Hail and Damaging Wind in New York, July 21, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1041 AM EDT MON JUL 21 2008

.SYNOPSIS...
A LARGE AND WEAK LOW PRESSURE SYSTEM ALONG WITH PLENTY OF WARM AND
HUMID AIR WILL REMAIN OVER THE LOWER GREAT LAKES AND NORTHEAST
THROUGH MIDWEEK AND BRING A CONTINUATION OF UNSETTLED WEATHER WITH A
CHANCE OF A FEW SHOWERS OR THUNDERSTORMS EACH DAY. HIGH PRESSURE IS
EXPECTED TO FINALLY BUILD INTO THE REGION BY LATE IN THE WEEK
BRINGING A RETURN TO DRY WEATHER AND SUNSHINE ALONG WITH SEASONABLE
MIDSUMMER TEMPERATURES. ANOTHER COLD FRONT WILL BEGIN TO APPROACH
THE REGION NEXT WEEKEND BRINGING THE NEXT CHANCE OF RAIN.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE SURFACE TROUGH THAT EXTENDS FROM LAKE HURON TO OSWEGO COUNTY IS
SERVING AS THE PRIMARY FOCUS FOR CONVECTION THIS MORNING. THE MOST
ACTIVE CONVECTION IS FORMING JUST NORTH OF LAKE ONTARIO WHERE ADDED
LIFT IS BEING GENERATED BY THE MID LEVEL SHORT WAVE THAT IS PUSHING
THROUGH THE WESTERN END OF LAKE ONTARIO. BASED ON THIS TREND...WILL
KEEP THE HIGHEST CHANCE POPS ACROSS THE NORTHERN FINGER LAKES AND
NORTH COUNTRY THIS MORNING INTO THE EARLY AFTERNOON.

AFTER THE LOWER STRATUS DISSIPATES BY EARLY AFTERNOON...EXPECT THE
LAKE ERIE AND LAKE ONTARIO BREEZES TO BECOME BETTER DEFINED. WILL
INDICATE THE HIGHEST CHANCE POPS ALONG THESE BOUNDARIES. THERE IS A
GOOD POTENTIAL FOR HEAVY RAIN WITH PRECIPITABLE WATER VALUES
FORECAST TO INCREASE TO INCREASE TO ABOUT 1.5 INCHES BY MID
AFTERNOON.

TEMPERATURES TODAY LOOK TO BE A FEW DEGREES BELOW NORMAL WITH 850 MB
TEMPERATURES ONLY AROUND PLUS 14C...PROBABLY LOOKING AT THE UPPER
HALF OF THE 70S FOR MOST OF THE AREA BUT COULD REACH 80 DEGREES IF
ENOUGH SUNSHINE DEVELOPS.

CYCLONIC FLOW CONTINUING ACROSS THE GREAT LAKES REGION TONIGHT AS
UPPER LEVEL FLOW BECOMES MUCH MORE AMPLIFIED. CHANCES FOR CONVECTION
SHOULD BE DIMINISHING WITH LOSS OF HEATING...BUT UNDERNEATH THE
CYCLONIC FLOW THERE COULD BE SCATTERED SHOWERS JUST ABOUT ANY
TIME.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
OVERALL LONGWAVE PATTERN ACROSS NOAM THROUGH THE SHORT TERM PERIOD
WILL FEATURE A TREND TOWARDS PATTERN AMPLIFICATION AS WAVELENGTHS
SHORTEN AND A RIDGE BUILDS FROM THE WESTERN CONUS THROUGH CENTRAL
CANADA. THE RIDGE EXTENDING THROUGH CENTRAL CANADA WILL BECOME VERY
NARROW...AND BY DEFINITION WILL BE DYNAMICALLY UNSTABLE WITH A
NARROW RADIUS OF CURVATURE. AIR PARCELS ROUNDING THE TOP OF THIS
RIDGE WILL BE UNABLE TO REMAIN IN GEOSTROPHIC BALANCE AND TEND TO
MOVE LEFT OF THE MID LEVEL HEIGHT FIELD INITIALLY...THEN MOVE BACK
TO THE RIGHT AS THEY COME BACK INTO GEOSTROPHIC BALANCE...
EFFECTIVELY HELPING TO CARVE OUT A CLOSED LOW DOWNSTREAM OF THE
SKINNY RIDGE. THIS CUTOFF LOW HAS BEEN FORECAST FOR SEVERAL DAYS NOW
BY MEDIUM RANGE MODEL GUIDANCE... HOWEVER MODELS CONTINUE TO
STRUGGLE WITH THE EXACT TIMING AND PLACEMENT OF THIS FEATURE.

