Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 071821
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
221 PM EDT TUE JUL 7 2015

.SYNOPSIS...
A VERY WARM AND MUGGY AIRMASS WILL REMAIN IN PLACE
TODAY...UNTIL A COLD FRONT WITH SHOWERS AND THUNDERSTORMS PASSES
ACROSS THE REGION LATE AFTERNOON AND EVENING. SOME OF THESE STORMS
COULD BECOME STRONG TO SEVERE WITH TORRENTIAL DOWNPOURS AND GUSTY
WINDS. BEHIND THE COLD FRONT...WEDNESDAY WILL DRY OUT WITH A RETURN
TO SUNSHINE THROUGH THE DAY AND NOTICEABLY COOLER DEWPOINTS.

&&

.NEAR TERM /THROUGH TONIGHT/...
AN APPROACHING COLD FRONT HAS VEERED THE WINDS A LITTLE MORE
SOUTHWESTERLY ACROSS WESTERN NEW YORK EARLY THIS AFTERNOON...
ACCENTUATING THE LOW LEVEL CONVERGENCE ALONG THE LAKE ERIE SHORE TO
THE CHAUTAUQUA RIDGE. A WEAK PREFRONTAL TROUGH HAS MAINTAINED WIDELY
SCATTERED WEAK CONVECTION ACROSS WESTERN LAKE ERIE INTO SOUTHERN
ONTARIO AND IS WORKING ITS WAY EASTWARD. HIGHER CAPE VALUES BUILDING
TO THE 1200-2000 J/KG RANGE ACROSS NORTHWEST PA AND SOUTHWESTERN NY
INDICATE THE CONVECTIVE POTENTIAL...ESPECIALLY ONCE THE TROUGH MOVES
FARTHER ENOUGH TO THE EAST TO INTERACT WITH THE LAKE BREEZE
CONVERGENCE. WILL HAVE HIGH LIKELY POPS LATE THIS AFTERNOON RISING
TO CATEGORICAL FROM THE CHAUTAUQUA RIDGE EASTWARD TO THE FINGER
LAKES THIS EVENING. HIGH PRECIPITABLE WATER VALUES IN EXCESS OF 2
INCHES ALSO INDICATE VERY HEAVY RAIN POTENTIAL. WILL HAVE TO WATCH
FOR FLASH FLOODING RISK OVER THE HIGHER TERRAIN OF SOUTHERN TIER AND
HILLS OF THE FINGER LAKES IF STORMS START TO TRAIN OVER THE SAME
AREAS. SIMILAR CONDITIONS ARE EXPECTED ALONG AND AHEAD OF THE COLD
FRONT FOR THE TUG HILL REGION AND THE BLACK RIVER VALLEY. HIGH
CAPES...HIGH WATER CONTENT...LAKE BREEZE CONVERGENCE AND PREFRONTAL
TROUGH ALL POINT TOWARD A STORMY LATE DAY AND EVENING FOR THE
EASTERN LAKE ONTARIO REGION.


PATCHY FOG IS POSSIBLE OVERNIGHT AS FALLING TEMPERATURES WILL COOL
TO NEAR THE DEWPOINTS. EXPECT CLOUDS TO REMAIN ABUNDANT OVERNIGHT
WITH LOWS DROPPING BACK TO THE UPPER 50S TO LOWER 60S.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
PROGRESSIVE POST-FRONTAL DRYING WILL OCCUR WEDNESDAY FROM NORTHWEST
TO SOUTHEAST. THIS WILL RESULT IN A PERIOD OF DRY AND STABLE
CONDITIONS WEDNESDAY AND WEDNESDAY EVENING AS HIGH PRESSURE BUILDS
ACROSS THE REGION. HIGHS WEDNESDAY OF LOWER TO MID 70S WITH
NOTICEABLY LOWER HUMIDITY COMPARED TO TODAY.

MID LEVEL FLOW TRANSITIONS TO LOWER AMPLITUDE SOUTHWESTERLIES
IMMEDIATELY UPSTREAM OF EXPANDING SUBTROPICAL RIDGING TAKING HOLD
OVER THE SOUTHEAST CONUS. THIS EVOLUTION WILL POTENTIALLY RESULT IN
A PERIODICALLY ACTIVE PERIOD THROUGH THE LATTER HALF OF THE SHORT
TERM PERIOD. THIS PROCESS WILL INITIATE LATE WEDNESDAY NIGHT AND
THURSDAY AS A LEAD WAVE EJECTS OUT OF THE GROWING UPPER HEIGHT FIELD
ACROSS THE SOUTHERN CONUS. RESPECTABLE SURFACE WAVE APPEARS TO
EMERGE WITH THIS FEATURE...RESULTING IN A COMPACT BUT STRONG
CORRIDOR OF FORCING AND ACCOMPANYING MOISTURE TRANSPORT THAT SHIFTS
INTO THE OHIO VALLEY/GREAT LAKES DURING THIS TIME. EXACT TIMING AND
POSITIONING REMAINS SOMEWHAT ILL-DEFINED YET...POTENTIAL EXISTS FOR
AT LEAST SOUTHERN PORTIONS OF WESTERN NEW YORK TO GET INTO THE
EVENTUAL PRECIPITATION SWATH. THIS CONTINUES TO WARRANT A BROADER
AND MORE CONSERVATIVE DISTRIBUTION OF PRECIPITATION CHANCES AT THIS
STAGE WITH STILL A GOOD DEAL OF MODEL SPREAD REMAINING. THE
EXTENSIVE HIGHER CLOUD COVER AND NORTHERLY LOW LEVEL GRADIENT WILL
CAP HIGHS IN THE 70S THURSDAY...REGARDLESS OF PRECIPITATION
TIMING/COVERAGE.

