Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 211455 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1055 AM EDT MON APR 21 2014 .SYNOPSIS... HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH EARLY TUESDAY. WHILE WARMER ON TUESDAY...SHOWERS ASSOCIATED WITH A COLD FRONT WILL LIKELY OCCUR TUESDAY NIGHT INTO WEDNESDAY MORNING. AS THE FRONT MOVES OFFSHORE...EXPECT BRISK AND COOLER CONDITIONS LATE WEDNESDAY INTO THURSDAY. WINDS MAY BE ESPECIALLY GUSTY WEDNESDAY AFTERNOON INTO THE EVENING. THERE WILL BE ANOTHER CHANCE FOR SHOWERS ON SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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MOSTLY CLEAR SKIES WITH THIN CIRRUS MOVING ACROSS. THIS SHOULD CONTINUE THROUGH THE AFTERNOON. MAIN CONCERN REMAINS THE DEVELOPMENT OF A SEA BREEZE. LOW LEVEL WINDS ALOFT ARE SOUTHWEST WITH 9-13 KNOTS AT 1000-2000 FEET OVER METRO BOSTON BUT 5 KNOTS OR LESS ELSEWHERE. LIGHT WINDS ABOVE 2000 FEET. THIS COULD BE ENOUGH TO MAINTAIN SOUTHWESTERS WITH ANY E MASS SEABREEZE CONFINED TO THE IMMEDIATE SHORE/PERHAPS WITHIN A MILE OF SHORE. TEMPERATURES IN THE SOUTHWEST FLOW ARE WARMING AS EXPECTED. NO SIGNIFICANT CHANGES TO INLAND MAX TEMPS. BUMPED BOSTON IMMEDIATE COASTAL AREA UP TO UPPER 50S/AROUND 60.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... TONIGHT... AS THE HIGH PRES RIDGE FINALLY SETTLES S OF THE REGION...SW WINDS WILL BE IN PLACE WITH CONTINUED WARM AIR ADVECTION IN PLACE. MID AND HIGH CLOUDS WILL PUSH ACROSS THE REGION AS WELL. EXPECT TEMPS TO ONLY FALL BACK TO THE 40S...WHICH IS ACTUALLY CLOSE TO OR JUST ABOVE SEASONAL NORMALS. TUESDAY... SHORT RANGE MODELS ALL SIGNALING LOW PRES PUSHING E...APPROACHING NORTHERN NEW ENGLAND LATE IN THE DAY. MOST OP RUNS SUGGESTING THAT THE PRECIP WILL TRY TO HOLD OFF UNTIL TUE NIGHT...CAN NOT RULE OUT SOME SCT SHOWERS TO PUSH ACROSS DURING THE AFTERNOON. HAVE CHANCE POPS GOING FOR MOST AREAS...BUT THINK BEST SHOT WILL BE ACROSS THE CT VALLEY TO THE WORCESTER HILLS INTO NE CT/W RI. MILD AIR WILL CONTINUE TO PUSH ACROSS THE REGION AS SW WINDS INCREASE AHEAD OF APPROACHING FRONT. EXPECT HIGHS TO REACH TO THE 60S ONCE AGAIN...WITH SOME LOWER 70S POSSIBLE WELL INLAND...THOUGH TEMPS WILL REMAIN IN THE MID 50S TO AROUND 60 ALONG THE IMMEDIATE S COAST....CAPE COD AND THE ISLANDS. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... HIGHLIGHTS... * SHOWERS LIKELY TUESDAY NIGHT...POSSIBLY LINGERING INTO WEDNESDAY MORNING * BREEZY AND COOLER FOR WEDNESDAY AND THURSDAY * RISK FOR MORE SHOWERS FRIDAY NIGHT INTO SATURDAY OVERVIEW... PROPENSITY FOR CLOSED 500 MB LOWS TO FORM...WHICH FITS THE CLIMATOLOGICAL PATTERN FOR SPRING. FOR THE MOST PART MEDIUM RANGE MODELS KEEP SYSTEMS FAIRLY PROGRESSIVE FOR NOW. NAO INDEX IS PROJECTED TO GO NEGATIVE...HOWEVER...AND SO WILL NEED TO WATCH THE POTENTIAL FOR SLOWER AND HIGHER AMPLITUDE SYSTEMS WITH TIME. LOOKS LIKE THREE PRIMARY