Flash Flood in Pennsylvania, September 15 to 16, 2003

Name: Flash Flood in Pennsylvania, September 15 to 16, 2003
Start: 2003-09-15T05:37
End: 2003-09-16T04:47
Location: Pennsylvania

September 15 to 16, 2003 · NWS PHI · 1 event in 1 county or zone

Where it happened

Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: $3.5 million
Crop damage: None recorded
Events: 1

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.

What happened

The episode as NWS PHI wrote it up.

Remnant moisture from Tropical Storm Henri produced copious amounts of rain during the early morning of the 15th across Chester County. The heaviest rain fell from Downingtown south through Kenneth Square. Thunderstorms with torrential downpours moved from south to north across the same areas and produced five to ten inches of rain across the region. The worst flood damage occurred in Avondale, Downingtown and Kenneth Square. During the flooding there were 2,600 emergency calls to the county 911 center. Over half required dispatches. There were 100 water rescues from vehicles and homes. Twelve homes were destroyed. One hundred eighty homes suffered major damage. One hundred fifty-six homes suffered minor damage. PECO Energy reported about 109,000 of its customers lost power due to downed trees (from loosened soil) and flooding. Twenty-two bridges were damaged. Damage to private homes and businesses and public infrastructure was estimated at $3.5 million dollars. In Downingtown, parts of nine streets were submerged with up to six feet of water. Both Kerr and Johnson Parks were flooded. The Borough Hall was even surrounded by water. In Kenneth Square, 50 to 60 people were rescued from cars and front porches. The McFarlands Bridge and Chandler's Bridge were both closed indefinitely. In Avondale, about 250 people were evacuated from an apartment building. Damage was not confined to those locations as the heavy rain caused about $40,000 in damage to Newlin Township. The Red Clay Creek in Kenneth Square had a record crest of 14.99 feet at 9 a.m. EDT on the 15th. The East Branch of the Brandywine Creek in Downingtown had its second highest crest on record at 13.56 feet at 1130 a.m. EDT on the 15th. Flood Stage is 7 feet. The creek was above flood stage from 637 a.m. EDT through 1046 p.m. EDT on the 15th. Farther downstream, the Brandywine Creek at Chadds Ford had its sixth highest crest on record at 13.72 feet at 557 p.m. EDT on the 15th. Flood stage is 9 feet. The creek was above its flood stage 1029 a.m. EDT on the 15th through 547 a.m. EDT on the 16th. The French Creek in Phoenixville had its 4th highest crest on record at 9.70 feet at 1215 p.m. EDT on the 15th. Flood stage is 8 feet. It was above flood stage from 842 a.m. EDT through 741 p.m. EDT on the 15th. The Valley Creek at Valley Forge had its 4th highest crest on record at 8.94 feet at 530 p.m. EDT on the 15th. Flood stage is 7 feet. The creek was above flood stage from 357 p.m. EDT through 820 p.m. EDT on the 15th. The West Branch of the Brandywine Creek at Honey Brook was briefly above its 7 foot flood stage from 619 p.m. through 703 p.m. EDT on the 15th. It crested at 7.03 feet at 630 p.m. EDT. Storm totals included 8.75 inches in Downingtown, 8.00 inches in East Marlborough Township, 6.57 inches in East Caln Township, 6.00 inches in Longwood Gardens, 4.43 inches in Modena, 4.12 inches in Thorndale, 3.87 inches in Chadds Ford, 3.59 inches in West Chester and 3.50 inches in Glenmoore.

What forecasters said that day

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 Sep 15, 1:42 AM EST, 3 hours 55 minutes earlier.

Area forecast discussion, Sep 15, 1:42 AM EST, 3 hours 55 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
242 AM EDT MON SEP 15 2003

TROPICAL AIRMASS REMAINS IN PLACE INTO EARLY TNGT...THEN A COLD
FRONT DROPS DOWN FROM THE NW FOLLOWED BY HIGH PRESSURE THAT WILL
ALLOW THE HUMIDITY TO DECREASE. WITH AND AHEAD OF THE FRONT SHOULD
BE SHOWERS AND SCATTERED TSTMS. BEHIND IT...CLEARING.

