Thunderstorms produced heavy rain and several instances of isolated flash flooding in Warren County throughout the day.
Every event with a place to put it. Tap one for its entry below.
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 CTP wrote it up.
Thunderstorms produced heavy rain and several instances of isolated flash flooding in Warren County throughout the day.
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 State College, PA wrote its last area forecast discussion before the first event at Aug 10, 6:48 AM EST, 43 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 748 AM EDT MON AUG 10 2009 .SYNOPSIS... AN UPPER LEVEL RIDGE OVER PENNSYLVANIA WILL PUSH OFF THE EAST COAST BY TUESDAY...ALLOWING A COLD FRONT TO PUSH THROUGH INTO THE AREA. HIGH PRESSURE WILL BUILD OVER THE STATE FOR THE SECOND HALF OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPPER LVL RIDGE CRESTING OVR PENNSYLVANIA EARLY TODAY...PUSHING RING OF FIRE NORTH OF THE BORDER. LATEST BLENDED TOTAL PWAT PRODUCT SHOWING EVIDENCE OF THIS...AS BAND OF HIGHEST PWATS HAS LIFTED INTO UPSTATE NY DURING THE LAST FEW HRS. HOWEVER...A FEW SHRA CURRENTLY NOTED OVR THE NW MTNS...ALONG OLD OUTFLOW BOUNDARY FROM EARLIER MCS. THIS AREA WILL SHOULD CONTINUE TO BE THE FOCUS FOR ISOLATED CONVECTION DURING THE NEXT SEVERAL HRS. FOR LATER TODAY...STILL A RISK OF STRONG TO SEVERE STORMS...AS FRONTAL BOUNDARY REMAINS TO THE NORTH...AND VERY UNSTABLE AIR REMAINS IN PLACE. HIGHEST POPS WILL BE RESERVED FOR THIS AFTN ACROSS THE NW MTNS...AS LARGE SCALE FORCING OVERSPREADS REGION FROM THE WEST IN ADVANCE OF SHORTWAVE APPROACHING FROM THE N PLAINS. LATEST ENSEMBLE DATA SUPPORTS LIKELY POPS ACROSS THE NW MTNS...TAPERING TO SLIGHT CHC ACROSS THE LOWER SUSQ VALLEY...WHERE CAP SHOULD REMAIN IN PLACE. ALTHOUGH MID LVL FLOW NOT AS STRONG AS YESTERDAY...SVR WX STILL A THREAT GIVEN DEGREE OF INSTABILITY. UNIDIRECTIONAL DEEP LYR SHEAR ARND 30KTS COULD SUPPORT LONG LIVED LINE SEGMENTS/BOWS...MAINLY NORTHERN PA CLOSEST TO UPPER LVL JET. ENS MEAN 850 TEMPS SUPPORT MAX READINGS AS HIGH AS THE M90S ACROSS THE LOWER SUSQ VALLEY TODAY. THE COMBINATION OF HEAT AND HUMIDITY WILL LIKELY PUSH HEAT INDICES TO ARND 100F FOR SEVERAL HRS ACROSS THE SUSQ VALLEY. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... A GENERAL DECREASE IN CONVECTION OVERNIGHT WITH DIURNAL COOLING. HOWEVER...WILL KEEP MENTION OF TSRA THRU THE NIGHT AS SHORTWAVE PRESSES SE INTO THE AREA. SRHA/TSRA EXPECTED TO REINVIGORATE ALONG SFC COLD FRONT TUESDAY...AS IT TRACKS SE ACROSS THE STATE. MREF PLUMES STILL INDICATING MODERATE INSTABILITY DEVELOPING AHEAD OF FRONT...ESP SUSQ VALLEY...WHERE SVR WX CAN/T BE RULED OUT. DRIER/CO0LER WX SHOULD FILTER INTO THE REGION WED NIGHT. HOWEVER...WILL MAINTAIN SLIGHT CHC POPS ALONG THE MASON DIXON LINE INTO THE EVENING. && .LONG TERM /THURSDAY THROUGH SUNDAY/... COSMETIC CHANGES FOR THE EXTENDED PERIODS THUR THROUGH SUN. THE CHALLENGES FOR THUR RESIDE AROUND TIMING AND PLACEMENT OF PRECIP AS WEAK MID-LVL VORT MAX SLOWLY SLIDES NE ACROSS PORTIONS OF MID-ATLANTIC REGION. 