An area of rain with embedded thunderstorms caused flash flooding in the Lehigh Valley and upper Bucks County and poor drainage flooding in Philadelphia as well as brief minor flooding along the Frankford Creek on the 28th. The rain started during the morning of the 28th, fell at its heaviest around Noon EDT and ended during the early evening of the 28th.
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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 PHI wrote it up.
An area of rain with embedded thunderstorms caused flash flooding in the Lehigh Valley and upper Bucks County and poor drainage flooding in Philadelphia as well as brief minor flooding along the Frankford Creek on the 28th. The rain started during the morning of the 28th, fell at its heaviest around Noon EDT and ended during the early evening of the 28th. Rainfall amounts varied across east central and southeast Pennsylvania, but averaged between 1 and 3 inches in most places. The precipitation formed and rode along a stationary front over Pennsylvania and New Jersey. This boundary started to sag southward during the late afternoon and night as a low pressure system that formed along the boundary passed south of Philadelphia.
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 Aug 28, 8:48 AM EST, 1 hour 12 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 948 AM EDT WED AUG 28 2013 .SYNOPSIS... WEAK LOW PRESSURE OVER LAKE ERIE THIS MORNING WILL MOVE SOUTHEASTWARD AND IT SHOULD PASS OFF THE VIRGINIA COAST LATE TONIGHT. WEAK HIGH PRESSURE FROM THE NORTHWEST AND NORTH IS ANTICIPATED TO FOLLOW FOR THURSDAY THROUGH SATURDAY. A WARM FRONT APPROACHING FROM THE SOUTHWEST WILL LIFT THROUGH OUR REGION ON SUNDAY OR SUNDAY NIGHT WITH A COLD FRONT FROM THE NORTHWEST EXPECTED TO ARRIVE ON MONDAY NIGHT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A MID LEVEL VORTEX LOCATED OVER NORTHWESTERN PENNSYLVANIA AT MID MORNING IS EXPECTED TO DROP SOUTHEASTWARD PASSING NEAR THE WASHINGTON DC AREA AROUND MID AFTERNOON AND MOVING OFF THE VIRGINIA COAST THIS EVENING. THE FEATURE WILL PROVIDE LIFT OVER OUR REGION THROUGH MUCH OF THE DAY RESULTING IN ADDITIONAL SHOWERS AND SCATTERED THUNDERSTORMS. BY MID MORNING, OVER AN INCH OF RAIN HAD FALLEN IN PARTS OF THE LEHIGH VALLEY AND UPPER BUCKS COUNTY. PRECIPITABLE WATER VALUES WILL REMAIN NEAR OR IN EXCESS OF 2 INCHES FOR MUCH OF THE DAY, ESPECIALLY IN EASTERN PENNSYLVANIA, NORTHEASTERN MARYLAND, DELAWARE AND SOUTHERN NEW JERSEY. THE STEERING FLOW WILL BE RATHER WEAK. AS A RESULT, SHOWERS AND THUNDERSTORMS WILL BE SLOW MOVING AND ADDITIONAL MODERATE TO HEAVY RAINFALL AMOUNTS ARE LIKELY, ESPECIALLY IN OUR WESTERN AND SOUTHERN COUNTIES. TODAY'S TEMPERATURE FORECAST REMAINS A BIT TRICKY DUE TO THE CLOUD COVER. WHERE THE CLOUD COVER REMAINS MOSTLY OPAQUE OUR CURRENT FORECAST WILL BE A BIT ON THE HIGH SIDE. IF ENOUGH THIN SPOTS AND BREAKS DEVELOP THE FORECAST SHOULD BE FINE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... LEFTOVER CONVECTION DURING THE EVENING...MAINLY TO THE S OF KPHL. THEN FOG AND STRATUS OVERNIGHT WITH POTENTIAL FOR 1/4MI DENSE FOG IN PLACES WITH LIGHT WIND AND CLEARING ALOFT LEAVING THE MOIST BL EXPOSED TO SATURATION. USED THE UPS CROSSOVER TOOL FOR FOG AFTER 06Z. CONFIDENCE: ABOVE AVERAGE. && .LONG TERM /THURSDAY THROUGH TUESDAY/... ALOFT...THE PERIOD STARTS OFF WITH A NORTHWEST FLOW. AS THE BIG RIDGE TO OUR WEST BECOMES SUPPRESSED ON SATURDAY, THE FLOW OVER THE MID-ATLANTIC BECOMES MORE WESTERLY. THE FLOW TURNS MORE SOUTHWESTERLY ON MONDAY AND TUESDAY AS A TROF MOVES THROUGH. AT THE SURFACE...WEAK HIGH PRESSURE WILL BE IN PLACE THURSDAY THROUGH SATURDAY. A WARM WILL MOVE THROUGH ON