THURSDAY NIGHT THIS SURFACE WAVE WILL EXIT INTO NEW ENGLAND WITH
RAIN CHANCES DIMINISHING FROM WEST TO EAST.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
FRIDAY AND SATURDAY A BUBBLE OF HIGH PRESSURE WILL STALL IN PLACE
OVER THE LOWER LAKES AND NEW ENGLAND WHILE A STALLED FRONTAL ZONE
REMAINS TO THE WEST ACROSS THE LOWER OHIO VALLEY AND WESTERN LAKES.
THIS SHOULD BRING DRY WEATHER BOTH DAYS WITH TEMPERATURES SLOWLY
WARMING BACK TO JUST ABOUT AVERAGE AFTER A FEW COOLER DAYS MIDWEEK.
THIS WILL TRANSLATE INTO HIGHS IN THE LOWER 80S ACROSS LOWER
ELEVATIONS.

SUNDAY INTO EARLY NEXT WEEK A MID LEVEL TROUGH WILL MOVE FROM THE
UPPER MIDWEST INTO THE WESTERN LAKES. THIS WILL FORCE INCREASING
MOISTURE AND INSTABILITY BACK INTO OUR REGION...WITH LARGE SCALE
FORCING INCREASING BY MONDAY AS THE MID LEVEL WAVE AND WEAK SURFACE
REFLECTION MOVE TOWARDS THE LOWER LAKES. THIS WILL BRING A CHANCE OF
SHOWERS AND STORMS AGAIN FROM LATER SUNDAY THROUGH MONDAY.
TEMPERATURES WILL REMAIN WARM SUNDAY AND MONDAY AS LONG AS SHOWERS
DONT BECOME TOO WIDESPREAD...WITH HIGHS IN THE LOWER 80S BOTH DAYS.
HUMIDITY WILL BE ON THE INCREASE AS WELL.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
ALL TAF SITES WILL START THIS FORECAST PERIOD WITH VFR CONDITIONS.
AN APPROACHING COLD FRONT WILL HAVE SHOWERS AND THUNDERSTORMS
PRECEDING AND ACCOMPANYING THE PASSAGE OF THE FRONT...GENERALLY FROM
21Z TO 03Z IN THE WEST AND 00Z TO 06Z FOR KART IN THE EAST. EXPECT
MVFR CIGS AND VSBYS DURING THIS TIMEFRAME WITH IFR OR EVEN SHORT
LIVED LIFR CONDITIONS DURING THUNDERSTORMS...HEAVIER CONVECTION
EXPECTED 22Z TO 01Z IN THE WEST AND 00Z TO 03Z IN THE EAST.

THERE WILL BE LOWER MVFR CLOUDS AND A LIGHT FOG FORMING OVERNIGHT
AFTER PRECIP WANES...SOME AREAS OF IFR TO LIFR CEILINGS IN THE
SOUTHERN TIER.

DRIER AND COOLER AIR FOLLOWING THE FRONT WILL BRING WIDESPREAD VFR
CONDITIONS FOR MOST OF WEDNESDAY.


OUTLOOK...

WEDNESDAY...VFR.
THURSDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND
THUNDERSTORMS.
FRIDAY AND SATURDAY...VFR.
SUNDAY...VFR TO MVFR IN SHOWERS AND THUNDERSTORMS.

&&

.MARINE...
ON THE LAKE WATERS SOUTHWESTERLY WINDS WILL FRESHEN TO
AROUND 15KTS TODAY AHEAD OF THE COLD FRONT...HOWEVER CONDITIONS
SHOULD REMAIN BELOW SMALL CRAFT LEVELS ON TUESDAY.

THE COLD FRONT WILL CROSS THE LAKES TUESDAY EVENING...POTENTIALLY
GENERATING A SQUALL LINE WITH A SHORT PERIOD OF STRONGER WINDS AS IT
CROSSES THE LAKES. WINDS WILL QUICKLY SLACKEN BEHIND THE FRONT AS
WEAK HIGH PRESSURE MOVES ACROSS THE REGION AND LINGERS THROUGH THE
REST OF THE WEEK.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...WCH
SHORT TERM...TMA
LONG TERM...HITCHCOCK
AVIATION...WCH
MARINE...THOMAS


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