Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 302310 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 710 PM EDT SAT MAY 30 2015 .SYNOPSIS... A COLD FRONT WILL MOVE SLOWLY SOUTH ACROSS THE REGION SUNDAY...THEN STALL SOUTH OF NEW ENGLAND EARLY NEXT WEEK. THIS WILL BRING NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS SUNDAY...AND A PERIOD OF RAIN EARLY NEXT WEEK. A COLD FRONT WILL STALL SOUTH OF NEW ENGLAND EARLY IN THE WEEK. A DISTURBANCE TRAVELLING ALONG THE FRONT WILL BRING SHOWERS TO THE REGION ON MONDAY AND TUESDAY. HIGH PRESSURE BUILDS OVER THE REGION WITH FAIR WEATHER FOR WEDNESDAY THROUGH FRIDAY. A COLD FRONT CROSSES NEW ENGLAND SATURDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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7 PM UPDATE... CONVECTION HAS REMAINED WEST AND NORTH OF THE REGION THROUGH THE EVENING. CAPE WAS FAVORABLE OVER WESTERN MASS THROUGH THE EVENING BUT STABILITY AND MOISTURE WERE MORE FAVORABLE FARTHER WEST. WE HAVE MAINTAINED A SLIGHT CHANCE OVER THE EAST SLOPES OF THE BERKSHIRES THROUGH EARLY NIGHT BASED ON LINGERING INSTABILITY AND EVENING CONVECTION IN THE CATSKILLS. NO FOG AND STRATUS ON SATELLITE AT SUNSET. COOLING TEMPS AT SUNSET SHOULD ALLOW THE FOG/STRATUS TO EXPAND AGAIN. HAVE SLOWED THE TIMING OF ONSET BY A FEW HOURS. DEWPOINTS IN THE LOW TO MID 60S SO MIN TEMP FORECAST IN THIS RANGE LOOKS GOOD. PREVIOUS DISCUSSION... COLD FRONT WILL BE DROPPING SOUTH ACROSS NORTHERN NEW ENG OVERNIGHT. MAINLY DRY CONDITIONS ARE EXPECTED THROUGH THIS EVENING...BUT A FEW SHOWERS AND AN ISOLD TSTM POSSIBLE AFTER MIDNIGHT...MAINLY INTERIOR AS FRONT APPROACHES FROM THE NORTH AND LOW LEVEL THETA-E RIDGE AXIS MOVES INTO THE REGION. DO NOT EXPECT MUCH RAINFALL OVERNIGHT AS HEAVIER RAIN WILL BE CONFINED TO THE NORTH WITH THE ACTUAL FRONT. WITH SW FLOW PERSISTING KEEPING HIGHER DEWPOINTS ACROSS THE REGION...EXPECT STRATUS TO EXPAND NORTH FROM THE COASTAL WATERS AND OVERSPREAD MUCH OF SNE OVERNIGHT. AREAS OF FOG SHOULD BE CONFINED MOSTLY TO SE NEW ENG. LOW TEMPS REMAINING IN THE 60S.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... SUNDAY... AS COLD FRONT MOVES SOUTH INTO SNE...SHOWERS WILL INCREASE IN COVERAGE ALONG WITH SCT TSTMS. TIMING OF FRONT WILL BE 15-18Z ACROSS N ZONES...REACHING THE S COAST 21-00Z SO SHOWERS AND TSTMS WILL BE FOCUSED IN THE NORTH DURING THE MORNING AND EARLY AFTERNOON SHIFTING S OF THE PIKE DURING THE AFTERNOON. SBCAPES ARE FORECAST TO INCREASE TO AROUND 1000 J/KG AROUND 18Z WITH AXIS OF HIGHEST INSTABILITY NEAR THE MASS PIKE. 0-6KM SHEAR REMAINS WEAK WITH HIGHER SHEAR VALUES TO THE NORTH IN THE MORE STABLE POST FRONTAL AIRMASS. HOWEVER...THERE MAY BE A NARROW CORRIDOR WHERE MAX INSTABILITY OVERLAPS SHEAR VALUES 20-25 KTS NEAR THE MASS PIKE SO CANT RULE OUT A STRONG TO ISOLD SEVERE STORM...WITH BEST CHANCE FROM N CT AND RI TO THE MASS PIKE REGION. GIVEN HIGH PWAT VALUES NEAR 1.75" AND THE POTENTIAL FOR SOME TRAINING WITH UPPER FLOW NEARLY PARALLEL TO THE FRONT...HEAVY RAINFALL WILL BE THE PRIMARY THREAT. MAX TEMPS SHOULD REACH THE 70S BEFORE THE FROPA WITH A FEW LOCATIONS S OF THE PIKE POSSIBLY NEAR 80 IF WE CAN GET ANY SUNSHINE...BUT CONFIDENCE IN SUNSHINE IS LOW. BEHIND THE FRONT TEMPS