Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 310813
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
413 AM EDT THU JUL 31 2014

.SYNOPSIS...
THE FALL LIKE WEATHER PATTERN THAT WE HAVE BEEN IN THE PAST COUPLE
DAYS WILL GRADUALLY MODIFY DURING THE REMAINDER OF THE WEEK. IN THE
MEANTIME...THE COOL UNSTABLE AIRMASS WILL SUPPORT A PASSING SHOWER
OR THUNDERSTORM THROUGH THIS AFTERNOON AND AGAIN ON FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE WESTERN US RIDGE/EASTERN US TROUGH CONTINUES WITH AN ANOMALOUSLY
DEEP UPPER LEVEL LOW OVER JAMES BAY THIS MORNING.  ONE STRONG
SHORTWAVE TROUGH IS ROUNDING THE BASE OF THE LOW AND WILL MOVE EAST
OF WESTERN NY THIS MORNING.  A SMALL BATCH OF SHOWERS AND
THUNDERSTORMS...ENHANCED BY THE WARM LAKE ERIE WATER OVERNIGHT
SHOULD MOVE EAST OF THE BUF METRO AREA DURING THE MORNING HOURS AND
WEAKEN AS IT MOVES INTO THE GENESEE VALLEY...ALTHOUGH ANOTHER ROUND
OF STORMS IS EXPECTED TO DEVELOP AFTER SUNRISE OVER PARTS OF WESTERN
NY.  THIS WILL BE DUE TO TO ANOTHER SHORTWAVE TROUGH FOLLOWING
CLOSELY ON THE HEELS OF THE FIRST ONE. SMALL CLUSTERS OF STORMS
ARE OVER SOUTHERN ONTARIO/LAKE ERIE EARLY THIS MORNING AND EXPECT THESE TO
EXPAND IN COVERAGE AFTER SUNRISE.

THIS TOO SHOULD WEAKEN LATER THIS MORNING AS DAYTIME HEATING
DISRUPTS THE UPPER LEVEL FORCING AND PROVIDES SURFACE LAND HEATING
FOR LAKE BREEZE BOUNDARIES.  BY THE TIME THESE ARE ESTABLISHED...THE
UPPER LEVEL SHORTWAVE TROUGHS WILL BE OVER CENTRAL TO EASTERN NY/SE
ONTARIO AND MOVING QUICKLY EAST.  THUS EXPECT SCATTERED
THUNDERSTORMS INLAND WITH LESS COVERAGE COMPARED TO
WEDNESDAY...WEAKENING TOWARD SUNSET.  THE CONTINUED COOL AIR IN
PLACE WILL CONTINUE TO DEPRESS TEMPERATURES TO AROUND 5 DEGREES
BELOW AVERAGE FOR THE END OF JULY WITH HIGHS IN THE LOW TO MID 70S.

