Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 262130 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 530 PM EDT TUE MAY 26 2015 .SYNOPSIS...
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WARM AND MUGGY CONDITIONS WILL INCREASE THROUGH TOMORROW. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED EACH DAY... WITH WEDNESDAY AND THURSDAY HAVING THE HIGHER POTENTIAL FOR STRONG STORMS.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... TEMPERATURES HAVE SOARED INTO THE UPPER 80S ACROSS THE CONNECTICUT...MERRIMACK AND PIONEER VALLEYS THIS AFTERNOON. ELSEWHERE...TEMPERATURES VARY FROM THE UPPER 70S TO THE LOWER 80S. CLOUD COVER HAS FINALLY DISSIPATED TO THIN CIRRUS WHICH HAS ALLOWED THE TEMPERATURES TO CLIMB JUST IN THE LAST COUPLE OF HOURS. IN ADDITION...DIURNAL CUMULUS CLOUDS HAVE ALSO DEVELOPED ACROSS NEW YORK STATE AND NORTHERN NEW ENGLAND...AS WELL AS FAR WESTERN MASSACHUSETTS. THIS IS IN RESPONSE TO THE GREATER INSTABILITY AND MOISTURE IN THESE AREAS. SHOWERS AND THUNDERSTORMS HAVE POPPED MAINLY OVER NEW YORK STATE AND PENNSYLVANIA. AS THESE TRAVEL EASTWARD INTO MASSACHUSETTS THEY HAVE BEEN DIMINISHING IN INTENSITY AND AREAL COVERAGE. WHILE I EXPECT THIS TREND TO CONTINUE...A SHOWER OR THUNDERSTORM OR TWO COULD MAKE IT INTO SOUTHERN NEW ENGLAND. IF THEY DO...EXPECT BRIEF HEAVY RAINFALL...SOME THUNDER AND LIGHTNING...AND GUSTY WINDS AT MOST. TONIGHT...THE UPPER RIDGE OVER THE EASTERN SEABOARD WILL START TO BREAK DOWN WHICH WILL ALLOW FOR BETTER MOISTURE AND INSTABILITY OVER SOUTHERN NEW ENGLAND. THIS COULD LEAD TO A FEW SPRINKLES OR LIGHT RAIN SHOWERS OVERNIGHT. MOST OF THE MODEL GUIDANCE WAS DRY BUT THE GFS HAS BEEN INDICATING NOT JUST SPRINKLES BUT A GOOD TWO TENTHS OF AN INCH OF PRECIP. FEEL THIS MAY BE SOME CONVECTIVE FEEDBACK FROM THE CONVECTION OVER NEW YORK AND PA THIS EVENING. OTHERWISE...EXPECT SOME CLOUDINESS AND THAT WITH THE MOIST SOUTHWESTERLY WINDS WILL KEEP TEMPERATURES FROM FALLING TOO MUCH. EXPECT LOW TEMPERATURES MAINLY IN THE 60S. THAT WARM...MOIST AIR FLOWING OVER THE COLDER OCEAN WILL LIKELY RESULT IN AREAS OF DENSE FOG OVER THE OCEAN AND BLEEDING ONTO THE SOUTH COAST...CAPE...AND ISLANDS. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... WEDNESDAY...ANOTHER WARM AND MUGGY DAY FOR SOUTHERN NEW ENGLAND WITH TEMPERATURES TOPPING OUT IN THE UPPER 80S IN THE CONNECTICUT AND MERRIMACK VALLEYS WITH MID 80S ELSEWHERE. EXCEPTION TO THIS IS ALONG THE SOUTH COAST...CAPE...AND ISLANDS WHERE BOTH ONSHORE WINDS AND PERHAPS LINGERING MARINE STRATUS AND FOG WILL KEEP TEMPERATURES FROM CLIMBING. EXPECT HIGH TEMPERATURES IN THE 60S IN THESE LOCATIONS. THIS LOOKS LIKE THE BETTER DAY FOR SOME SHOWERS AND THUNDERSTORMS TO AFFECT SOUTHERN NEW ENGLAND. HOWEVER...THIS DOESN/T APPEAR TO OCCUR UNTIL LATE AFTERNOON AND EVENING. INSTABILITY IS A BIT BETTER THAN IT WAS TODAY BUT IS STILL SOMEWHAT LACKING AND MID LEVEL LAPSE RATES LEAVE PLENTY TO BE DESIRED. THE MAIN FOCUS FOR STORMS WILL BE OVER NEW YORK AND PENNSYLVANIA WHERE THE BETTER INSTABILITY AND FOCUSING WILL BE. THESE STORMS...MUCH LIKE TODAY...WILL LIKELY MOVE INTO THE WESTERN PART OF THE CWA TOWARDS THE LATE AFTERNOON/EARLY EVENING. WHILE THESE STORMS HAVE THE POTENTIAL TO BE STRONG TO SEVERE...THE MOST LIKELY THREATS WITH THESE STORMS ARE HEAVY DOWNPOURS AND GUSTY WINDS. WEDNESDAY NIGHT...SHOWERS AND THUNDERSTORMS ARE EXPECTED TO LAST INTO THE EVENING AS WIND SHEAR INCREASES WITH A STRONG LOW LEVEL JET MOVING OVER SOUTHERN NEW ENGLAND. ANOTHER WARM NIGHT IN STORE WITH LOWS IN THE 60S. && .LONG TERM /THURSDAY THROUGH TUESDAY/...
