Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 310105
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
905 PM EDT WED JUL 30 2014

.SYNOPSIS...
THE FALL LIKE WEATHER PATTERN THAT WE HAVE BEEN IN THE PAST COUPLE
DAYS WILL GRADUALLY MODIFY AS WE PUSH THROUGH THURSDAY AND FRIDAY.
IN THE MEANTIME...THE COOL UNSTABLE AIRMASS WILL SUPPORT AN
OCCASIONAL SHOWER OR THUNDERSTORM...WHICH COULD BE ENHANCED BY THE
WARMER WATERS OF THE LOWER GREAT LAKES.

&&

.NEAR TERM /THROUGH THURSDAY/...
BROAD CYCLONIC FLOW AROUND AN ANOMALOUSLY DEEP UPPER LOW PARKED NEAR
JAMES BAY WILL KEEP CONDITIONS COOL AND UNSETTLED THROUGH
THURSDAY...BEFORE THE LOW FINALLY BEGINS TO RETREAT TOWARDS THE
ARCTIC BY THE END OF THE WEEK. IN THE MEANTIME...WESTERN AND
NORTH-CENTRAL NEW YORK WILL HAVE AT LEAST A FEW HOURS TO DRY OUT AS
AN AREA OF SUBSIDENCE BEHIND THIS AFTERNOON`S SHORTWAVE CROSSES THE
STATE. YET ANOTHER SHORTWAVE WILL FOLLOW HOT ON IT`S HEELS
HOWEVER...BRINGING ANOTHER ROUND OF SCATTERED SHOWERS AND
THUNDERSTORMS TO WESTERN NEW YORK LATE TONIGHT AND INTO THURSDAY
MORNING. THE MOST LIKELY AREAS TO SEE ADDITIONAL RAINFALL WILL ONCE
AGAIN BE EAST/NORTHEAST OF THE LAKES THANKS TO FAVORABLE LAKE-EFFECT
PARAMETERS. WITH LAKE-INDUCED EQUILIBRIUM LEVELS ONCE AGAIN
APPROACHING 30KFT AND PLENTY OF COLD AIR ALOFT...LIGHTNING AND SMALL
HAIL WILL ONCE AGAIN BE POSSIBLE.

AS WE MOVE THROUGH THE MORNING HOURS...THE HEAVIEST SHOWERS AND
THUNDERSTORMS ARE EXPECTED CROSS THE AREA FROM WEST TO EAST...TIED
PRIMARILY TO THE SHORTWAVE. WHILE THERE WILL LIKELY BE SOME CLEARING
IN THE SUBSIDENCE BEHIND THIS DISTURBANCE...WE MAY SEE ENOUGH
LINGERING DIURNAL INSTABILITY TO SQUEEZE OUT A FEW MORE SCATTERED
SHOWERS IN THE AFTERNOON GIVEN THE PERSISTENT CYCLONIC FLOW AND COOL
AIR ALOFT. THIS COOL AIR IN PLACE WILL CONTINUE TO DEPRESS
TEMPERATURES TO AROUND 5 DEGREES BELOW AVERAGE FOR THE END OF JULY
WITH LOWS IN THE 50S TONIGHT AND HIGHS IN THE LOW TO MID 70S ON
THURSDAY.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
THE PERSISTENT BROAD UPPER LEVEL TOUGH WILL REMAIN ACROSS THE
EASTERN CONUS INTO THE UPCOMING WEEKEND. WHILE THIS GENERALLY SHOULD
KEEP A THREAT FOR SHOWERS AND THUNDERSTORMS IN PLAY...MODELS ARE IN
GOOD CONSENSUS SHOWING A SHORT PERIOD OF FLAT RIDGING ACROSS NEW
YORK STATE THURSDAY NIGHT AND FRIDAY. THIS SHOULD PROVIDE A WINDOW
OF DRY CONDITIONS. LATER ON FRIDAY PWATS AND MOISTURE TRANSPORT
VECTORS SHOW A SURGE OF MOISTURE NORTH FROM THE MID-ATLANTIC WHICH
WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS MAINLY TO THE
SOUTHERN TIER. BY SATURDAY THE UPPER TROUGH WILL RELOAD AS THE NEXT
STRONG SHORTWAVE TROUGH SHIFTS ACROSS THE GREAT LAKES. THE
COMBINATION OF THIS COOLING ALOFT WITH INCREASE IN MOISTURE WILL
BRING A HIGHER CHANCE OF STORMS SATURDAY. FORECAST BULK SHEAR LOOKS
TOO LOW AT THIS TIME FOR ANY SEVERE THREAT.

