Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 070228 CCA
AFDBUF

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE BUFFALO NY
1028 PM EDT MON JUL 6 2015

.SYNOPSIS...
A WARM AND MUGGY AIRMASS WILL REMAIN IN PLACE OVERNIGHT AND
TUESDAY WITH SHOWERS AND THUNDERSTORMS BECOMING MORE WIDESPREAD
DURING THE COURSE OF TUESDAY AFTERNOON AND EVENING IN ADVANCE OF
AN APPROACHING COLD FRONT... WITH SOME OF THE STORMS HAVING THE
POTENTIAL TO BECOME STRONG TO SEVERE WITH STRONG GUSTY WINDS. THE
COLD FRONTAL PASSAGE TUESDAY NIGHT WILL THEN BRING THE SHOWERS AND
STORMS TO AN END...WHILE USHERING IN COOLER AND DRIER WEATHER FOR
MIDWEEK.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 1025 PM...THE VAST MAJORITY OF THE DIURNALLY-DRIVEN
CONVECTION FROM LATE THIS AFTERNOON/EARLY THIS EVENING HAS
DISSIPATED WITH THE LOSS OF HEATING. THE REMAINDER OF THE NIGHT
SHOULD BE MAINLY DRY... THOUGH AN ADDITIONAL STRAY SHOWER OR TWO
CANNOT BE COMPLETELY RULED OUT OVERNIGHT AS THE WEAK UPPER LOW
OVER THE UPPER OHIO VALLEY LIFTS NORTHEAST INTO OUR REGION...WHERE
A VERY WARM AND MUGGY AIRMASS WILL REMAIN IN PLACE. SPEAKING OF
WHICH...A LIGHT TO MODEST SOUTHERLY LOW LEVEL FLOW WILL KEEP
DEWPOINTS UP INTO THE 60S OVERNIGHT...WITH OVERNIGHT LOWS RANGING
FROM THE MID 60S TO AROUND 70...WITH THE WARMEST READINGS FOUND
ALONG THE LAKE PLAINS.

ON TUESDAY...OUR AIRMASS WILL BECOME EVEN WARMER AS 850MB TEMPS
WILL BE RUNNING ANYWHERE FROM +16C TO +18C...WHICH WILL TRANSLATE
INTO AFTERNOON HIGHS IN THE MID TO UPPER 80S IN MOST PLACES...WITH
THE GENESEE VALLEY SOARING INTO THE LOWER 90S THANKS TO A
FRESHENING DOWNSLOPE SOUTHWESTERLY FLOW.

AFTER A MAINLY DRY MORNING...CONVECTION WILL ALSO BECOME MORE
LIKELY WITH TIME TUESDAY AFTERNOON AS A STRONGER UPPER LEVEL
TROUGH PUSHES EASTWARD FROM THE UPPER GREAT LAKES. WITH SBCAPES
CLIMBING TOWARD 1500 J/KG ACROSS WESTERN NEW YORK IN THE
AFTERNOON...IT IS LIKELY THAT WE WILL SEE CONVECTION INITIATE
ALONG THE LAKE BREEZE BOUNDARIES BY MID TO LATE AFTERNOON. WHILE
SHEAR LEVELS WILL NOT BE PARTICULARLY IMPRESSIVE AND ONLY ON THE
ORDER OF 25 KTS...A SIGNIFICANT AMOUNT OF MID-LEVEL DRY AIR COULD
ALLOW FOR THE DEVELOPMENT OF DOWNBURSTS CAPABLE OF PRODUCING
ISOLATED DAMAGING WINDS. AS WE MOVE INTO THE EVENING HOURS... THE
ACCOMPANYING COLD FRONT WILL APPROACH THE REGION...LIKELY
RESULTING IN ANOTHER ROUND OF CONVECTION TUESDAY EVENING.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
TUESDAY NIGHT A MID LEVEL TROUGH WILL SWING EAST ACROSS QUEBEC WITH
A TRAILING COLD FRONT CROSSING THE LOWER LAKES. MOST OF THE LARGE
SCALE FORCING FOR ASCENT WILL REMAIN WELL NORTH ACROSS CANADA...WITH
WEAK DPVA ON THE SOUTHERN EDGE OF THE TROUGH CROSSING OUR REGION.
MOST OF THE FORCING WILL COME FROM MESOSCALE FEATURES...INITIALLY
THE LAKE BREEZE CONVERGENCE BOUNDARIES LATE TUESDAY AFTERNOON AND
EVENING FOLLOWED BY CONVERGENCE ALONG THE COLD FRONT OR PRE-FRONTAL
TROUGH. MODERATE INSTABILITY WILL BE PRESENT UPSTREAM ACROSS OHIO
WHERE RICHER BOUNDARY LAYER MOISTURE EXISTS...WITH WEAKER
INSTABILITY EXTENDING INTO WESTERN NY.

SUFFICIENT INSTABILITY AND FORCING LOOK TO BE PRESENT ALONG THE
ADVANCING FRONT TO JUSTIFY HIGH LIKELY POPS FOR TUESDAY EVENING.
DEEP LAYER SHEAR IS MARGINAL AT AROUND 30 KNOTS...BUT IF STORMS CAN
ORGANIZE INTO LINES SOME MAY PRODUCE GUSTY WINDS. SPC HAS CONTINUED
A MARGINAL RISK FOR A PORTION OF THE AREA...AND THIS LOOKS
REASONABLE GIVEN UNCERTAINTY ON CONVECTIVE EVOLUTION UPSTREAM. IF A
STRONGER LINE CAN DEVELOP UPSTREAM...THERE IS SOME RISK FOR DAMAGING
WINDS ACROSS WESTERN NY DURING THE EVENING. PWAT WILL REACH 2 INCHES
JUST AHEAD OF THE FRONT...AND THIS WILL BRING A RISK OF VERY HEAVY
DOWNPOURS WITH ANY STRONGER CONVECTION. IF TRAINING OR BACKBUILDING
OCCURS THIS MAY RESULT IN SOME ISOLATED FLOOD RISK.

