A strong cold frontal passage triggered severe thunderstorms across Eastern Pennsylvania on the afternoon of the 27th. The combination of lightning and damaging winds caused about 62,000 homes and businesses to lose power.
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 PHI wrote it up.
A strong cold frontal passage triggered severe thunderstorms across Eastern Pennsylvania on the afternoon of the 27th. The combination of lightning and damaging winds caused about 62,000 homes and businesses to lose power. Most of the outages (about 49,000) were in PECO Energy's service area in southeast Pennsylvania.
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 Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Jul 27, 9:46 AM EST, 1 hour 22 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1046 AM EDT SUN JUL 27 2008 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE REGION LATER THIS AFTERNOON INTO TONIGHT. THE FRONT WILL MOVE OFFSHORE ON MONDAY. A LOW PRESSURE AREA OVER THE GREAT LAKES REGION ON WEDNESDAY WILL MOVE ACROSS THE REGION ON THURSDAY. HIGH PRESSURE WILL BUILD INTO THE AREA TOWARD THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A SURFACE ANALYSIS THIS MORNING SHOWS A COLD FRONT DRAPED FROM UPSTATE NEW YORK THROUGH CENTRAL PENNSYLVANIA, THEN BACK THROUGH THE OHIO VALLEY. MEANWHILE, A PRE-FRONTAL TROUGH WAS ANALYZED FROM EASTERN PENNSYLVANIA THROUGH VIRGINIA AND THE CAROLINAS. AN UPPER AIR ANALYSIS SHOWS A SHARPENING TROUGH IN THE GREAT LAKES, WITH WATER VAPOR IMAGERY SHOWING THIS FEATURE AMPLIFYING INTO THE NORTHEAST, WITH AN INITIAL SHORT WAVE FROM CENTRAL NEW YORK TO WEST VIRGINIA. AN UPPER-LEVEL JET IS POSITIONED FROM THE MIDWEST INTO THE MID ATLANTIC WITH A CYCLONICALLY CURVED JET BRUSHING WESTERN NEW ENGLAND. AS THE UPPER TROUGH CONTINUES TO SLIDE EASTWARD, HEIGHT FALLS WILL OCCUR ACROSS OUR AREA THIS AFTERNOON AND TONIGHT. THIS COMBINED WITH INCREASED LOW-LEVEL MOISTURE AND BUILDING INSTABILITY ON THE ORDER OF SOME 2500 J/KG WILL ALLOW FOR CONVECTIVE INITIATION. GIVEN THE INCREASED MOISTURE, THERE HAS BEEN SOME MAINLY MID TO HIGH CLOUDS AROUND. A STABILITY ANALYSIS AT 14Z, COURTESY OF THE LAPS DATA, ALREADY HAS SOME 2000 J/KG OF SBCAPE FROM ABOUT TRENTON ON SOUTH AND WESTWARD /LESS RIGHT ALONG THE COAST/. THE INCOMING HEIGHT FALLS COMBINED WITH PLENTY OF INSTABILITY AND SOME SHEAR POINT TO AN INCREASING CONVECTIVE THREAT. ONE FOCUSING MECHANISM MAY BE THE PRE-FRONTAL SURFACE TROUGH JUST TO OUR WEST. OUR SEVERE WEATHER CHECKLIST SUGGESTS THAT DAMAGING WINDS WILL BE THE PRIMARY THREAT, HOWEVER WITH WET- BULB ZERO HEIGHTS NEAR THE UPPER RANGE /ABOUT 11000 FEET/, SEVERE HAIL IS DEFINITELY POSSIBLE ESPECIALLY GIVEN THE PROJECTED INSTABILITY PROFILES WHICH WOULD TEND TO ENHANCE UPDRAFT STRENGTHS. WITH MODEST WESTERLY FLOW ALOFT, THERE APPEARS TO BE ENOUGH SHEAR TO PROMOTE STORMS TO ORGANIZE INTO LINES WITH POSSIBLY EVEN SOME MIDLEVEL STORM