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OVERVIEW AND MODEL PREFERENCES... TO START OFF...MEDIUM RANGE MODELS AND ENSEMBLES KEEP OVERALL UPPER LEVEL PATTERN IN PLACE ACROSS THE LOWER 48...WITH RIDGING ALONG OR JUST E OF THE EASTERN SEABOARD AND TROUGHING ACROSS THE ROCKIES INTO THE SOUTHWEST. MODEL TRENDS CONTINUE TO SIGNAL SLOW DEAMPLIFICATION OF THE UPPER PATTERN GOING INTO THIS WEEKEND...WITH RIDGE AXIS FLATTENING OUT ACROSS THE NORTHEAST AS A SURFACE FRONT THAT TRIES TO WORK ACROSS THE REGION WASHES OUT DURING FRIDAY. BERMUDA HIGH RE- ESTABLISHES FOR EARLY THIS WEEKEND WHILE ANOTHER FRONT WORKS SE OUT OF QUEBEC. THIS FRONT LOOKS STRONG ENOUGH TO WORK SLOWLY SE AS THE WESTERN ATLC RIDGE SHIFTS S AND UPPER TROUGHING TAKES OVER ACROSS THE NORTHERN STREAM. BIG QUESTION WILL BE WHETHER THE FRONT WILL CLEAR OFF THE S COAST EARLY NEXT WEEK OR WILL IT STALL CLOSER TO OR OVER SOUTHERN AREAS. USED A BLEND OF AVAILABLE GUIDANCE FOR THIS FORECAST PACKAGE... THOUGH DID LEAN TOWARD MORE TOWARD THE ENSEMBLES FROM THIS WEEKEND ONWARD DUE TO TIMING DIFFERENCES WITH THE APPROACHING FRONT. FOR THE LATTER TIMEFRAME...LEANED CLOSER TO THE SLOWER ECMWF AND ECENS MEANS. DETAILS... THURSDAY...WILL SEE LEFTOVER SCT SHOWERS/TSTMS ACROSS WESTERN AREAS THU MORNING WITH PWATS ON ORDER OF AROUND 1.5 INCHES. THE FRONT SHIFTS S TAKING THE HIGHER PWAT AIR WITH IT...SO EXPECT THE PRECIP TO TEND TO WEAKEN THOUGH WILL LINGER WHERE MILDER TEMPS ARE THANKS TO DIURNAL INFLUENCES. INSTABILITY ALSO SHIFTS OFFSHORE AND WEAKENS SO EXPECT ANY THUNDERSTORMS TO TAPER OFF BY AROUND MIDDAY. BEST SHOT FOR PRECIP WILL BE FROM THE MERRIMACK VALLEY SE ACROSS CENTRAL MA TO THE MID AND LOWER CT VALLEY. CAN NOT RULE OUT A FEW QUICK DOWNPOURS THROUGH MIDDAY WITH THE HIGHER PWAT AIRMASS. WILL SEE AREAS OF FOG...LOCALLY DENSE...DEVELOP ACROSS S COASTAL AREAS THU NIGHT INTO FRI MORNING. FRIDAY...MODELS STARTED TO SIGNAL DRIER AIR WORKING IN ON MONDAY... BUT MOST OF THE MODEL SUITE HAS HIGH PRES RIDGE BUILDING S OUT OF QUEBEC SO EXPECT A DRY