500MB WAVE PATTERN HOLDS A BROAD RIDGE WITH A RELATIVELY ZONAL FLOW. BASED ON ENSEMBLE MEMBERS SFC RIDGE SHUD REMAIN AN INFLUENCE THUR/FRI...WHICH SUGGESTS ANY PRECIP WILL REMAIN LIGHT. ANTICIPATE WITH PLACEMENT OF BERMUDA RIDGE A STEADY RETURN MOISTURE FEED FROM GULF OF MEXICO WILL PUSH NE INTO THE CAROLINAS...THUS HAVE KEPT A SLT CHC FOR PRECIP FRI/SAT FOCUS ATTM WILL BE ACROSS LOWER SUSQ-VALLEY. TEMPS APPEAR TO BE ARND SEASONAL CONDS...WITH 850MB TEMPS PROGGED IN THE LOW/MID TEENS. QUIET WEATHER THEN RETURNS TO THE REGION SAT...HOWEVER A HANDFUL OF ENSEMBLE MEMBERS PROG SOME AFTN SHRA/TSRA SAT/SUN. FOR NOW CONFIDENCE REMAINS LOW BASED ON TIMING AND PLACEMENT...SO HAVE OPTED FOR A DRY SAT NGT THRU MON. TEMPS ALSO REMAIN SEASONAL FOR THE UPCOMING WEEKEND. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... SCATTERED TSTORMS CONTINUE TO AFFECT PORTIONS OF NORTHERN TIER...INCLUDING KBFD...BUT SHOULD SEE A BREAK IN THE ACTION FOR SEVERAL HOURS. SOME MVFR CONDITIONS SCATTERED ABOUT CENTRAL PA WILL GIVE WAY TO VFR BY MID MORNING AND WINDS WILL INCREASE FROM THE WEST AT 10 KTS ALONG WITH SOME GUSTINESS ESPECIALLY ACROSS THE WEST. THEN STARTING IN THE MID/LATE AFTERNOON...THE VFR WILL BE INTERRUPTED AT TIMES BY SCATTERED CONVECTION...ESPECIALLY IN THE NORTH AND WEST...AND LATER DURING THE EVENING IN THE EAST AS WELL. STILL KEPT TAFS PRETTY GENERIC AS IT WILL REMAIN VFR MUCH OF THE TIME AND CAN/T PINPOINT EXACTLY WHEN STORMS WILL AFFECT A GIVEN POINT YET. FOR TONIGHT...EXPECT TO SEE A BREAK IN THE CONVECTION FROM MID EVENING THROUGH MUCH OF THE NIGHT...BUT ANOTHER ROUND WILL BE MOVING IN FROM THE WEST BY 12Z TUE ALONG WITH A RETURN OF MVFR CONDITIONS. OUTLOOK... TUE...AREAS OF MVFR WITH SCT SHRA/ISO TSRA. WED AND THU...VFR. FRI...VFR. ISO SHRA/TSRA DURING AFTN HOURS. && .CTP WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 7 PM EDT THIS EVENING FOR PAZ036-046-049>053-056>059-063>066. && SYNOPSIS...FITZGERALD NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD LONG TERM...BEACHLER AVIATION...RXR
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE STATE COLLEGE PA 758 AM EDT MON AUG 10 2009 PAZ004>006-010>012-017>019-024>028-037-041-042-045-111200- WARREN-MCKEAN-POTTER-ELK-CAMERON-NORTHERN CLINTON-CLEARFIELD- NORTHERN CENTRE-SOUTHERN CENTRE-CAMBRIA-BLAIR-HUNTINGDON-MIFFLIN- JUNIATA-TIOGA-NORTHERN LYCOMING-SULLIVAN-SOUTHERN CLINTON- 758 AM EDT MON AUG 10 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. THUNDERSTORMS WILL DEVELOP ACROSS THE AREA THIS AFTERNOON IN ADVANCE OF A FRONTAL SYSTEM APPROACHING FROM THE GREAT LAKES. A FEW OF THE STORMS COULD BE ACCOMPANIED BY DAMAGING WIND GUSTS OR LARGE HAIL. THUNDERSTORMS WILL BE CAPABLE OF LOCALLY HEAVY RAINFALL AND LOCAL FLOODING. