Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 311806 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 206 PM EDT SUN MAY 31 2015 .SYNOPSIS... A COLD FRONT WILL MOVE SLOWLY SOUTH ACROSS THE REGION TODAY...THEN STALL SOUTH OF NEW ENGLAND EARLY THROUGH TUESDAY. HIGH PRESSURE BUILDS OVER THE REGION WITH FAIR WEATHER FOR WEDNESDAY THROUGH FRIDAY. TEMPERATURES DROP BELOW NORMAL MONDAY...THEN SHOULD GRADUALLY RETURN TO SEASONABLE LEVELS BY WEDNESDAY NIGHT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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2 PM UPDATE... SPC MESOANALYSIS INDICATING SBCAPES 1000-1500 J/KG ACROSS N CT INTO RI AND ADJACENT AREAS OF MA BUT THIS AREA IS JUST OUTSIDE AREA OF BEST MOISTURE AS NOTED BY KI VALUES. WILL HAVE TO WATCH ANY STORMS THAT DEVELOP S OF THE MASS PIKE WHERE INSTABILITY IS FAVORABLE FOR DEVELOPMENT...ALTHOUGH 0-6KM SHEAR REMAINS WEAK. THE GREATER CONCERN IS FOR VERY HEAVY RAINFALL AND LOCALIZED FLASH FLOODING...ESPECIALLY ACROSS CT INTO ADJACENT AREAS OF SW MA AND CENTRAL MA. STRONGER CONVECTION DEVELOPING ACROSS E PA AND N NJ WHERE INSTABILITY IS GREATER...BUT AXIS OF INSTABILITY EXTENDS NE INTO CT SO POTENTIAL PERSISTS FOR THESE STORMS TO HOLD TOGETHER AS THEY MOVE EWD INTO OUR SW ZONES. HIRES-WRF SHOWING LOCALIZED 3-4" QPF BETWEEN 18-00Z ACROSS PORTIONS OF CT WHICH SIGNALS POTENTIAL FOR VERY HEAVY RAINFALL. WILL HAVE TO WATCH THIS CLOSELY. IF THREAT MATERIALIZES THINK FLASH FLOODING WILL BE LOCALIZED. COLD FRONT APPROACHING THE MASS PIKE WITH TEMPS FALLING SHARPLY THROUGH THE 60S AND SOME UPPER 50S BEHIND THE FRONT. THE FRONT WILL CONTINUE PUSHING S REACHING THE S COAST REGION LATE AFTERNOON AND EARLY EVENING. NE WIND GUSTS TO 30 MPH WILL DEVELOP ACROSS NE MA.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... TONIGHT... SURFACE COLD FRONT WILL PUSH NEAR OR JUST SOUTH OF THE REGION ALLOWING FOR COOL NORTHERLY FLOW TO MOVE INTO THE REGION. TEMPS WILL BE A LOT COOLER THEN WHAT HAS BEEN FELT IN SEVERAL DAYS. NOT EXPECTING MUCH IN THE WAY OF HEAVY PRECIP TONIGHT AS SURFACE FORCING MECHANISM IS SOUTH OF THE REGION AND THE 850 MB FRONT WILL BE WELL NORTH OF THE REGION. BUT COULD SEE STRATUS/DRIZZLE AND FOG OVERNIGHT. APPEARS THAT NORTHERN NEW ENGLAND WILL SEE THE HEAVIEST PRECIP WHERE THE 850 MB FRONT WILL BE COLLOCATED WITH THE UPPER LEVEL JET AND SHORTWAVE APPROACHING THE REGION. TOMORROW... MARITIME AIR WILL CONTINUE TO DOMINATE SOUTHERN NEW ENGLAND KEEPING HIGHS WELL BELOW AVERAGE....IN THE MID 50S TO LOW 60S. SURFACE AND 850MB LOW WILL BEGIN TO DEVELOP AND APPROACH THE REGION TOMORROW. EXPECT THE FIRST HALF OF THE DAY TO BE SCT SHOWERS WITH PERHAPS SOME DRIZZLE. BUT AS THE SYSTEM AND BETTER FORCING APPROACHES FROM THE WEST EXPECT COVERAGE TO INTENSIFY...ESP ACROSS WESTERN ZONES. PWAT VALUES WILL BE NEAR 1.5 INCHES COMBINED WITH AN INCREASING LLJ...BELIEVE HEAVY RAINFALL IS POSSIBLE. LOW PROBABILITY THAT THUNDER WILL DEVELOP AS THE MARITIME AIR WILL KEEP MOST OF THE REGION STABLE. