Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 302016 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 416 PM EDT TUE SEP 30 2014 .SYNOPSIS...
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COOL DAMP CONDITIONS REMAIN IN PLACE INTO THURSDAY...WITH MORE WIDESPREAD RAINFALL EXPECTED TOMORROW. DRY WEATHER RETURNS LATER THURSDAY INTO FRIDAY AS HIGH PRESSURE BUILDS BACK ACROSS THE REGION. A COLD FRONT WITH ASSOCIATED LOW PRESSURE WILL LIKELY BRING A PERIOD OF RAIN SATURDAY FOLLOWED BY COOLER AND DRIER CONDITIONS FOR SUNDAY INTO MONDAY.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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BAND OF LIGHT WITH A FEW POCKETS OF MOD RAINFALL CONTINUES TO SLOWLY DISSIPATE LATE THIS AFTERNOON AND SHIFT E. THIS IS THE EXPECTED TREND WITH TIME AS OCEAN LOW PRES CONTINUES TO DEVELOP WELL SOUTHEAST OF THE 40/70 BENCHMARK AND BEGINS PULLING MOISTURE TO THE E AT LEAST THROUGH THE EVENING HOURS. HOWEVER...GIVEN ALL THE N-NE FLOW OFF THE COOL GULF OF MAINE...THE CLOUDY DAMP CONDITIONS WILL REMAIN WITH SHOWERS POSSIBLY TRANSITIONING TO MIX OF FOG AND DRIZZLE THROUGH THE EVENING HOURS. GIVEN THIS FACT...EXPECT MINS TO BE NOT TOO FAR AWAY FROM CURRENT HIGH TEMPS...ONLY DIPPING BACK INTO THE LOW-MID 50S WITH MAYBE A SPOT UPPER 40F. THROUGH THE EARLY MORNING HOURS HOWEVER...EXPECT INVERTED TROF BETWEEN THE OFFSHORE LOW PRES AND THE E MOVING UPPER CUTOFF TO BEGIN TO ENHANCE. NOTE INCREASE IN BAROCLINICITY AND DEFORMATION ACROSS THE AREA THROUGH THE MORNING...WHICH COMBINED WITH DEEPENING MOISTURE FROM THE SFC TO H4 OR SO...SUSPECT INCREASE IN MORE WIDESPREAD RAINFALL ACROSS SRN NEW ENGLAND DURING THE EARLY MORNING HOURS...SUCH THAT IT/S LIKELY RAINING AT OVER MUCH OF THE BOX CWA BY 12Z. MORE ON THIS FOR IN THE TOMORROW DISCUSSION BELOW. HAVE POPS INCREASING AFTER 06Z TO LIKELY...BUT IT/S LIKELY CATEGORICAL POPS WILL BE NEEDED.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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TOMORROW... AS MENTIONED ABOVE...AS UPPER LVL CUTOFF SHIFTS ALMOST DIRECTLY OVERHEAD AND LOW PRES CONTINUES WELL TO THE SE OF THE BENCHMARK...A MODERATE INVERTED TROF IS LIKELY TO CONTINUE TO DEVELOP THROUGH THE MORNING AND INTO THE AFTERNOON. THIS PROVIDES BETTER F-GEN AND EVEN A DEFORMATION AXIS FOR DEEPER LIFT ACROSS THE AREA. THIS IS ALSO COMBINED WITH MODEST ELY LLJ WITH WIND SPEEDS AT H85 AROUND 25-30 KT /2+ STD DEVIATIONS ABOVE NORMAL/ AND PWATS TO AROUND 1.5 INCHES WHICH IS 1-2 STD DEVIATIONS ABOVE NORMAL FOR EARLY OCTOBER. THEREFORE...EXPECT MORE