TROUGHS TO MONITOR OVER THE NEXT 7 TO 10 DAYS WITH THE THIRD ONE LIKELY NOT AN ISSUE UNTIL BEYOND THIS CURRENT 7 DAY PERIOD. MEDIUM RANGE MODELS HAVE ROUGHLY SIMILAR THEME BUT BEGIN TO DIVERGE MORE SIGNIFICANTLY IN THE DETAILS OF THE SECOND TROUGH DURING THE COURSE OF THE COMING WEEKEND INTO NEXT WEEK. AS ONE MIGHT EXPECT...BOTH THE ECMWF AND GFS SHOW SIGNIFICANTLY GREATER SPREAD IN INDIVIDUAL MEMBERS STARTING WITH THIS COMING WEEKEND. HENCE...A MODEL CONSENSUS APPROACH WOULD APPEAR TO MAKE SENSE AT THIS TIME RANGE. DETAILS... TUE NIGHT...MODELS IN REASONABLE AGREEMENT OF A COLD FRONT SWEEPING THROUGH...ALTHOUGH THE GFS APPEARS TO BE FASTER THAN MODEL CONSENSUS AND PROBABLY A LITTLE TOO FAST GIVEN TENDENCY FOR MID LEVEL FLOW TO CLOSE OFF AND SURFACE LOW FORM IN VICINITY OF THE GULF OF ME. SHOWALTER AND K INDICES AROUND DEEP CONVECTION THRESHOLDS WHICH WOULD SUGGEST ISOLATED ELEVATED THUNDER A POSSIBILITY. WED...SOME RAIN MAY LINGER THROUGH THE MORNING IN THE EAST GIVEN PROPENSITY FOR UPPER TROF CLOSING OFF AND SURFACE LOW FORMING JUST EAST OR NORTHAST OF FORECAST AREA. THE 00Z ECMWF SEEMS A BIT BULLISH ON THIS IDEA AND HENCE HELD BACK LOW CHANCE POPS IN EAST FOR A WHILE ON WED. AFTERNOON DRIES OUT BUT THEN THE ISSUE BECOMES GUSTY WINDS. FAIRLY STRONG NORTHWEST FLOW WED AFTERNOON INTO WED NIGHT WITH COLD ADVECTION AND 925 MB WIND SPEEDS PROGGED AROUND 40 KT. NOT SURE IF WINDS WILL BE STRONG ENOUGH FOR WIND ADVISORY CRITERIA BUT GUSTS TO AT LEAST NEAR 40 MPH LOOK LIKELY AT THIS POINT WED AFTERNOON/EVENING. SOME DECOUPLING MAY OCCUR LATE WED NIGHT BUT THINK EXPOSED HIGHER TERRAIN AND COASTAL PLAIN MAY REMAIN GUSTY THROUGHOUT THE NIGHT. THU...LOOKS DRY. A LITTLE GUSTY THROUGH EARLY AFTERNOON...THEN WINDS SHOULD GRADUALLY DIMINISH. TEMPERATURES LOOK TO BE FAIRLY SEASONABLE TO PERHAPS A LITTLE BELOW THE SEASONAL NORM HIGHER ELEVATION AREAS. FAIRLY CHILLY AIR MASS THU...BUT APRIL SUNSHINE AND DOWNSLOPING WIND WILL HELP COMPENSATE. FRI...SHOULD BE DRY WITH SEA BREEZES POSSIBLE ALONG COASTAL AREAS. SAT...UPPER SHORT WAVE TROF AND SURFACE OCCLUDED OR COLD FRONT MAY CROSS AREA. THE LATEST ECMWF RUN KEEPS THE ENERGY FURTHER NORTH WHEREAS THE 00Z GFS RUN IS MORE ROBUST WITH SIGNS OF A TRIPLE POINT LOW PASSING ACROSS SOUTHERN NEW ENGLAND AND FAIRLY HIGH AMPLITUDE TROF CROSSING NEW ENGLAND. CONFIDENCE ON JUST HOW THIS WILL PLAY OUT IS RELATIVELY LOW THIS FAR OUT GIVEN ONLY FAIR RUN TO RUN CONSISTENCY AND DIFFERENCES IN THE VARIOUS ENSEMBLE MEMBERS. HENCE HAVE GONE WITH A CONSENSUS APPROACH TO THE GUIDANCE WHICH YIELDS A CHANCE OF SHOWERS FOR SAT. SUN...DRY OUT THE FORECAST AREA FOR NOW GIVEN MODEL CONSENSUS OF MOVING SYSTEM OUT. HOWEVER...CONFIDENCE IS NOT ALL THAT HIGH. IF UPPER LOW CLOSES OFF JUST A LITTLE FURTHER WEST AND SOUTH...THEN MIGHT SEE SOME RAIN HOLDING BACK INTO THE FORECAST AREA FOR AT LEAST SOME OF THE DAY. && .AVIATION /14Z MONDAY THROUGH FRIDAY/...