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... BIG PICTURE... CHANGEABLE PATTERN MUCH OF THIS WEEK. AN UPPER TROUGH SLOWLY CROSSES THE NORTHEAST USA EARLY THIS WEEK. AN UPPER RIDGE FROM THE WESTERN USA THEN SHIFTS EAST OVER THE EASTERN USA LATE THIS WEEK. EARLY INDICATIONS FOR THE END OF THE WEEK SHOW POTENTIAL INTERACTION BETWEEN NORTHERN AND SOUTHERN STREAM SHORTWAVES THAT COULD BRING SHOWERS TO NEW ENGLAND TOWARD NEXT WEEKEND. MODELS DIFFER MONDAY-TUESDAY REGARDING PLACEMENT OF FEATURES THAT WOULD FOCUS RAIN/SHOWERS AND BRING HIGHER AMOUNTS. BUT THE LONG RANGE MODELS ARE SIMILAR REGARDING LARGER SCALE FEATURES AND THE GENERAL FLOW OF WEATHER THROUGH THE WEEK. WE USED A BLEND OF THE MODELS TO GENERATE OUR GRID DATA. THE DAILIES... MONDAY NIGHT-TUESDAY... COLD FRONT REMAINS STALLED SOUTH OF NEW ENGLAND. A HIGH PRESSURE BUILDS OVER EASTERN CANADA. THIS WILL BRING AN INCREASING EAST- NORTHEAST WIND ACROSS THE GULF OF MAINE AND INTO SOUTHERN NEW ENGLAND. EXPECTING A COOL MOIST ENVIRONMENT...ESPECIALLY ACROSS EASTERN MA...WITH BELOW NORMAL TEMPERATURES. A LOW PRESSURE MOVES ALONG THE STALLED FRONT TO OUR SOUTH DURING THIS TIME. THIS WILL PROVIDE THE FOCUS FOR WIDESPREAD SHOWERS...AND PERHAPS A THUNDERSTORM OR TWO. THE MAIN CONCERN WILL BE LOCALLY HEAVY RAINFALL. RAINFALL CHANCES BEGIN TO DIMINISH FROM WEST TO EAST TUESDAY AFTERNOON. WEDNESDAY THROUGH FRIDAY...A NORTHERN STREAM SHORTWAVE MOVES EAST OF OUR REGION WEDNESDAY. HIGH PRESSURE BUILDS OVER THE NORTHEAST USA. THIS WILL FAVOR A DRY PERIOD WITH TEMPERATURES TRENDING HIGHER EACH DAY. THE PREVAILING FLOW WEDNESDAY WILL BE NORTHERLY. LIGHTER WINDS WILL FAVOR SEA BREEZES ALONG PORTIONS OF THE COASTLINE THURSDAY AND FRIDAY. SATURDAY...NORTHERN STREAM SHORTWAVE MAY DRIVE A COLD FRONT TOWARD NEW ENGLAND. SHOWERS AHEAD OF THIS FRONT MAY REACH THE WESTERN HALF OF SOUTHERN NEW ENGLAND...BUT LOW CONFIDENCE AT THIS TIME. WE ARE ALSO WATCHING A SOUTHERN STREAM TROUGH...WHICH MAY GENERATE A COASTAL LOW LATE THIS WEEK THAT COULD BRING RAIN UP THE COAST LATE NEXT WEEKEND. && .AVIATION /18Z 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. THROUGH 00Z...MODERATE CONFIDENCE. WIDESPREAD SHOWERS WITH SCT TSTMS WILL CONTINUE TO DEVELOP ACROSS SNE. LOCALLY VERY HEAVY RAINFALL POSSIBLE ACROSS CT. WIDESPREAD MVFR CONDITIONS DEVELOPING WITH LOCALIZED IFR. NE WIND GUSTS TO 25-30 KT DEVELOPING ACROSS NE MA. WIND SHIFT TO N/NE WILL OCCUR LATE AFTERNOON/EARLY EVENING ALONG THE S COAST. TONIGHT AND MONDAY...MODERATE CONFIDENCE. WIDESPREAD MVFR/IFR CONDITIONS. OCCASIONAL SHOWERS AND PERHAPS AN EMBEDDED TSTM WILL PERSIST...WITH GREATEST COVERAGE ACROSS INTERIOR. NE WIND GUSTS TO 25 KT NE MA IN THE EVENING...THEN DIMINISHING OVERNIGHT BUT ANOTHER PULSE TO GUSTS TO 25 KT POSSIBLE MONDAY. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. AREAS OF IFR LIKELY DEVELOP THIS AFTERNOON ALONG WITH NUMEROUS SHOWERS AS WINDS SHIFT TO NE BEHIND THE FRONT. NE WIND GUSTS TO 25 KT DEVELOPING THIS AFTERNOON INTO EARLY EVENING. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...MODERATE CONFIDENCE. MONDAY NIGHT AND TUESDAY...EAST TO NORTHEAST FLOW WITH WINDS ALONG THE MA EAST COAST 10 TO 15 KNOTS WITH GUSTS 15 TO 20 KNOTS POSSIBLE. LIGHTER NORTHEAST WINDS FARTHER INLAND. MVFR/IFR CIGS AND VSBYS... WITH THE GREATEST RISK ACROSS THE COASTAL PLAIN AND EASTERN SLOPES OF THE WORCESTER HILLS. SHOWERS POSSIBLE BOTH DAYS. WEDNESDAY...VFR WITH A NORTH-NORTHWEST WIND. THURSDAY...VFR. LOCAL SEABREEZES POSSIBLE.
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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 /TODAY THROUGH SUNDAY/...HIGH CONFIDENCE. TODAY...SW WINDS WILL SHIFT TO NE ACROSS E MA WATERS THIS AFTERNOON. A PERIOD OF GUSTS TO 30 KT EXPECTED OVER NE MA WATERS...A SCA HAS BEEN ISSUED. ACROSS S COASTAL WATERS...SW WINDS WILL PERSIST. EXPECT SHOWERS WITH EMBEDDED THUNDERSTORMS TO DEVELOP BY THE AFTERNOON. TONIGHT...SCT SHOWERS ALONG WITH PATCHY FOG REDUCING VSBYS. OTHERWISE ANY SOUTHERLY FLOW SHOULD SWITCH TO THE NORTHEAST AND GUST TO NEAR 15 KTS. SCA FOR BUILD SEAS FOR NORTHERN OUTER WATERS HAS BEEN ISSUED. TOMORROW...PERSISTENT NORTHEASTERLY FLOW WILL CONTINUE TO BUILD SEAS AND SWELLS ACROSS THE NORTHEASTERN WATERS. A SCA MAY NEED TO BE EXTENDED. OTHERWISE EXPECT SCT SHOWERS LIMITING VSBYS DURING THE DAY. OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...MODERATE CONFIDENCE. MONDAY NIGHT-WEDNESDAY NIGHT...SMALL CRAFT ADVISORIES FOR ROUGH SEAS WILL LIKELY BE NEEDED ACROSS THE COASTAL WATERS EAST OF MASSACHUSETTS. SMALL CRAFT ADVISORIES MAY BE NEEDED ACROSS THE SOUTHERN OUTER COASTAL WATERS AS WELL. THURSDAY...NO HEADLINES EXPECTED. HIGH PRESSURE MOVES OVERHEAD. WINDS AND SEAS WILL BE LESS THAN SMALL CRAFT ADVISORY THRESHOLDS. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EDT MONDAY FOR ANZ250-254. SMALL CRAFT ADVISORY UNTIL 2 AM EDT MONDAY FOR ANZ230-231-251.
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&& $$ SYNOPSIS...BELK/DUNTEN NEAR TERM...KJC SHORT TERM...DUNTEN LONG TERM...BELK AVIATION...BELK/KJC MARINE...BELK/DUNTEN

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