Alert archive / Pennsylvania / Flash Flood Warnings in 2026

Flash Flood Warning 153, NWS Philadelphia/Mount Holly

September 3, 2026New Castle County, Delaware; Burlington County, Camden County, Gloucester County, New Jersey; 5 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 3, 2026, 1:34 AM EDT for New Castle County, Delaware; Burlington County, Camden County, Gloucester County, New Jersey; 5 counties in Pennsylvania. It was in force for 4 hr. 5 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: Sep 3, 2026, 1:34 AM EDT (05:34 UTC)
Expired: Sep 3, 2026, 5:30 AM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties New Castle County, DE, Burlington County, NJ, Camden County, NJ, Gloucester County, NJ, Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 112 km from the middle of the area, began a volume at 05:37 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.

What was reported inside it

Time	Report	Where	Remark
Sep 3, 2:25 AM EDT	FLASH FLOOD	1 W Conshohocken, PA	Flooding on FAIRFIELD RD / NEW ELM ST / CONSHOHOCKEN RD both directions between OLD ELM ST and UNKNOWN RD. All lanes closed. Time given in report.
Sep 3, 3:27 AM EDT	FLOOD	1 Sw Shawmont - Philade, PA	Flooding on I-76 eastbound between 1 miles WEST of Exit 338: GREEN LANE/BELMONT AVE and Exit 338: GREEN LANE/BELMONT AVE. There is a lane restriction.
Sep 3, 3:33 AM EDT	FLOOD	1 N Trainer, PA	Flooding on I-95 northbound at Exit 3: HIGHLAND AVENUE. There is a lane restriction.
Sep 3, 4:30 AM EDT	FLASH FLOOD	1 Wsw West Conshohocken, PA	DOT cameras show flooding on a ramp between I-476 and I-76 in West Conshohocken. Onset time estimated. Flooding is still ongoing as of 645 AM.
Sep 3, 4:44 AM EDT	FLOOD	1 Nw Woodlyn, PA	Flooding on I-476 southbound between 0.7 miles north of Exit 1: MACDADE BLVD and Exit 1: MACDADE BLVD. There is a traffic disruption.

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 00:00Z, 5.6 hours before the alert went out and 177 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: 316 J/kg
Mixed-layer CIN: -263 J/kg
Mixed-layer LCL: 1068 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 22 m²/s²
0-3 km storm-relative helicity: 95 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.8

Open this sounding in Storm Lab

The text

As transmitted.

678 
WGUS51 KPHI 030534
FFWPHI
DEC003-NJC005-007-015-PAC017-029-045-091-101-030930-
/O.NEW.KPHI.FF.W.0153.260903T0534Z-260903T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
134 AM EDT Thu Sep 3 2026

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Northern New Castle County in northern Delaware...
  Northwestern Burlington County in southern New Jersey...
  Northwestern Camden County in southern New Jersey...
  Northwestern Gloucester County in southern New Jersey...
  Southeastern Bucks County in southeastern Pennsylvania...
  Chester County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...
  Southeastern Montgomery County in southeastern Pennsylvania...
  Philadelphia County in southeastern Pennsylvania...

* Until 530 AM EDT.

* At 134 AM EDT, Doppler radar and automated rain gauges indicated
  thunderstorms producing heavy rain across the warned area. Between
  0.5 and 1 inch of rain has fallen. The expected rainfall rate is
  0.5 to 1 inch in 30 minutes. 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 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...
  Philadelphia, Camden, Wilmington, Newark, West Chester, Gloucester
  City, Cherry Hill, Bensalem, Mount Laurel, Norristown, Chester and
  Willingboro.