ROTATION. THE 12Z RAOB FROM STERLING, VIRGINIA HAS -10C AIR AT 500 MB, RELATIVELY STEEP LAPSE RATES AND A WEAK CAP. THIS RAOB ALSO HAS A DRY LAYER JUST BELOW THE MIDLEVELS, AND IF THIS WERE TO REMAIN, CONVECTIVE DOWNDRAFTS COULD BE ENHANCED. IN SUMMARY, LOCALLY DAMAGING WIND GUSTS AND HAIL WILL BE POSSIBLE WITH THE MORE ROBUST CONVECTIVE ELEMENTS THIS AFTERNOON AND EVENING. IN ADDITION, LOCAL DOWNPOURS WILL OCCUR WITH PW VALUES AROUND 1.5 INCHES AND GIVEN THE MOIST ATMOSPHERE, STORMS MAY TEND TO GENERATE FREQUENT CLOUD TO GROUND LIGHTNING. THE STORM PREDICTION CENTER /SPC/ CONTINUES WITH A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS OUR ENTIRE CWA. BASED ON THE ABOVE, WE MADE LITTLE IN THE WAY OF CHANGES TO THE GOING FORECAST AS IT LOOKS PRETTY GOOD WITH THE IDEA OF SHOWERS AND STORMS DEVELOPING AND BECOMING MORE NUMEROUS. THE TIMING OF ACTUAL INITIATION THOUGH IS MORE DIFFICULT GIVEN SOME CLOUD COVER AROUND AT THE MOMENT, HOWEVER REGIONAL RADAR IMAGERY SHOWING SOME CELLS ALREADY STARTING TO DEVELOP. SPC HAS INCREASED THE PERCENTAGE OF HAIL AND DAMAGING WINDS ACROSS OUR AREA, THEREFORE WE DECIDED TO BUMP UP THE ENHANCED WORDING, AND WE ALSO ADDED FREQUENT LIGHTNING. BASED ON TEMPERATURE TRENDS SO FAR TODAY, WE CONTINUED TO LEAN MORE TOWARD THE WARMER GFS HIGH TEMPERATURES THIS AFTERNOON ESPECIALLY ACROSS THE SOUTHERN AND EASTERN PORTIONS OF THE CWA. THE HOURLY GRIDS WERE UPDATED TO REFLECT THE CURRENT CONDITIONS AND ANTICIPATED TRENDS THROUGH THE AFTERNOON. WFO STERLING, VIRGINIA IS PLANNING TO LAUNCH A SPECIAL RAOB AROUND 18Z DUE TO THE THREAT OF SEVERE WEATHER. THAT IS ALL FOR NOW. ALL THE UPDATED PRODUCTS WILL BE SENT SHORTLY. HAVE A GREAT AFTERNOON AND KEEP AN EYE TO THE SKY && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... FEW CHANGES IN THIS PERIOD FROM THE PREVIOUS FORECAST PACKAGE. FOR TONIGHT, WE MAINLY CONFINE THE POPS TO THE EVENING PERIOD, AND WE SWITCH THE HIGHER POPS TO THE SOUTHEAST AS THE UPPER JET AND THE ASSOCIATED IMPULSE PUSH THROUGH. FOR MONDAY...WITH UPPER TROUGH STILL ROTATING THROUGH...WENT WITH WIDELY SCT CONVECTION DURING AFTERNOON...RAN HIGHER THAN MOS POP GUIDANCE. WX IS DRY FOR MONDAY NIGHT. ETA MOS STILL LOOKS TOO COOL WITH TOO MUCH CLOUD COVER AND WENT WITH WARMER GFS MOS FOR MON HIGH TEMP. && .LONG TERM /TUESDAY THROUGH SATURDAY/... VERY FEW CHANGES FROM THE PREVIOUS FORECAST IN THIS TIME PERIOD. TRENDED A LITTLE WARMER FOR WED IN DEFERENCE TO LATEST GFS MOS. THERE IS PRETTY GOOD AGREEMENT ON THE LARGE SCALE PATTERN IN THE LONG TERM. AT MID LEVELS, THERE IS A MID LEVEL VORTEX OVER SOUTHEASTERN CANADA AND AN ASSOCIATED TROUGH DROPPING INTO OUR REGION. AT THE SURFACE, THERE IS AN ASSOCIATED BOUNDARY THAT HANGS AROUND THE MID-ATLANTIC REGION. CONFIDENCE IN TIMING ENERGY ROTATING AROUND THE MID LEVEL FEATURE AND THE ASSOCIATED SURFACE BOUNDARY IS NOT TERRIBLY HIGH, BUT PER THE ECMWF AND ITS ENSEMBLE MEAN, WHICH MAKE UP THE BULK OF WHAT HPC AND WE HAVE USED, THE BEST CHANCE FOR ACTIVITY LOOKS TO BE IN THE WEDNESDAY AFTERNOON TO THURSDAY AFTERNOON TIME FRAME. OTHERWISE, ANY POPS WILL BE IN THE SLIGHT CHANCE RANGE AS PER THE LOW LEVEL OF CONFIDENCE. TEMPERATURES THROUGH THE PERIOD ARE FORECAST TO BE AT OR A TAD ABOVE NORMAL. