Alert archive / Pennsylvania / Flash Flood Warnings in 2026
Flash Flood Warning 147, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 30, 2026, 10:04 PM EDT for Chester County, Pennsylvania. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Aug 30, 2026, 10:04 PM EDT (02:04 UTC)
- Expired
- Aug 31, 2026, 2:00 AM EDT
- In force
- 4 hr
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Flood severity
- None
County Chester County, PA
The radar
The Philadelphia radar (KDIX), 117 km from the middle of the area, began a volume at 02:07 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 00:00Z, 2.1 hours before the alert went out and 179 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 195 J/kg
- Mixed-layer CIN
- -83 J/kg
- Mixed-layer LCL
- 1197 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 164 m²/s²
- 0-3 km storm-relative helicity
- 195 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.1
The text
As transmitted.
122
WGUS51 KPHI 310204
FFWPHI
PAC029-310600-
/O.NEW.KPHI.FF.W.0147.260831T0204Z-260831T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
Issued by National Weather Service New York NY
1004 PM EDT Sun Aug 30 2026
The National Weather Service in Mount Holly has issued a
* Flash Flood Warning for...
Central Chester County in southeastern Pennsylvania...
* Until 200 AM EDT.
* At 1004 PM EDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 0.5 and 1 inch of rain
has fallen. The expected rainfall rate is 1 to 2 inches in 1 hour.
Additional rainfall amounts of 1 to 2 inches are possible in the
warned area. Flash flooding is ongoing or expected to begin
shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar indicated.
IMPACT...Flash flooding of small creeks and streams, urban areas,
highways, streets and underpasses as well as other poor
drainage and low-lying areas.
* Some locations that will experience flash flooding include...
West Chester, Coatesville, Westtown, Downingtown, Kennett Square,
Parkesburg, Marshallton, West Goshen, Atglen, South Coatesville,
Modena and Thorndale.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
&&
LAT...LON 3993 7554 3981 7569 3993 7598 3994 7598
3994 7599 3995 7599 3999 7597 4004 7594
4005 7594 4006 7593 3999 7546 3995 7551
3994 7552
FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL RATE...1-2 INCHES IN 1 HOUR
$$2 follow-up statements
982
WGUS71 KPHI 310324
FFSPHI
Flash Flood Statement
National Weather Service Mount Holly NJ
Issued by National Weather Service New York NY
1124 PM EDT Sun Aug 30 2026
PAC029-310600-
/O.CON.KPHI.FF.W.0147.000000T0000Z-260831T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
1124 PM EDT Sun Aug 30 2026
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 2 AM EDT MONDAY FOR
CENTRAL CHESTER COUNTY...
At 1124 PM EDT, Doppler radar and automated rain gauges indicated
thunderstorms produced heavy rain across the warned area. Between 1
and 2.5 inches of rain have fallen. Additional rainfall amounts up to
0.5 inches are possible in the warned area. Flash flooding is ongoing
or expected to begin shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar and automated gauges.
IMPACT...Flash flooding of small creeks and streams, urban areas,
highways, streets and underpasses as well as other poor
drainage and low-lying areas.
Some locations that will experience flash flooding include...
West Chester, Coatesville, Westtown, Downingtown, Kennett Square,
Parkesburg, Marshallton, West Goshen, Atglen, South Coatesville,
Modena and Thorndale.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Be especially cautious at night when it is harder to recognize the
dangers of flooding.
&&
LAT...LON 3993 7554 3981 7569 3993 7598 3994 7598
3994 7599 3995 7599 3999 7597 4004 7594
4005 7594 4006 7593 3999 7546 3995 7551
3994 7552
FLASH FLOOD...RADAR AND GAUGE INDICATED
$$
Staarmann474
WGUS71 KPHI 310552
FFSPHI
Flash Flood Statement
National Weather Service Mount Holly NJ
Issued by National Weather Service New York NY
152 AM EDT Mon Aug 31 2026
PAC029-310602-
/O.EXP.KPHI.FF.W.0147.000000T0000Z-260831T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
152 AM EDT Mon Aug 31 2026
...FLASH FLOOD WARNING WILL EXPIRE AT 2 AM EDT EARLY THIS MORNING FOR
CENTRAL CHESTER COUNTY...
The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed remaining road closures.
&&
LAT...LON 3993 7554 3981 7569 3993 7598 3994 7598
3994 7599 3995 7599 3999 7597 4004 7594
4005 7594 4006 7593 3999 7546 3995 7551
3994 7552
$$
StaarmannNearby
Flash Flood Warnings in Pennsylvania, 2026Every flash flood warning in 2026
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.