LOOKING AT THE DETAILS...ON TUESDAY THE QUASI-STATIONARY COMPLEX
BAROCLINIC ZONE WHICH HAS BEEN DRAPED ACROSS THE REGION FOR DAYS
SHOULD SINK A LITTLE FURTHER SOUTH. THE DEEPEST MOISTURE AND
INSTABILITY...AS SHOWN BY 850-700MB THETA-E FORECASTS OFF BOTH THE
NAM AND GFS MODELS...IS FORECAST TO SHIFT SOUTH INTO PA AND
SOUTHEAST NY ON TUESDAY. NAM BUFKIT POINT SOUNDINGS FARTHER NORTH
ACROSS WESTERN NY SHOW ONLY MINIMAL AFTERNOON INSTABILITY...OWING TO
A WARM LAYER IN THE MID LEVELS WHICH SHOULD EFFECTIVELY CAP THE
ATMOSPHERE TO DEEP MOIST CONVECTION ACROSS NORTHERN SECTIONS OF THE
AREA. WILL GO WITH A DRY FORECAST FOR TUESDAY ACROSS THE NIAGARA
FRONTIER OVER TO ROCHESTER...BUT KEEP CHANCE POPS GOING DURING THE
AFTERNOON ACROSS THE SOUTHERN TIER AND FINGER LAKES WHERE FORCING
FOR ASCENT ALONG THE SOUTHERN FRINGE OF A STRONGER BELT OF
WESTERLIES AND CLOSER PROXIMITY TO RICHER THETA-E AIR MAY COMBINE TO
PRODUCE ISOLATED TO SCATTERED AFTERNOON CONVECTION. WILL ALSO CARRY
CHANCE POPS ALL DAY EAST OF LAKE ONTARIO AND IN THE SAINT LAWRENCE
VALLEY WHERE DIFFLUENT FLOW ALOFT AHEAD OF THE DEVELOPING CLOSED LOW
MAY PROVIDE ENOUGH FORCING FOR A FEW ROUNDS OF SHOWERS AND ISOLATED
STORMS...AS SUPPORTED BY THE SREF MEAN. EXPECT ALL OF THIS ACTIVITY
TO END TUESDAY EVENING WITH THE LOSS OF DAYTIME HEATING...WITH MOST
OF THE AREA REMAINING DRY TUESDAY NIGHT.

ON WEDNESDAY THE AFOREMENTIONED CLOSED LOW WILL MATURE AND FULLY CUT
OFF...HOWEVER THERE IS STILL SOME VARIANCE IN MODEL GUIDANCE AS TO
PLACEMENT. LATEST 00Z/21 GFS RUN HAS TRENDED TOWARDS A SLOWER AND
FARTHER WEST SOLUTION...KEEPING THE BEST COLD POOL ACROSS SOUTHERN
ONTARIO WEDNESDAY. THE 00Z/21 CANADIAN GEM AND 12Z/20 ECMWF ARE
STILL A LITTLE FASTER AND FARTHER SOUTHEAST WITH THIS FEATURE...
BRINGING THE CORE OF THE COLDEST MID LEVEL AIR OVERHEAD DURING PEAK
AFTERNOON HEATING ON WEDNESDAY. IN EITHER CASE LIFT AHEAD OF THIS
FEATURE WILL BRING CHANCES OF DIURNAL CONVECTION...ESPECIALLY AWAY
FROM THE STABILIZING EFFECTS OF THE LAKES AND WILL CONTINUE TO CARRY
CHANCE POPS. IF THE ECMWF/GEM PLACEMENT VERIFIES...COLD AIR ALOFT
COUPLED WITH A STILL RELATIVELY MOIST BOUNDARY LAYER WILL PRODUCE A
SOUNDING VERY FAVORABLE TO HAIL PRODUCTION AND WILL CONTINUE TO
MONITOR THIS POTENTIAL.