WIDESPREAD RAINFALL ACROSS MOST OF SRN NEW ENGLAND THROUGH THE DAY...ITS NOT UNTIL THE SFC OCEAN SYSTEM PULLS E LATE IN THE DAY THAT THE MOISTURE BEGINS TO DECREASE. MANY AREAS MAY RECEIVE SOME OF THE STEADY SOAKING RAINFALL THEY HAVE NEEDED FOR SOME TIME NOW WITH THE POSSIBILITY OF RAINFALL AMOUNTS RANGING 0.25-0.75 INCHES. POCKETS OF HEAVIER RAIN ARE ALSO POSSIBLE GIVEN THE BANDING POTENTIAL WHICH MAY BE ENHANCED THANKS TO K-VALUES IN THE LOW 30S...BUT IT/S DIFFICULT TO SAY EXACTLY WHERE THIS WILL SET UP. SO WILL AT LEAST HIGHLIGHT THE POTENTIAL FOR SOME LOCALIZED AREAS OF 1.0+ INCHES. FOR NOW...THE BEST CHANCE LOOKS LIKE SE MA...WHERE THE INVERTED TROF HOLDS IN THE LONGEST...BUT IT/S NOT OUT OF THE QUESTION IT IS OBSERVED INLAND...ESPECIALLY WHERE AN E COMPONENT TO THE FLOW ENHANCES UPSLOPE. OTHER THAN THE RAINFALL...COOL TEMPS ARE EXPECTED AS MANY LOCATIONS REMAIN IN THE UPPER 50S TO AROUND 60 DEGREES. TOMORROW NIGHT... RAINFALL WILL SLOWLY COME TO AN END FROM W TO E THROUGH THE EVENING...POSSIBLY LINGERING ACROSS RI AND SE MA INTO THE EARLY MORNING HOURS. HOWEVER...WITH E COMPONENT TO THE FLOW...AND LOW LVL MOISTURE REMAINING IN PLACE...EXPECT ANOTHER CHANCE FOR FOG AND DRIZZLE AT TIMES THROUGH THE OVERNIGHT HOURS. MIN TEMPS REMAIN LIKELY IN THE 50S.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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HIGHLIGHTS... * SUNSHINE AND LIGHT WINDS FRIDAY * RAIN LIKELY SATURDAY * COOLER AND MAINLY DRY WEATHER SUNDAY INTO MONDAY * MORE SHOWERS POSSIBLE TUESDAY OVERVIEW... MEDIUM RANGE DETERMINISTIC AND ENSEMBLE GUIDANCE IN GENERAL AGREEMENT ON THE LARGE SCALE PATTERN DURING THE EXTENDED PERIOD. MID LEVEL LOW EXITS THE REGION TOWARD THE END OF THE WEEK...THEN MAIN FEATURE WILL BE AN ANOMALOUS MID LEVEL TROF/LOW DIGGING INTO THE UPPER MIDWEST AND WESTERN GT LAKES BY SAT. A PIECE OF ENERGY ROTATING AROUND THE MID LEVEL LOW WILL BRING A FRONTAL SYSTEM INTO NEW ENG LATE SAT/SAT NIGHT WHICH WILL BE ACCOMPANIED BY A PERIOD OF RAIN WHICH MAY BE LOCALLY HEAVY...BUT EXACT TIMING IS UNCERTAIN. AFTER SHORTWAVE EXITS...BROAD TROF WILL REMAIN ACROSS SOUTHERN CANADA AND GT LAKES SUNDAY INTO EARLY NEXT WEEK WITH NEXT SHORTWAVE AND FRONT APPROACHING NEXT TUESDAY. THERE ARE ALSO TIMING DIFFERENCES WITH THIS FRONT AS THE GFS IS MORE PROGRESSIVE THAN THE ECMWF WHICH WILL AFFECT TIMING OF POTENTIAL SHOWERS EARLY NEXT WEEK. DAILIES... THURSDAY... MID LEVEL LOW WILL GRADUALLY PULL AWAY FROM SE NEW ENG AS HIGH PRES BUILDS INTO THE REGION. CROSS SECTIONS SUGGEST MOCLDY SKIES DURING THE MORNING AND CANT RULE