LATER TUESDAY NIGHT THE FRONT WILL ADVANCE SOUTHEAST AND AWAY FROM
THE AREA. SHOWERS AND THUNDERSTORMS WILL TAPER OFF FROM NORTHWEST TO
SOUTHEAST WITH THE PASSAGE OF THE COLD FRONT OVERNIGHT.

ON WEDNESDAY THE FRONT WILL PUSH SOUTH INTO CENTRAL PA AND STALL...
WITH ONE OR TWO WEAK WAVES RIPPLING ALONG THE FRONT. LATEST 12Z
GUIDANCE CONTINUES TO KEEP THE FRONTAL ZONE FAR ENOUGH SOUTH TO KEEP
OUR ENTIRE REGION DRY WEDNESDAY. A COOLER AND LESS HUMID AIRMASS
WILL ARRIVE WITH HIGHS IN THE MID 70S ACROSS LOWER ELEVATIONS AND
AROUND 70 ON THE HILLS.

LATER WEDNESDAY NIGHT AND THURSDAY A CONVECTIVELY GENERATED MID
LEVEL WAVE WILL MOVE NORTHEAST ALONG THE FRONTAL ZONE ACROSS THE
OHIO VALLEY AND SPAWN ANOTHER WEAK WAVE OF LOW PRESSURE. THIS WAVE
IS FORECAST BY THE 12Z GFS/NAM/ECMWF SUITES TO BRING THE FRONTAL
ZONE BACK NORTHWARD INTO WESTERN AND CENTRAL NY. EVEN WITH THE MODEL
CONSISTENCY IN THE 12Z RUN...PREVIOUS MODEL RUNS HAVE SHOWN A GOOD
DEAL OF VARIABILITY WITH RESPECT TO THE TIMING AND PLACEMENT OF THIS
WAVE. COMBINE THAT WITH THE FACT THAT THE SYSTEM OF INTEREST IS
BEING GENERATED FROM SUBTLE MONSOONAL CONVECTION ACROSS THE FOUR
CORNERS REGION...AND CONFIDENCE IS STILL ONLY AVERAGE AT BEST FOR
THURSDAY. WITH THIS IN MIND WILL KEEP POPS IN THE CHANCE RANGE FOR
SHOWERS AND THUNDERSTORMS THURSDAY...WITH THE GREATER CHANCES FOR
SOUTHERN AREAS.

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

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
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 /03Z TUESDAY THROUGH SATURDAY/...
MAINLY DRY AND QUIET WEATHER IS EXPECTED OVERNIGHT...THOUGH AN
ADDITIONAL STRAY SHOWER OR TWO WILL REMAIN POSSIBLE AS A WEAK
UPPER LEVEL LOW LIFTS INTO OUR REGION FROM THE OHIO VALLEY. EXPECT
GENERAL VFR CONDITIONS TO CONTINUE TO PREVAIL...THOUGH SOME
LOCALIZED REDUCTIONS TO MVFR IN HAZE/LIGHT FOG CANNOT BE
COMPLETELY RULED OUT GIVEN THE VERY WARM AND HUMID AIRMASS THAT
WILL BE IN PLACE.

GENERAL VFR CONDITIONS WILL THEN CONTINUE THROUGH TUESDAY
MORNING... BEFORE THE COMBINATION OF INCREASING DIURNAL
HEATING/INSTABILITY AND DEVELOPING LAKE BREEZE BOUNDARIES LEADS TO
AN INCREASING COVERAGE OF SHOWERS AND THUNDERSTORMS DURING TUESDAY
AFTERNOON...A FEW OF WHICH COULD BECOME STRONG TO SEVERE WITH
LOCALIZED STRONG WIND GUSTS. SHOWERS AND STORMS WILL THEN BECOME
MOST WIDESPREAD VERY LATE TUESDAY AFTERNOON AND EVENING WITH THE
APPROACH OF A COLD FRONT... WHICH COULD POTENTIALLY GENERATE A
SQUALL LINE WITH ACCOMPANYING STRONG WIND GUSTS. AS THE STORMS
DEVELOP TUESDAY AFTERNOON AND EVENING...EXPECT AN INCREASING
POTENTIAL FOR REDUCTIONS TO MVFR/ IFR.

OUTLOOK...
TUESDAY NIGHT...AREAS OF MVFR AND BRIEF IFR/GUSTY WINDS WITH SHOWERS
AND THUNDERSTORMS LIKELY.
WEDNESDAY...VFR.
THURSDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS.
FRIDAY AND SATURDAY...VFR.

&&

.MARINE...
LIGHT WINDS WILL PERSIST OVERNIGHT WITH CORRESPONDINGLY TRANQUIL
CONDITIONS ON THE LAKES. SOUTHWESTERLY WINDS WILL FRESHEN TO
AROUND 15KTS ON TUESDAY AHEAD OF AN APPROACHING 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 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...JJR/WOOD
NEAR TERM...JJR/WOOD
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...JJR/WOOD
MARINE...JJR/WOOD


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