Low pressure brought a steady rain across much of central Pennsylvania on September 12, 2015. Modest CAPE developed across the Lower Susquehanna Valley, with enough instability to generate a severe thunderstorm that knocked down trees in York County, PA.
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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 CTP wrote it up.
Low pressure brought a steady rain across much of central Pennsylvania on September 12, 2015. Modest CAPE developed across the Lower Susquehanna Valley, with enough instability to generate a severe thunderstorm that knocked down trees in York County, PA.
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 Sep 12, 1:20 PM EST, 13 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 220 PM EDT SAT SEP 12 2015 .SYNOPSIS... A SLOW MOVING FRONTAL SYSTEM WILL MOVE OFF EAST OF THE REGION TONIGHT. THE UPPER LEVEL LOW ASSOCIATED WITH THE FRONT WILL KEEP US UNSETTLED THROUGH SUNDAY. FAIR AND WARMER CONDITIONS WILL RETURN BEGINNING MONDAY AND CONTINUE THROUGH MOST OR ALL OF NEXT WEEK AS A LARGE AREA OF HIGH PRESSURE DRIFTS OVER THE OHIO VALLEY AND MID ATLANTIC REGION. && .NEAR TERM /THROUGH TONIGHT/... SURFACE LOW AS OF NOON LOOKS LIKE IT IS PRETTY MUCH ON TOP OF JOHNSTOWN. THE WAVY FRONT EXTENDS NNE TO BETWEEN WILLIAMSPORT AND WELLSBORO...AND SOUTH FROM THE LOW THROUGH WESTERN VIRGINIA. LIGHTNING DATA IS STARTING TO SHOW SOME STRIKES SNEAKING INTO THE MARYLAND BORDER COMMUNITIES OF FRANKLIN AND ADAMS COUNTIES. WESTERN 1/4 OR SO OF MY FCST AREA HAS JUST SHOWERY PRECIPITATION AT NOON...WHILE A STEADY MODERATE TO HEAVY RAIN IS FALLING OVER MOST OF THE REMAINDER OF THE AREA. HRRR CONTINUES TO GENERATE NEW RAIN OVER VIRGINIA WHICH IT SURGES NNE OVER CENTRAL AND EASTERN ZONES THROUGH LATE AFTERNOON. OBSERVED RADAR TRENDS SUGGEST THIS MAY BE A LITTLE TOO FAR WEST...AND THE BEST RAINS COULD TAPER OFF LOCALLY BETWEEN 2 AND 3PM AS THE BACK EDGE SLOWLY PROPAGATES EASTWARD. OTHER ISSUE TO CONTEND WITH WILL BE THE POTENTIAL FOR STRONG/SEVERE THUNDERSTORMS TO DEVELOP IN THE INCREASINGLY UNSTABLE AIRMASS PUSHING UP INTO SERN PA. SPC HAS PLACED THE EASTERN 1/3 OF THE STATE UNDER A MARGINAL RISK. CLOUD COVER IS EXTENSIVE AND INSTABILITY ISN'T VERY IMPRESSIVE SO THE CHANCES WILL NOT BE HIGH...BUT CANNOT RULE OUT AN ISOLATED STRONG STORM TO DEVELOP IN THE INCREASINGLY HUMID ENVIRONMENT AS WIND FIELDS INTENSIFY WITH THE APPROACH OF THE JET. TEMPS TODAY WILL RISE ONLY VERY SLOWLY ACROSS CENTRAL AND WESTERN PA THIS MORNING. WARMEST TEMPS TODAY WILL BE OVER THE SUSQ VALLEY WHERE HIGHS WILL REACH THE LOW TO MID 70S...WHILE THE NW MTNS AND LAUREL HIGHLANDS SEE THE MERCURY HOLD BETWEEN 59-62F. HAVE MODIFIED POPS AND STORM TOTAL RAINFALL SLIGHTLY...BUT STILL FEEL THAT MODEL CONSENSUS STILLS POINTS TWD A BENEFICIAL AMOUNT OF .50" TO 1.00" INCHES ACROSS THE REGION BY LATE TONIGHT. SHORT RANGE OPERATIONAL MODELS AGREE WITH THE STEADY RAIN TAPERING OFF QUICKLY THIS EVENING...WITH JUST SCATTERED SHOWERS REMAINING FOR MUCH OF THE OVERNIGHT. THIS WILL PROMPT AN OVERALL LOWERING OF THE POPS...WITH THE HIGHEST CHANCES CONFINED TO MY WESTERN AND NORTHER HIGHER ELEVATIONS. && .SHORT TERM /SUNDAY/... THE UPPER LOW AND TROUGH WILL BE SWINGING THROUGH DURING THE DAY SUNDAY. COLD AIR ALOFT WILL HELP DESTABILIZE THE ATMOSPHERE LEADING TO THE CHANCE OF A FEW POP UP SHOWERS...AND WITH TOTAL- TOTALS TICKLING 50...WOULDN'T BE SURPRISED TO SEE SOME LOW TOPPED THUNDER AND PEA SIZED HAIL. A GRADUALLY INCREASING NW BREEZE WILL DEVELOP LATE TONIGHT AND SUNDAY WITH WIND GUSTS OF 15-25 MPH FROM THE NW EXPECTED DURING THE DAY SUNDAY. HIGHS AVERAGING IN THE 60S WILL BE SOME 5-10 DEG COOLER THAN NORMAL FOR THE SECOND WEEK OF SEPTEMBER. