Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 311138 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 738 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. SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THIS FEATURE HAVE MOVED INTO CENTRAL NY WITH A TAIL OF LAKE ENHANCED SHOWERS STRETCHING BACK TO LAKE ERIE. THE STORMS ASSOCIATED WITH THE SHORTWAVE SHOULD EVENTUALLY WEAKEN AS THE CONTINUE TO MOVE EAST...ALTHOUGH THEY WERE FAIRLY PERSISTENT OVERNIGHT WITH SOME IMPRESSIVE SMALL HAIL/ACCUMULATION REPORTS OVER THE WESTERN FINGER LAKES REGION. MEANWHILE THE BROKEN LAKE BAND MAY BRIEFLY FIRE UP SOME MORE THIS MORNING...ALTHOUGH THIS TOO SHOULD EVENTUALLY WEAKEN AS THE LAND BREEZE REORGANIZES INTO A LAKE BREEZE LATER THIS MORNING. THERE IS ANOTHER SUBTLE BOUNDARY THAT IS STILL UPSTREAM AS WELL. THIS AREA HAD SOME SHOWERS ASSOCIATED WITH IT OVERNIGHT...BUT THEY WEAKENED SUBSTANTIALLY OVER THE PAST SEVERAL HOURS. THIS MAY FIRE UP OVER WESTERN NY AGAIN THIS MORNING...BUT HAVE LOWERED CONFIDENCE WITH ITS REDEVELOPMENT. LATER THIS MORNING AFTER THE LAKE BREEZE DEVELOPS...THE MAIN SHORTWAVE TROUGH WILL BE OVER CENTRAL NY WITH MINIMAL SUPPORT ALOFT FOR WIDESPREAD CONVECTIVE DEVELOPMENT. THEREFORE 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 /12Z THURSDAY THROUGH MONDAY/... AN UPPER LEVEL TROUGH REMAINS OVER THE REGION THIS MORNING. A BROKEN AREA OF LAKE ENHANCED SHOWERS CAN BE FOUND EAST OF LAKE ERIE. THIS SHOULD WEAKEN THIS MORNING AND BE REPLACED BY INLAND CONVECTION FROM LAKE BREEZE BOUNDARIES. EAST OF LAKE ONTARIO...EXPECT A LINE CONVECTION TO QUICKLY MOVE EAST THIS MORNING...WITH ISOLATED TO SCATTERED CONVECTION LATER THIS AFTERNOON. ANY THUNDERSTORMS SHOULD QUICKLY DISSIPATE TOWARD SUNSET. AREAS UNDER SHOWERS/THUNDERSTORMS MAY SEE SOME BRIEF IFR...BUT IN GENERALLY EXPECT VFR CONDITIONS FOR ALL BUT THE SOUTHERN TIER WHERE SOME IFR CONDITIONS CAN BE FOUND THIS MORNING UNDER LOW CIGS. VFR CAN BE 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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