Alert archive / Pennsylvania / Flash Flood Warnings in 2025

Flash Flood Warning 30, NWS Philadelphia/Mount Holly

July 1, 2025Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 1, 2025, 4:44 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: Jul 1, 2025, 4:44 PM EDT (20:44 UTC)
Expired: Jul 1, 2025, 8:45 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), 119 km from the middle of the area, began a volume at 20:46 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 12:00Z, 8.7 hours before the alert went out and 182 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 822 J/kg
Mixed-layer CIN: -69 J/kg
Mixed-layer LCL: 994 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: -2 m²/s²
0-3 km storm-relative helicity: 32 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

743 
WGUS51 KPHI 012044
FFWPHI
PAC029-020045-
/O.NEW.KPHI.FF.W.0030.250701T2044Z-250702T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
444 PM EDT Tue Jul 1 2025

The National Weather Service in Mount Holly has issued a

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

* Until 845 PM EDT.

* At 444 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 to 3 inches in 1 hour. 
  Additional rainfall amounts of 1.5 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...
  Phoenixville, Coatesville, Downingtown, Parkesburg, Honey Brook, 
  Glenmoore, Lionville, Lionville-Marchwood, Chester Springs, Paoli, 
  Malvern and Atglen.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3993 7598 3995 7599 4004 7593 4011 7594
      4014 7587 4015 7551 4004 7551 3999 7558
      3996 7570

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL RATE...1-3 INCHES IN 1 HOUR

$$

Hoeflich

1 follow-up statement

411 
WGUS71 KPHI 020035
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
835 PM EDT Tue Jul 1 2025

PAC029-020045-
/O.EXP.KPHI.FF.W.0030.000000T0000Z-250702T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
835 PM EDT Tue Jul 1 2025

...FLASH FLOOD WARNING WILL EXPIRE AT 845 PM EDT THIS EVENING FOR 
CENTRAL CHESTER COUNTY...

Flood waters have receded. The heavy rain has ended. Flooding is no 
longer expected to pose a threat. Please continue to heed remaining 
road closures.

&&

LAT...LON 3993 7598 3995 7599 4004 7593 4011 7594
      4014 7587 4015 7551 4004 7551 3999 7558
      3996 7570

$$

Hoeflich

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 30, 11:20 PM EDT	Flash Flood Warning	PHI	Berks	4 hr
Jun 30, 11:47 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Delaware, Montgomery	43 min
Jul 1, 12:38 AM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	36 min
Jul 1, 2:30 AM EDT	Flood Watch	PHI	Berks, Bucks, Chester, Delaware, Montgomery, Philadelphia	19 hr
Jul 1, 6:15 AM EDT	River Flood Warning	PHI	Chester	3 hr
Jul 1, 6:21 AM EDT	Areal Flood Warning	PHI	Delaware	2 hr
Jul 1, 2:32 PM EDT	Severe Thunderstorm Warning	PHI	Chester	43 min
Jul 1, 2:58 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	47 min
Jul 1, 3:00 PM EDT	Flash Flood Warning	PHI	Chester	4 hr
Jul 1, 3:06 PM EDT	River Flood Warning	PHI	Chester, Delaware	8 hr
Jul 1, 3:31 PM EDT	Flash Flood Warning	PHI	Bucks, Montgomery, Philadelphia	4 hr
Jul 1, 3:34 PM EDT	Severe Thunderstorm Warning	PHI	Berks	56 min
Jul 1, 3:39 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Philadelphia	66 min
Jul 1, 4:27 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Lehigh, Montgomery	63 min
Jul 1, 4:47 PM EDT	Tornado Warning	PHI	Berks, Montgomery	28 min
Jul 1, 4:55 PM EDT	Flash Flood Warning	PHI	Berks, Chester, Montgomery	4 hr
Jul 1, 5:07 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Lehigh, Montgomery, Northampton	38 min
Jul 1, 5:14 PM EDT	Flash Flood Warning	PHI	Berks, Bucks, Lehigh, Montgomery	4 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2025 Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.