A large subtropical ridge over the western Atlantic and adjacent southeastern United States pumped unseasonably warm air and rich moisture into the Ohio Valley and Mid-Atlantic. This ring-of-fire pattern of moderate instability and strong deep layer wind shear on the northern periphery of the upper-level ridge was conducive for the development of several early-season thunderstorm complexes…
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.
A large subtropical ridge over the western Atlantic and adjacent southeastern United States pumped unseasonably warm air and rich moisture into the Ohio Valley and Mid-Atlantic. This ring-of-fire pattern of moderate instability and strong deep layer wind shear on the northern periphery of the upper-level ridge was conducive for the development of several early-season thunderstorm complexes (QLCS/MCS). The severe storms with embedded bow echoes moved eastward from the Ohio Valley along and south of a strong low-level frontal zone and produced damaging winds and marginally severe hail in central Pennsylvania during the afternoon and evening hours.
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 Apr 10, 7:05 AM EST, 1 hour 40 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 805 AM EDT WED APR 10 2013 .SYNOPSIS... AN EAST-WEST FRONTAL BOUNDARY WILL CONTINUE TO WAVER OVER CENTRAL PENNSYLVANIA INTO THURSDAY. A DYNAMIC STORM SYSTEM CROSSING THE CENTRAL UNITED STATES WILL SEND A STRONG COLD FRONT THROUGH THE REGION ON FRIDAY. COOLER TEMPERATURES ARE EXPECTED OVER THE WEEKEND WITH ANOTHER WARMING TREND LIKELY INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... UPDATED GRIDS WITH LATEST OBSERVATIONS AND TWEAKED TO A MODEL BLEND OVER NEXT 36 HOURS. THERE STILL ARE SOME SHOWERS NEAR THE NY/PA BORDER WHERE THERE IS QUITE A PESKY FRONTAL BOUNDARY. THE LIGHTNING STRIKES IN THESE SHOWERS...MORE TO WEST...IS DIMINISHING. NICE BOUNDARY WITH TEMPERATURES IN THE 40S ACROSS SOUTHERN NY AND 5OS ON THE PA SIDE AND ABOUT 80 MILES SOUTH MORNING TEMPERATURES WERE MORE JUNE-LIKE THAN APRIL WITH READINGS IN THE 6OS TO LOW 70S. DEW POINTS IN THE WARM AIR...ON OUR SIDE OF THE BOUNDARY ARE QUITE HIGH FOR APRIL IN THE 50S. THE OLD 1970S-80S APRIL SEVERE WEATHER RULE OF DEW POINTS OVER 55 COULD COME INTO PLAY TODAY. MOST GUIDANCE SHOWS TEMPERATURES IN THE LOWER 80S PUSHING INTO AT LEAST CENTRAL PA WITH A VERY TIGHT FRONTAL BOUNDARY NEAR THE PA/NY BORDER. VERY STRONG TEMPERATURE GRADIENT NORTHERN PA/SOUTHERN NY. TEMPERATURE ERRORS OF 10-15 DEGREES POSSIBLE IN OUR NORTHERN TIER TODAY DEPENDING ON WHERE THE BOUNDARY SPENDS MOST OF ITS DAY. ALL GUIDANCE SHOWS AN INSTABILITY SURGE INTO WEST/SOUTHWEST PA. NOT SURPRISINGLY SLIGHT RISK AREA COMES INTO THE REGION. RAP AND NAM SOLUTIONS VARY ON THIS TODAY. BUT THERE IS A CLEAR RING-OF-FIRE FLOW IN OUR REGION WITH A SURGE OF HIGH PW AIR AND STRONG LOW- LEVEL WESTERLY FLOW COMBINED WITH INSTABILITY IMPLYING AN INCREASED RISK OF SHOWERS AND THUNDERSTORMS DEVELOPING THIS AFTERNOON. CAPE VALUES OF 600-1200JKG-1 IN MOST GUIDANCE ALONG WITH +2SD PW ANOMALIES IMPLIES TODAY WILL BE MORE LIKE A JUNE THAN APRIL AFTERNOON. BEST RAIN AND HEAVIEST RAIN WOULD LIKELY BE IN THE STORMS THAT EVOLVE ALONG AND THE BOUNDARY NEAR THE NY BORDER TODAY. KEPT CATEGORICAL POPS AND BEST RAINFALL VALUES IN NORTHERN PA AND MUCH LOWER IN SOUTHERN PA. IF WE GET CONVECTION IT COULD ORGANIZE INTO BOWING SEGMENTS AND WOULD LIKELY MOVE PRETTY MUCH EAST-EAST- SOUTHEAST ACROSS THE STATE. PREVIOUS DISCUSSION ALLUDED TO 4KM NAM CONVECTION IMPLYING SOME BOW-LIKE SEGMENTS LATER THIS AFTERNOON. