Non-convective winds associated with a strong low pressure system brought down trees and wires across western Pennsylvania, causing thousands of power outages. The majority of the outages were in high elevation areas served by Penelec and Allegheny Power.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
Non-convective winds associated with a strong low pressure system brought down trees and wires across western Pennsylvania, causing thousands of power outages. The majority of the outages were in high elevation areas served by Penelec and Allegheny Power.
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 May 11, 1:15 PM EST, 15 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 215 PM EDT SUN MAY 11 2008 .SYNOPSIS... A POTENT STORM SYSTEM WILL TRACK FROM OHIO TO THE CHESAPEAKE BAY BY MONDAY AFTERNOON...BRINGING HEAVY RAIN AND SOME THUNDERSTORMS TO SOUTHERN PENNSYLVANIA. A RIDGE OF HIGH PRESSURE WILL BUILD OVER THE REGION TUESDAY AND EARLY WEDNESDAY. A COLD FRONT WILL LIKELY PUSH INTO THE REGION BY LATE WEDNESDAY OR THURSDAY. && .NEAR TERM /UNTIL 11 PM THIS EVENING/... ACCORDING TO LATEST SFC OBS AND RWIS DATA...THE SE WINDS CONTINUE TO GUST TO 35 OR 40 MPH ALONG THE WESTERN HIGHLANDS. WILL STICK WITH GUSTS JUST UNDER ADVSRY CRITERIA FOR NOW...AND THEY SHOULD BEGIN TO DIMINISH AS THE RAIN BEGINS THIS EVENING AND THE SFC WINDS BECOME NOT AS WELL-ALIGNED WITH THE MID LEVEL FLOW. THE SHOWERS ASSOCIATED WITH THE CONVECTION IN WESTERN PA WILL BE THE START TO OUR RAIN OVER MOST OF THE REGION. THUNDER SHOULD DIMINISH AS IT NEARS THE LOCAL CWA...BUT THE SWRN COS ARE LIKELY TO HEAR A RUMBLE OR TWO. THE HEAVIEST RAIN STILL LOOKS LIKE IT WILL BE AFTER MIDNIGHT...BUT HEAVY RAIN POSSIBLE IN THE SRN MTNS BEFORE MIDNIGHT. && .SHORT TERM /11 PM THIS EVENING THROUGH MONDAY NIGHT/... MOD TO HVY RAIN EXPECTED TO FALL OVER SOUTHERN PA TONIGHT AS SFC LO TRACKS JUST SOUTH OF THE MASON DIXON LINE. LATEST SREF DATA INDICATES A 12HR PERIOD OF IMPRESSIVE MOISTURE FLUX/ISENTROPIC LIFT TONIGHT AND MONDAY MORNING OVER SOUTHERN PA ASSOCIATED WITH ANOMALOUS EASTERLY LL JET. SOME CONVECTION POSSIBLE AS WELL. LATEST SREF QPF INDICATES PORTIONS OF SOUTHERN PA LIKELY TO RECEIVE IN EXCESS OF 2 INCHES...WITH MUCH OF THE AREA OVER AN INCH. ANTECEDENT CONDS IN THIS AREA PRETTY WET...WITH LATEST 12HR HEADWATER GUIDANCE ARND 1.2 INCHES FOR 12 HOURS AT SHIRLEYSBURG. OTHER FFG NUMBERS IN THE 1.5 TO 2 INCH RANGE. THEREFORE...WILL CONTINUE THE FLOOD WATCH FOR ROUGHLY THE SOUTHERN THIRD OF THE CWA INTO MONDAY. MODEL SOUNDINGS ACTUALLY BECOME MARGINALLY COLD ENOUGH FOR SNOW OVR THE HIGH TERRAIN OF THE ALLEGHENIES MON MORNING...AS STRONG LIFT/DYNAMIC COOLING DEVELOPS IN ADVANCE OF UPPER LO CENTER. HAVE INCLUDED A CHC OF SNOW ABV 1900FT ELEV FOR NOW IN THE SW AND THE NW DURING THE FEW HOURS AROUND SUNRISE...BUT SFC TEMPS SHOULD ONLY BE DOWN TO THE M30S AT THE COLDEST. RAIN SHOULD TAPER OFF BY MONDAY AFTN...AS SFC LO PUSHES OFF THE MID ATLANTIC COAST. HOWEVER...CLOUDS/NE FLOW WILL KEEP TEMPS FROM REBOUNDING. HIGHS MOSTLY IN THE 40S FOR MONDAY...WHICH ARE SOME 20-25F BELOW NORMAL. && .LONG TERM /TUESDAY THROUGH SATURDAY/... LITTLE DEVIATION AMONGST ENSEMBLE MEMBERS TUE THRU THUR...WITH A LARGER SPREAD DEVELOPING TOWARDS NEXT WEEKEND. HIGH CONFIDENCE RIDGE OFF OF THE PAC-NW COAST WILL RESULT IN A TROUGHING ACROSS EASTERN THIRD OF THE CONUS AND MARGINALLY SUB-SEASONAL TEMPS AND A SEMI-ACTIVE WX PATTERN THRU THE NEXT 7 DAYS WITH PERIODS OF DRY WX MIXED IN. SFC RIDGE WILL INFLUENCE WX TUE AFTN...PROVIDING DRY WX THRU FIRST HALF WED. RIDGE SLIDES EAST WED AS A WEAK SHORTWAVE DROPS SOUTH INTO THE WESTERN GRT LKS BUT STRUGGLES TO SLIDE EAST BUMPING INTO PESKY MID-LVL RIDGE. FRONTAL BNDRY WILL STRETCH SOUTH THROUGH PLAINS EARLY WED...AND AS IT APPROACHES THE MID-ATLANTIC EXPECT SOME LVL OF FRONTOLYSIS TO OCCUR. SFC VORT SLIDES NE INTO ONTARIO WITH SECONDARY VORT SPLITTING TOWARDS GULF COASTAL STATES. THUS EXPECT AS PRECIP ARRIVES EARLY THUR IT WILL BE WAINING. 