MAIN CONCERN THIS FCST IS FROM THU INTO FRI NIGHT WHEN POWERFUL
HURRICANE ISABEL THREATENS. IF THE STORM TRACKS CLOSE OR OVER THE
FORECAST AREA...THE WINDS ASSOCIATED WITH THE HURRICANE COULD BE
STRONGER THAN MANY OF US HAVE EVER EXPERIENCED. THIS STORM SHOULD BE
TAKEN SERIOUSLY

IN ADDITION...THERE IS POTENTIAL FOR VERY HEAVY RAINS DEPENDING ON
THE TRACK, SO HYDROLOGY IS ALSO A CONCERN.

USERS OF EXPERIMENTAL FORECAST GRIDS...BE AWARE THAT POLICY LIMITS
MAXIMUM SUSTAINED WIND STRENGTH TO 33 KTS OUT PAST THE 72 HOUR
FORECAST.  THIS IS TO REFLECT THE INHERENT UNCERTAINTY IN THE
HURRICANE FORECAST TRACK AT GREATER TIME RANGES.  REFER TO NHC FOR
THE OFFICIAL TRACK AND STRENGTH OF THE STORM.

POP QUIZ...WHEN WAS THE LAST OFFICIAL LANDFALLING HURRICANE IN NEW
JERSEY?  SEPTEMBER 16TH IN 1903.  THE 100TH ANNIVERSARY IS
TOMORROW...COINCIDENCE?.

NOW IS THE TIME WHERE BEING PREPARED PAYS OFF.  KEEP UP TO DATE WITH
THE LATEST FORECASTS.   CHECK OUR WEB SITE...WWW.ERH.NOAA.GOV/PHI
FOR THE LATEST FORECAST INFORMATION...AS WELL AS PREPAREDNESS
INFORMATION IF THE HURRICANE THREATENS YOUR LOCATION.

ON THE COAST WE WILL CARRY SCA DUE TO SEAS. ALSO THERE IS A HIGH
RISK FOR RIP CURRENTS.

FCSTID =    9
MPO   71  55  73  54 /  70  30  10  10
ABE   78  63  78  57 /  70  40  10  10
RDG   78  63  78  58 /  70  40  10  10
PHL   81  66  81  63 /  60  40   0   0
12N   75  59  76  57 /  70  40  10  10
SMQ   78  67  79  62 /  60  50   0   0
TTN   79  66  80  63 /  60  50   0   0
MIV   80  66  79  66 /  60  50   0   0
ACY   78  67  80  69 /  60  50   0   0
ILG   81  65  80  62 /  60  40   0   0
DOV   81  66  80  65 /  50  40   0   0
GED   81  67  80  67 /  50  40   0   0
ESN   81  66  80  64 /  50  40   0   0

.PHI...
DE...NONE.
MD...NONE.
NJ...NONE.
PA...NONE.
MARINE...SCA ALONG THE COAST.

RNS

Hazardous weather outlook, Sep 15, 3:14 AM EST, 2 hours 23 minutes before

DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-055-
060>062-067>071-151100-

HAZARDOUS WEATHER OUTLOOK - CORRECTION FOR RIP CURRENTS
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
414 AM EDT MON SEP 15 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL AND SOUTHEAST
PENNSYLVANIA...DELAWARE...THE NORTHERN MARYLAND EASTERN SHORE...AND
NEW JERSEY EXCLUDING THE FIVE NORTHEAST COUNTIES.

.DAY ONE...TODAY

THERE IS A HIGH RISK OF RIP CURRENTS ALONG THE COAST.

SHOWERS ARE LIKELY TODAY ALONG WITH SCATTERED THUNDERSTORMS. SOME
RAIN COULD BE HEAVY.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

RIP CURRENTS ARE POSSIBLE THROUGH MOST OF THE PERIOD.

THE MAIN THREAT WILL BE FROM POWERFUL HURRICANE ISABEL. THE
FORECASTED TRACK FOR ISABEL HAS IT AFFECTING THE REGION
THURSDAY INTO FRIDAY.