BUT MILD DAY. DEWPTS DROP A BIT...DOWN TO THE 50S...BUT WILL BEGIN TO RISE AGAIN FRI NIGHT. WILL SEE A LIGHT E-SE WIND FLOW SO WILL BE COOLER ALONG THE COAST...HIGHS MAINLY IN THE 70S EXCEPT 65-70 ACROSS COASTAL AREAS...RANGING TO THE LOWER TO MID 80S ACROSS THE CT VALLEY. SATURDAY...HIGH PRESSURE REPOSITIONS OFF THE EASTERN SEABOARD SO SW WINDS KICK IN AGAIN BRINGING A RETURN TO MORE HUMID AIR. ANOTHER COLD FRONT START TO APPROACH OUT OF GREAT LAKES AND WESTERN QUEBEC. ALSO NOTING INCREASING INSTABILITY PARAMETERS AHEAD OF THE FRONT... WITH K INDICES RISING TO THE LOWER-MID 30S AND TQ VALUES IN THE UPPER TEENS SO COULD SEE SOME ELEVATED CONVECTION WHICH COULD LAST INTO SAT NIGHT. BEST LIFT MOVES CLOSER DURING LATE SAT/SAT NIGHT SO WILL SEE SCT SHOWERS/THUNDERSTORMS DEVELOP. A PWAT SWATH OF 1.6 TO 1.75 INCHES PUSHES OUT AHEAD OF THE FRONT...SO MAY SEE SOME HEAVIER DOWNPOURS WITH ANY CONVECTION. WILL SEE QUITE A BIT OF SUNSHINE EARLY SATURDAY...SO TEMPS WILL REBOUND TO THE 80S FOR MOST LOCATIONS EXCEPT THE LOWER-MID 70S ALONG S COASTAL AREAS. SUNDAY...COLD FRONT SLOWLY ACROSS THE REGION SUNDAY MORNING...THEN REACHES THE S COAST BY SUNDAY NIGHT. EXPECT CHANCE SHOWERS AND THUNDERSTORMS. STILL SOME TIMING ISSUES BETWEEN THE GFS AND ECMWF BUT A BIT BETTER FOR THIS TIMEFRAME. WITH THE SLOW MOVEMENT OF THE FRONT...EXPECT SCT PRECIP TO CONTINUE THROUGH SUN NIGHT. MONDAY-TUESDAY...SOMEWHAT LOWER CONFIDENCE DUE TO TIMING AND PLACEMENT DIFFERENCES WITH THE FRONT AND WHETHER IT STALLS NEAR THE S COAST OR OFFSHORE. AT THIS POINT...KEPT CHANCE POPS ACROSS CENTRAL AND SOUTHERN AREAS THROUGH MIDDAY THEN SHOULD PUSH JUST OFFSHORE BUT MAY LINGER ACROSS THE ISLANDS THROUGH MOST OF THE DAY SUNDAY. MAY SEE SOME THUNDERSTORMS EARLY...THEN INSTABILITY WORKS OFFSHORE BUT COULD STILL SEE SOME SHOWERS WHILE HIGH PRES MOVES ACROSS NORTHERN NEW ENGLAND. HAVE KEPT SLIGHT CHANCE POPS GOING FOR SOUTHERN AREAS INTO TUESDAY AS FRONT LOOKS TO LINGER...THEN MAY TRY TO MAKE A RUN BACK NE AS THE HIGH PUSHES OFF INTO THE GULF OF MAINE.