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 3973 7609 3974 7610 3976 7606 3983 7604
      3983 7602 3985 7602 3987 7599 3995 7599
      4004 7593 4011 7594 4017 7551 4018 7491
      4012 7481 3996 7490 3986 7498 3978 7544
      3962 7558 3961 7579 3972 7579 3972 7613

FLASH FLOOD...RADAR AND GAUGE INDICATED
EXPECTED RAINFALL RATE...0.5-1 INCH IN 30 MINUTES

$$

Staarmann

2 follow-up statements

130 
WGUS71 KPHI 030738
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
338 AM EDT Thu Sep 3 2026

DEC003-NJC005-007-015-PAC017-029-045-091-101-030930-
/O.CON.KPHI.FF.W.0153.000000T0000Z-260903T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Burlington NJ-Camden NJ-Gloucester NJ-Bucks PA-
Chester PA-Delaware PA-Montgomery PA-Philadelphia PA-
338 AM EDT Thu Sep 3 2026

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 530 AM EDT EARLY THIS
MORNING FOR NORTHERN NEW CASTLE, NORTHWESTERN BURLINGTON,
NORTHWESTERN CAMDEN, NORTHWESTERN GLOUCESTER, SOUTHEASTERN BUCKS,
CHESTER, DELAWARE, SOUTHEASTERN MONTGOMERY AND PHILADELPHIA
COUNTIES...

At 338 AM EDT, Doppler radar and automated rain gauges indicated
thunderstorms produced heavy rain across the warned area. Additional
storms will impact the warned area through 530 AM. Between 0.5 and 1
inch of rain has fallen. The expected rainfall rate is 0.5 to 1 inch
in 30 minutes. Additional rainfall amounts of 0.5 to 1.5 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...
  Philadelphia, Camden, Wilmington, Newark, West Chester, Gloucester
  City, Cherry Hill, Bensalem, Mount Laurel, Norristown, Chester and
  Willingboro.

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 3973 7609 3974 7610 3976 7606 3983 7604
      3983 7602 3985 7602 3987 7599 3995 7599
      4004 7593 4011 7594 4017 7551 4018 7491
      4012 7481 3996 7490 3986 7498 3978 7544
      3962 7558 3961 7579 3972 7579 3972 7613

FLASH FLOOD...RADAR AND GAUGE INDICATED
EXPECTED RAINFALL RATE...0.5-1 INCH IN 30 MINUTES

$$

Staarmann

070 
WGUS71 KPHI 030926
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
526 AM EDT Thu Sep 3 2026

DEC003-NJC005-007-015-PAC017-029-045-091-101-030936-
/O.EXP.KPHI.FF.W.0153.000000T0000Z-260903T0930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Burlington NJ-Camden NJ-Gloucester NJ-Bucks PA-
Chester PA-Delaware PA-Montgomery PA-Philadelphia PA-
526 AM EDT Thu Sep 3 2026

...FLASH FLOOD WARNING WILL EXPIRE AT 530 AM EDT EARLY THIS MORNING
FOR NORTHERN NEW CASTLE, NORTHWESTERN BURLINGTON, NORTHWESTERN
CAMDEN, NORTHWESTERN GLOUCESTER, SOUTHEASTERN BUCKS, CHESTER,
DELAWARE, SOUTHEASTERN MONTGOMERY AND PHILADELPHIA COUNTIES...

Streams continue to rise due to excessive runoff. Minor flooding of
urban and poor drainage areas remains possible through early this
morning. Do not drive through flooded roads.

&&

LAT...LON 3973 7609 3974 7610 3976 7606 3983 7604
      3983 7602 3985 7602 3987 7599 3995 7599
      4004 7593 4011 7594 4017 7551 4018 7491
      4012 7481 3996 7490 3986 7498 3978 7544
      3962 7558 3961 7579 3972 7579 3972 7613

$$

Staarmann

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 3, 12:02 AM EDT	Severe Thunderstorm Warning	PHI	Kent	43 min
Sep 3, 5:26 AM EDT	Areal Flood Warning	PHI	New Castle	4 hr
Sep 3, 8:09 AM EDT	River Flood Warning	PHI	Chester	3 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2026 Flash Flood Warnings in New Jersey, 2026 Flash Flood Warnings in Delaware, 2026 Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.