Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 270545 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 145 AM EDT WED MAY 27 2015 .SYNOPSIS... 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. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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200 AM UPDATE... SOUTHERLY FLOW CONTINUES ACROSS THE REGION STREAMING IN HIGHER DEWPOINTS...MOISTENING UP THE PROFILE. THIS WILL EVENTUALLY LEAD TO FOG DEVELOP ACROSS THE SOUTH COAST...CAPE AND ISLANDS. HOWEVER BUFKIT SOUNDINGS CONTINUE TO INDICATE THAT STRATUS WILL DOMINATE TONIGHT...WITH FOG DEVELOPING TOMORROW. CAN SEE STRATUS ALREADY DEVELOPING PER LATEST OBSERVATIONS AND SATELLITE IMAGERY. OTHERWISE TEMPS REMAIN QUITE MILD WITH MUCH OF THE REGION IN THE UPPER 60S AWAY FROM THE SOUTH COAST. SOUTHWEST FLOW CONTINUES TO REMAIN A TAD GUSTY ACROSS THE CAPE AND ISLANDS. OTHERWISE FORECAST REMAINS ON TRACK FOR TONIGHT.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... 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 NIGHT THROUGH TUESDAY/... 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. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. BEFORE 12Z...MODERATE CONFIDENCE. COULD SEE IFR CIGS AND VSBYS ACROSS THE SOUTH COAST...CAPE AND ISLANDS. OTHERWISE VFR. TODAY...MODERATE CONFIDENCE. IFR/MVFR ALONG THE SOUTH COAST WHILE THE REMAINDER OF THE REGION IS VFR. WESTERN SITES COULD DROP TO MVFR WITHIN ANY -SHRA/-TSRA THAT DEVELOPS. EXPECT SW WINDS TO GUST UP TO 20-30 KT AT TIMES MAINLY ACROSS RI/SE MA. TONIGHT...MODERATE CONFIDENCE. CONDITIONS DETERIORATE TO IFR ALONG THE SOUTH COAST...CAPE...AND ISLANDS AS MARITIME FOG AND STRATUS ROLL IN. THURSDAY...MODERATE CONFIDENCE. COLD FRONT WILL PASS ACROSS THE REGION SWITCHING THE SOUTHERLY WINDS TO THE WEST DURING THE DAY. IFR...FOG AND STRATUS IS POSSIBLE BEFORE FRONTAL PASSAGE ALONG SE TAF SITES. CANNOT RULE OUT A FEW SHOWERS/T-STORMS ALONG THE FRONT DROPPING CONDITIONS TO MVFR. OTHERWISE VFR WILL PREVAIL. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. COULD SEE CONDITIONS DROP TO MVFR WITHIN ANY THUNDERSTORM TODAY. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...MODERATE CONFIDENCE. 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... 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 AT MIDNIGHT FOR THE INNER WATERS. SOUTHWESTERLY WINDS WILL DIMINISH...BUT MAY LINGER FOR A FEW HOURS 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. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ235-237-250-254>256.
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&& $$ SYNOPSIS...RLG/EVT NEAR TERM...DUNTEN SHORT TERM...RLG LONG TERM...EVT AVIATION...DUNTEN/EVT MARINE...RLG/EVT

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