DIURNAL CONVECTION WILL END WEDNESDAY EVENING ACROSS MOST OF THE
AREA. CLOSED LOW IS FORECAST TO MIGRATE SLOWLY EAST AND GRADUALLY
OPEN UP THROUGH THURSDAY. THIS WILL PLACE THE BULK OF THE CWA ON THE
DRY WESTERN SIDE OF THE TROUGH BY THURSDAY...HOWEVER THE EASTERN
LAKE ONTARIO REGION WILL REMAIN ON THE MOIST EASTERN FLANK OF THIS
FEATURE WITH RAIN CHANCES CONTINUING WEDNESDAY NIGHT AND THURSDAY.
IN FACT...EASTERN NY INTO NEW ENGLAND APPEARS TO BE IN LINE FOR AN
IMPRESSIVE HEAVY RAIN EVENT AS A SURGE OF SUB-TROPICAL MOISTURE IS
DRAWN NORTH AHEAD OF THE DIGGING TROUGH.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
SURFACE HIGH PRESSURE FINALLY BUILDS INTO THE GREAT LAKES THURSDAY
THEN INTO THE OHIO VALLEY THURSDAY NIGHT THROUGH FRIDAY AS THE SLOW
MOVING TROUGH GRADUALLY EXITS THROUGH NEW ENGLAND. GENERAL TROUGH
AND CYCLONIC FLOW ALOFT MAY REMAIN IN PLACE THROUGH THURSDAY OR EVEN
LONGER...BUT GRADUAL DIMINISHING TREND IN LOW LEVEL MOISTURE SHOULD
BRING AN END TO PRECIP CHANCES BY THURSDAY. THE EXCEPTION WILL BE
EAST OF LAKE ONTARIO...CLOSER TO THE MID LEVEL TROUGH AND DEEPER
MOISTURE PLUME SPREADING UP THE EASTERN SEABOARD.

FRIDAY NIGHT INTO THE WEEKEND THE LATEST OPERATIONAL MODEL GUIDANCE
AND MANY OF THE OLDER ENSEMBLE MEMBERS SUPPORT ANOTHER TROUGH
DIGGING INTO THE GREAT LAKES AND NEW ENGLAND. TIMING IS QUITE
UNCERTAIN HOWEVER...WITH LATEST GUIDANCE HOLDING ON TO THE TROUGHING
RIGHT THROUGH SUNDAY. GIVEN THE INHERENT UNCERTAINTY AT THIS TIME
RANGE...WILL STICK WITH FORECAST CONTINUITY WITH CHANCE POPS FRIDAY
NIGHT AND SATURDAY THEN GO DRY ON SUNDAY INSTEAD OF JUMPING ON THE
LATEST AND GREATEST MODEL RUN.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
WEAK LOW PRESSURE OVER EASTERN NEW YORK STATE WILL DRIFT EAST ACROSS
NEW ENGLAND TODAY...WHILE ANOTHER WEAK LOW PUSHES ACROSS SOUTHERN
ONTARIO. BETWEEN THESE SYSTEMS...ABUNDANT LOW LEVEL MOISTURE WILL
LINGER ACROSS THE AREA THIS MORNING...BEFORE DIURNAL HEATING
HELPS TO MIX THIS OUT BY EARLY AFTERNOON. AS A RESULT...EXPECT
WIDESPREAD MVFR CONDITIONS WITH AREAS OF IFR/VLIFR CONDITIONS IN
LOW CLOUDS/FOG TO CONTINUE THROUGH MOST OF THIS MORNING...BEFORE
IMPROVEMENT TO VFR CONDITIONS ARRIVES BY EARLY AFTERNOON.

