Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 021430 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1030 AM EDT THU JUL 2 2015 .SYNOPSIS...
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A STALLED COLD FRONT NEAR THE SOUTH COAST THIS AFTERNOON MOVES OFFSHORE TONIGHT. ASIDE FROM A FEW WIDELY SCATTERED SHOWERS LATE AFTERNOON AND TONIGHT OVER CAPE COD AND THE ISLANDS...AND A SPOT SHOWER NEAR THE SOUTH COAST ON SATURDAY...DRY WEATHER PREVAILS INTO EARLY NEXT WEEK WITH GRADUALLY WARMING CONDITIONS.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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SURFACE OBS SHOW THE FRONTAL WIND SHIFT ACROSS CAPE COD BAY/CANAL/SOUTH MASS COAST. DRY AIRMASS NORTHWEST OF THIS FRONT WITH DEW POINTS IN THE 50S. A LITTLE MORE HUMID SOUTH OF THE FRONT WITH DEWS ON CAPE COD AND ISLANDS IN THE LOW TO MID 60S. SHORTWAVE SWINGING THROUGH THE GREAT LAKES AS INDICATED BY WATER VAPOR IMAGERY. THIS IS SUPPORTING A WAVE ALONG THE COLD FRONT OVER THE OHIO VALLEY. THE WAVE WILL MOVE EAST THIS AFTERNOON AND BRING AN INCREASE IN SKY COVER MOSTLY IN CT-RI-SOUTHEAST MASS. THIS MAY ALLOW FOR WIDELY SCATTERED SHOWERS ALONG OR SOUTH OF THE FRONT TOWARD EVENING. NO CHANGES TO POPS FROM EARLIER FORECAST. TEMPS AT 10 AM WERE MOSTLY IN THE LOW TO MID 70S. TEMPERATURE PROFILE FROM THE 8 AM ALY SOUNDING SHOWS SUPPORT FOR MAX SFC TEMPS FROM MIXING AROUND 81 DEGREES. THE EXISTING FORECAST HANDLES THIS QUITE WELL. THE 10 AM TEMPS AND CLIMATOLOGY ALSO SUGGEST LOW 80S WITH A FEW MID 80S POSSIBLE IN THE CT VALLEY AND SE MASS/RI.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... WEAK FRONT MOVES FARTHER OFFSHORE TONIGHT AS A FRONTAL WAVE PASSES BY THE BENCHMARK. MAJORITY OF THE RAINFALL WILL STAY SOUTH OF OUR REGION. HOWEVER...THERE IS A CHANCE OF SHOWERS TOWARD NANTUCKET...WITH A LOWER RISK OF THESE SHOWERS REACHING AS FAR NORTH AS CAPE COD...AND AS FAR WEST AS THE VINEYARD. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... HIGHLIGHTS... * LOW CHANCE OF A SHOWER ON SATURDAY. * GRADUALLY WARMING CONDITIONS INTO EARLY NEXT WEEK. OVERVIEW AND MODEL PREFERENCES...AMPLIFIED BLOCKING FLOW PATTERN CONTINUES MAINLY ACROSS THE ERN PACIFIC AND WRN ATLANTIC UNDER STRONG RIDGING...ESPECIALLY IN THE PACIFIC WHERE THE EPO IS FORECAST TO CONTINUE TO DIVE STRONGLY NEGATIVE. THIS LEAVES MUCH OF THE CONUS IN A NEARLY ZONAL FLOW REGIME. NEARLY...BECAUSE VERY WEAK TROUGHING IS EVIDENT PARTICULARLY AS NRN STREAM ENERGY MOVES SHIFTS THROUGH HE NRN PERIPHERY OF THE MEAN JET. HOWEVER...UNTIL ABOUT THE MID PORTION OF NEXT WEEK...GUIDANCE CONTINUES TO SHOW SRN NEW ENGLAND UNDER THE INFLUENCE OF THE WRN ATLANTIC RIDGING. SO EVEN WITH THE PASSAGE OF A SHORTWAVE THIS WEEKEND...IT LOOKS TO MOVE THROUGH WITH LITTLE FANFARE AS SOUNDINGS SHOW DRY/SUBSIDENCE IN PLACE. WITH MODERATE AGREEMENT BETWEEN OPERATIONAL GFS/ECMWF /SOME SMALLER SCALE DIFFERENCES EXIST/ A BLEND WILL BE USED THROUGH EARLY NEXT WEEK. BEYOND THIS...THERE IS SOME SIGNIFICANT UNCERTAINTY REGARDING A SHIFT AS THE NRN STREAM VORTEX REGAINS CONTROL ACROSS THE AREA...LEADING TO A MORE UNSETTLED PATTERN. DETAILS... FRI NIGHT INTO SAT NIGHT...WITH A WEAK SHORTWAVE MOVING E FROM THE GREAT LAKES AND A STALLED FRONTAL BOUNDARY TO THE S...WILL LIKELY SEE CYCLOGENESIS OF A WEAK LOW PRES CENTER WELL TO THE S. THIS WILL ALSO INTRODUCE RIDGE