SEE THE LATEST ADVISORY FROM THE NATIONAL HURRICANE CENTER.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

In the hours before

Special weather statement, Sep 15, 3:16 AM EST, 2 hours 21 minutes before

DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-055-
060>062-067>071-152100-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
416 AM EDT MON SEP 15 2003

...A GOOD TIME TO REVIEW YOUR FAMILY DISASTER PLAN...

AS MAJOR HURRICANE ISABEL CONTINUES TO MOVE WEST NORTHWEST TOWARD
THE EAST COAST OF THE UNITED STATES...NOW IS A GOOD TIME TO REVIEW
AND UPDATE YOUR FAMILY DISASTER PLAN.

PART OF YOUR FAMILY DISASTER PLAN SHOULD BE PREPARING IN CASE A
HURRICANE THREATENS YOUR AREA.   SOME ACTIVITIES WHICH YOU STILL
HAVE TIME TO COMPLETE INCLUDE KNOWING THE HURRICANE RISKS IN YOUR
AREA SUCH AS WHETHER YOU LIVE IN A POTENTIAL FLOOD ZONE...LEARNING
SAFE ROUTES INLAND FROM COASTAL AREAS...FINDING OUT WHERE OFFICIAL
SHELTERS ARE LOCATED...TRIMMING TREES AND SHRUBBERY...CLEARING LOOSE
AND CLOGGED RAIN SPOUTS AND GUTTERS...AND DETERMINING WHERE TO MOVE
YOUR BOAT IN AN EMERGENCY.

ONE OF THE MOST IMPORTANT PARTS OF YOUR FAMILY DISASTER PLAN IS THE
PREPARATION OF A DISASTER SUPPLIES KIT.  THIS KIT SHOULD INCLUDE THE
FOLLOWING MATERIALS...A THREE DAY SUPPLY OF WATER WITH ONE GALLON
PER PERSON PER DAY...FOOD THAT WILL NOT SPOIL...ONE CHANGE OF
CLOTHING AND SHOES PER PERSON...PRESCRIPTION MEDICINES...ONE BLANKET
OR SLEEPING BAG PER PERSON...A FIRST AID KIT...A BATTERY POWERED
NOAA WEATHER RADIO AND A PORTABLE RADIO...EMERGENCY TOOLS...A
FLASHLIGHT WITH EXTRA BATTERIES...AN EXTRA SET OF CAR KEYS...AND ANY
SPECIAL ITEMS FOR INFANT...ELDERLY OR DISABLED FAMILY MEMBERS.

IF YOU HAVE A SECOND RESIDENCE NEAR THE COAST...WE RECOMMEND YOU
TAKE THE OPPORTUNITY EARLY THIS WEEK TO INSURE THAT LOOSE OBJECTS
ARE PACKED AWAY...AND YOUR RESIDENCE IS SECURE.

STAY TUNED OVER THE NEXT SEVERAL DAYS ON THE EXPECTED PATH OF
HURRICANE ISABEL.  BE PREPARED TO TAKE ADDITIONAL ACTION IF A
HURRICANE WATCH IS ISSUED FOR THE AREA. A WATCH IS ISSUED WHEN THERE
IS A POTENTIAL FOR HURRICANE CONDITIONS IN YOUR AREA WITHIN 36
HOURS. REMEMBER THAT STRONG DAMAGING WINDS AND TORRENTIAL RAINFALL
CAN EXTEND WELL INLAND WITH A MAJOR HURRICANE.

MORE PREPAREDNESS INFORMATION CAN BE FOUND ON OUR WEB SITE AT
WWW.ERH.NOAA.GOV/PHI   CHECK OUT THE MENU SELECTION ENTITLED
PREPAREDNESS ON THE LEFT HAND SIDE.

AND PLEASE SEE THE FOLLOWING INTERNET SOURCES FOR ADDITIONAL
HURRICANE POTENTIAL INFORMATION AND PREPAREDNESS ISSUES...

