Alert archive / Pennsylvania / Flash Flood Warnings in 2026
Flash Flood Warning 142, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 27, 2026, 10:36 PM EDT for Berks County, Chester County, Montgomery County, Pennsylvania. It was in force for 3 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 27, 2026, 10:36 PM EDT (02:36 UTC)
- Expired
- Aug 28, 2026, 1:17 AM EDT
- In force
- 3 hr
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Flood severity
- None
Counties Berks County, PA, Chester County, PA, Montgomery County, PA
The radar
The Philadelphia radar (KDIX), 123 km from the middle of the area, began a volume at 02:37 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, 2.6 hours before the alert went out and 194 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
- 1155 J/kg
- Mixed-layer CIN
- -14 J/kg
- Mixed-layer LCL
- 1287 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 27 m²/s²
- 0-3 km storm-relative helicity
- 65 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 2.3
The text
As transmitted.
451
WGUS51 KPHI 280236
FFWPHI
PAC011-029-091-280530-
/O.NEW.KPHI.FF.W.0142.260828T0236Z-260828T0530Z/
/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
1036 PM EDT Thu Aug 27 2026
The National Weather Service in Mount Holly has issued a
* Flash Flood Warning for...
Southeastern Berks County in eastern Pennsylvania...
North Central Chester County in southeastern Pennsylvania...
West Central Montgomery County in southeastern Pennsylvania...
* Until 130 AM EDT.
* At 1036 PM EDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 1 and 2 inches of rain
have fallen. The expected rainfall rate is 1 to 2 inches in 1 hour.
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...
Pottstown, Birdsboro, Elverson, New Morgan, Cedarville, Stowe,
Amity Gardens, South Pottstown, Kenilworth, Halfway House,
Pottsgrove and Sanatoga.
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.
Please report observed flooding to local emergency services or law
enforcement and request they pass this information to the National
Weather Service when you can do so safely.
&&
LAT...LON 4019 7596 4029 7578 4029 7566 4024 7552
4013 7587 4014 7588 4014 7587 4015 7588
FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL RATE...1-2 INCHES IN 1 HOUR
$$1 follow-up statement
531
WGUS71 KPHI 280517
FFSPHI
Flash Flood Statement
National Weather Service Mount Holly NJ
Issued by National Weather Service New York NY
117 AM EDT Fri Aug 28 2026
PAC011-029-091-280527-
/O.CAN.KPHI.FF.W.0142.000000T0000Z-260828T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Chester PA-Montgomery PA-
117 AM EDT Fri Aug 28 2026
...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHEASTERN BERKS, NORTH
CENTRAL CHESTER AND WEST CENTRAL MONTGOMERY COUNTIES...
The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed remaining road closures.
A Flood Watch remains in effect until 400 AM EDT for portions of New
Jersey and Pennsylvania.
&&
LAT...LON 4019 7596 4029 7578 4029 7566 4024 7552
4013 7587 4014 7588 4014 7587 4015 7588
$$The office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 27, 8:09 PM EDT | Areal Flood Warning | PHI | Bucks, Montgomery | 5 hr |
| Aug 27, 8:16 PM EDT | Flash Flood Warning | PHI | Berks | 4 hr |
| Aug 27, 8:40 PM EDT | Severe Thunderstorm Warning | PHI | Berks | 50 min |
| Aug 27, 9:09 PM EDT | Areal Flood Warning | PHI | Bucks, Chester, Montgomery | 4 hr |
| Aug 27, 9:21 PM EDT | Flash Flood Warning | PHI | Berks | 3 hr |
| Aug 27, 9:32 PM EDT | River Flood Warning | PHI | Bucks | 6 hr |
| Aug 27, 10:22 PM EDT | Severe Thunderstorm Warning | PHI | Berks, Chester | 38 min |
Nearby
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.