Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 051101 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 701 AM EDT SAT SEP 5 2015 .SYNOPSIS...
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HIGH PRESSURE WILL DOMINATE THE WEATHER THROUGH THE MIDDLE OF NEXT WEEK. AFTER A COOL START TO THIS WEEKEND...A SIGNIFICANT WARMING TREND DEVELOPS THROUGH THE MIDDLE OF NEXT WEEK WITH TEMPERATURES BECOMING MUCH WARMER THAN NORMAL ALONG WITH INCREASING HUMIDITY. A COLD FRONT MAY YIELD THE RISK FOR SCATTERED SHOWERS AND THUNDERSTORMS BEGINNING WEDNESDAY...WITH A GREATER RISK THURSDAY AND FRIDAY.
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&& .NEAR TERM /UNTIL 7 PM THIS EVENING/...
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7 AM UPDATE... A TOUCH OF AUTUMN THIS MORNING WITH MANY LOCATIONS IN THE MU40S AT 630 AM. THIS INCLUDES MVY/TAN/OWD/BED/CEF AND ORE. THIS IS IN RESPONSE TO 1027 MB HIGH OVER SOUTHERN NH PROVIDING A DRY AIRMASS...LIGHT WINDS AND CLEAR SKIES. ONLY CHANGE WITH THIS FORECAST UPDATE WAS TO MODIFY HOURLY TEMPS/DEW PTS AND WINDS TO BETTER MATCH CURRENT CONDITIONS. OTHERWISE FORECAST REMAINS ON TRACK. EARLIER DISCUSSION BELOW. ================================================================== THE MAINLY CLEAR SKIES...COOL START...LIMITED MIXING THANKS TO STRONG SUBSIDENCE AND SEA BREEZES THANKS TO WEAK FLOW...WILL ALL COMBINE TO IMPACT HIGH TEMPERATURES. WERE MOST MIXING IS REALIZED...AND H85 TEMPS REMAIN AROUND +12C EXPECT LOW 80S...MAINLY WRN MA/CT. FURTHER E...WHERE SEA BREEZES ARE EXPECTED...HIGH TEMPS WILL ONCE AGAIN REMAIN IN THE LOW TO MID 70S...UPPER 70S INLAND OF THE IMMEDIATE COAST. DEWPOINTS REMAIN LOW...MAINLY UPPER 40S AND LOW 50S...SO VERY COMFORTABLE HUMIDITY.
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&& .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM SUNDAY/... TONIGHT... VERY WEAK PRES GRADIENT AND CLEAR SKIES THANKS TO DRY AIR THROUGH THE COLUMN WILL ONCE AGAIN ALLOW FOR RADIATIONAL COOLING THROUGH THE NIGHT. THEREFORE...LOWS ONCE AGAIN SLIDE INTO THE UPPER 40S AND LOW 50S. SUN... H85 TEMPS WILL INCREASE CLOSER TO +15C AND BETTER MIXING IS EXPECTED. IN SPITE OF THE COOL START...HIGHS WILL BE WARMER SUN...MORE WIDESPREAD LOW-MID 80S. UPPER 80S IN THE W. SEA BREEZES ARE LIKELY AGAIN...SO NEAR SHORE LOCATIONS SHOULD SEE HIGHS REMAIN IN THE LOW 80S...MID 70S CAPE/ISLANDS. HUMIDITY SHOULD STILL REMAIN COMFORTABLE THANKS TO DWPTS REMAINING IN THE 50S...ALTHOUGH A LITTLE HIGHER /MAINLY MID 50S/. THE INCREASE IN TEMPS THOUGH WILL COUNTER THE DWPTS...KEEPING RH VALUES CLOSE TO THOSE OBSERVED SAT. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... HIGHLIGHTS... * SUMMER HEAT RETURNS MON THRU WED W/90+ TEMPS POSSIBLE EACH DAY * REMAINING DRY THRU TUE WITH SHOWERS/T-STORMS POSSIBLE WED THRU FRI SYNOPTIC OVERVIEW AND GUIDANCE EVALUATION... SUBTROPICAL RIDGE DOMINATES OUR WEATHER INTO WEDNESDAY AS RIDGE HOLDS FIRM FROM TEXAS NORTHEASTWARD INTO SOUTHERN NEW ENGLAND. BY WED ENSEMBLES AND DETERMINISTIC GUIDANCE SUGGEST LEAD NORTHERN STREAM SHORT WAVE TROUGH BEGINS TO ERODE THE RIDGE ACROSS NEW ENGLAND. THIS WILL BE ACCOMPANIED BY A FRONTAL BOUNDARY DROPPING SOUTHEAST INTO THE REGION. HOWEVER WITH THIS TROUGH DEAMPLIFYING WITH TIME ITS FRONTAL BOUNDARY LIKELY STALLS SOMEWHERE ACROSS THE NORTHEAST/NEW ENGLAND. HOWEVER BY FRIDAY ENSEMBLES AND DETERMINISTIC GUIDANCE SUGGEST AMPLIFYING MID LEVEL TROUGH OVER THE GREAT LAKES AND MS VLY WITH POSSIBLE SURFACE WAVE DEVELOPING ALONG THE EASTERN SEABOARD ON THE STALLED FRONTAL BOUNDARY. DETERMINISTIC GUIDANCE /00Z GFS AND ECMWF/ IN FAIRLY GOOD AGREEMENT THRU TUE BUT THEN SHOW