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. PAZ046-049>053-056>059-111200- SOUTHERN LYCOMING-UNION-SNYDER-MONTOUR-NORTHUMBERLAND-COLUMBIA-PERRY- DAUPHIN-SCHUYLKILL-LEBANON- 758 AM EDT MON AUG 10 2009 ...HEAT ADVISORY IN EFFECT FROM 1 PM THIS AFTERNOON TO 7 PM EDT THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV/STATECOLLEGE ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. HEAT ADVISORY. THUNDERSTORMS WILL DEVELOP ACROSS THE AREA THIS AFTERNOON IN ADVANCE OF A FRONTAL SYSTEM APPROACHING FROM THE GREAT LAKES. A FEW OF THE STORMS COULD BE ACCOMPANIED BY DAMAGING WIND GUSTS OR LARGE HAIL. THUNDERSTORMS WILL BE CAPABLE OF LOCALLY HEAVY RAINFALL AND LOCAL FLOODING. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. PAZ033>035-111200- SOMERSET-BEDFORD-FULTON- 758 AM EDT MON AUG 10 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. PAZ036-063>066-111200- FRANKLIN-CUMBERLAND-ADAMS-YORK-LANCASTER- 758 AM EDT MON AUG 10 2009 ...HEAT ADVISORY IN EFFECT FROM 1 PM THIS AFTERNOON TO 7 PM EDT THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV/STATECOLLEGE ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. HEAT ADVISORY. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
655 AM EDT MON AUG 10 2009
PAZ004-005-101130-
MCKEAN PA-WARREN PA-
655 AM EDT MON AUG 10 2009
...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN WARREN AND WESTERN
MCKEAN COUNTIES...
AT 654 AM EDT...A STRONG THUNDERSTORM WAS LOCATED NEAR RUSSELL...
MOVING EAST AT 30 MPH.
WIND GUSTS TO 50 MPH ARE POSSIBLE WITH THIS STORM. VERY HEAVY RAIN
WILL FALL FROM THIS STORM...AND WILL CAUSE WATER TO POND ON ROADS AND
FILL POOR DRAINAGE AREAS. THE RAIN WILL CAUSE RAPID RISES ON SMALL
STREAMS AND CREEKS.
THIS STORM WILL BE NEAR CLARENDON AROUND 700 AM...SCANDIA AROUND 705
AM...KINZUA DAM AROUND 710 AM...LUDLOW AROUND 720 AM AND MARSHBURG
AROUND 730 AM.
LAT...LON 4200 7918 4201 7893 4198 7858 4164 7876
4184 7938 4201 7929 4201 7918
EXPERIMENTAL
FORECASTER: KFThe Buffalo radar (KBUF), 118 km away, was scanning. The volume nearest the first event began at 12:31 UTC.
3 flash flood. Local standard time, as filed.
Thunderstorms produced heavy rain and flash flooding in northern and Eastern Warren County. Roads were closed in Chandlers Valley and Pine Grove Township.
Thunderstorms produced heavy rain and flash flooding near Warren. Water was covering roads in North Warren, and one house was surrounded by water in Warren.
Thunderstorms produced heavy rain, and caused mudslides across Route 59 near Kinzua Dam.
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: 179813, 179815, 179817.