850MB THERMAL RIDGE IS PROGGED TO PERSIST THUR ACROSS NEW ENGLAND/MID-ATLANTIC...THEN BECOME CHOCKED OFF AS COOLER AIR SLIDES IN BEHIND BNDRY LATE THUR/EARLY FRI. THUR COULD FEATURE A LARGE DIURNAL SWING WITH TEMPS NEARING LOW/MID 70S. QUASI-STATIONARY MID-LVL VORT JUST SOUTH OF HUDSON BAY WILL SEND A FEW VORT LOBES THRU SOUTHERN GRT LKS FRI/SAT...KEEPING LOW CHC PRECIP THROUGH THE WEEKEND. 500MB TROUGH IS PROGGED TO BECOME NEGATIVELY TILTED TOWARDS THE WEEKEND...WHICH MAY HELP DEVELOP A COASTAL LOW OFF-SHORE OF THE CAROLINAS NEXT WEEKEND. CONFIDENCE IS LOW ATTM WITH THE FRI-SUN PERIODS. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... VFR CONDITIONS WILL DETERIORATE AS WE HEAD INTO THE EVENING. SE FLOW AHEAD OF THE LOW OVER OHIO WILL TRANSPORT MOISTURE INTO THE REGION RESULTING IN THE ONSET OF PRECIP FROM WEST TO EAST. MVFR CONDS WILL QUICKLY FALL TO IFR CIGS AS PRECIP BECOMES HEAVIER BY MID/LATE EVENING...ESPECIALLY ACROSS THE SOUTH. VISBYS MOST LIKELY IN THE MVFR RANGES. A RUMBLE OF THUNDER IS POSSIBLE...BUT STABILITY SO HIGH IN LOWEST LEVELS THAT I WILL LEAVE T OUT OF TAFS FOR NOW. IFR CIGS WILL STICK AROUND THRU MIDDAY MON...AS UPPER LOW SLIDES OFF OF THE DELMARVA COAST MON AFTN. SINCE WE REMAIN NORTH OF THE LOW...FLOW BECOMES NORTHERLY WITH COOL AIR FOR LATE MON. EXPECT VFR CONDS TO DEVELOP MON NGT INTO TUE. SOME LOCATIONS MIGHT SEE RADIATIONAL FOG MAY DEVELOP EARLY TUE AS CLEARING AND WET GROUND MAKE FOR GOOD FOG CONDITIONS. TUE/WED WILL BE DRY...WITH THE FIRST OF A SERIES OF WEAKER WAVES POISED TO MOVE THROUGH WED NGT BRINGING A CHC FOR PRECIP LATE WED/EARLY THUR FOLLOWED BY MORE UNSETTLED WEATHER THE REMAINDER OF THE WEEK. && .CTP WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH FROM MIDNIGHT EDT TONIGHT THROUGH MONDAY EVENING FOR PAZ024>028-033>036-056-057-063>066. && SYNOPSIS...DANGELO/FITZGERALD NEAR TERM...DANGELO SHORT TERM...DANGELO LONG TERM...BEACHLER AVIATION...DANGELO
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE STATE COLLEGE PA 501 AM EDT SUN MAY 11 2008 PAZ004>006-010>012-017>019-037-041-042-045-046-049>053-058-059- 120915- WARREN-MCKEAN-POTTER-ELK-CAMERON-NORTHERN CLINTON-CLEARFIELD- NORTHERN CENTRE-SOUTHERN CENTRE-TIOGA-NORTHERN LYCOMING-SULLIVAN- SOUTHERN CLINTON-SOUTHERN LYCOMING-UNION-SNYDER-MONTOUR- NORTHUMBERLAND-COLUMBIA-SCHUYLKILL-LEBANON- 501 AM EDT SUN MAY 11 2008 THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT THE PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER IS LOW. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY THE PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. PAZ024>028-033>036-056-057-063>066-120915- CAMBRIA-BLAIR-HUNTINGDON-MIFFLIN-JUNIATA-SOMERSET-BEDFORD-FULTON- FRANKLIN-PERRY-DAUPHIN-CUMBERLAND-ADAMS-YORK-LANCASTER- 501 AM EDT SUN MAY 11 2008 ...FLOOD WATCH IN EFFECT FROM LATE TONIGHT THROUGH MONDAY 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. FLOOD WATCH. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV/STATECOLLEGE ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. FLOOD WATCH. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
The national radar mosaic for the moment the first event began.
5 high wind. Local standard time, as filed.
The Cambria County 911 center received several reports of trees and wires down during the early to mid afternoon. The damage was mainly confined to the central part of the county.
The Bedford County 911 center received several reports of trees and wires down during the early afternoon. The damage was mainly confined to the western part of the county.
The Clearfield County 911 center received several reports of trees and wires down during the mid afternoon. One tree fell onto a house at Treasure Lake.
The Somerset County 911 center received several reports of trees and wires down during the mid afternoon.
The Blair County 911 center reported trees down during the mid afternoon in the Altoona area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2008Every state in 2008This day in weather historyWarnings in Pennsylvania, May 2008
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: 86915, 86916, 86917, 86918, 86919.