Area Forecast Discussion Issued by NWS Boston, MA
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000
FXUS61 KBOX 200707
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
307 AM EDT THU JUN 20 2013
.SYNOPSIS...
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HIGH PRESSURE BUILD OVER THE REGION TODAY. THE HIGH WILL MOVE
OFFSHORE FRIDAY AND BEGIN A TREND TOWARD WARMER AND MORE HUMID
WEATHER INTO THIS WEEKEND AND NEXT WEEK. THE VAST MAJORITY OF THE
TIME WILL BE DRY...BUT AT LEAST A FEW BOUTS OF SCATTERED
SHOWERS AND THUNDERSTORMS ARE EXPECTED FRIDAY THROUGH SUNDAY.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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305 AM UPDATE...
CLEAR SKIES/LIGHT WINDS ALLOWING PATCHY FOG TO DEVELOP ACROSS
PARTS OF INTERIOR AND NEAR S COAST. ONCE THIS BURNS OFF AROUND
SUNRISE...PLENTY OF SUNSHINE EXPECTED TODAY AS HIGH PRESSURE
BUILDS OVER NEW ENGLAND AND COLUMN REMAINS FAIRLY DRY ALOFT.
SHOULD SEE SOME DIURNAL CUMULUS BUT COVERAGE WILL BE SPARSE.
GRADIENT IS WEAK ENOUGH THROUGH EARLY AFTERNOON TO ALLOW FOR SEA
BREEZES TO DEVELOP ALONG E AND S COASTS...ALTHOUGH BY MID TO LATE
AFTERNOON SOUTHERLY FLOW INCREASES WHICH SHOULD CAUSE E COAST SEA
BREEZE TO ERODE.
HIGHS TODAY WILL REACH 70S TO LOWER 80S...COOLEST ALONG S COAST...
CAPE COD AND ISLANDS. GFS/NAM MOS IN LINE WITH MODEL 2M
TEMPERATURES.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
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HIGH PRESSURE SHIFTS OFFSHORE WHICH PUTS OUR AREA INTO SW FLOW
REGIME. STILL DRY THROUGH COLUMN SO CLEAR SKIES EXPECTED...BUT
AIRMASS MODIFIES SOMEWHAT SO EVEN WITH LIGHT WINDS TEMPERATURES
WILL NOT COOL AS MUCH AS THIS MORNING...MAINLY IN 50S.
00Z MODELS SHOW POTENTIAL FOR CONVECTION FRI AFTERNOON AS WEAK
TROUGH DROPS DOWN FROM NORTHERN NEW ENGLAND. INSTABILITY SEEMS TO
BE LIMITING FACTOR WITH SB CAPES ONLY ON ORDER OF 500-1000 J/KG.
MID LEVEL LAPSE RATES LOOK RATHER WEAK AS WELL AND SUFFICIENT LOW
LEVEL MOISTURE IS LACKING. HOWEVER THERE IS DECENT 0-6KM SHEAR
/30-40KT/ AS WE ARE ON SOUTHERN EDGE OF UPPER LEVEL JET...WHICH
COULD SERVE TO COMPENSATE. THINKING IS WE MAY SEE ISOLATED
SHOWERS/STORMS TRY TO DEVELOP ACROSS NW MA/SW NH FRI AFTERNOON...
SO INCLUDED SLIGHT CHANCE POPS FOR THESE AREAS. ANY ACTIVITY WILL
DIMINISH QUICKLY TOWARD EVENING WITH LOSS OF DAYTIME HEATING.
SEVERE THREAT IS MINIMAL.
LOOKS TO BE WARMER DAY DUE TO INCREASING SW FLOW. BLENDED IN
WARMER NAM MOS WHICH YIELDS HIGHS IN LOW-MID 80S /70S S COAST/...
BUT IT WILL STILL BE COMFORTABLE WITH DEW POINTS IN 50S.-- End Changed Discussion --
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
HIGHLIGHTS...
* HIGH PRESSURE BRINGS QUIET WEATHER FRI
* HIGH PRES S OF SNE BRINGS WARM...HUMID CONDITIONS THIS WEEKEND
* SHOWERS AND THUNDERSTORMS POSSIBLE SATURDAY
THERE IS GOOD GENERAL AGREEMENT AMONGST THE MODELS THROUGH MUCH OF
THE LONG TERM. THERE ARE SOME MODEL DISCREPANCIES REGARDING THE
STRENGTH AND EXTENT OF AN UPPER LEVEL RIDGE OVER THE EASTERN U.S.
INTO EARLY NEXT WEEK. ULTIMATELY THIS WILL AFFECT THE WEATHER IN
THIS AREA MAINLY IN WHERE AND WHEN SHOWERS AND THUNDERSTORMS ARE
ABLE TO DEVELOP. THE CONSENSUS IS WITH THE ECMWF AND THE UPPER
LEVEL RIDGE OVER THE SE CONUS GRADUALLY BUILDING NORTHWARD INTO THE
OHIO VALLEY BY SATURDAY THEN SINKING BACK SOUTH EARLY NEXT WEEK.
THERE ARE ALSO SOME DISCREPANCIES IN HOW QUICKLY THE RIDGE BREAKS
DOWN AND ALLOWS AN UPPER TROUGH TO MOVE THROUGH THE NORTHEAST. THE
ECMWF KEEPS ENOUGH RIDGING OVER SOUTHERN NEW ENGLAND TO KEEP THE
TROUGH TO THE NORTH IN SOUTHEASTERN CANADA WHILE THE GFS BREAKS IT
DOWN...ALLOWING THE TROUGH TO MOVE OVER NEW ENGLAND.
