Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 181052 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 652 AM EDT MON AUG 18 2014 .SYNOPSIS...
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DRY AND SEASONABLY WARM WEATHER INTO WEDNESDAY...THEN A COOLING TREND IS EXPECTED THU AND FRI AS CLOUDS INCREASE ALONG WITH ONSHORE WINDS AND THE RISK OF A FEW SHOWERS. DRY WEATHER LIKELY RETURNS NEXT WEEKEND BUT WITH COOLER THAN NORMAL TEMPERATURES...AS HIGH PRESSURE BUILDS SOUTHWARD FROM THE CANADIAN MARITIMES.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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7 AM UPDATE... NOT MUCH CHANGE FROM PREVIOUS FORECAST. LATEST WATER VAPOR IMAGERY SHOWS IMPRESSIVE SHORT WAVE TROUGH MOVING ACROSS NORTHERN ME. THIS FEATURE THIS GENERATING AN AREA OF SHOWERS ALONG THE ME COAST AND OFFSHORE. THIS ACTIVITY WILL REMAIN OVER THE OCEAN AND BYPASS SOUTHERN NEW ENGLAND. HOWEVER SOME OF THE MID LEVEL CLOUDINESS MAY CLIP CAPE ANN AND CAPE COD BASED ON LATEST SATELLITE TRENDS AND SURFACE OBSERVATIONS. OTHERWISE PARTLY TO MOSTLY SUNNY SKIES WILL WARM OUR COOL MORNING TEMPS FROM THE 50S TO 75 TO 80 THIS AFTERNOON...LOW 70S FOR THE ISLANDS AND THE HIGHER TERRAIN. PREVIOUS FORECAST CAPTURES THESE DETAILS NICELY SO NO MAJOR CHANGES WITH THIS UPDATE. ================================================================ FORECAST REMAINS ON TRACK FOR THE EARLY MORNING HOURS. UPPER LEVEL SHORTWAVE HAS SPARKED SOME SHOWERS ACROSS UPSTATE NY AS WELL AS IN NORTHERN NEW ENGLAND. THESE SHOWERS WILL STRUGGLE TO REACH SOUTHERN NEW ENGLAND AS THERE IS A GOOD AMOUNT OF DRY AIR ALLOWING FOR THE SHOWERS TO FIZZLE OUT AS THEY APPROACH. AT THE SURFACE...DRY AIR HAS FILTERED INTO THE REGION WITH SITES DROPPING INTO THE LOW 50F FOR DEWPOINTS. WINDS ARE FAIRLY LIGHT AND WITH CLEAR SKIES...ANTICIPATE RADIATIONAL COOLING. IN FACT MVY HAS DROPPED DOWN TO 51F WHICH IS ONE OF THE COOLEST TEMP ACROSS SOUTHERN NEW ENGLAND. TODAY... ALTHOUGH UPPER LEVEL TROUGH IS OVER THE REGION ANTICIPATE A DRY WEATHER DAY THANKS TO HIGH PRESSURE BUILDING INTO THE REGION. EXPECT MOSTLY CLEAR SKIES...WITH SOME DIURNAL CLOUDS DEVELOPING IN THE AFTERNOON. BUFKIT SOUNDINGS SHOW THE BOUNDARY LAYER MIXING THIS AFTERNOON SO GUSTS UP TO 15 MPH ARE POSSIBLE. OTHERWISE TEMPERATURES WILL BE NEAR AVERAGE WITH HIGHS IN THE MID 70S TO PERHAPS 80F AS 850 MB WILL ONLY BE 8C. MAY NEED TO WATCH FOR THE POTENTIAL FOR SEA BREEZES ALONG THE COASTLINE.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... TONIGHT AND TOMORROW... UPPER LEVEL FLOW BECOMES MORE ZONAL DURING THIS TIME FRAME. UPPER LEVEL SYSTEM MOVING ACROSS THE OHIO VALLEY TODAY WILL STAY SOUTH OF THE REGION AND MOVE ACROSS THE MID-ATLANTIC TOMORROW THANKS TO A STRONG GREENLAND BLOCK. AT THE SURFACE...HIGH PRESSURE WILL REMAIN OVERHEAD. ANTICIPATE LIGHT WINDS AND MOSTLY CLEAR SKIES ASIDE FROM SOME DIURNAL CU. PATCHY GROUND FOG MAY DEVELOP IN THE TYPICAL PRONE REGIONS OVERNIGHT. TEMPERATURES TONIGHT WILL DROP INTO THE 50S TO LOW 60S AND WILL WARM INTO THE UPPER 70S TO LOW 80S TOMORROW. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... HIGHLIGHTS... * DRY AND SEASONABLY WARM WEDNESDAY * COOLER THU AND FRI WITH A RISK OF A FEW SHOWERS * DRYING TREND NEXT WEEKEND BUT COOLER THAN NORMAL SYNOPTIC OVERVIEW AND MODEL EVALUATION... MAIN WEATHER FEATURE THIS PERIOD WILL BE A HIGH AMPLITUDE RIDGE OF +2 TO +3 STANDARD DEVIATIONS ABOVE CLIMO OVER GREENLAND AND THE DAVIS STRAIT. THIS RESULTS IN A REX TYPE BLOCK PATTERN TO DEVELOP OVER THE NORTHEAST STATES INTO SOUTHEAST CANADA. THIS SHIFTS THE JET STREAM/STORM TRACK/FRONTAL BOUNDARY SOUTH OF NEW ENGLAND...ALLOWING MAINLY DRY WEATHER AS COOL MARITIME HIGH PRESSURE BUILDS SOUTHWARD INTO NEW ENGLAND. REGARDING MODEL GUIDANCE...GEFS AND ECENS ENSEMBLES IN GOOD AGREEMENT ON THE LARGE SCALE FLOW THIS PERIOD. AS FOR THE DETERMINISTIC RUNS OF THE GFS AND ECMWF...TYPICAL TIMING AND AMPLITUDE DIFFERENCES AT THIS TIME RANGE...BUT OVERALL IN GOOD AGREEMENT ON THE OVERALL PATTERN AND THEME. THUS ABOVE AVERAGE FORECAST CONFIDENCE THIS PERIOD. SENSIBLE WEATHER DETAILS... WED... SHORT WAVE RIDGING PERSIST OVER NEW ENGLAND TO YIELD DRY WEATHER AND SEASONABLY WARM TEMPS...U70S TO L80S. WEAK HIGH PRES OVER THE AREA WILL SUPPORT LIGHT WINDS BUT ALSO AFTERNOON SEABREEZES KEEPING THE COASTLINE SLIGHTLY COOLER. FAIRLY COMFORTABLE WITH DEW PTS IN THE U50S TO L60S. SHORT WAVE TROUGH AND DEEPER MOISTURE FROM THE GREAT LAKES APPROACHES NEW ENGLAND LATE IN THE DAY AND ESPECIALLY WED NIGHT. THUS A LOW RISK OF A FEW SHOWERS ACROSS WESTERN CT-MA- SOUTHWEST NH. ELSEWHERE DRY WEATHER SHOULD PREVAIL. NOT EXPECTING ANY THUNDER GIVEN THE LACK OF SFC BASED AND INSTABILITY ALOFT. THU INTO FRI... SHORT WAVE TROUGH TRACKS FROM THE GREAT LAKES TO SOUTHERN NEW ENGLAND. THE BULK OF THE DEEP LAYER MOISTURE AND SURFACE LOW TRACK WELL SOUTH OF NEW ENGLAND. HOWEVER THE ONSHORE FLOW AND ESPECIALLY THE UPSLOPE COMPONENT ACROSS THE HIGHER TERRAIN OF WESTERN CT-MA INTO SOUTHWEST NH ALONG WITH CYCLONIC FLOW ALOFT MAY YIELD PERIODIC SHOWERS. GREATEST RISK WILL BE ACROSS THE INTERIOR. ELSEWHERE LOWER RISK OF SHOWERS. OVERALL NOT A WASHOUT JUST A FEW SPOTTY SHOWERS... PERHAPS MORE NUMEROUS OVER THE HIGHER TERRAIN. GIVEN THE COOL ONSHORE WINDS...SB INSTABILITY IS NIL AND MID LEVEL LAPSE RATES ARE LESS THAN 6C/KM. THUS NOT ANTICIPATING ANY THUNDER. NEXT WEEKEND... MEAN MID LEVEL TROUGH AXIS EXPECTED TO MOVE OFFSHORE AND ALLOWS 1024 MB MARITIME HIGH TO BUILD SOUTHWARD INTO NEW ENGLAND. THIS PROMOTES A DRYING TREND BUT ALSO COOLER THAN NORMAL TEMPS WITH HIGHS MAINLY IN THE LOW TO MID 70S. && .AVIATION /12Z MONDAY THROUGH FRIDAY/...