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LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY/...HIGH CONFIDENCE. THIS AFTERNOON...VFR WITH SOME THIN HIGH-LEVEL CIRRUS. SOUT TO SOUTHWEST WIND AROUND 10 KT. POTENTIAL REMAINS FOR SEA BREEZES TO KICK IN ALONG THE IMMEDIATE COAST FOR MOST OF THE AFTERNOON...ENDING BETWEEN 21Z AND 23Z. S COAST SEA BREEZES SHOULD PENETRATE TO 10-15 MILES BUT ONLY TO ABOUT 1-3 MILES INLAND ALONG EAST COAST. TONIGHT...VFR. LIGHT S-SW WINDS. SOME HIGH CLOUDS MOVE IN AFTER MIDNIGHT TUESDAY...VFR. CLOUDS WILL LOWER AND THICKEN...ESPECIALLY DURING THE AFTERNOON. MAY SEE CONDITIONS LOWER TO MVFR ALONG S COAST AFTER 20Z IN PATCHY FOG AND SCT SHOWERS. SW WINDS INCREASE DURING THE LATE MORNING AND AFTERNOON...GUSTING TO AROUND 20 KT MAINLY ACROSS E MA/RI. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. SEA BREEZE ANTICIPATED BY 16Z-18Z TODAY. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...TUESDAY NIGHT INTO FRIDAY... TUE NIGHT INTO WED MORNING...MODERATE CONFIDENCE. MVFR CIGS AND VSBYS IN SHOWERS WITH SCATTERED AREAS OF IFR CIGS/VSBYS POSSIBLE. WED AFTERNOON...MODERATE TO HIGH CONFIDENCE. VFR WEST AND BECOMING VFR EAST. GUSTY SFC WINDS...POSSIBLY TO 30 KT. THU THRU FRI...HIGH CONFIDENCE OF 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 /THROUGH TUESDAY/...HIGH CONFIDENCE. THIS AFTERNOON AND TONIGHT...EXPECT WINDS AND SEAS WILL REMAIN BELOW ADVISORY THRESHOLDS. S WINDS GUSTING UP TO 20 KT ON THE EASTERN OPEN WATERS LATE THIS AFTERNOON AND TONIGHT. ONSHORE WINDS ALONG THE NEARSHORE WATERS THROUGH 21Z-23Z. TUESDAY...S-SW WINDS EXPECTED TO GUST UP TO 20 KT AS PRES GRADIENT BEGINS TO INCREASE. SEAS MAY REACH UP TO AROUND 5 FT ON THE EASTERN OUTER WATERS LATE. OUTLOOK...TUESDAY NIGHT INTO FRIDAY... MODERATE CONFIDENCE. TUE NIGHT...SEAS MAY APPROACH 5 FT IN SW FLOW AHEAD OF COLD FRONT TUE EVE. VSBYS MAY DROP TO A MILE OR LESS IN AREAS OF FOG AND SHOWERS. WED...INCREASING NW WIND TO AT LEAST SCA CRITERIA LIKELY ALL WATERS DURING WED AFTERNOON...AND WIND MAY APPROACH GALE FORCE LATE WED AFTERNOON AND WED NIGHT WITH FREQUENT GUSTS TO 35 KT POSSIBLE. THU...LINGERING GUSTY NW WINDS MAY REQUIRE CONTINUATION OF SCA FOR AT LEAST SOME OF DAY. SEAS SUBSIDING LATE. FRI...FOR NOW LOOKS LIKE FAIRLY LIGHT WINDS AND SEAS BELOW 5 FT.
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&& .HYDROLOGY...
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MINOR FLOODING CONTINUES ALONG PORTIONS OF THE MAINSTEM CT RIVER. SEE THE LATEST FLOOD STATEMENT FOR DETAILS. FLOOD WARNINGS REMAIN POSTED ALONG CT RIVER AT... HARTFORD AND MIDDLE HADDAM CT RIVER AT HARTFORD CONTINUES TO RECEDE AND AT MID MORNING HAD DIPPED JUST A SMIDGE BELOW FLOOD STAGE. WILL GIVE IT ANOTHER HOUR OR TWO TO MAINTAIN THAT TREND...AND IF IT DOES THEN WE WILL CANCEL THE WARNING.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...EVT/THOMPSON NEAR TERM...WTB/EVT/THOMPSON SHORT TERM...EVT LONG TERM...THOMPSON AVIATION...EVT/THOMPSON MARINE...EVT/THOMPSON HYDROLOGY...

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