Alert archive / Pennsylvania / Flash Flood Warnings in 2025

Flash Flood Warning 44, NWS Philadelphia/Mount Holly

July 9, 2025Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 9, 2025, 6:39 PM EDT for Chester County, Pennsylvania. It was in force for 4 hr. 11 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Jul 9, 2025, 6:39 PM EDT (22:39 UTC)
Expired
Jul 9, 2025, 10:45 PM 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), 120 km from the middle of the area, began a volume at 22:39 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.

What was reported inside it

TimeReportWhereRemark
Jul 9, 7:37 PM EDTFLASH FLOODWest Grove, PAFlooding on Summit Ave at the bottom of the hill is underwater. Time given in report.
Jul 9, 8:05 PM EDTFLASH FLOODCoatesville, PACar stranded in flooded roadway. Boundary Ct. and Foundry St.
Jul 9, 8:25 PM EDTFLASH FLOODJennersville, PAMultiple small streams overflowing banks into roadways throughout Jennersville.
Jul 9, 8:37 PM EDTFLASH FLOOD1 Sw West Bradford Twp, PABroad Run is flowing over Beacon Hill Road at intersection of Broad Run Rd.
Jul 9, 8:45 PM EDTFLASH FLOOD2 Ese London Britain Tw, PAThe White Clay Creek at Strickersville rapidly went into flood stage.
Jul 9, 8:50 PM EDTFLASH FLOODCaln Twp, PAFlooding on roadways at Lincoln Hwy and S Bailey Rd.
Jul 9, 8:50 PM EDTFLASH FLOODLondon Grove, PARoadway flooding with vehicle stranded on Garden Station Rd. east of Elicott Rd.
Jul 9, 9:00 PM EDTFLASH FLOOD1 S Avondale, PAEast Branch White Clay Creek has overflown its banks, flowing over portions of Ellicott Rd shown in pictures.
Jul 9, 9:15 PM EDTFLASH FLOOD1 Wsw Kennett Square, PAThe Red Clay Creek at Kennett Square went into flood stage rapidly.
Jul 9, 9:15 PM EDTFLASH FLOODNew Garden, PAFlooded roadways at Hillendale Rd. and Scarlett Rd. Vehicle stranded.
Jul 9, 10:30 PM EDTFLASH FLOOD2 Ese London Britain Tw, PAThe White Clay Creek at Strickersville went into Major Flood stage.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.7 hours before the alert went out and 173 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.

Skew-T log-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2025-07-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 647 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2025-07-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -8 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
647 J/kg
Mixed-layer CIN
-65 J/kg
Mixed-layer LCL
836 m above ground
0-6 km bulk shear
24 kt
0-1 km storm-relative helicity
-8 m²/s²
0-3 km storm-relative helicity
42 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

As transmitted.

716 
WGUS51 KPHI 092239
FFWPHI
PAC029-100245-
/O.NEW.KPHI.FF.W.0044.250709T2239Z-250710T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
639 PM EDT Wed Jul 9 2025

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Chester County in southeastern Pennsylvania...

* Until 1045 PM EDT.

* At 639 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to 0.5 inches of rain have 
  fallen. The expected rainfall rate is 1.5 to 2.5 inches in 1 hour. 
  Additional rainfall amounts of 1 to 2.5 inches are possible in the 
  warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets, and underpasses as well as other
           drainage and low lying areas.

* Some locations that may experience flash flooding include...
  West Chester, Coatesville, Westtown, Downingtown, Kennett Square, 
  Oxford, Parkesburg, West Grove, Honey Brook, Cochranville, 
  Marshallton and Landenberg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most 
flood deaths occur in vehicles.

&&

LAT...LON 3997 7553 3993 7553 3993 7554 3987 7560
      3984 7560 3980 7570 3973 7577 3972 7606
      3974 7609 3983 7604 3983 7602 3985 7602
      3987 7599 3993 7600 3993 7598 3995 7599
      4004 7594 4009 7594 4009 7562 4006 7556

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL RATE...1.5-2.5 INCHES IN 1 HOUR

$$

Hoeflich
2 follow-up statements
584 
WGUS71 KPHI 092348
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
748 PM EDT Wed Jul 9 2025

PAC029-100245-
/O.CON.KPHI.FF.W.0044.000000T0000Z-250710T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
748 PM EDT Wed Jul 9 2025

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1045 PM EDT THIS 
EVENING FOR CHESTER COUNTY...

At 748 PM EDT, trained weather spotters reported thunderstorms 
producing heavy rain in West Grove with roads completely covered in 
water.  Between 2 and 3 inches of rain have fallen. The expected 
rainfall rate is 1.5 to 2.5 inches in 1 hour. Additional rainfall 
amounts of 1 to 2.5 inches are possible in the warned area. Flash 
flooding is ongoing or expected to begin shortly.

HAZARD...Life threatening flash flooding caused by thunderstorms.

SOURCE...Trained spotters reported.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets, and underpasses.

Some locations that may experience flash flooding include...
  West Chester, Coatesville, Westtown, Downingtown, Kennett Square, 
  Oxford, Parkesburg, West Grove, Honey Brook, Cochranville, 
  Marshallton and Landenberg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most 
flood deaths occur in vehicles.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3997 7553 3993 7553 3993 7554 3987 7560
      3984 7560 3980 7570 3973 7577 3972 7606
      3974 7609 3983 7604 3983 7602 3985 7602
      3987 7599 3993 7600 3993 7598 3995 7599
      4004 7594 4009 7594 4009 7562 4006 7556

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL RATE...1.5-2.5 INCHES IN 1 HOUR

$$

Hoeflich
261 
WGUS71 KPHI 100236
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1036 PM EDT Wed Jul 9 2025

PAC029-100246-
/O.EXP.KPHI.FF.W.0044.000000T0000Z-250710T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
1036 PM EDT Wed Jul 9 2025

...FLASH FLOOD WARNING WILL EXPIRE AT 1045 PM EDT THIS EVENING FOR 
CHESTER COUNTY...

Flood waters have receded. The heavy rain has ended. Please continue 
to heed remaining road closures. A more targeted Flood Warning was 
issued for portions of Chester County as some river gauges remain 
above flood stage and road closures have been reported. Please see 
that bulletin for updated information.

A Flood Watch remains in effect until 200 AM EDT for a portion of 
southeast Pennsylvania.

A Flood Watch remains in effect until 200 AM EDT for portions of 
central, northern, and southern Delaware.

&&

LAT...LON 3997 7553 3993 7553 3993 7554 3987 7560
      3984 7560 3980 7570 3973 7577 3972 7606
      3974 7609 3983 7604 3983 7602 3985 7602
      3987 7599 3993 7600 3993 7598 3995 7599
      4004 7594 4009 7594 4009 7562 4006 7556

$$

Hoeflich

The office that day

Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 8, 9:52 PM EDTFlood WatchPHIBerks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more26 hr
Jul 9, 7:18 PM EDTFlash Flood WarningPHIDelaware4 hr
Jul 9, 7:24 PM EDTSevere Thunderstorm WarningPHIChester, Delaware51 min
Jul 9, 7:38 PM EDTFlash Flood WarningPHIDelaware4 hr
Jul 9, 7:47 PM EDTFlash Flood WarningPHIChester, Delaware, Montgomery, Philadelphia4 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2025Every flash flood warning in 2025

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.