SUNDAY. A COLD FRONT WILL FOLLOW ON MONDAY NIGHT. PRECIPITATION...LOTS OF SMALL POPS(20/30%) THROUGH SUNDAY WITH THE HIGHEST POPS ACROSS THE I-95 CORRIDOR WESTWARD AND DURING THE AFTERNOON AND EVENING. WITH A COLD FRONT APPROACHING ON MONDAY AND MOVING THROUGH MONDAY NIGHT, POPS ARE EVENLY DISTRIBUTED. EVEN THOUGH WEAK HIGH PRESSURE IS IN PLACE, MODELS HAVE BEEN PUSHING PRECIP ACROSS THE INTERIOR LATE THIS WEEK AND INTO THE WEEKEND FOR A COUPLE DAYS. WITH WEAK S/W'S MOVING ACROSS THE TOP OF US COMBINED WITH AFTERNOON INSTABILITY AND SHALLOW MOISTURE CONVERGENCE, IT SEEMS REASONABLE. THE ONLY REAL CHANGE I MADE IN THE GRIDS THIS MORNING WAS TO FOCUS MORE ON THE INTERIOR. THOSE VISITING THE BEACHES MAY NOT SEE A DROP. AND THOSE FURTHER INLAND, THE FORECAST WILL SOUND WETTER THAN REALITY. TEMPERATURES...AROUND NORMAL THROUGH MONDAY. SLIGHTLY BELOW NORMAL ON TUESDAY. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...VFR CIGS. ANY MVFR MORNING FOG WILL BURN OFF BY 15Z. LIGHT WIND. SHOWERS AND SCT TSTMS EXPECTED MOST TAF SITES FOR 1-4 HOURS. MOST LIKELY AREA FOR TSTMS IS VCNTY KABE- KPHL- KILG- KMIV. THE TAFS HAVE 3SM MDT SHOWERS WHERE MY CONFIDENCE IS GREATEST FOR CONVECTION BUT NO MENTION OF TSTM ATTM DESPITE MY EXPECTATION THAT KRDG/KPHL/KILG WILL RECORD A TSTM TODAY. CONFIDENCE ON DETAILS: AVERAGE. TONIGHT...VFR CIGS OR MVFR CONDS IN FOG/SCT SHOWERS AND ISO TSTMS DIMINISHING EARLY WITH IFR CONDS IN ST/FOG APPEARING LIKELY LATE FOR MOST TAF SITES. 21Z/27 SREF PROBS FOR THIS IFR OCCURRENCE ARE ABOUT 40-50 PCT FOCUSED ON KMIV-KPHL AXIS. CONFIDENCE ON CIGS/VSBY EARLY IS BELOW AVG. CONFIDENCE ON SOME SORT OF IFR IN FOG/STRATUS LATE IS ABOVE AVERAGE...MAINLY AFTER 06Z. OUTLOOK... THURSDAY...MAINLY VFR. THERE IS A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY AFTERNOON. THURSDAY NIGHT...MAINLY VFR WITH LATE NIGHT AND EARLY MORNING VISIBILITY RESTRICTIONS POSSIBLE. FRIDAY...MAINLY VFR. THERE IS A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY AFTERNOON. FRIDAY NIGHT...MAINLY VFR WITH LATE NIGHT AND EARLY MORNING VISIBILITY RESTRICTIONS POSSIBLE. SATURDAY THROUGH SUNDAY...MAINLY VFR WITH LATE NIGHT AND EARLY MORNING VISIBILITY RESTRICTIONS POSSIBLE. THERE IS A CHANCE OF MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. && .MARINE... NO HEADLINES THROUGH TONIGHT. ATLC SEAS WILL CONTINUE TO RUN AROUND 1-3 FEET. LIGHT AND VARIABLE WINDS TREND SOUTHERLY OR SOUTHEASTERLY DURING THE DAY THEN EVENTUALLY NE TONIGHT. NE GUSTS 15-20 KT POSSIBLE S NJ AND DE COASTS NEAR DAYBREAK THURSDAY. OUTLOOK... WEAK HIGH PRESSURE CAN BE EXPECTED THURSDAY THROUGH SATURDAY. A WARM FRONT WILL MOVE ACROSS THE WATERS FROM THE SOUTHWEST ON SUNDAY. WIND SPEEDS AND WAVE HEIGHTS ARE EXPECTED TO REMAIN BELOW THE SMALL CRAFT ADVISORY CRITERIA THROUGH THE PERIOD. && .RIP CURRENTS... TODAY...LOW RISK DOES NOT MEAN NO RISK BUT ITS BEEN A LOW RISK SUMMER IN OUR FCST AREA SINCE THE ATLANTIC TROPICAL BASIN HAS BEEN NOTABLY QUIET...DESPITE A FEW NAMED STORMS THAT JUST HAVENT SENT MUCH SWELL UP OUR WAY. THURSDAY...CURRENTLY IS OUTLOOKED LOW RISK BUT IF NE WINDS AVG 20 KT ALONG THE DE COAST...THIS COULD RESULT IN A MDT RISK THERE WITH A HIGHER THAN MODELED SWELL. SO THERE IS RISK UNCERTAINTY FOR THURSDAY. FRIDAY THROUGH MONDAY OUTLOOK AS LOW RISK DAYS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && SYNOPSIS...KRUZDLO NEAR TERM...IOVINO SHORT TERM...DRAG LONG TERM...KRUZDLO AVIATION...DRAG/KRUZDLO MARINE...DRAG/KRUZDLO RIP CURRENTS...DRAG