OF HIGHER THETA-E AIR WHICH LOOKS TO REMAIN TO THE W. FOR NOW...THE BEST CHANCE LOOKS TO REMAIN NEAR THE S COAST...CLOSER TO THE DEVELOPING LOW PRES. HOWEVER...COLUMN REMAINS MOSTLY DRY AND SUGGESTS SOME INFLUENCE OF THE RIDGE MOVING E OF THE REGION. SO SUSPECT ONLY A FEW SPOT SHOWERS TO CONTEND WITH AT MOST. TEMPS AT H85 ARE AROUND +10C...SO SUSPECT 2M TEMPS TO REMAIN NEAR SEASONAL NORMALS. SUN INTO TUE...AS STRONG NRN STREAM SHORTWAVE CONTINUES TO DEEPEN ACROSS CENTRAL CANADA...THE WARM ADVECTION WILL LEAD TO RIDGE AMPLIFICATION OVER THE GREAT LAKES AND NEW ENGLAND. THIS WILL LEAD TO FAIRLY STRONG HIGH PRES DEVELOPMENT WHICH MAY LOCK IN PLACE FOR A FEW DAYS OF DRY WX. HOWEVER...IT WILL BE ACCOMPANIED BY MODERATING MID LVL TEMPS AND RISING HUMIDITY PARTICULARLY MON AND TUE. H85 TEMPS INCREASE TO AN AVERAGE OF +12C MON...THEN CLOSER TO +14C BY TUE. THEREFORE...AWAY FROM COASTLINES /WHERE SEA BREEZES WILL LIMIT WARMING/ EXPECT TEMPS WARMER THAN EARLY JULY NORMALS. MID-LATE NEXT WEEK...AS MENTIONED ABOVE...BECAUSE THIS IS SUCH A ROBUST SHORTWAVE/CUTOFF THAT MODELS ARE TRYING TO DEVELOP...THERE IS LITTLE AGREEMENT BETWEEN THEM REGARDING TIMING/STRENGTH...AND ENSEMBLES ARE LITTLE HELP. HOWEVER...WITH FAIRLY WARM/HUMID CONDITIONS AND AN APPROACHING SHORTWAVE...THERE WILL LIKELY BE A TRANSITION TO A WETTER AND MORE UNSETTLED PATTERN TOWARD THE LATTER HALF OF NEXT WEEK. && .AVIATION /14Z THURSDAY THROUGH MONDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. THIS AFTERNOON...HIGH CONFIDENCE. VFR. TONIGHT...MODERATE CONFIDENCE. MAINLY VFR. AREAS OF MVFR/IFR POSSIBLE CAPE COD AND THE ISLANDS. SHOWERS LIKELY FOR KACK...POSSIBLY REACHING THE S COAST AND CAPE COD. FRIDAY...HIGH CONFIDENCE. VFR. SEA BREEZES DEVELOPING. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... HIGH CONFIDENCE. MAINLY VFR. WEAK SEA BREEZES LIKELY MOST DAYS.
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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. LINGERING ROUGH SEAS ACROSS PORTIONS OF THE SOUTHERN COASTAL WATERS WILL SLOWLY DIMINISH THIS AFTERNOON. SO SMALL CRAFT ADVISORIES WILL PERSIST OVER THESE WATERS FOR A WHILE LONGER. CHANGEABLE WINDS AS A COLD FRONT FIRST STALLS ACROSS THE WATERS...THEN MOVES FARTHER OFFSHORE TONIGHT. WINDS EXPECTED TO REMAIN LESS THAN 15 KT. ONCE SEAS DIMINISH BELOW 5 FEET...EXPECTING RATHER TRANQUIL BOATING CONDITIONS THROUGH FRIDAY. THE MAIN ISSUE AT THAT POINT WOULD BE REDUCED VISIBILITY IN SCATTERED SHOWERS AND PATCHY FOG. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... FRI NIGHT INTO SAT...MODERATE CONFIDENCE. A WEEK LOW PRES WILL PASS WELL S OF THE WATERS. THIS MAY LEAD TO E FLOW REACHING 20-25 KT ON THE SRN WATERS AND A BUILDING SWELL WHICH COULD REACH 5-6 FT. SMALL CRAFT ADVISORIES MAY BE NEEDED. OTHERWISE...SOME SHOWERS AND FOG AT TIMES MAY LEAD TO REDUCED VSBYS...MAINLY ON THE SRN WATERS AS WELL. SUN AN MON...HIGH CONFIDENCE. HIGH PRES WILL MOVE OVER THE WATERS ALLOWING AND REMNANT SWELL TO SUBSIDE. AFTER WHICH QUIET BOATING WEATHER WILL PREVAIL.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ255- 256. SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR ANZ235- 237. && $$ SYNOPSIS...WTB/BELK/DOODY NEAR TERM...WTB/BELK/DOODY SHORT TERM...BELK LONG TERM...DOODY AVIATION...BELK/DOODY MARINE...BELK/DOODY

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