WITH SUBSIDENCE BEHIND THE SHORTWAVE TROUGHS AND WARMING
ALOFT...EXPECT A DRY NIGHT.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
THE UPPER LEVEL LOW WILL SLOWLY WORKS ITS WAY ACROSS EASTERN CANADA
THROUGH THE PERIOD. THERE IS REASONABLE AGREEMENT AMONG THE MODEL
SUITE THAT SHORT WAVE ENERGY ROTATING AROUND THE BACK SIDE OF THIS
TROUGH WILL UNDERGO SOME AMPLIFICATION AS IT TRACKS FROM THE THE
GREAT LAKES AND OHIO VALLEY FRIDAY INTO SATURDAY. SUBTLE COOLING
ALOFT AND FAIRLY GOOD LOW LEVEL MOISTURE QUALITY WILL LEAD TO MODEST
DAYTIME DESTABILIZATION BOTH FRIDAY AND SATURDAY....SUPPORTIVE OF
THE CURRENT CHANCE OF SHOWERS/THUNDERSTORMS. MOST LIKELY TIMING BOTH
DAYS WILL BE DURING THE AFTERNOON AND EVENING. THERE LOOKS TO BE
LITTLE OVERALL CHANGE IN THE THERMAL PROFILE AND THE EXPECTED MIXING
HEIGHTS WILL MAINTAIN NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURE
THROUGH THE PERIOD.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A FULL CONUS 500MB TROUGH WILL EXTEND FROM THE GREAT LAKES TO THE
NORTHERN GULF ON SUNDAY. THE AXIS OF THE TROUGH IS FORECAST BY
GFS/ECMWF TO SHIFT ACROSS THE LOWER GREAT LAKES EAST TO NEW ENGLAND
BY SUNDAY NIGHT. THIS COMBINED WITH PWATS BETWEEN 1.25 AND 1.5
INCHES WILL KEEP A HIGH CHANCE OF SHOWERS AND THUNDERSTORMS IN THE
FORECAST THROUGH SUNDAY NIGHT. A SHORT WINDOW OF FLAT RIDGING AND
SURFACE HIGH PRESSURE LOOKS TO BRING DRY WEATHER ON MONDAY FOR MOST
OF WESTERN AND CENTRAL NEW YORK. THE UPPER FLOW PATTERN LOOKS TO
THEN AGAIN EXHIBIT A DEEPENING BUT THIS TIME PROGRESSIVE GREAT LAKES
TROUGH TUESDAY INTO WEDNESDAY WHICH BRINGS BACK CHANCES OF
PRECIPITATION GOING INTO MID NEXT WEEK. A PACIFIC SOURCED UPPER FLOW
PATTERN WILL KEEP TEMPERATURES NEAR AVERAGE WITH HIGHS RANGING FROM
THE MID 70S TO NEAR 80 AND LOWS FALLING INTO THE UPPER 50S TO LOW
60S.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
ROUNDS OF THUNDERSTORMS WILL DEVELOP OVER LAKE ERIE DURING THE NEXT
SEVERAL HOURS AND MOVE EAST INTO THE KBUF/KIAG REGIONS AND WEAKEN AS
THEY MOVE TOWARD THE GENESEE VALLEY/KROC AREA.  BY 18Z LAKE BREEZE
BOUNDARIES SHOULD DEVELOP WITH SCATTERED INLAND THUNDERSTORM
DEVELOPMENT.  SOME BRIEF IFR CONDITIONS ARE POSSIBLE WITH EARLY
MORNING THUNDERSTORMS...OTHERWISE EXPECT MAINLY VFR CONDITIONS.  VFR
EXPECTED AT ALL LOCATIONS AFTER SUNSET...ALTHOUGH MAY HAVE TO BE
WARY OF VALLEY FOG DEVELOPMENT LATE TONIGHT IF THERE IS SIGNIFICANT
CLEARING.

OUTLOOK...
FRIDAY...VFR.
SATURDAY AND SUNDAY...MAINLY VFR WITH A CHANCE OF -TSRA.
MONDAY...VFR.

&&

.MARINE...
AN UNSEASONABLY COOL AIRMASS OVER THE WARM WATERS OF LAKES ERIE AND
ONTARIO HELPED TO GENERATE SOME LAKE INDUCED SHOWERS OVER THE LAST
FEW NIGHTS...AND TODAY WILL ALSO BE FAVORABLE FOR THE DEVELOPMENT OF
WATERSPOUTS.

THIS FORECAST IS SUPPORTED BY THE EXCELLENT GUIDANCE OFFERED BY THE
SZILAGYI NOMOGRAM. OUR H85 TEMPS IN THE VICINITY OF 9C COMBINED WITH
A CONVECTIVE CLOUD DEPTH IN EXCESS OF 30K SUGGESTS THE POSSIBILITY
OF WATERSPOUTS. THESE HAVE BEEN IN THE FORECAST FOR SOME TIME NOW
AND WILL REMAIN IN PLACE. ANY SHOWERS THAT DEVELOP WILL THUS CARRY
THE RISK OF A WATERSPOUT.

WINDS AND WAVES SHOULD REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA...ALTHOUGH SOME GUSTS REQUIRE A SHORT-LIVED ISSUANCE OVER
LAKE ERIE AGAIN THIS AFTERNOON.

MARINERS SHOULD BE ALERT TO SHORT FUSED SPECIAL MARINE WARNINGS THAT
ARE BASED ON HEAVY SHOWERS OR THUNDERSTORMS THAT COULD BEAR
WATERSPOUTS.

&&

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

&&

$$

SYNOPSIS...RSH/ZAFF
NEAR TERM...ZAFF
SHORT TERM...TMA
LONG TERM...SMITH
AVIATION...ZAFF
MARINE...RSH/ZAFF






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