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... THE TAFS WERE UPDATED TO REFLECT THE LATEST THINKING. IT APPEARS THAT A GOOD AMOUNT OF CONVECTION SHOULD DEVELOP ACROSS THE ENTIRE AREA THIS AFTERNOON AS A COLD FRONT ARRIVES AND COMBINES WITH INSTABILITY AND UPPER-LEVEL SUPPORT. WE CHANGED TO A THUNDER MENTION AS OPPOSED TO SHOWERS AND A CB. GIVEN THE ATMOSPHERIC SET-UP THIS AFTERNOON, WE ADDED IN GUSTY WINDS IN A TEMPO GROUP WITH THUNDER AS SOME STORMS COULD BE RATHER GUSTY. IT IS STILL A BIT UNCLEAR ON HOW ORGANIZED STORMS CAN GET, BUT THEY MAY TEND TO DEVELOP INTO LINES. OTHERWISE, WE ARE EXPECTING THE LINGERING DEBRIS TYPE CLOUDS TO THIN SOME MORE OVER THE NEXT FEW HOURS WITH CUMULUS DEVELOPING WITH CONTINUED SURFACE HEATING AND DEW POINTS WELL INTO THE 60S TO NEAR 70. SOME OF THE MODEL GUIDANCE SUGGEST THAT THE STORMS TAPER OFF SOONER ESPECIALLY FOR KRDG AND KABE, THEREFORE WE TRIED TO INCORPORATE SOME OF THIS THINKING INTO THE UPDATED TAFS. GIVEN THE ATMOSPHERE SHOULD BE CONVECTIVELY OVERTURNED TONIGHT AND THE COLD FRONT SLIDES TO OUR EAST, CLOUD COVER IS EXPECTED TO BE ON THE DECREASE. A LIGHT SOUTH TO SOUTHWEST WIND WILL INCREASE SOME THROUGH THE AFTERNOON, AND MAY TEND TO TURN MORE TO THE SOUTH MAINLY AT KACY FOR AWHILE. OUTLOOK... THE COLD FRONT WILL SLIDE SOUTH AND EAST OF THE AREA AND THEN PROBABLY BECOME NEARLY STATIONARY THROUGH MIDWEEK. A LOW PRESSURE SYSTEM MAY MOVE THROUGH LATER WEDNESDAY INTO THURSDAY, POTENTIALLY BRINGING AN INCREASING CHANCE FOR SHOWERS AND THUNDERSTORMS. && .MARINE... SOUTHERLY FLOW WILL CONTINUE ACROSS THE WATERS IN ADVANCE OF AN APPROACHING COLD FRONT. THIS FRONT WILL CROSS THE REGION LATER THIS AFTERNOON AND EVENING THEN MOVE OFF THE COAST. IT IS LIKELY TO STALL SOUTH OF THE AREA. SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG AND IN ADVANCE OF THE FRONT, AIDED BY DAYTIME HEATING. LATEST WAVEWATCH DATA INDICATES THAT SEAS WILL REMAIN BELOW SCA CRITERIA, AND EVEN THOUGH WINDS WILL INCREASE IN ADVANCE OF THE FRONT AS THE GRADIENT TIGHTENS, THEY SHOULD NOT REACH CRITERIA EITHER. HIGH PRESSURE WILL THEN BUILD IN FOR MONDAY INTO TUESDAY. THERE IS SOME UNCERTAINTY AS TO WHETHER OR NOT ANOTHER SYSTEM WILL AFFECT THE REGION THROUGH MIDWEEK. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && SYNOPSIS...SZATKOWSKI NEAR TERM...GORSE SHORT TERM...SZATKOWSKI LONG TERM...DELISI/SZATKOWSKI AVIATION...NIERENBERG/GORSE MARINE...NIERENBERG
HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1149 AM EDT SUN JUL 27 2008 DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-055- 060>062-067>071-281200- NEW CASTLE-KENT-INLAND SUSSEX-DELAWARE BEACHES-CECIL-KENT MD- QUEEN ANNES-TALBOT-CAROLINE-SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET- MIDDLESEX-WESTERN MONMOUTH-EASTERN MONMOUTH-MERCER-SALEM-GLOUCESTER- CAMDEN-NORTHWESTERN BURLINGTON-OCEAN-CUMBERLAND-ATLANTIC-CAPE MAY- ATLANTIC COASTAL CAPE MAY-COASTAL ATLANTIC-COASTAL OCEAN- SOUTHEASTERN BURLINGTON-CARBON-MONROE-BERKS-LEHIGH-NORTHAMPTON- CHESTER-MONTGOMERY-BUCKS-DELAWARE-PHILADELPHIA- 1149 AM EDT SUN JUL 27 2008 ...SEVERE THUNDERSTORM WATCH 759 IN EFFECT UNTIL 8 PM EDT THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL DELAWARE...NORTHERN DELAWARE...SOUTHERN DELAWARE...NORTHEAST MARYLAND...CENTRAL NEW JERSEY...NORTHERN NEW JERSEY...NORTHWEST NEW JERSEY...SOUTHERN NEW JERSEY...EAST CENTRAL PENNSYLVANIA...NORTHEAST PENNSYLVANIA AND SOUTHEAST PENNSYLVANIA. .DAY ONE...THIS AFTERNOON AND TONIGHT PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. SEVERE THUNDERSTORM WATCH. SOME THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE DAMAGING WINDS AND LARGE HAIL, AS WELL AS FREQUENT CLOUD TO GROUND LIGHTNING AND LOCALLY HEAVY RAINFALL THROUGH EARLY THIS EVENING. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL LIKELY BE NEEDED. ANZ450>455-281200- COASTAL WATERS FROM SANDY HOOK TO MANASQUAN INLET NJ OUT 20 NM- COASTAL WATERS FROM MANASQUAN INLET TO LITTLE EGG INLET NJ OUT 20 NM- COASTAL WATERS FROM LITTLE EGG INLET TO GREAT EGG INLET NJ OUT 20 NM- COASTAL WATERS FROM GREAT EGG INLET TO CAPE MAY NJ OUT 20 NM- COASTAL WATERS FROM CAPE MAY NJ TO CAPE HENLOPEN DE OUT 20 NM- COASTAL WATERS FROM CAPE HENLOPEN TO FENWICK ISLAND DE OUT 20 NM- 1149 AM EDT SUN JUL 27 2008 THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS. .DAY ONE...THIS AFTERNOON AND TONIGHT SOME THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE LOCALLY GUSTY WINDS, FREQUENT CLOUD TO GROUND LIGHTNING AND HEAVY RAINFALL THIS AFTERNOON AND EVENING. MARINERS SHOULD BE PREPARED TO SEEK SAFE HARBOR QUICKLY AS THE STORMS DEVELOP. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED. ANZ430-431-281200- DELAWARE BAY WATERS NORTH OF EAST POINT NJ TO SLAUGHTER BEACH DE- DELAWARE BAY WATERS SOUTH OF EAST POINT NJ TO SLAUGHTER BEACH DE- 1149 AM EDT SUN JUL 27 2008 ...SEVERE THUNDERSTORM WATCH 759 IN EFFECT UNTIL 8 PM EDT THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR DELAWARE BAY WATERS. .DAY ONE...THIS AFTERNOON AND TONIGHT PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS. SEVERE THUNDERSTORM WATCH. SOME THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE DAMAGING WINDS AND LARGE HAIL, AS WELL AS FREQUENT CLOUD TO GROUND LIGHTNING AND LOCALLY HEAVY RAINFALL THROUGH EARLY THIS EVENING. MARINERS SHOULD BE PREPARED TO SEEK SAFE HARBOR QUICKLY AS THE STORMS DEVELOP. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL LIKELY BE NEEDED. GORSE
The Philadelphia radar (KDIX), 141 km away, was scanning. The volume nearest the first event began at 16:08 UTC.