AM EXPECTING FAIRLY QUIET WEATHER OVERALL WITH MORE SUMMER LIKE
TEMPERATURES AND A FEW HUMID DAYS THROWN IN THERE AS WELL. THERE IS
POTENTIAL FOR SHOWERS AND THUNDERSTORMS EACH DAY IN THE LONG TERM
WITH PLENTY OF MOISTURE AND INSTABILITY AVAILABLE. THE ONE MISSING
INGREDIENT IS A WELL-DEFINED TRIGGER. WHILE THERE IS POTENTIAL EACH
DAY...THE BEST DAYS FOR SHOWERS AND THUNDERSTORMS ARE MONDAY AND
WEDNESDAY WITH A PRE-FRONTAL TROUGH AND A COLD FRONT...RESPECTIVELY.
ACTIVITY ON OTHER DAYS WILL DEPEND ON THE TIMING OF SHORTWAVES
MOVING OVER THE UPPER RIDGE.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...HIGH CONFIDENCE. VFR THROUGH FRI.
MAY SEE BRIEF MVFR/IFR IN PATCHY GROUND FOG THROUGH SUNRISE...
PRIMARILY AROUND CAPE COD AND ISLANDS AS WELL AS INTERIOR VALLEYS.
GRADIENT REMAINS WEAK ENOUGH TO ALLOW SEA BREEZES TO DEVELOP
AROUND 15Z ON BOTH COASTS...THOUGH BY MID TO LATE AFTERNOON S/SW
FLOW INCREASES ENOUGH THAT IT WILL ERODE E COAST SEA BREEZE.
PATCHY GROUND FOG AND BRIEF MVFR/IFR AGAIN TONIGHT NEAR CAPE COD
AND ISLANDS AS WELL AS INTERIOR VALLEYS.
SW FLOW DEVELOPS FRI WITH POTENTIAL FOR ISOLATED SHOWERS/TSTMS
DURING AFTERNOON...MAINLY ACROSS NW MA AND SW NH.
KBOS TERMINAL...HIGH CONFIDENCE. SEA BREEZE ONSET 14Z-15Z. EXPECT
IT TO DECAY 21Z-22Z AS SOUTHERLY FLOW GETS UNDERWAY.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK...SATURDAY THROUGH MONDAY...
MODERATE CONFIDENCE. MAINLY VFR. THERE IS A LOW PROBABILITY OF
SHOWERS AND THUNDERSTORMS AND ACCOMPANYING MVFR/IFR CONDITIONS EACH
AFTN/EVE.
&&
.MARINE...
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FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
HIGH CONFIDENCE THROUGH FRI. NO HEADLINES ANTICIPATED.
HIGH PRESSURE BUILDS OVER WATERS TODAY. LIGHT WINDS WILL GIVE WAY
TO LOCAL SEA BREEZES LATE THIS MORNING INTO EARLY AFTERNOON...
BEFORE INCREASING S WINDS ERODE E MA COAST SEA BREEZE. COULD SEE
FEW 20KT GUSTS ALONG NEAR SHORE S COASTAL WATERS THIS AFTERNOON.
SW FLOW GETS UNDERWAY TONIGHT/FRI AS HIGH PRESSURE SHIFTS
OFFSHORE. GRADIENT TIGHTENS SOMEWHAT FRI AFTERNOON AHEAD OF WEAK
TROUGH PUSHING DOWN FROM NORTHERN NEW ENGLAND...SO WINDS WILL
APPROACH 25KT ON NEAR SHORE S COASTAL WATERS. NOT CONFIDENT ENOUGH
TO HEADLINE SMALL CRAFT ADVISORIES JUST YET HOWEVER.
OUTLOOK...FRIDAY THROUGH MONDAY...
HIGH CONFIDENCE.
QUIET BOATING WEATHER EXPECTED THROUGH MONDAY WITH HIGH PRESSURE
NEAR OR OVER THE WATERS. THERE IS A LOW PROBABILITY OF SHOWERS AND
THUNDERSTORMS EACH AFTN/EVE THAT MAY LIMIT VISIBILITIES ON THE
WATERS. SEAS INCREASE MONDAY NIGHT AS A WEAK COLD FRONT OR PRE-
FRONTAL TROUGH MOVES ACROSS THE WATERS.-- End Changed Discussion --
&&
.HYDROLOGY...
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CHARLES RIVER AT DOVER MA CONTINUES TO RECEDE BUT REMAINS JUST
ABOVE FLOOD STAGE. LATEST NERFC FORECAST MAINTAINS MINOR FLOODING
THROUGH FRI...BEFORE RIVER FALLS BELOW FLOOD STAGE FRI NIGHT.
FARMINGTON RIVER AT SIMSBURY CT WAS CRESTING ABOUT 0.5 FT BELOW
ITS 12 FT FLOOD STAGE EARLY THIS MORNING. LATEST NERFC FORECAST
SHOWS SLOW RECESSION TODAY AND FLOODING IS NOT EXPECTED.-- End Changed Discussion --
&&
.CLIMATE...
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LOOKS LIKE RECORD LOWS FOR TODAY WILL NOT BE BROKEN. WINDSOR
LOCKS /BRADLEY/ MAY COME CLOSE...BUT RECORD SET IN 1918 APPEARS TO
BE SAFE.
BOSTON... 47 IN 1918
HARTFORD... 45 IN 1918
PROVIDENCE... 45 IN 1918
WORCESTER... 37 IN 1926-- End Changed Discussion --
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SIPPRELL/JWD
NEAR TERM...JWD
SHORT TERM...JWD
LONG TERM...RLG
AVIATION...SIPPRELL/JWD
MARINE...SIPPRELL/JWD
HYDROLOGY...JWD
CLIMATE...JWD