Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 181409 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1009 AM EDT MON AUG 18 2014 .SYNOPSIS...
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DRY AND SEASONABLY WARM WEATHER INTO WEDNESDAY...THEN A COOLING TREND IS EXPECTED THURSDAY AND FRIDAY 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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1030 AM UPDATE... STRETCHED MID-LEVEL ENERGY AND ACCOMPANYING JET AXIS THROUGH THE W-PERIPHERY OF CYCLONIC FLOW OF THE LINGERING BROADER TROUGH WILL RESULT IN WINDS AROUND 4-6 KFT TO REMAIN SUSTAINED AROUND 20 MPH. COMBINED WITH A WELL-MIXING BOUNDARY LAYER UP TO H8...EXPECTING SOME OF THAT MOMENTUM TO TRANSFER TO THE SURFACE. ALREADY SEEING WIND GUSTS ACROSS THE REGION UP TO 20 MPH. EXPECT THAT TO BE THE THEME THROUGHOUT THE REMAINDER OF THE DAY...TAPERING WITH SUNDOWN. SHOULD ALSO SEE SCATTERED TO BROKEN DIURNAL CUMULUS DEVELOP ACROSS THE REGION BENEATH THE BROADER CYCLONIC FLOW. PLENTY OF LINGERING MOISTURE AT THE SURFACE DESPITE THE 50-DEWPOINTS AND LARGE DEWPOINT DEPRESSIONS...AND NOT LOOKING TOO DRY ALOFT PER WATER- VAPOR IMAGERY. EXPECT JUST-BELOW SEASONABLE CONDITIONS WITH HIGHS AROUND THE MID-70S. CONSIDERING DAYTIME HEATING AND THE WEAK PRESSURE GRADIENT...THERE IS SOME POSSIBILITY OF AN ONSHORE SEA-BREEZE. MAJORITY OF HIGH-RES MODEL SOLUTIONS CONCUR ON A WEAK SEA-BREEZE ENCROACHING ON JUST THE IMMEDIATE SHORELINE DURING THE LATE AFTERNOON HOURS. HAVE GONE IN THAT DIRECTION WITH THE FORECAST ACCORDINGLY.
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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 /14Z 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. 14Z UPDATE... VFR. W/NW WINDS WITH OCCASIONAL GUSTS UP TO 20 KTS. SEA-BREEZE POSSIBLE AROUND 20Z ALONG THE IMMEDIATE SHORELINE. SCT-BKN CIGS AROUND 5-6 KFT. CONDITIONS QUIET OVERNIGHT WITH THE POSSIBILITY OF SOME PATCHY MVFR-IFR GROUND FOG. LIGHT WINDS CONTINUE INTO TUESDAY WITH SEA-BREEZE DEVELOPMENT AFTER 14Z. KBOS TERMINAL...MODERATE CONFIDENCE. BRISK NW FLOW PRESENTLY... BUT WINDS TO TAPER TOWARDS 20Z WITH POTENTIAL SEA-BREEZE. AS MENTIONED PREVIOUSLY...SEA-BREEZE 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...SIPPRELL SHORT TERM...DUNTEN LONG TERM...NOCERA AVIATION...NOCERA/DUNTEN/SIPPRELL MARINE...NOCERA/DUNTEN

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