OUT A FEW SHOWERS NEAR THE COAST IN PERSISTENT CYCLONIC FLOW...THEN BECOMING PTSUNNY FROM WEST TO EAST IN THE AFTERNOON AS DRIER AIR MOVES IN. WITH NE FLOW... TEMPS WILL HOLD IN THE 60S. FRIDAY... SNE WILL BE IN BETWEEN SYSTEMS WITH HIGH PRES OVERHEAD LEADING TO MOSUNNY SKIES AND LIGHT WINDS. WILL HAVE TO WATCH CLOUDS BACKING IN FROM THE OCEAN ASSOCIATED WITH OFFSHORE STORM WHICH MAY BRING MORE CLOUDS TO THE OUTER CAPE. GFS AND NAM ARE SUGGESTING THIS INCREASED CLOUD COVER WHILE ECMWF KEEPS CLOUDS TO THE EAST. WITH CONTINUED ONSHORE FLOW TEMPS EXPECTED TO BE IN THE 60S...COOLEST E MA COAST. SATURDAY INTO SATURDAY NIGHT... MODELS ARE IN GOOD AGREEMENT ON TIMING OF COLD FRONT INTO SNE LATE SAT INTO SAT NIGHT. DECENT LOW LEVEL JET AND ANOMALOUS PWAT PLUME AHEAD OF THE FRONT WILL BRING A PERIOD OF RAIN TO SNE WHICH MAY BE LOCALLY HEAVY...BUT THIS SYSTEM IS FAIRLY PROGRESSIVE. TIMING IS STILL UNCERTAIN BUT IT APPEARS BULK OF RAIN WILL FALL DURING SAT...WHICH MAY LINGER INTO SAT EVENING ACROSS E NEW ENG. SUNDAY... FRONT IS OFFSHORE SUNDAY WITH DRY WESTERLY FLOW WHICH WILL LEAD TO SUNSHINE AND BLUSTERY CONDITIONS. 850 MB TEMPS BELOW NORMAL AND WILL LEAD TO BELOW NORMAL TEMPS SUNDAY. MONDAY AND TUESDAY... NEXT FRONT APPROACHES FROM THE WEST BUT THERE ARE DIFFERENCES IN TIMING AND AMPLITUDE OF THE SHORTWAVE AND HOW PROGRESSIVE THE FRONT WILL BE. EVEN FASTER GFS IS MAINLY DRY FOR MON SO WE ARE GOING WITH A DRY FORECAST FOR NOW. THE MAIN UNCERTAINTY IS WITH TUE AS PROGRESSIVE GFS MOVES THE SHOWERS OFFSHORE WHILE MORE AMPLIFIED ECMWF IS WET.
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&& .AVIATION /19Z 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. SHORT TERM...HIGH CONFIDENCE ON TRENDS BUT LOWER CONFIDENCE IN TIMING. THROUGH TONIGHT... MAINLY IFR IN EAST OF AN IJD-ORH-MHT LINE...WITH MVFR WEST. THIS IS MAINLY DUE TO CIGS THROUGH EVENING...BUT AROUND 23Z AND AFTER VSBYS MAY BEGIN TO DIP AS WELL IN A MIX OF DRIZZLE/FOG/LIGHT RAIN. POSSIBILITY OF PERIODIC IFR VSBYS...BUT MAINLY VFR EXPECTED. CIGS REMAIN LOW...BUT VSBYS LIFT DURING THE MORNING HOURS AS RAIN BECOMES MORE WIDESPREAD AND ALLOWS VSBYS TO LIFT TO MAINLY MVFR/VFR. WINDS PICK UP NEAR SHORE IN THE EAST...WITH A FEW GUSTS APPROACHING 20 KT AT COASTAL TERMINALS. TOMORROW AND TOMORROW NIGHT.... MUCH OF THE SAME...MAINLY IFR/MVFR CIGS WITH SOME MVFR CONDITIONS IN RAIN. EXPECT A VERY SLOW IMPROVEMENT FROM W TO E LATE IN THE DAY AND OVERNIGHT...BUT THIS WILL BE MAINLY TOWARD RAIN ENDING...WITH CATEGORIES ONLY REALLY IMPROVING DURING THE DAYLIGHT HOURS ON THU. KBOS...HIGH