8 thunderstorm wind, 8 hail, 2 lightning. Local standard time, as filed.
A thunderstorm wind gust of 59 mph was measured at the Reading Regional Airport. Marble size (half inch) hail fell from the same storm in both Reading and Exeter Township. Trees were uprooted in a cemetery in nearby Muhlenberg Township. Some poor drainage flooding also occurred within Reading.
Large hail damaged farm produce in Lower Alsace Township.
A severe thunderstorm dropped penny size hail and produced wind gusts to around 45 mph near Albrightsville in Penn Forest Township.
A severe thunderstorm knocked over some large trees in the eastern part of Berks County. One large downed tree damaged a minivan and the roof of a home on Old Airport Road in Amity Township. There were about 300 weather related calls associated with the strong to severe thunderstorms in Berks County on the afternoon of the 27th. About 6,400 homes and businesses lost power. Power was not fully restored until the morning of the 28th.
A severe thunderstorm dropped penny size hail Colebrookdale Township.
Penny size hail was reported in Upper Pottsgrove Township.
A severe thunderstorm tore down a couple of trees in Pottstown. One truck was struck and damaged by a fallen tree.
Penny size hail fell in Honey Brook Township.
A severe thunderstorm dropped penny to nickel size hail in Royersford. There was enough hail to cover the ground.
A severe thunderstorm tore down several trees in Eagleville in Lower Providence Township.
A severe thunderstorm tore down a few trees and wires in Montgomery Township. In nearby Lansdale, wires were knocked down on Cannon Avenue and a car was damaged by a fallen tree off of Main Street. The severe thunderstorms and lightning caused about 4,500 Metropolitan Edison and 1,900 Pennsylvania Power and Light customers to lose power in Montgomery County. In addition, about 30,000 PECO Energy homes and businesses in both Bucks and Montgomery Counties lost power.
A woman suffered a minor injury when she was shocked by an direct lightning strike in Montgomery Township. She was apparently on a laptop computer when lightning struck nearby. She was shicked, but not seriously injured.
A series of lightning strikes caused a couple of house fires and other damage across central Bucks County. One firefighter was treated for heat exhaustion. In Hilltown, a home on Paige Trail was struck by lightning on its roof. Smoke spewed from the garage section of the home. Firefighters removed a three foot by three foot section of the roof to help battle the blaze. Five fire companies assisted. The fire was contained to the attic and the second floor master bedroom of the house. In Solebury Township, the chimney of a house on Brighton Way was struck by lightning. The lightning traveled down into the basement where a fire was ignited. Four fire companies battled the blaze for two and a half hours. The fire was contained to one area of the house, but caused heavy smoke damage throughout. The house was expected to be uninhabitable for a few days. Also in Solebury Township, a lightning strike caused a transformer fire. In Warrington Township, another lightning strike damaged a home's chimney. In New Britain Township, lightning struck a PECO Energy substation. U.S. Route 202 was closed as firefighters battled the blaze. One firefighter was treated for heat exhaustion. The combination of damaging winds and lightning strikes caused about 30,000 homes and businesses to lose power in Bucks and Montgomery Counties.
A severe thunderstorm tore down a few trees and wires in New Britain, Warwick and Warrington Townships. In Warrington Township, Pennsylvania State Route 611 was closed in both directions because of downed trees. About 30,000 PECO Energy customers in Bucks and Montgomery Counties lost power because of downed trees.
Penny size hail fell in the Roxborough section of Philadelphia.
A severe thunderstorm tore down a few trees in Philadelphia. Downed trees were reported in the northeast, south and western parts of the city.
Penny size hail was reported in Boothwyn.
A severe thunderstorm tore down several large tree limbs and wires across southeastern Delaware County.
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, July 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: 125003, 128696, 125011, 128703, 125015, 125016, 128705, 125021, 125027, 125073, 125104, 125119, 128717, 125123, 125131, 125151, 125165, 125166.