NATIONAL HURRICANE CENTER HOME PAGE:
HTTP://WWW.NHC.NOAA.GOV

PENNSYLVANIA EMERGENCY MANAGEMENT AGENCY:
HTTP://PEMA.STATE.PA.US

MARYLAND EMERGENCY MANAGEMENT AGENCY:
HTTP://WWW.MEMA.STATE.MD.US

NEW JERSEY OFFICE OF EMERGENCY MANAGEMENT:
HTTP://WWW.STATE.NJ.US/NJOEM

DELAWARE EMERGENCY MANAGEMENT AGENCY:
HTTP://WWW.STATE.DE.US/DEMA

FEDERAL EMERGENCY MANAGEMENT AGENCY HOME PAGE:
HTTP://WWW.FEMA.GOV/HAZARDS/HURRICANES

AMERICAN RED CROSS HOME PAGE:
HTTP://WWW.RED CROSS.ORG

Special weather statement, Sep 15, 4:41 AM EST, 56 minutes before

DEZ001-PAZ054-055-060-061-067-068-151230-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
541 AM EDT MON SEP 15 2003

...HEAVY RAINS WERE TRAINING FROM SOUTH TO NORTH THROUGH EASTERN
PENNSYLVANIA EARLY THIS MORNING...

A BAND OF SHOWERS AND THUNDERSTORMS WAS PERCHED FROM NORTHERN
DELAWARE NORTHWARD TO THE POCONOS OF PENNSYLVANIA THIS MORNING. THE
HEAVIEST RAINS HAVE BEEN OVER CHESTER COUNTY IN SOUTHEASTERN
PENNSYLVANIA...WHERE RADAR HAS ESTIMATED BETWEEN 2 AND 2.5 INCHES OF
RAIN IN A COUPLE OF HOURS.

THIS BAND OF RAIN IS EXPECTED TO MOVE SLIGHTLY TO THE NORTHWEST AS
WELL AS TAPER OFF DURING THE NEXT 2 OR 3 HOURS...BUT UNTIL THEN
WATCH FOR PONDING OF WATER ON ROADS AND IN LOW SPOTS.

STAY TUNED TO NOAA WEATHER RADIO OR OTHER MEDIA OUTLETS FOR ANY
UPDATES. WEATHER INFORMATION IS ALSO AVAILABLE ON THE INTERNET AT
WWW.ERH.NOAA.GOV/PHI.

Special weather statement, Sep 15, 4:41 AM EST, 56 minutes before

DEZ001-PAZ054-055-060-061-067-068-151230-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
540M EDT MON SEP 15 2003

...HEAVY RAINS WERE TRAINING FROM SOUTH TO NORTH THROUGH EASTERN
PENNSYLVANIA EARLY THIS MORNING...

A BAND OF SHOWERS AND THUNDERSTORMS WAS PERCHED FROM NORTHERN
DELAWARE NORTHWARD TO THE POCONOS OF PENNSYLVANIA THIS MORNING. THE
HEAVIEST RAINS HAVE BEEN OVER CHESTER COUNTY IN SOUTHEASTERN
PENNSYLVANIA...WHERE RADAR HAS ESTIMATED BETWEEN 2 AND 2.5 INCHES OF
RAIN IN A COUPLE OF HOURS.

THIS BAND OF RAIN IS EXPECTED TO MOVE SLIGHTLY TO THE NORTHWEST AS
WELL AS TAPER OFF DURING THE NEXT 2 OR 3 HOURS...BUT UNTIL THEN
WATCH FOR PONDING OF WATER ON ROADS AND IN LOW SPOTS.

STAY TUNED TO NOAA WEATHER RADIO OR OTHER MEDIA OUTLETS FOR ANY
UPDATES. WEATHER INFORMATION IS ALSO AVAILABLE ON THE INTERNET AT
WWW.ERH.NOAA.GOV/PHI.

The radar

The Philadelphia radar (KDIX), 114 km away, was scanning. The volume nearest the first event began at 10:36 UTC.

Open the radar archive at this moment

Event by event

1 flash flood. Local standard time, as filed.

Flash Flood, Chester

When: September 15, 5:37 AM EST to September 16, 4:47 AM EST
Where: Chester County, Countywide
Property damage: $3.5 million
Reported by: EMERGENCY MANAGER
Coordinates: 39.973, -75.748 (the zone’s center; the record gives no point)

What these are

Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Pennsylvania in 2003 Every state in 2003 This day in weather history Warnings in Pennsylvania, September 2003

Sources

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: 5371968.