CONFIDENCE ON TRENDS...LOWER CONFIDENCE ON TIMING. ALSO LOW CONFIDENCE OF A BRIEF PERIOD OF LIFR CONDITIONS POSSIBLE DURING THE OVERNIGHT HOURS BEFORE IMPROVEMENT IN THE MORNING. KBDL...HIGH CONFIDENCE ON TRENDS...LOWER CONFIDENCE ON TIMING. OUTLOOK...THURSDAY THROUGH SUNDAY... THU...MODERATE CONFIDENCE. AREAS OF IFR IN THE MORNING SHOULD IMPROVE TO VFR IN THE AFTERNOON AS CIGS LIFT AND CLOUDS BREAK UP. FRI...HIGH CONFIDENCE. VFR. SAT...MODERATE CONFIDENCE. CONDITIONS LOWERING TO MVFR/IFR AS SHOWERS MOVE INTO THE REGION. LOWER CONFIDENCE ON TIMING. GUSTY SOUTHERLY WINDS POSSIBLE AHEAD OF A COLD FRONT SHIFTING TO WEST SAT NIGHT. SUN...MODERATE CONFIDENCE. VFR.
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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...HIGH CONFIDENCE THROUGH TOMORROW NIGHT. N-NE FLOW WILL GRADUALLY INCREASE THROUGH THE EARLY MORNING HOURS INTO TOMORROW...WITH WIND GUSTS AROUND 25 KT AT TIMES POSSIBLE PARTICULARLY BY TOMORROW AFTERNOON AND OVERNIGHT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED FOR THE OCEAN WATERS AS WELL AS RI/BI SOUND FOR THESE WINDS...AND MAY NEED TO BE ADDED FOR THE WATERS SURROUNDING CAPE COD FOR LATE IN THE DAY TOMORROW. OTHERWISE...SMALL CRAFT ADVISORY CONDITIONS ARE LIKELY DUE TO INCREASING SWELL ALONE...WHICH HAS THE POTENTIAL TO REACH 7-8FT BY TOMORROW AFTERNOON ON THE OCEAN WATERS. IT/S LIKELY THAT THESE SMALL CRAFT ADVISORIES WILL NEED TO LINGER INTO THURSDAY. OUTLOOK...THURSDAY THROUGH SUNDAY...MODERATE CONFIDENCE. THU INTO FRI...EXPECT NE WIND GUSTS TO 25-30 KT THU MORNING OVER SE WATERS WHICH WILL GRADUALLY DIMINISH THU AFTERNOON AND NIGHT. CONTINUED NE WINDS FRI BUT SPEEDS LESS THAN SCA. HAZARDOUS SEA CONDITIONS EXPECTED THU INTO FRI OVER OUTER WATERS. SAT...SOUTHERLY WINDS DEVELOPING AHEAD OF A COLD FRONT WITH GUSTS INCREASING TO 25-30 KT. WINDS SHIFTING TO WEST DURING SAT NIGHT. HAZARDOUS SEA CONDITIONS CONTINUE OVER OUTER WATERS. VSBYS MAY BE REDUCED IN SHOWERS AND FOG. SUN...WEST WINDS MAY GUST TO 25-30 KT IN POST FRONTAL AIRMASS. HAZARDOUS SEAS CONTINUE OVER OUTER WATERS.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM WEDNESDAY TO 8 AM EDT THURSDAY FOR ANZ235-237. SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR ANZ250-251. SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 8 AM EDT THURSDAY FOR ANZ254>256.
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&& $$ SYNOPSIS...KJC/DOODY NEAR TERM...DOODY SHORT TERM...DOODY LONG TERM...KJC AVIATION...KJC/DOODY MARINE...KJC/DOODY

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