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... KEY POINT FOR THURSDAY IS THE BOUNDARY AND HOW FAR SOUTH IT SAGS. BIG POTENTIAL ERRORS IN TEMPERATURE AND SENSIBLE WEATHER FORECAST ACROSS MUCH OF NORTHERN THIRD OF PA THURSDAY. PREVIOUS DISCUSSION....AMPLIFIED UPPER- LEVEL TROUGH WILL EVOLVE OVER THE CENTRAL CONUS AND TAKE ON A NEGATIVE TILT CROSSING THE MS RVR...AS SHORTWAVE IMPULSE WITHIN THE BASE OF THE TROUGH ACCELERATES E/NEWD FROM SRN TX THRU THE LWR MS/TN VLY INTO THE CENTRAL APPALACHIANS. MEANWHILE...TRIPLE PT LOW FROM DES MOINES IA TO CHICAGO IL WILL TRACK EWD INTO THE GRT LKS/UPPER OH VLY WITH TRAILING COLD FRONT SWEEPING EWD TO THE APPALACHIAN SPINE BY 12Z FRI. CONCEIVABLY THE STNRY/WARM FRONT DRAPED OVER CENTRAL PA SHOULD LIFT BACK NWD AS THE MIDWEST FRONTAL SYSTEM BEGINS TO LIFT NEWD TOWARD THE GRT LKS/OH VLY. HOWEVER NAM/GFS SUGGEST A BACKDOOR SCENARIO MAY OCCUR AS THE BNDRY SLIPS SWD TOWARD THE MASON DIXON LINE. THE RESULT IS A VERY TRICKY/LOW CONFIDENCE TEMP FCST WITH BIG-BUST POTENTIAL. BASED ON PREV THINKING...I WEIGHTED THE FINAL BLEND ON THE WARM-SIDE OF THE GUIDANCE CLOSER TO THE ECMWF/RGEM FOR TEMPS WHICH WOULD ALLOW FOR ONE MORE VERY MILD DAY. TO GET A SENSE OF THE UNCERTAINTY...THE SPREAD IN THE GEFS MOS FOR UNV IS 15 DEGS AND 23F IN THE ECENS MOS. PCPN-WISE THE HIGHEST POPS REMAIN OVER THE NRN TIER DURING THE DAY BUT QUICKLY INCREASE FROM WEST TO EAST THUR NGT AHEAD OF EWD SURGING COLD FRONT. THE MEAN POSITION OF THE LARGE SCALE UPPER TROUGH SHOULD REMAIN CENTERED ACROSS THE GREAT LAKES WITH SEVERAL EMBEDDED SHORTWAVE IMPULSES GYRATING AROUND THE CENTER. THE MAIN IMPULSE TO INFLUENCE HEAVY RAIN AND LOW-TOPPED NCFRB POTENTIAL SHOULD CROSS THE REGION BTWN 12-18Z FRI. THE GFS IS STILL ABOUT 6HRS FASTER THAN THE ECMWF IN SHIFTING ITS HVY QPF AXIS OUT OF CENTRAL PA. STRONG DYNAMICS COUPLED WITH AMPLE MSTR/HIGH PWATS SHOULD LEAD TO MOD TO LOCALLY HEAVY RAFL AMTS ALONG THE FRONTAL BAND. CONDS WILL DRY OUT LATER FRI AFTN INTO FRI NGT WITH ANOTHER S/W AND SECONDARY COLD FRONT PUSHING EWD THROUGH THE CWA...USHERING IN THE COOLER AIR FOR THE WEEKEND. SCT RA/SN SHOWERS ARE POSSIBLE FRI NGT IN THE FAVORED UPSLOPE AREAS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... CYCLONIC FLOW PATTERN WILL PREVAIL THROUGH THE WEEKEND AS UPPER LOW MOVES EWD THRU ONTARIO AND NRN MAINE. ANOTHER S/W TROUGH SHOULD SWEEP THROUGH ON SATURDAY AND MAY TRIGGER A BAND OF SHOWERS. HIGH PRESSURE WILL BUILD INTO THE CWA ON SUNDAY. TEMPS SHOULD AVG NEAR TO BELOW NORMAL BEFORE MODERATING INTO EARLY NEXT WEEK. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... CURRENTLY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE NORTHERN TIER OF PA BRINGING IFR CIGS AND VSBYS TO BFD. EXPECT THESE PERIODS OF IFR AND MAINLY MVFR CIGS AND VSBYS THROUGH MOST OF THE DAY. THESE CONDITIONS WILL SLOWLY SPREAD OVER THE WESTERN AND CENTRAL TAF SITES THROUGH MIDDAY. THE SOUTHEASTERN TAF SITES SHOULD REMAIN VFR TODAY...THROUGH AFTERNOON CONVECTION ASSOCIATED WITH THE STATIONARY BOUNDARY DRAPED ACROSS PA COULD ALLOW FOR BRIEF PERIODS OF MVFR CONDITIONS LATE THIS AFTERNOON...AND EARLY EVENING. THIS BOUNDARY IS EXPECTED TO REMAIN IN THE VICINITY OF CNTRL PA THRU TODAY AND TONIGHT. BFD SHOULD BE ENTRENCHED IN THE LOW STRATOCU OVERNIGHT. THE BOUNDARY WILL MAKE ITS WAY SLOWLY EASTWARD THURSDAY INTO FRIDAY. .OUTLOOK... THU...EARLY AM LOW CIGS POSS NW MTNS. PM TSRA IMPACTS POSS NORTH. FRI...RAIN/LOW CIGS POSS...ESP EARLY. SHRA POSS NW PM. SAT-SUN...NO SIG WX EXPECTED. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...CERU