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... THE BULK OF THE SENSIBLE WEATHER WILL OCCUR VERY EARLY IN THIS EXTENDED FCST PERIOD AS WE EXPERIENCE THE EFFECTS OF THE UPPER TROUGH CLOSING OFF AS IT DROPS THROUGH THE EASTERN GR LAKES AND EVENTUALLY MOVES OVERHEAD. ENSEMBLES INDICATE THE RAIN TAPERING TO SHOWERS AND ENDING SUNDAY NIGHT. THIS WILL SET THE STAGE FOR ANOTHER EXTENDED PERIOD OF DRY WEATHER WHICH SHOULD LAST THROUGH THE END OF THE WORK WEEK AND POSSIBLY INTO THE WEEKEND AS THE MEAN UPPER RIDGE IS PROJECTED TO SURGE BACK INTO THE NERN US. GEFS AND ECMWF HINT AT SHORTWAVE ENERGY BEGINNING TO CHEW THE TOP OFF THE RIDGE BY NEXT WEEKEND WHICH LEADS TO THE MENTION OF A SMALL CHANCE OF SHOWERS...BUT CONFIDENCE IS LOW THIS FAR OUT. UNTIL THEN IT LOOKS LIKE ANOTHER BOUT OF LATE SUMMER WARMTH ON THE WAY. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... THE SURFACE COLD FRONT WILL EDGE SLOWLY EAST ACROSS PA TODAY...MOVING EAST OF THE REGION OVERNIGHT. WIDESPREAD IFR/MVFR WILL DOMINATE INTO THE OVERNIGHT. THERE COULD BE ENOUGH INSTABILITY THAT AN ISOLATED THUNDERSTORM CANNOT BE RULED OUT OVER THE SOUTHERN AND ESPECIALLY SOUTHEASTERN AREAS THROUGH LATE AFTERNOON. RAIN WILL TAPER TO SHOWERS THIS EVENING AS THE MAIN WAVE BEGINS TO EXIT...BUT EXPECT WIDESPREAD IFR/MVFR TO CONTINUE AS THE UPPER LOW MOVES OVER THE AREA. AS TROUGH LIFTS TO THE NE....MUCH OF SUNDAY WILL FEATURE GUSTY WINDS...MVFR CONDITIONS AND SHOWERS...MOST NUMEROUS IN THE NW. CANNOT RULE OUT A GUSTY THUNDERSTORM AS WELL. OUTLOOK... MON-THU...SCT MORNING VALLEY FOG...OTHERWISE VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && SYNOPSIS...LA CORTE NEAR TERM...LA CORTE SHORT TERM...LA CORTE LONG TERM...LA CORTE AVIATION...LA CORTE
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE STATE COLLEGE PA 600 AM EDT SAT SEP 12 2015 PAZ004>006-010>012-017>019-024>027-033>035-037-045-131000- WARREN-MCKEAN-POTTER-ELK-CAMERON-NORTHERN CLINTON-CLEARFIELD- NORTHERN CENTRE-SOUTHERN CENTRE-CAMBRIA-BLAIR-HUNTINGDON-MIFFLIN- SOMERSET-BEDFORD-FULTON-TIOGA-SOUTHERN CLINTON- 600 AM EDT SAT SEP 12 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. PERIODS OF MODERATE...TO BRIEFLY HEAVY RAIN WILL OCCUR TODAY...ALONG WITH ISOLATED THUNDERSTORMS. STORM TOTAL RAINFALL BY LATE TONIGHT WILL VARY FROM ONE-HALF OF AN INCH...TO A LITTLE OVER ONE INCH. A FEW LOCATIONS THAT EXPERIENCE THUNDERSTORMS COULD SEE BETWEEN 1.5 AND 2 INCHES OF RAIN. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY. NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. PAZ028-036-041-042-046-049>053-056>059-063>066-131000- JUNIATA-FRANKLIN-NORTHERN LYCOMING-SULLIVAN-SOUTHERN LYCOMING-UNION- SNYDER-MONTOUR-NORTHUMBERLAND-COLUMBIA-PERRY-DAUPHIN-SCHUYLKILL- LEBANON-CUMBERLAND-ADAMS-YORK-LANCASTER- 600 AM EDT SAT SEP 12 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING. THE PRIMARY SEVERE WEATHER IMPACTS WILL BE IN THE FORM OF LOCALIZED DAMAGING WIND GUSTS AND PERHAPS A FEW INSTANCES OF HAIL OF BETWEEN DIME AND QUARTER SIZE. IN ADDITION...ERIODS OF MODERATE...TO BRIEFLY HEAVY RAIN WILL OCCUR TODAY...ALONG WITH ISOLATED THUNDERSTORMS. STORM TOTAL RAINFALL BY LATE TONIGHT WILL VARY FROM ONE-HALF OF AN INCH...TO A LITTLE OVER ONE INCH .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY. NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Sterling radar (KLWX), 112 km away, was scanning. The volume nearest the first event began at 18:32 UTC.
1 thunderstorm wind. Local standard time, as filed.
A thunderstorm producing winds estimated near 60 mph knocked down trees in Shrewsbury.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2015Every state in 2015This day in weather historyWarnings in Pennsylvania, September 2015
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: 594179.