IN TERMS OF PRECIPITATION...THE COMBINATION OF THE UPSTREAM WEAK
WAVE...ABUNDANT LOW LEVEL MOISTURE...AND THE WEAK INSTABILITY ALONG
THE FRONTAL BOUNDARY DRAPED ACROSS THE AREA SHOULD LEAD TO
SCATTERED CONVECTIVE DEVELOPMENT ACROSS THE AREA THIS AFTERNOON...
ESPECIALLY ALONG THE TYPICAL LAKE BREEZE CONVERGENCE ZONE BETWEEN
KIAG AND KROC. GIVEN THE EXPECTED SCATTERED COVERAGE TO THE
PRECIPITATION...FOR NOW HAVE JUST COVERED ALL OF THIS WITH
VCSH/VCTS IN THE TAFS.

OUTLOOK...
MONDAY AND TUESDAY...VFR WITH LOCAL MVFR IN SCATTED SHRA/TSRA.
WEDNESDAY THROUGH FRIDAY...VFR.

&&

.MARINE...
NO MARINE HEADLINES FOR THE FORESEEABLE FUTURE. DIFFICULT FORECAST
FOR WIND DIRECTION TODAY WITH WEAK BOUNDARIES AND WIND SHIFT LINES
SCATTERED ABOUT THE AREA...REMNANTS OF CONVECTION FROM THE PAST FEW
DAYS. WINDS SHOULD AVERAGE NORTHEAST OR EAST ON LAKE ONTARIO
TODAY...WITH WINDS BECOMING SOUTHWEST ON LAKE ERIE. IN ANY EVENT...
WIND SPEEDS WILL REMAIN BELOW 15 KNOTS WITH WAVES 2 FEET OR LESS
OVER THE NEXT SEVERAL DAYS.

&&

.CLIMATE...
LOCALLY HEAVY RAINS FELL SUNDAY E OF LK ONTARIO AND OVER TO ROCH
AREA WITH MANY LOCATIONS RECEIVING WELL OVER AN INCH. ROCHESTERS
1.01 INCHES WAS ACTUALLY THEIR HEAVIEST DAILY RAIN SINCE WAY BACK ON
FEBRUARY 6 WHEN 1.17 INCHES FELL.

&&

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

&&

SYNOPSIS...HITCHCOCK
NEAR TERM...TJP/TMA
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...TMA
MARINE...HITCHCOCK
CLIMATE...SFM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BUFFALO NY
530 AM EDT MON JUL 21 2008

NYZ001>008-010>014-019>021-085-220930-
NIAGARA-ORLEANS-MONROE-WAYNE-NORTHERN CAYUGA-OSWEGO-JEFFERSON-LEWIS-
NORTHERN ERIE-GENESEE-WYOMING-LIVINGSTON-ONTARIO-CHAUTAUQUA-
CATTARAUGUS-ALLEGANY-SOUTHERN ERIE-
530 AM EDT MON JUL 21 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND NORTH CENTRAL NEW
YORK.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ONCE AGAIN THIS
AFTERNOON AND EVENING. NO WIDESPREAD SEVERE WEATHER IS
ANTICIPATED...HOWEVER AN ISOLATED STORM PRODUCING DAMAGING WINDS
OR LARGE HAIL CANNOT BE ENTIRELY RULED OUT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP TUESDAY AFTERNOON
AND EVENING...MAINLY ACROSS THE SOUTHERN TIER AND FINGER LAKES AS
WELL AS THE EASTERN LAKE ONTARIO REGION. NO WIDESPREAD SEVERE
WEATHER IS ANTICIPATED...HOWEVER AN ISOLATED STORM PRODUCING
DAMAGING WINDS OR LARGE HAIL CANNOT BE ENTIRELY RULED OUT.