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE STATE COLLEGE PA 537 AM EDT WED APR 10 2013 PAZ006-011-012-037-041-042-046-110945- POTTER-CAMERON-NORTHERN CLINTON-TIOGA-NORTHERN LYCOMING-SULLIVAN- SOUTHERN LYCOMING- 537 AM EDT WED APR 10 2013 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...THURSDAY THROUGH TUESDAY. LOCALIZED HEAVY RAINFALL IS POSSIBLE ON FRIDAY AS A STRONG COLD FRONT CROSSES THE REGION. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. PAZ017>019-024>028-033>036-045-049>053-056>059-063>066-110945- CLEARFIELD-NORTHERN CENTRE-SOUTHERN CENTRE-CAMBRIA-BLAIR-HUNTINGDON- MIFFLIN-JUNIATA-SOMERSET-BEDFORD-FULTON-FRANKLIN-SOUTHERN CLINTON- UNION-SNYDER-MONTOUR-NORTHUMBERLAND-COLUMBIA-PERRY-DAUPHIN- SCHUYLKILL-LEBANON-CUMBERLAND-ADAMS-YORK-LANCASTER- 537 AM EDT WED APR 10 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EARLY TONIGHT. DAMAGING WIND GUSTS AND LARGE HAIL ARE THE PRIMARY SEVERE WEATHER THREATS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY. LOCALIZED HEAVY RAINFALL IS POSSIBLE ON FRIDAY AS A STRONG COLD FRONT CROSSES THE REGION. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. PAZ004-005-010-110945- WARREN-MCKEAN-ELK- 537 AM EDT WED APR 10 2013 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...THURSDAY THROUGH TUESDAY. 2 TO 3 INCHES OF RAIN IS POSSIBLE THROUGH FRIDAY WHICH COULD RESULT IN FLOODING ALONG SOME STREAMS AND CREEKS. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Buffalo radar (KBUF), 128 km away, was scanning. The volume nearest the first event began at 13:45 UTC.
16 thunderstorm wind, 2 hail, 1 lightning. Local standard time, as filed.
Lightning struck a county-owned building next to the Warren Hospital. Damage to the roof was limited to one small hole.
Thunderstorm winds estimated near 60 mph knocked down trees in Ridgway.
Thunderstorm winds estimated near 60 mph knocked down trees and utility wires in Fox Township southwest of St. Mary's.
Thunderstorm winds estimated near 60 mph knocked down trees in St. Mary's.
Thunderstorm winds estimated around 70 mph knocked down a swath of 75-100 trees in a heavily wooded area at the Sizerville State Park. The damage straddled the Cameron/Potter county line with most of the damage in Cameron County.
Thunderstorm winds estimated near 60 mph knocked down trees in Leidy Township near Tamarack.
IPT ASOS measured a peak thunderstorm wind gust of 58 mph at 20:19 UTC.
Thunderstorm winds estimated near 60 mph knocked down numerous trees just north of Montoursville.
Thunderstorm winds estimated near 60 mph knocked down several trees and utility wires in and around the city of Williamsport. Wind damage was reported across Piatt, Old Lycoming, Hepburn, Muncy and Wolf Townships along with Hughesville and South Williamsport Boroughs.
Penny-size hail (0.75 inch) reported in Yeagertown.
Quarter-size hail (1 inch) reported in Burnham.
Thunderstorm winds estimated between 60-70 mph knocked down power poles and utility wires along SR 46 near Smethport.
Thunderstorm winds estimated between 60-70 mph knocked down several trees in and around Clearfield.
Thunderstorm winds estimated between 60-70 mph knocked down numerous trees in Houtzdale.
Thunderstorm winds gusted over 60 mph for several minutes at the NWS office. The peak gust was measured at 64 mph.
UNV AWOS measured a peak thunderstorm wind gust of 67 mph at 23:53 UTC.
Thunderstorm winds estimated between 60-70 mph knocked down trees in Armagh Township.
KMUI ASOS measured a peak thunderstorm wind gust of 59 mph at 2107 EDT.
Thunderstorm winds estimated near 60 mph knocked down trees in Addison.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2013Every state in 2013This day in weather historyWarnings in Pennsylvania, April 2013
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: 433912, 433895, 433896, 433897, 435482, 433898, 433900, 433899, 433901, 433902, 433903, 433904, 433905, 433906, 433909, 433910, 433907, 433911, 433908.