A cold front was located northwest of the region during the afternoon and evening hours of the 10th. A warm and unstable airmass caused showers and thunderstorms to develop shortly after noontime and persist through the afternoon and evening hours.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS CLE wrote it up.
A cold front was located northwest of the region during the afternoon and evening hours of the 10th. A warm and unstable airmass caused showers and thunderstorms to develop shortly after noontime and persist through the afternoon and evening hours. Some of the thunderstorms became severe producing severe winds and hail.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Cleveland, OH wrote its last area forecast discussion before the first event at Aug 10, 12:59 PM EST, 47 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 159 PM EDT MON AUG 10 2009 .SYNOPSIS... A COLD FRONT WILL APPROACH THE REGION THIS EVENING...BRINGING SHOWERS AND THUNDERSTORMS TO THE LOWER GREAT LAKES REGION. HIGH PRESSURE WILL RETURN TO THE AREA ON TUESDAY WITH DRY WEATHER AND NORMAL TEMPERATURES EXPECTED THROUGH THE REST OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... ALL QUIET ACROSS THE FORECAST AREA AS OF 10AM...HOWEVER I EXPECT THAT TO CHANGE AS WE GET CLOSER TO NOON AND BEYOND. GOT A LOOK AT THE 12Z NAM AS WELL AS THE MOST RECENT RUC13...CAPES ARE ALREADY APPROACHING 2000J/KG ACROSS A GOOD MAJORITY OF THE AREA. SURFACE TEMPS WARMING QUICKLY WHILE TEMPS AT BOTH 850MB AND 700MB ARE DROPPING SLIGHTLY. THIS DIFFERENTIAL TEMPERATURE ADVECTION ALONG WITH NUMEROUS LINGERING BOUNDARIES FROM OVERNIGHT CONVECTION LEADS ME TO BELIEVE THAT SHOWERS AND THUNDERSTORMS WILL DEVELOP QUICKLY THIS AFTERNOON. THE PLACEMENT OF THESE STORMS IS A BIT MURKY AT THE MOMENT BUT I DREW IN THE HIGHEST POPS ACROSS THE WESTERN HALF OF THE AREA IN CLOSE PROXIMITY TO A PRE-FRONTAL SURFACE TROUGH. ALREADY IN AN SPC SLIGHT RISK AND WILL WAIT TO SEE IF ANY SORT OF WW COMES OUT LATER TODAY. ANOTHER WARM DAY TODAY BUT HEAT INDICES LOOK TO REMAIN JUST BELOW ADVISORY CRITERIA. NO HEAT HEADLINES TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... THE THREAT FOR THUNDERSTORMS WILL CONTINUE THROUGH THE EVENING HOURS TONIGHT WITH COLD FRONT PUSHING EAST INTO THE REGION. THERE IS THE POSSIBILITY THAT SOME OF THE THUNDERSTORMS WILL BE SEVERE EVEN INTO THE EVENING HOURS. ACTIVITY GRADUALLY EXITS TO THE EAST TUESDAY MORNING AND BRINGS AN END TO THE PRECIPITATION AS HIGH PRESSURE BUILDS EAST OVER THE REGION. HIGH PRESSURE WILL BECOME THE DOMINANT WEATHER FEATURE WEDNESDAY THROUGH THURSDAY NIGHT. TEMPERATURES THROUGH THIS PERIOD WILL SLIP BACK DOWN TO MORE REASONABLE LEVELS AS SLIGHTLY COOLER AIR WORKS ITS WAY SOUTH INTO THE REGION BY MID WEEK. THIS WILL BE SHORT LIVED AS WARM AIR ADVECTION TAKES PLACE BY WEDNESDAY NIGHT INTO THURSDAY. && .LONG TERM /FRIDAY THROUGH SUNDAY/... PLENTY OF HIGH PRESSURE FOR FRIDAY AND THE WEEKEND. THE GFS IS TRYING TO HINT AT SOME QPF IN THE RETURN FLOW SATURDAY NIGHT AND SUNDAY IN THE EASTERN PORTION OF THE FORECAST AREA. AT THIS TIME THE ECMWF HAS IT DRY WITH PLENTY OF UPPER RIDGING ALOFT AND AT THE SURFACE. WENT CLOSE TO GRIDDED MOS FOR THE TEMPERATURES AND THAT SEEM TO FOLLOW LOCAL SCHEMES. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... THUNDERSTORMS ALREADY DEVELOPING NEAR AND AHEAD OF A TROUGH AXIS THAT IS LOCATED FROM SOUTHERN ONTARIO INTO NORTHWESTERN OHIO. APPEARS THAT KTOL IS IN THE CLEAR AND KFDY HAS ONLY A SMALL WINDOW OF OPPORTUNITY THROUGH 19Z-20Z. ADDITIONAL CONVECTION IS DEVELOPING ALONG THE HIGHER TERRAIN OF NW PA INTO ASHTABULA COUNTIES. THIS CONVECTION MAY MOVE VERY LITTLE SO THIS COULD BE A PROLONGED PERIOD OF RAINFALL. ERIE WILL GET ANOTHER ROUND OF THUNDERSTORMS OFF OF LAKE ERIE AFTER 20Z. ELSEWHERE STRONG TO SEVERE CONVECTION WILL CONTINUE TO DEVELOP WITH STRONG GUSTY WINDS POSSIBLE. AS TROUGH AXIS PASSES THE MVFR/IFR CONDITIONS SHOULD IMPROVE THROUGH THE EVENING. WILL THEN HAVE TO WATCH FOR A RETURN OF SOME LOWER CEILINGS AND FOG AHEAD OF A COLD FRONT THAT WILL ARRIVE TUESDAY MORNING. .OUTLOOK...SOME MVFR CEILINGS POSSIBLE INTO TUESDAY MORNING. OTHER MAINLY VFR. && .MARINE... SOUTHWEST WINDS WILL CONTINUE TO DECREASE THIS MORNING AHEAD OF A WEAK COLD FRONT THAT WILL MOVE THROUGH OVERNIGHT. AT THIS TIME NOT EXPECTING WINDS TO BE STRONG ENOUGH TO WARRANT A SMALL CRAFT ADVISORY. SPECIAL MARINE WARNINGS WILL BE ISSUED THIS AFTERNOON AND TONIGHT FOR STRONG TO SEVERE THUNDERSTORMS. FOR MID WEEK A NORTHEAST FLOW WILL DEVELOP...WAVES COULD BE 2 TO 4 FEET...THIS WILL HAVE TO BE MONITORED. OTHER THEN THE THUNDERSTORMS FOR TODAY AND TONIGHT AND THE NORTHEAST FLOW FOR WEDNESDAY THE LAKE SHOULD BE QUIET. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && SYNOPSIS...LEINS NEAR TERM...LEINS SHORT TERM...LOMBARDY LONG TERM...KIELTYKA AVIATION...MULLEN MARINE...KIELTYKA
