Alert archive / New Jersey / Flash Flood Warnings in 2021

Flash Flood Warning 84, NWS Philadelphia/Mount Holly

September 23, 2021Gloucester County, Salem County, New Jersey; Chester County, Delaware County, Pennsylvania; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 23, 2021, 11:57 AM EDT for Gloucester County, Salem County, New Jersey; Chester County, Delaware County, Pennsylvania; New Castle County, Delaware. It was in force for 3 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 23, 2021, 11:57 AM EDT (15:57 UTC)
Expired: Sep 23, 2021, 3:00 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties New Castle County, DE, Gloucester County, NJ, Salem County, NJ, Chester County, PA, Delaware County, PA

The radar

The Dover AFB radar (KDOX), 97 km from the middle of the area, began a volume at 15:56 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 23, 12:55 PM EDT	FLASH FLOOD	Chester, PA	WATER RESCUE NEAR THE INTERSECTION OF 4TH STREET AND CROSBY STREET. TIME BASED ON DISPATCH REPORT.
Sep 23, 1:00 PM EDT	FLOOD	Chester Twp, PA	FLOODING WITH LANE RESTRICTIONS ON INTERSTATE 95 IN CHESTER TWP. TIME BASED ON DISPATCH REPORT.
Sep 23, 2:00 PM EDT	FLASH FLOOD	1 Nne Marshallton, PA	THE GAUGE ON EAST BRANCH BRANDYWINE CREEK BELOW DOWNINGTOWN (DWNP1) REACHED FLOOD STAGE.
Sep 23, 2:00 PM EDT	FLASH FLOOD	Chester, PA	SEVERAL ROADS FLOODED AND CLOSED IN CHESTER. TIME BASED ON SURROUNDING DISPATCH REPORTS. REPORT VIA SOCIAL MEDIA.
Sep 23, 2:20 PM EDT	FLASH FLOOD	Trainer, PA	MAIN STREET AND 7TH STREET CLOSED FROM FLOODING. TIME BASED ON DISPATCH REPORT.

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, 4.0 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-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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 517 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: -71 m²/s²
0-3 km storm-relative helicity: 88 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.0

Open this sounding in Storm Lab

The text

As transmitted.

559 
WGUS51 KPHI 231557
FFWPHI
DEC003-NJC015-033-PAC029-045-231900-
/O.NEW.KPHI.FF.W.0084.210923T1557Z-210923T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
1157 AM EDT Thu Sep 23 2021

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  New Castle County in northern Delaware...
  Northwestern Gloucester County in southern New Jersey...
  Northwestern Salem County in southern New Jersey...
  Southeastern Chester County in southeastern Pennsylvania...
  Southwestern Delaware County in southeastern Pennsylvania...

* Until 300 PM EDT.

* At 1157 AM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. 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...
  Wilmington, Newark, West Chester, Chester, Pennsville, Westtown, 
  Carneys Point, Elsmere, Kennett Square, New Castle, Penns Grove, 
  and Salem.

This includes the following highways...
	New Jersey Turnpike near exit 1.
	Interstate 95 in Pennsylvania between mile markers 0 and 6.
	Interstate 95 in Delaware between mile markers 0 and 23.
	Interstate 295 in New Jersey between mile markers 0 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3972 7579 3973 7579 3994 7582 4000 7553
      3985 7533 3972 7536 3953 7541 3952 7545
      3951 7553 3951 7557 3950 7578 3966 7579
      3968 7579

FLASH FLOOD...RADAR INDICATED

$$

NC

2 follow-up statements

250 
WGUS71 KPHI 231715
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
115 PM EDT Thu Sep 23 2021

DEC003-NJC015-033-PAC029-045-231900-
/O.CON.KPHI.FF.W.0084.000000T0000Z-210923T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Gloucester NJ-Salem NJ-Chester PA-Delaware PA-
115 PM EDT Thu Sep 23 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 3 PM EDT THIS 
AFTERNOON FOR NORTHERN NEW CASTLE, NORTHWESTERN GLOUCESTER, 
NORTHWESTERN SALEM, SOUTHEASTERN CHESTER, AND SOUTHWESTERN DELAWARE 
COUNTIES...

At 115 PM EDT, Doppler radar indicated thunderstorms producing heavy 
rain in portions of Delaware and Chester Counties. Between 1.5 and 
2.5 inches of rain have fallen. Flash flooding is already occurring 
in portions of Delaware County with several water rescues reported 
in the Woodlyn and EddyStone areas.

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...
  Wilmington, West Chester, Chester, Pennsville, Westtown, Carneys 
  Point, Elsmere, Kennett Square, New Castle, Penns Grove, Salem, 
  and Quinton.