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 357 AM EDT WED AUG 28 2013 DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-055- 060>062-070-071-101>106-290800- 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- DELAWARE-PHILADELPHIA-WESTERN CHESTER-EASTERN CHESTER- WESTERN MONTGOMERY-EASTERN MONTGOMERY-UPPER BUCKS-LOWER BUCKS- 357 AM EDT WED AUG 28 2013 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...TODAY AND TONIGHT. SHOWERS AND THUNDERSTORMS WILL SPREAD INTO THE REGION TODAY. LOCALIZED POOR DRAINAGE AND LOW LYING FLOODING IS LIKELY. THE MOST PRONE AREAS WILL BE SOUTHEAST PENNSYLVANIA, SOUTHERN NEW JERSEY, AND THE DELMARVA. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. ANZ430-431-450>455-290800- DELAWARE BAY WATERS NORTH OF EAST POINT NJ TO SLAUGHTER BEACH DE- DELAWARE BAY WATERS SOUTH OF EAST POINT NJ TO SLAUGHTER BEACH DE- 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- 357 AM EDT WED AUG 28 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS AND DELAWARE BAY WATERS. .DAY ONE...TODAY AND TONIGHT. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY. 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 MOUNT HOLLY NJ 923 AM EDT WED AUG 28 2013 PAZ061-062-105-281415- LEHIGH PA-NORTHAMPTON PA-UPPER BUCKS PA- 923 AM EDT WED AUG 28 2013 ...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN BUCKS...SOUTH CENTRAL NORTHAMPTON AND SOUTHEASTERN LEHIGH COUNTIES... AT 922 AM EDT...A STRONG THUNDERSTORM WAS NEAR COOPERSBURG...MOVING EAST AT 5 TO 10 MPH. WIND GUSTS TO 30 MPH ARE POSSIBLE WITH THIS STORM. FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS STORM. DO NOT STAY IN THE OPEN NOR SEEK SHELTER UNDER TREES WHEN LIGHTNING THREATENS...MOVE INDOORS WHEN A THUNDERSTORM APPROACHES. VERY HEAVY RAIN WILL FALL FROM THIS STORM...AND WILL CAUSE WATER TO POND ON ROADS AND FILL POOR DRAINAGE AREAS. THE RAIN CAN CAUSE RAPID RISES ON SMALL STREAMS AND CREEKS. THIS STORM WILL BE NEAR QUAKERTOWN AROUND 930 AM...RICHLANDTOWN AROUND 940 AM...PLEASANT VALLEY AROUND 1000 AM AND SPRINGTOWN AROUND 1010 AM. LAT...LON 4062 7524 4043 7514 4041 7539 4055 7549 FORECASTER: HEAVENER
The Philadelphia radar (KDIX), 96 km away, was scanning. The volume nearest the first event began at 15:01 UTC.
3 flash flood, 1 flood. Local standard time, as filed.
Heavy rain caused flash flooding of smaller creeks as well as roadway flooding in upper Bucks County in and around Quakertown. Flooding was reported along Pennsylvania State Route 309. Event precipitation totals included 1.60 inches in Quakertown.
Heavy rain caused flash flooding of smaller creeks as well as poor drainage and roadway flooding from Allentown southward in Lehigh County. The heavy rain fell so quickly that manhole covers were popping. Roadway flooding, stranded vehicles and water rescues in Allentown were reported on Mack Boulevard, Basin and Auburn Streets, Elmo Street, Mohawk Street and South 4th, 8th and 12th Streets. Farther to the south, Pennsylvania State Route 309 was flooded and closed in Upper Saucon Township. Event precipitation totals included 2.91 inches at the Lehigh Valley International Airport and 1.64 inches in Orefield.
Heavy rain caused flash flooding of smaller creeks as well as poor drainage and roadway flooding in Bethlehem. Flash flooding isolated forty homes around Pennsylvania State Route 412 in the city. Event precipitation totals included 2.91 inches at the Lehigh Valley International Airport.
The Frankford Creek at Castor Avenue was briefly above its 7 foot flood stage from 1245 p.m. EDT through 101 p.m. EDT on the 28th. It crested at 7.19 feet. Event precipitation totals included 1.80 inches in Wyndmoor and 1.04 inches at the Philadelphia International Airport.
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, August 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: 475811, 475814, 475815, 475250.