WILL FALL SHARPLY INTO THE 50S. THIS WILL OCCUR AROUND MIDDAY OR EARLY AFTERNOON N OF THE PIKE BUT THE COOLER AIR WILL BE DELAYED UNTIL LATE AFTERNOON FURTHER S. IN ADDITION...A PERIOD GUSTY NE WINDS TO 30 MPH IS POSSIBLE ACROSS NE MA IN THE AFTERNOON. SUNDAY NIGHT... COLD FRONT MOVES S OF THE COAST WITH COOL MOIST NE FLOW ACROSS SNE. MORE SHOWERS ARE EXPECTED...BUT HEAVIEST RAINFALL WILL LIKELY BE CONFINED ACROSS UPSTATE NY AND N NEW ENG ASSOCD WITH GOOD LOW LEVEL FRONTOGENESIS AND CONVERGENCE WITH THE 850 MB BOUNDARY WHICH SETS UP TO THE NORTH. BEST CHANCE OF SHOWERS WILL BE ACROSS N AND W ZONES CLOSEST TO THE BEST FORCING AND WE WILL HAVE HIGHEST POPS IN THIS AREA. A MUCH COOLER NIGHT WITH TEMPS UPPER 40S TO LOWER 50S. && .LONG TERM /MONDAY THROUGH SATURDAY/... BIG PICTURE... CHANGEABLE PATTERN MUCH OF NEXT WEEK. AN UPPER TROUGH SLOWLY CROSSES THE NORTHEAST USA EARLY IN THE WEEK. AN UPPER RIDGE FROM THE WESTERN USA THEN SHIFTS EAST OVER THE EASTERN USA FOR THE LATE 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. 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-TUESDAY... COLD FRONT STALLS SOUTH OF NEW ENGLAND. HIGH PRESSURE BUILDS OVER EASTERN CANADA. THIS WILL BRING AN INCREASING EAST-NORTHEAST WIND ACROSS THE GULF OF MAINE AND INTO SOUTHERN NEW ENGLAND. THE PRESSURE GRADIENT WILL GENERATE A 20-25 KNOT FLOW AROUND 2000 FEET. WHILE SURFACE WINDS WILL BE LESS...THIS STILL SUGGESTS A STIFF WIND OFF THE GULF INTO EAST COASTAL MASS. EXPECT A COOL MOIST ENVIRONMENT ESPECIALLY IN EASTERN MASS. LOW PRESSURE DEVELOPS OVER THE CENTRAL APPALACHIANS MONDAY. THIS WILL BRING A SOUTHERLY LOW LEVEL JET OF 20-30 KNOTS UP THE COASTAL PLAIN INTO EASTERN PARTS OF NY AND PA MONDAY...SHIFTING EAST MONDAY NIGHT AND TUESDAY. AS THIS RUNS OVER THE LOW LEVEL MARINE AIR IT WILL GENERATE SUFFICIENT LIFT TO SUPPORT RAIN OR RAIN SHOWERS. MEANWHILE PRECIP WATER VALUES WILL BE ABOVE NORMAL ALL AREAS AND AROUND 1.50 INCHES CT-RI-SE MASS. EXPECT THE HEAVIEST RAIN TO BE NORTH OF US...BUT WITH NOTICEABLE AMOUNTS STILL LIKELY HERE IN THE SOUTH. THE HEAVIEST RAINFALL HERE IN THE SOUTH SHOULD BE LATE MONDAY NIGHT INTO TUESDAY AS THE LOW LEVEL JET MOVES ACROSS...FOLLOWED BY THE SURFACE LOW PASSING OFFSHORE TO THE SOUTH. WEDNESDAY THROUGH FRIDAY... NORTHERN STREAM SHORTWAVE MOVES EAST OF THE REGION WEDNESDAY. HIGH PRESSURE BUILDS OVER THE NORTHEAST USA. THIS WILL FAVOR A DRY PERIOD WITH TEMPS TRENDING WARMER EACH DAY. THE PREVAILING FLOW WEDNESDAY WILL BE NORTHERLY. LIGHTER WINDS WILL FAVOR SEA BREEZES ON SOME OR ALL OF THE COASTLINE THURSDAY AND FRIDAY. SATURDAY... NORTHERN STREAM SHORTWAVE MAY DRIVE A COLD FRONT INTO NEW ENGLAND. SHOWERS AHEAD OF THE FRONT MAY REACH PARTS OF OUR AREA...BUT LOW CONFIDENCE ATTM. WE ARE ALSO WATCHING THE SOUTHERN STREAM. TROUGH IN THE SOUTHERN FLOW MAY GENERATE A COASTAL LOW LATE WEEK THAT COULD BRING RAIN UP THE COAST NEXT WEEKEND. STAY TUNED. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TONIGHT...MODERATE CONFIDENCE. EXPECT IFR/LIFR STRATUS AND FOG TO DEVELOP ALONG THE S COAST FIRST PART OF THE NIGHT. FOG WILL BE MAINLY CONFINED TO THE SE COASTAL NEW ENG WITH AREAS OF MVFR/IFR CIGS WILL EXPAND N ACROSS MUCH OF THE REGION OVERNIGHT. A FEW SHOWERS AND POSSIBLE A TSTM DEVELOPING OVERNIGHT IN THE INTERIOR. SUNDAY...MODERATE CONFIDENCE. WIDESPREAD MVFR/IFR CONDITIONS. NUMEROUS SHOWERS AND TSTMS DEVELOPING AS COLD FRONT DROPS S ACROSS SNE. MAIN FOCUS WILL BE NEAR THE MASS PIKE. WINDS SHIFTING FROM SW TO NE BEHIND THE FRONT WITH G25 KT POSSIBLE NE MA IN THE AFTERNOON. TIMING OF FRONT...15-18Z ALONG AND N OF MASS PIKE REACHING S COAST 21-00Z. SUNDAY NIGHT...MODERATE CONFIDENCE. WIDESPREAD MVFR/IFR CONDITIONS. SHOWERS LIKELY...ESPECIALLY INTERIOR. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. IFR CONDITIONS LIKELY DEVELOP SUN AFTERNOON AS WINDS SHIFT TO NE BEHIND THE FRONT. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. OUTLOOK...MONDAY THROUGH THURSDAY...MODERATE CONFIDENCE. MONDAY AND TUESDAY... EAST TO NORTHEAST FLOW WITH WINDS ALONG THE MASS EAST COAST 10 TO 15 KNOTS WITH GUSTS 15 TO 20 KNOTS POSSIBLE. LIGHTER NORTHEAST WINDS FARTHER INLAND. MVFR/IFR CIGS AND VSBYS WITH BEST CHANCE OVER THE COASTAL PLAIN AND EASTERN SLOPES OF THE WORCESTER HILLS. SHOWERS POSSIBLE BOTH DAYS. WEDNESDAY... VFR WITH A NORTH-NORTHWEST WIND. THURSDAY...VFR. LOCAL SEA BREEZES POSSIBLE.
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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 /TODAY THROUGH SUNDAY/...HIGH CONFIDENCE. TONIGHT...WINDS AND SEAS HAVE DIMINISHED OVER THE NEARSHORE WATERS EXCEPT FOR BOSTON HARBOR WHERE LOGAN AIRPORT WAS GUSTING TO 24 KNOTS AT 7 PM. WE WILL END THE SMALL CRAFT ADVISORY AT THIS TIME OVER MOST WATERS BUT MAINTAIN IT FOR BOSTON HARBOR AND MASS BAY UNTIL 10 PM. OTHERWISE EXPECT SW WINDS BELOW SCA TONIGHT WITH SEAS BUILDING TO 5 FT OVER OUTER WATERS DUE TO INCREASING SWELL. AREAS OF DENSE FOG EXPECTED TO DEVELOP OVER S COASTAL WATERS RESULTING IN POOR VSBYS. SUNDAY...SW WINDS WILL SHIFT TO NE ACROSS E MA WATERS IN THE AFTERNOON. A PERIOD OF GUSTS TO 30 KT EXPECTED OVER NE MA WATERS AND SCA WILL BE NEEDED. ACROSS S COASTAL WATERS...SW WINDS WILL PERSIST. EXPECT SHOWERS WITH EMBEDDED THUNDERSTORMS TO DEVELOP. SUNDAY NIGHT...NE WIND GUSTS TO 25 KT NE MA WATERS IN THE EVENING...OTHERWISE WINDS DIMINISHING. SW WINDS SHIFTING TO NE OVER S COASTAL WATERS IN THE EVENING. SCT SHOWERS ALONG WITH PATCHY FOG REDUCING VSBYS. OUTLOOK...MONDAY THROUGH THURSDAY...MODERATE CONFIDENCE. MONDAY-TUESDAY...SMALL CRAFT ADVISORY MAY BE NEEDED ESPECIALLY ON THE WATERS EAST OF MASSACHUSETTS. NORTHEAST WINDS GUSTING 20 KNOTS WITH A POTENTIAL TO REACH 25 KNOTS MONDAY. SEAS REACH TO 9 FEET ON THE EASTERN MASS WATERS...AND 3 TO 5 FEET ON THE SOUTHERN WATERS. WEDNESDAY...A SMALL CRAFT ADVISORY MAY BE NEEDED...MAINLY DUE TO SEAS ON THE EASTERN WATERS AND SOUTHERN OUTER WATERS. DIMINISHING NORTH TO NORTHWEST WINDS LESS THAN 20 KNOTS. SEAS OF 5 FEET MAY LINGER ON THE EASTERN OUTER WATERS WEDNESDAY NIGHT. THURSDAY...NO HEADLINES EXPECTED. HIGH PRESSURE MOVES OVERHEAD. WINDS AND SEAS WILL BE LESS THAN SMALL CRAFT THRESHOLDS.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ230>237-251. SMALL CRAFT ADVISORY UNTIL 3 PM EDT SUNDAY FOR ANZ250-254>256. && $$ SYNOPSIS...WTB/KJC NEAR TERM...WTB/KJC SHORT TERM...KJC LONG TERM...WTB AVIATION...WTB/KJC MARINE...WTB/KJC

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