANY EVENT...HAVE MORE CHANCES FOR SHOWERS/THUNDERSTORMS FOR SUNDAY AS THE FRONT LOOKS TO SLOWLY PUSH ACROSS THE REGION...THEN STALLING NEAR OR JUST OFF THE S COAST ON MONDAY WITH LOWER CHANCE FOR SHOWERS. MAY SEE DRIER AIR WORK INTO N MA DURING MON AFTERNOON...BUT AGAIN LOW CONFIDENCE ON THIS TIMING. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY NIGHT/...HIGH CONFIDENCE. 00Z UPDATE... TONIGHT...VFR. MAY SEE PATCHY FOG WITH MVFR VSBYS LATE S COAST/ CAPE COD/ISLANDS. SW WINDS WILL INCREASE 40-45 KT AT 1000-2000 FT ABOVE THE SURFACE...HIGHEST ALONG THE S COAST. NOT QUITE STRONG ENOUGH FOR LOW LEVEL WIND SHEAR TO BE INSERTED INTO TERMINALS...BUT SHOULD BE AWARE OF THIS. TUESDAY...VFR. COULD STILL HAVE SOME PATCHY MVFR VSBYS IN FOG NEAR THE S COAST...MAINLY EARLY. CHANCE OF A TSTM WITH MVFR VSBYS IN NW CT AND WESTERN MA...INCLUDING BDL/BAF AND IN THE BERKSHIRES LATE IN THE AFTERNOON. TUESDAY NIGHT...VFR DETERIORATING TO MVFR/IFR IN AREAS OF FOG PARTICULARLY ALONG THE SOUTH COAST...CAPE...AND ISLANDS. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...WEDNESDAY THROUGH SATURDAY...MODERATE CONFIDENCE. WEDNESDAY...EXPECT SW WINDS TO GUST UP TO 20-25 KT AT TIMES MAINLY ACROSS RI/SE MA WED AFTERNOON/EVENING. AREAS OF FOG DEVELOP WED NIGHT WITH MVFR-IFR VSBYS. MAY SEE PATCHY LIFR CIGS/VSBYS WITH OCEAN CLOUDS/DENSE FOG ALONG THE IMMEDIATE S AND SE COASTS OVERNIGHT. CHANCE FOR -SHRA/TSRA WITH LOCAL MVFR-IFR CONDITIONS WED AFTERNOON/NIGHT. THURSDAY AND FRIDAY...EXPECT CHANCE FOR -SHRA/TSRA WITH LOCAL MVFR-IFR CONDITIONS. WILL ALSO SEE AREAS OF FOG DEVELOP EACH LATE NIGHT/EARLY MORNING PERIOD WITH IFR-LIFR VSBYS. SATURDAY...PATCHY FOG EARLY SAT MORNING WITH MVFR-IFR CONDITIONS WILL IMPROVE. SCT SHRA/TSRA SAT THROUGH SAT NIGHT WITH LOCAL MVFR-IFR CONDITIONS. SUNDAY...S-SW WINDS WILL GUST UP TO 25 KT AT TIMES SAT AFTERNOON/ EVENING...MAINLY ALONG THE S COAST...CAPE COD AND THE ISLANDS. SCT SHOWERS/ISOLD TSTMS MAY LINGERING THROUGH SUNDAY...BUT SHOULD END SUN NIGHT. MAY SEE BRIEF MVFR CONDITIONS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY NIGHT/...HIGH CONFIDENCE. SMALL CRAFT ADVISORIES ARE UP FOR TONIGHT THROUGH TUESDAY NIGHT...MAINLY ON THE OUTER WATERS FOR INCREASING SEAS AND SOUTHWESTERLY WINDS. WHILE THE WINDS MAY ONLY REACH CRITERIA BRIEFLY...SEAS WILL CLIMB TO 5 FEET AND REMAIN THERE THROUGH THE PERIOD. IN ADDITION...AREAS OF FOG ARE LIKELY TO DEVELOP TUESDAY NIGHT...REDUCING VISIBILITIES. OUTLOOK...WEDNESDAY THROUGH SATURDAY...MODERATE CONFIDENCE. WEDNESDAY...SW WINDS GUSTING UP TO 25 KT OVER THE OUTER WATERS. MAY NEED TO EXTEND SMALL CRAFTS INTO WED NIGHT. SEAS UP TO 5-6 FT. REDUCED VSBYS AREAS OF FOG...LOCALLY DOWN TO ONE QUARTER OF A MILE OR LESS...MAINLY ACROSS THE OPEN WATERS DURING THE OVERNIGHT HOURS INTO THE EARLY MORNING HOURS. THURSDAY THROUGH SATURDAY...S-SW WINDS REMAIN PERSISTENT WITH GUSTS UP TO AROUND 20 KT MAINLY THU INTO THU NIGHT. SEAS LINGERING AT AROUND 5 FT ACROSS THE SOUTHERN OPEN WATERS THROUGH THU THEN SHOULD SUBSIDE. VSBYS REDUCED IN AREAS OF FOG...LOCALLY DENSE OFFSHORE BOTH THU AND FRI NIGHTS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM TUESDAY TO 6 AM EDT WEDNESDAY FOR ANZ250-254-255. SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ235-256. && $$ SYNOPSIS...RLG/EVT NEAR TERM...RLG/EVT SHORT TERM...RLG LONG TERM...EVT AVIATION...RLG/EVT MARINE...RLG/EVT

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