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&& .AVIATION /22Z TUESDAY THROUGH SUNDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. THROUGH 00Z...HIGH CONFIDENCE. VFR. CHANCE OF A TSTM WITH MVFR VSBYS/CIGS ACROSS CT/PIONEER VALLEY THIS AFTERNOON. IFR STRATUS AND FOG WILL INCREASE ACROSS SOUTH COAST LATE AFTERNOON/EVENING. TONIGHT...MODERATE CONFIDENCE. VFR DETERIORATING TO MVFR/IFR IN AREAS OF FOG ALONG THE SOUTH COAST...CAPE...AND ISLANDS. COULD SEE PASSING SHOWER OVERNIGHT. WEDNESDAY...MODERATE CONFIDENCE. IFR ALONG THE SOUTH COAST DURING THE MORNING SHOULD PUSH OFFSHORE. ANTICIPATE VFR CONDITIONS ACROSS THE INTERIOR... DROPPING TO MVFR WITHIN ANY -SHRA/-TSRA THAT DEVELOPS. EXPECT SW WINDS TO GUST UP TO 20-25 KT AT TIMES MAINLY ACROSS RI/SE MA. WEDNESDAY NIGHT...MODERATE CONFIDENCE. CONDITIONS DETERIORATE TO IFR ALONG THE SOUTH COAST...CAPE...AND ISLANDS AS MARITIME FOG AND STRATUS ROLLS BACK IN. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. COULD SEE CONDITIONS DROP TO MVFR WITHIN A POP-UP THUNDERSTORM TODAY. OUTLOOK...THURSDAY THROUGH SUNDAY...MODERATE CONFIDENCE. THURSDAY...MAINLY VFR. WILL SEE SCT -SHRA/TSRA WITH LOCAL MVFR-IFR CONDITIONS. EXPECT AREAS OF FOG DEVELOP DURING THE LATE NIGHT/EARLY MORNING PERIOD WITH IFR-LIFR VSBYS. FRIDAY...VFR. MAY SEE LOCAL MVFR-IFR CONDITIONS EARLY FRI MORNING ALONG S COAST IN PATCHY FOG...THEN WILL LOWER AGAIN LATE FRI NIGHT/SAT MORNING TO MVFR-IFR. SATURDAY...PATCHY FOG EARLY SAT MORNING WITH MVFR-IFR CONDITIONS WILL IMPROVE. SCT SHRA/TSRA SAT THROUGH SAT NIGHT WITH LOCAL MVFR- IFR CONDITIONS. SW WINDS GUSTING TO 20-25 KT MAINLY ALONG THE COAST SAT AFTERNOON/EVENING. SUNDAY...SCT SHOWERS TSTMS LINGER THROUGH SUNDAY...BUT SHOULD END SUN NIGHT. MAY SEE BRIEF MVFR CONDITIONS.
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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. SHORT TERM /THROUGH WEDNESDAY NIGHT/...HIGH CONFIDENCE. SMALL CRAFT ADVISORIES ARE UP THROUGH TONIGHT...MAINLY ON THE OUTER WATERS FOR SEAS AND SOUTHWESTERLY WINDS. SEAS WILL CLIMB TO 5 FEET AND REMAIN THERE THROUGH THE PERIOD. SMALL CRAFT ADVISORIES WILL EXPIRE THIS EVENING FOR THE INNER WATERS. SOUTHWESTERLY WINDS WILL DIMINISH AFTER SUNSET. IN ADDITION...AREAS OF DENSE FOG ARE LIKELY TO DEVELOP ON THE WATERS TONIGHT...SUBSTANTIALLY REDUCING VISIBILITIES. OUTLOOK...THURSDAY THROUGH SUNDAY...MODERATE CONFIDENCE. THURSDAY...EXPECT SW WINDS GUSTING TO AROUND 20 KT. SEAS BUILD TO AROUND 5 FT ACROSS THE SOUTHERN WATERS TO THE OUTER WATERS E OF CAPE COD...BUT SHOULD SUBSIDE BELOW 5 FT THU NIGHT. VSBYS REDUCED IN AREAS OF FOG...LOCALLY DENSE OFFSHORE BOTH THU AND FRI NIGHTS. FRIDAY...LIGHT N-NE WINDS BECOME E DURING THE DAY...THEN SHIFT TO S-SW FRI NIGHT. EXPECT WINDS AND SEAS BELOW SMALL CRAFT CRITERIA. SATURDAY-SUNDAY...SW WINDS MAY BRIEFLY GUST TO 25 KT DURING SAT ON THE EASTERN WATERS...OTHERWISE EXPECT GUSTS UP TO 20 KT SEAS BUILD AGAIN TO AROUND 5 FT ACROSS THE OUTER WATERS...WHICH WILL SLOWLY SUBSIDE LATE SUN OR SUN NIGHT.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ231>234. SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ235-237- 250-254>256. && $$ SYNOPSIS...RLG/EVT NEAR TERM...RLG SHORT TERM...RLG LONG TERM...EVT AVIATION...RLG/EVT MARINE...RLG/EVT

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