This includes the following highways...
	New Jersey Turnpike near exit 1.
	Interstate 95 in Pennsylvania between mile markers 0 and 6.
	Interstate 95 in Delaware between mile markers 8 and 23.
	Interstate 295 in New Jersey between mile markers 0 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3994 7582 4000 7553 3985 7533 3972 7536
      3953 7541 3954 7543 3958 7548 3958 7549
      3960 7552 3973 7573 3975 7575

FLASH FLOOD...RADAR INDICATED

$$

NC

935 
WGUS71 KPHI 231851
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
251 PM EDT Thu Sep 23 2021

DEC003-NJC015-033-PAC029-045-231901-
/O.EXP.KPHI.FF.W.0084.000000T0000Z-210923T1900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Gloucester NJ-Salem NJ-Chester PA-Delaware PA-
251 PM EDT Thu Sep 23 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 3 PM EDT THIS AFTERNOON FOR 
NORTHERN NEW CASTLE, NORTHWESTERN GLOUCESTER, NORTHWESTERN SALEM, 
SOUTHEASTERN CHESTER, AND SOUTHWESTERN DELAWARE COUNTIES...

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.

A Flash Flood Watch remains in effect until 200 AM EDT Friday for 
portions of northern Delaware...and southeast Pennsylvania.

A Flash Flood Watch remains in effect until 200 AM EDT Friday for 
portions of east central Pennsylvania...northeast Pennsylvania...and 
southeast Pennsylvania.

LAT...LON 3994 7582 4000 7553 3985 7533 3972 7536
      3953 7541 3954 7543 3958 7548 3958 7549
      3960 7552 3973 7573 3975 7575

$$

NC

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 22, 8:43 PM EDT	Gale Warning	PHI		18 hr
Sep 23, 9:12 AM EDT	Coastal Flood Advisory	PHI	Burlington, Camden, Gloucester	10 hr
Sep 23, 11:33 AM EDT	Areal Flood Advisory	PHI	Cumberland, Gloucester, Salem	3 hr
Sep 23, 12:12 PM EDT	Severe Thunderstorm Warning	PHI	Gloucester, Salem	48 min
Sep 23, 12:54 PM EDT	Special Weather Statement	PHI	Gloucester	51 min
Sep 23, 12:56 PM EDT	Areal Flood Advisory	PHI	Burlington, Camden, Hunterdon, Mercer, Warren	3 hr
Sep 23, 1:13 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Camden, Gloucester, Salem	47 min
Sep 23, 1:42 PM EDT	Flash Flood Warning	PHI	Burlington, Camden, Gloucester	4 hr
Sep 23, 1:58 PM EDT	Special Weather Statement	PHI	Camden, Hunterdon	32 min
Sep 23, 2:37 PM EDT	Areal Flood Advisory	PHI	Burlington, Hunterdon, Mercer, Middlesex, Monmouth, Morris and 3 more	3 hr
Sep 23, 2:47 PM EDT	Special Weather Statement	PHI	Hunterdon, Mercer	28 min
Sep 23, 2:52 PM EDT	Special Weather Statement	PHI	Camden	23 min
Sep 23, 3:13 PM EDT	Special Weather Statement	PHI	Mercer, Somerset	32 min
Sep 23, 3:16 PM EDT	Special Weather Statement	PHI	Burlington	29 min
Sep 23, 3:23 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Mercer, Middlesex, Morris, Somerset	52 min
Sep 23, 3:26 PM EDT	Flash Flood Warning	PHI	Burlington, Hunterdon, Mercer, Middlesex, Morris, Somerset	2 hr
Sep 23, 3:50 PM EDT	Special Weather Statement	PHI	Burlington	25 min
Sep 23, 4:21 PM EDT	Areal Flood Advisory	PHI	Middlesex, Monmouth, Morris, Ocean, Somerset, Sussex	15 min
Sep 23, 4:36 PM EDT	Flash Flood Warning	PHI	Middlesex, Monmouth, Morris, Somerset, Sussex	3 hr
Sep 23, 5:00 PM EDT	Special Weather Statement	PHI	Monmouth	30 min
Sep 23, 10:52 AM EDT	Areal Flood Advisory	PHI	Chester	3 hr
Sep 23, 11:40 AM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Carbon, Lehigh, Montgomery, Northampton	3 hr
Sep 23, 12:28 PM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	4 hr
Sep 23, 12:57 PM EDT	Special Weather Statement	PHI	Bucks	33 min
Sep 23, 1:48 PM EDT	River Flood Warning	PHI	Chester	5 hr
Sep 23, 4:26 PM EDT	Areal Flood Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	80 min
Sep 23, 7:18 PM EDT	Areal Flood Warning	PHI	Berks, Montgomery	36 min
Sep 23, 11:11 AM EDT	Special Weather Statement	PHI	New Castle	64 min
Sep 23, 11:42 AM EDT	Severe Thunderstorm Warning	PHI	New Castle	33 min

Nearby

Flash Flood Warnings in New Jersey, 2021 Flash Flood Warnings in Pennsylvania, 2021 Flash Flood Warnings in Delaware, 2021 Every flash flood warning in 2021

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.