SIGNIFICANT DIFFERENCES WED THRU FRI WITH TIMING AND AMPLITUDE OF INDIVIDUAL SHORT WAVES. THUS AS USUALLY LEANED MORE ON THE ENSEMBLES AT THIS TIME RANGE /WED THRU FRI/. DAILY DETAILS... SUN NIGHT/MONDAY... AIRMASS REMAINS DRY AS RIDGE AXIS HOLDS FIRM OVER THE AREA WITH MORE HUMID AIRMASS ADVECTING WEST AND NORTH OF NEW ENGLAND. SO DRY WEATHER PREVAILS WITH SEASONABLE TEMPS SUN NGT BUT AIRMASS GRADUAL WARMS BY MONDAY WITH 850 TEMPS +16C TO 18C BY DAYS END MONDAY. THIS WILL SUPPORT HIGHS OF 85 TO 90 AWAY FROM THE SOUTH COAST. HUMIDITY WILL REMAIN TOLERABLE WITH DEW PTS IN THE U50S TO L60S. TUESDAY AND WEDNESDAY... BECOMING HUMID BY TUE AS DEW PTS CLIMB INTO THE 60S REGIONWIDE. GEFS AND ECENS ENSEMBLES BOTH SUPPORT AIRMASS WARMING AND ADVECTING 850 TEMPS OF +18C AND +22C AT 925 MB ACROSS SNE. THIS WILL SUPPORT TEMPS IN THE 90S BOTH DAYS AWAY FROM THE SOUTH COAST...WHERE SW WINDS OFF THE OCEAN WILL KEEP HIGHS IN THE 80S. IN FACT 2 METER TEMPS FROM THE 00Z GFS AND ECMWF OFFER 90-95 BOTH TUE AND WED. RECORD HIGHS TUE ARE IN THE M90S WITH RECORDS WED IN THE L90S. LOW TO MODERATE PROBABILITY WE COME CLOSE TO RECORD HIGH TEMPS BOTH DAYS. LOW RISK OF CONVECTION WED ACROSS WESTERN MA/CT ASSOCIATED WITH WEAK HEIGHT FALLS AND SURFACE TROUGH APPROACHING FROM NY STATE. GEFS SUGGESTING SOME INSTABILITY ACROSS WESTERN NEW ENGLAND INTO NY. NONETHELESS DRY TUE WITH MUCH OF THE REGION REMAINING DRY WED AS WELL EXCEPT VERY LOW RISK OF STORMS WESTERN MA/CT. THURSDAY AND FRIDAY... WITH LONG WAVE TROUGH SETTING UP ACROSS THE GREAT LAKES AND MS VLY A COLD FRONT WILL ENTER THE NORTHEAST AND LIKELY STALL FOR A TIME AS THE MID LEVEL FLOW PARALLELS THE FRONT. THIS COMBINED WITH PWATS ABOVE NORMAL ACROSS THE NORTHEAST COUPLED WITH SOME INSTABILITY SHOULD YIELD SCATTERED SHOWER/T-STORMS. BOTH GEFS AND ECENS ENSEMBLES SUGGEST A FRONTAL WAVE POSSIBLY TRACKING INTO THE REGION IN RESPONSE TO MID LEVEL TROUGH AMPLIFICATION. THUS PRECIP COULD BE WIDESPREAD AND APPRECIABLE. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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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 SUNDAY/...HIGH CONFIDENCE. 7 AM UPDATE... NO MAJOR CHANGES TO 06Z AND 09Z TAF ISSUANCES. PREVIOUS DISCUSSION BELOW. ================================================================== MAINLY VFR. ONLY CAVEAT WILL BE OCCASIONAL MVFR/IFR FOG AT TYPICALLY PRONE LOW-LYING TERMINALS DURING THE EARLY MORNING HOURS. NE WINDS ASSISTED BY SEA BREEZES TODAY. SW WINDS WITH SEA BREEZES SUN. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. SEABREEZE DEVELOPING BY 16Z. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK /SUNDAY NIGHT THROUGH WEDNESDAY/...HIGH CONFIDENCE. VFR THROUGH THE PERIOD. AREAS OF EARLY MORNING IFR CIGS/VSBYS POSSIBLE IN FOG. INCREASING WEST-SOUTHWEST FLOW MONDAY-TUESDAY. LOW RISK OF AFTN/EVENING SHOWERS/T-STORMS WED ACROSS WESTERN MA/CT.
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH SUNDAY/...HIGH CONFIDENCE. STRONG HIGH PRES WILL BUILD ACROSS THE WATERS THROUGH THE WEEKEND. ALTHOUGH SOME WIND GUSTS ALONG THE SRN WATERS WILL REACH ABOUT 15 KTS...EXPECT MAINLY QUIET BOATING WEATHER THROUGH THE PERIOD. OUTLOOK /SUNDAY NIGHT THROUGH WEDNESDAY/...HIGH CONFIDENCE. TRANQUIL BOATING WEATHER THIS PERIOD AS A LARGE HIGH PRESSURE REMAINS OVER...OR NEAR...THE WATERS SUN NIGHT THEN SHIFTING SOUTH OF NEW ENGLAND NEXT WEEK YIELDING SW WINDS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...NOCERA/DOODY NEAR TERM...NOCERA/DOODY SHORT TERM...DOODY LONG TERM...NOCERA AVIATION...NOCERA/DOODY MARINE...NOCERA/DOODY

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