ADDITIONAL SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP
WEDNESDAY AFTERNOON AND EVENING. A VIGOROUS UPPER LEVEL
DISTURBANCE AND MUCH COLDER AIR ALOFT ARE EXPECTED TO APPROACH THE
AREA...WHICH MAY ALLOW SOME STORMS TO PRODUCE LARGE HAIL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

THIS PRODUCT...ALONG WITH OTHER WATCHES...WARNINGS...ADVISORIES...
AND STATEMENTS ISSUED BY THE NATIONAL WEATHER SERVICE OFFICE IN
BUFFALO CAN BE FOUND ON THE INTERNET AT HTTP://WWW.WEATHER.GOV/BUF

LEZ020-040-041-LOZ042>045-062>065-SLZ022-024-220930-
UPPER NIAGARA RIVER AND BUFFALO HARBOR-
LAKE ERIE NEARSHORE WATERS FROM RIPLEY TO DUNKIRK-
LAKE ERIE NEARSHORE WATERS FROM DUNKIRK TO BUFFALO-
LAKE ONTARIO NEARSHORE WATERS FROM THE NIAGARA RIVER TO HAMLIN BEACH-
LAKE ONTARIO NEARSHORE WATERS FROM HAMLIN BEACH TO SODUS BAY-
LAKE ONTARIO NEARSHORE WATERS FROM SODUS BAY TO MEXICO BAY-
LAKE ONTARIO NEARSHORE WATERS FROM MEXICO BAY TO THE SAINT LAWRENCE
RIVER-
LAKE ONTARIO OPEN WATERS FROM THE NIAGARA RIVER TO HAMLIN BEACH-
LAKE ONTARIO OPEN WATERS FROM HAMLIN BEACH TO SODUS BAY-
LAKE ONTARIO OPEN WATERS FROM SODUS BAY TO MEXICO BAY-
LAKE ONTARIO OPEN WATERS FROM MEXICO BAY TO THE SAINT LAWRENCE RIVER-
SAINT LAWRENCE RIVER FROM CAPE VINCENT TO OGDENSBURG-
SAINT LAWRENCE RIVER FROM OGDENSBURG TO SAINT REGIS-
530 AM EDT MON JUL 21 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE ERIE...LAKE
ONTARIO AND SAINT LAWRENCE RIVER.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON AND
EVENING. A FEW OF THESE STORMS MAY PRODUCE GUSTY WINDS AND LOCALLY
HIGHER WAVES.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP WEDNESDAY AFTERNOON
AND EVENING. A FEW OF THESE STORMS MAY PRODUCE GUSTY WINDS AND
LOCALLY HIGHER WAVES ALONG WITH THE POTENTIAL FOR HAIL.

THIS PRODUCT...ALONG WITH OTHER WATCHES...WARNINGS...ADVISORIES...
AND STATEMENTS ISSUED BY THE NATIONAL WEATHER SERVICE OFFICE IN
BUFFALO CAN BE FOUND ON THE INTERNET AT HTTP://WWW.WEATHER.GOV/BUF

HITCHCOCK

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BUFFALO NY
1252 PM EDT MON JUL 21 2008

NYZ003>005-013-014-211800-
MONROE-WAYNE-NORTHERN CAYUGA-LIVINGSTON-ONTARIO-
INCLUDING THE CITIES OF...ROCHESTER...NEWARK...FAIR HAVEN...
GENESEO...CANANDAIGUA
1252 PM EDT MON JUL 21 2008

...THUNDERSTORMS WITH DOWNPOURS MOVING ACROSS PORTIONS OF THE
REGION...

AT 1245 PM, A STRONG THUNDERSTORM WITH TORRENTIAL DOWNPOURS, AND
POSSIBLY GUSTY WIND AND HAIL, WAS LOCATED NEAR PENFIELD IN MONROE
COUNTY. THIS STORM WAS MOVING SOUTHEAST AND SHOULD BE NEAR
WALWORTH AROUND 1 PM, AND MARION AROUND 120 PM. ANOTHER THUNDERSTORM
WAS NEAR GENESEO AND SHOULD BE NEAR HEMLOCK AROUND 1 PM, HONEOYE
AROUND 110 PM, AND BRISTOL MOUNTAIN AROUND 120 PM. IT TO MAY ALSO
CONTAIN TORRENTIAL DOWNPOURS. BE ON THE ALERT FOR PONDING ON
ROADS, AND POSSIBLY SOME POOR DRAINAGE FLOODING.