Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 021919 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 319 PM EDT THU JUL 2 2015 .SYNOPSIS...
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A COLD FRONT SHIFTS SOUTH OF NEW ENGLAND TONIGHT. HIGH PRESSURE BUILDS OVER THE REGION LATER TONIGHT AND FRIDAY. DRY WEATHER PREVAILS INTO EARLY NEXT WEEK WITH GRADUALLY WARMING CONDITIONS.
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&& .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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COLD FRONT LIES ALONG OUR SOUTH COAST. ONE AREA OF SHOWERS/TSTMS IS PASSING SOUTH OF THE REGION. THE TRACK OF THIS WEATHER KEEPS MOST OF IT OFFSHORE...BUT COULD CLIP THE ISLANDS DURING THIS EVENING. OUTSIDE CHANCE OF SHOWERS REACHING THE SOUTH COAST ESPECIALLY AROUND THE ELBOW OF CAPE COD. PER WATER VAPOR IMAGERY...A SHORTWAVE MOVING THROUGH THE GREAT LAKES IS INDUCING A WAVE ALONG THE COLD FRONT THAT IS MOVING ACROSS THE APPALACHIANS. THE RIGHT ENTRANCE REGION OF THE SUPPORTING UPPER JET WILL SWEEP ACROSS NEW ENGLAND DURING THE FIRST PART OF TONIGHT. THIS SHOULD SUPPORT CLOUDS AND SHOWERS THROUGH MIDNIGHT...BUT MOSTLY OFFSHORE. AGAIN...THE BEST CHANCE WILL BE ACROSS THE ISLANDS WITH DIMINISHING CHANCE FARTHER NORTH. AS THE WAVE MOVES PAST THE SURFACE FLOW SHOULD TURN NORTHWEST AND DRAW DRIER AIR FARTHER SOUTH. EXPECT DRY WEATHER FOR MOST AREAS WITH DIMINISHING SKY COVER AFTER MIDNIGHT. DEW POINTS IN THE 50S INLAND AND LOWER 60S ALONG THE COAST...WHICH PROVIDES A GOOD ESTIMATE FOR OVERNIGHT LOW TEMPS.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
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FRIDAY... HIGH PRESSURE BUILDS OVER THE REGION WITH PLENTY OF SUBSIDENCE. EXPECT CLEAR OR MOSTLY CLEAR SKIES. PRESSURE GRADIENT WILL BE LIGHT...SO LIGHT WINDS THROUGH THE DAY. THIS SHOULD ALLOW SEA BREEZES TO FORM ALONG THE COASTS LATE MORNING/EARLY AFTERNOON. THE MIXED LAYER IS FORECAST TO REACH 850 MB WITH AFTERNOON TEMPS AT THAT LEVEL AROUND 10C. MIXING THIS TO THE SURFACE SHOULD SUPPORT MAX TEMPS IN THE UPPER 70S...CALL IT 75 TO 80. COOLER VALUES WHERE THE SEA BREEZE TAKES HOLD. FRIDAY NIGHT... HIGH PRESSURE SHIFTS EAST BUT REMAINS IN CONTROL OVER NEW ENGLAND. ANOTHER SHORTWAVE MOVES OVER THE GREAT LAKES AND FORMS ANOTHER WAVE ALONG THE FRONT TO OUR SOUTH. THIS SHOULD GENERATE ANOTHER AREA OF CLOUDS AND SHOWERS THAT APPROACH FROM OUR SOUTH OVERNIGHT. WE WILL BRING SOME INCREASE IN SKY COVER DURING THE NIGHT WITH THE MOST COVER ALONG THE SOUTH COAST. BUT THE DRY AIR IN PLACE AND THE FOCUS OF SUPPORTING LIFT TO OUR SOUTH SHOULD KEEP THE WEATHER DRY. WITH DEW POINTS IN THE 50S...MIN TEMPS SHOULD BE IN THE 50S AND AROUND 60.
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&& .LONG TERM /SATURDAY THROUGH THURSDAY/...
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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... SAT 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.
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&& .AVIATION /19Z THURSDAY THROUGH TUESDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TONIGHT...HIGH CONFIDENCE. MAINLY VFR. SHOWERS LIKELY FOR KACK...POSSIBLY REACHING THE VINEYARD. LOW PROBABILITY OF SHOWERS FOR CAPE COD. AREAS OF MVFR/IFR POSSIBLE IN ANY SHOWERS/FOG. FRIDAY...HIGH CONFIDENCE. VFR. SEA BREEZES DEVELOPING. FRIDAY NIGHT...HIGH CONFIDENCE. VFR. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...SATURDAY 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. TONIGHT... BUOY REPORTS CONTINUE TO SHOW 5 FOOT SEAS ON THE SOUTHERN OUTER WATERS...BUT MARGINAL. WE WILL KEEP SMALL CRAFTS UP THROUGH THE EVENING FOR THOSE WATERS. SEAS BELOW 5 FEET FOR MOST OF OUR WATERS. WEST TO SOUTHWEST WINDS BECOME NORTHWEST TO NORTH...BUT REMAIN WELL BELOW 20 KNOTS. FRIDAY AND FRIDAY NIGHT... HIGH PRESSURE MOVES OVER NEW ENGLAND. WINDS AND SEAS SHOULD REMAIN BELOW SMALL CRAFT THRESHOLDS. OUTLOOK...SATURDAY 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...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ255-256.
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&& $$ SYNOPSIS...WTB/BELK/DOODY NEAR TERM...WTB/DOODY SHORT TERM...WTB LONG TERM...DOODY AVIATION...WTB/DOODY MARINE...WTB/DOODY

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