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CLEVELAND OH 416 AM EDT MON AUG 10 2009 LEZ061-142>149-162>169-OHZ003-006>014-017>023-027>033-036>038-047- 089-PAZ001>003-110830- LAKE ERIE OPEN WATERS FROM RIPLEY TO BUFFALO NY- MAUMEE BAY TO RENO BEACH OH-RENO BEACH TO THE ISLANDS OH- THE ISLANDS TO VERMILION OH-VERMILION TO AVON POINT OH- AVON POINT TO WILLOWICK OH-WILLOWICK TO GENEVA-ON-THE LAKE OH-GENEVA- ON-THE-LAKE TO CONNEAUT OH-CONNEAUT OH TO RIPLEY NY- LAKE ERIE OPEN WATERS FROM MAUMEE BAY TO RENO BEACH- LAKE ERIE OPEN WATERS FROM RENO BEACH TO THE ISLANDS- LAKE ERIE OPEN WATERS FROM THE ISLANDS TO VERMILION- LAKE ERIE OPEN WATERS FROM VERMILION TO AVON POINT- LAKE ERIE OPEN WATERS FROM AVON POINT TO WILLOWICK- LAKE ERIE OPEN WATERS FROM WILLOWICK TO GENEVA-ON-THE-LAKE- LAKE ERIE OPEN WATERS FROM GENEVA-ON-THE-LAKE TO CONNEAUT- LAKE ERIE OPEN WATERS FROM CONNEAUT OH TO RIPLEY NY-LUCAS-WOOD- OTTAWA-SANDUSKY-ERIE OH-LORAIN-CUYAHOGA-LAKE-GEAUGA-ASHTABULA INLAND- HANCOCK-SENECA-HURON-MEDINA-SUMMIT-PORTAGE-TRUMBULL-WYANDOT-CRAWFORD- RICHLAND-ASHLAND-WAYNE-STARK-MAHONING-MARION-MORROW-HOLMES-KNOX- ASHTABULA LAKESHORE-NORTHERN ERIE-SOUTHERN ERIE-CRAWFORD PA- 416 AM EDT MON AUG 10 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR LAKE ERIE...NORTH CENTRAL OHIO...NORTHEAST OHIO...NORTHWEST OHIO AND NORTHWEST PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON INTO THIS EVENING AND COULD PRODUCE STRONG DAMAGING WINDS. THE STORMS WILL BE THE RESULT OF A PRE FRONTAL TROUGH AND COLD FRONT EXPECTED TO MOVE ACROSS THE REGION THIS AFTERNOON AND TONIGHT. HEAT INDEX VALUES ARE NOT EXPECTED TO REACH HEAT ADVISORY CRITERIA FOR TODAY BUT TEMPERATURES ARE EXPECTED TO CLIMB TO AROUND 90 DEGREES IN MANY AREAS. THE COMBINATION OF HIGH TEMPERATURES AND HUMIDITY CAN LEAD TO HEAT RELATED DISORDERS. CAUTION SHOULD BE EXERCISED TODAY BY AVOIDING OVEREXERTING THE BODY DURING THE HEAT OF THE DAY. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL LIKELY BE NEEDED. LOMBARDY
The Buffalo radar (KBUF), 151 km away, was scanning. The volume nearest the first event began at 18:45 UTC.
3 thunderstorm wind, 2 flash flood. Local standard time, as filed.
Many trees were reported down in the area. Several houses sustained damage from fallen trees.
Training thunderstorms produced nearly 3.5 inches of rain in less than 2 hours in south-central Erie county just north and west of Waterford, PA. Flash flooding ensued on several smaller creeks in the area, including an unnamed tributary to Le Boeuf Creek which flows through the Rainbow Valley Mobile Home Park north of Waterford. Several mobile homes were flooded and had their foundation skirting ripped off by the fast moving water. State Route 19 flooded as well, with large logs deposited on the roadway by the fast moving water.
Numerous trees, large limbs were reported down throughout the area. Significant tree damage was reported at a golf course in Venengo where many trees and large limbs were reported down and golf carts were destroyed. Power lines were down as at least a few dozen power poles were knocked down.
Automated weather observing equipment at the Meadville Airport measured a thunderstorm wind gust of 60 mph.
Heavy rainfall of up to 3 inches in 2 hours caused flash flooding on small creeks and streams in north central Crawford County near Venango. A moblie home was flooded, and US Highway 6/19 north of Venango was closed due to the high water.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2009Every state in 2009This day in weather historyWarnings in Pennsylvania, August 2009
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 192155, 195255, 192156, 192154, 195256.