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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. 7 AM UPDATE... SHOWERS OFF THE MAINE COAST WILL REMAIN OFFSHORE AND NOT IMPACT SOUTHERN NEW ENGLAND. SOME MID LEVEL CLOUDS STREAM ACROSS THE AREA BUT VFR CONDITIONS PREVAIL. EARLIER DISCUSSION BELOW. ================================================================= TODAY...VFR. W/NW WINDS WITH OCCASIONAL GUSTS UP TO 15-20 KTS. LOW CONFIDENCE ON THE AFTERNOON SEA BREEZE POTENTIAL. IF IT DOES DEVELOP...SHOULD BE AFTER 18Z TODAY. TONIGHT...VFR. PATCHY GROUND FOG IS POSSIBLE IN TYPICALLY PRONE SITE. TUESDAY...VFR. SEA BREEZE DEVELOPMENT AFTER 14Z. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. NW FLOW...LOW CONFIDENCE ON SEA BREEZE POTENTIAL TODAY. IT MAY STRUGGLE TO REACH THE TERMINAL/OR PARK OVER THE RUNWAY. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY... TUE NIGHT/WED...HIGH CONFIDENCE FOR VFR/DRY WEATHER AND AFTERNOON SEA BREEZES. WED NIGHT/THU/FRI...MODERATE CONFIDENCE. MAINLY VFR WITH A LOW RISK OF MVFR AT TIMES IN SCT SHOWERS...ESPECIALLY WESTERN NEW ENGLAND IN HIGHER TERRAIN.
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TODAY THROUGH TUESDAY...HIGH CONFIDENCE. QUIET BOATING WEATHER IS EXPECTED. NORTHWEST FLOW WITH OCCASIONAL GUSTS TO 20 KTS IN THE AFTERNOON. SEA BREEZES POSSIBLE MON AFTERNOON AND TUESDAY AFTERNOON. OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY...MODERATE TO HIGH CONFIDENCE. STORM TRACK REMAINS SOUTH OF NEW ENGLAND WITH A SERIES OF WEAK LOWS EXITING THE MID ATLC COAST AND TRACKING SOUTH OF 40N LATITUDE. HOWEVER HIGH PRES BUILDING SOUTH FROM QUEBEC COMBINED WITH THESE SERIES OF WEAK LOWS SOUTH OF NEW ENGLAND MAY RESULT IN ENE WINDS UP TO 20-25 KT ACROSS THE SOUTH COASTAL WATERS THU NIGHT INTO FRI. AS FOR VSBY MAINLY GOOD BUT MAY LOWER IN PATCHY FOG AND ISOLATED SHOWER WED NIGHT THRU FRI. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...NOCERA/DUNTEN NEAR TERM...NOCERA/DUNTEN SHORT TERM...DUNTEN LONG TERM...NOCERA AVIATION...NOCERA/DUNTEN MARINE...NOCERA/DUNTEN

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