IN TERMS OF TEMPERATURES...THE CORE OF THE UPPER LOW IS FORECAST TO
SHIFT FROM NEAR JAMES BAY TO NORTHERN QUEBEC. THIS WILL PULL THE
COLDEST AIR WITHIN THE TROUGH NORTHWARD. WARMING OVER THE LOWER LAKES
ALONG WITH A SOUTHERLY FLOW NEAR THE SURFACE WILL HELP BOOST
TEMPERATURES AND HUMIDITY LEVELS BACK TO NEAR AVERAGE FOR
MID-SUMMER. LOW TEMPERATURES THURSDAY NIGHT WILL DIP INTO TO THE MID
TO LOW 50S BUT BY SATURDAY NIGHT EXPECT OVERNIGHT LOWS TO ONLY FALL
INTO THE LOW 60S TO UPPER 50S. THE SHORTWAVE RIDGING FRIDAY WILL
HELP HIGH TEMPS PUSH INTO THE UPPER 70S AND LOW 80S BUT AN INCREASE
IN CLOUD COVER AND SHOWER/STORM COVERAGE ON SATURDAY SHOULD TOP OUT
TEMPS ABOUT 5 DEGREES COOLER.

&&

.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 /01Z THURSDAY THROUGH MONDAY/...
THE ROUND OF SHOWERS AND THUNDERSTORMS THAT MOVED THROUGH WESTERN
AND CENTRAL NY THIS AFTERNOON AND EVENING HAS LARGELY EXITED THE
FORECAST AREA AT THIS TIME. THERE WILL BE PERIOD OF CLEARING BEHIND
THIS ACTIVITY THROUGH THE REST OF EVENING WITH SCATTERED MID/HIGH
CLOUDS WORKING THEIR WAY ACROSS THE AREA IN THE BROAD CYCLONIC FLOW
THAT IS STILL IN PLACE ACROSS THE REGION.

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO MOVE INTO THE
WESTERN NEW YORK LATE TONIGHT AS ANOTHER UPPER LEVEL DISTURBANCE
ROTATES ACROSS THE AREA...WITH ACTIVITY BLOSSOMING FROM THE GENESEE
VALLEY EAST DURING THE LATE MORNING AND EARLY AFTERNOON AS THE
SYNOPTIC LIFT ASSOCIATED WITH THE PASSING DISTURBANCE IS ENHANCED BY
DIURNAL INSTABILITY. WHILE PREVAILING CONDITIONS WITH THESE SHOWERS
AND THUNDERSTORMS SHOULD REMAIN VFR...BRIEF PERIODS OF MVFR/IFR IN
HEAVIER THUNDERSTORMS WILL BE POSSIBLE. THE BULK OF THE ACTIVITY IS
EXPECTED TO TAPER OFF FROM WEST TO EAST THURSDAY AFTERNOON AS THE
DISTURBANCE MOVES OFF TO THE EAST...THOUGH AN ISOLATED SHOWER OR TWO
WILL BE POSSIBLE THROUGH THE REST OF THE AFTERNOON GIVEN THE
CONTINUED BROAD CYCLONIC CIRCULATION REMAINING IN PLACE ACROSS THE
FORECAST AREA.

OUTLOOK...
THURSDAY NIGHT AND FRIDAY...VFR.
SATURDAY AND SUNDAY...MAINLY VFR WITH CHANCE SHOWERS AND
THUNDERSTORMS.
MONDAY...VFR.

&&

.MARINE...
AN UNSEASONABLY COOL AIRMASS OVER THE WARM WATERS OF LAKES ERIE AND
ONTARIO HELPED TO GENERATE SOME LAKE INDUCED SHOWERS LAST NIGHT...
AND DURING THE COURSE OF THE NEXT 24 TO 30 HOURS...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 VCNTY OF 8C 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 ALSO HAVING A WATERSPOUT.

WHILE WINDS AND WAVES ON LAKE ONTARIO WILL REMAIN BELOW SMALL CRAFT
ADVISORY CRITERIA THROUGH THURSDAY...SOUTHWEST WINDS ON LAKE ERIE
HAVE INCREASED TO THE POINT WHERE A SHORT LIVED SCA HAS BEEN ISSUED.
WINDS ON LK ERIE WILL THEN DROP OFF RATHER QUICKLY THIS EVENING...
WITH MINIMAL WINDS AND WAVES EXPECTED OVERNIGHT AND THURSDAY.

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
NEAR TERM...WOOD
SHORT TERM...SMITH
LONG TERM...SMITH
AVIATION...WOOD
MARINE...RSH







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