Alert archive / Pennsylvania / Flash Flood Warnings in 2023

Flash Flood Warning 48, NWS Philadelphia/Mount Holly

July 9, 20234 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 9, 2023, 5:31 PM EDT for 4 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: Jul 9, 2023, 5:31 PM EDT (21:31 UTC)
Expired: Jul 9, 2023, 9:30 PM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 73 km from the middle of the area, began a volume at 21:30 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
Jul 9, 6:08 PM EDT	FLOOD	Middletown Twp., PA	Report of flooding in parking lots of Granite Run Mall along Rte 1.
Jul 9, 6:15 PM EDT	FLASH FLOOD	1 Nnw Horsham, PA	Closed due to flooding in Horsham Twp on Horsham Rd NB/SB between PA-611/Easton Rd and Dresher Rd.
Jul 9, 6:15 PM EDT	FLASH FLOOD	2 Wnw Willow Grove, PA	On-going water rescue at the intersection of Dreshertown Rd and Nicole Rd in Upper Dublin. 1 vehicle stranded.
Jul 9, 7:00 PM EDT	FLOOD	1 Ese Mantua, PA	Left lane blocked in Philadelphia on I-76 EB approaching University Ave/Exit 346 due to flooding.
Jul 9, 7:16 PM EDT	FLASH FLOOD	1 Ne Willow Grove, PA	Report of water rescue occurring in Upper Moreland Twp.

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, 9.5 hours before the alert went out and 215 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: 952 J/kg
Mixed-layer CIN: -58 J/kg
Mixed-layer LCL: 686 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 12 m²/s²
0-3 km storm-relative helicity: 37 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

673 
WGUS51 KPHI 092131
FFWPHI
PAC029-045-091-101-100130-
/O.NEW.KPHI.FF.W.0048.230709T2131Z-230710T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
531 PM EDT Sun Jul 9 2023

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Southeastern Chester County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...
  Southeastern Montgomery County in southeastern Pennsylvania...
  Philadelphia County in southeastern Pennsylvania...

* Until 930 PM EDT.

* At 531 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1 inch of rain 
  has fallen. Additional rainfall amounts of 1 to 3 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...
  Philadelphia, Camden, Chester, Yeadon, Westtown, Conshohocken, 
  Hatboro, Folcroft, Ambler, Swarthmore, Paulsboro, and Jenkintown.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 334 and 346.
	Interstate 95 in Pennsylvania between mile markers 0 and 33.
	Interstate 76 in Pennsylvania between mile markers 333 and 351.
	Interstate 676 in Pennsylvania between mile markers 0 and 1.
	Interstate 476 in Pennsylvania between mile markers 0 and 6...and
	between mile markers 18 and 19.

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 3985 7566 3997 7554 3995 7530 4000 7529
      4009 7531 4023 7517 4012 7497 4008 7496
      4006 7498 4005 7497 4001 7505 3998 7507
      3996 7513 3991 7513 3989 7515 3985 7525
      3985 7534 3980 7542 3984 7552 3983 7565

FLASH FLOOD...RADAR INDICATED

$$

Hoeflich

2 follow-up statements

721 
WGUS71 KPHI 092217
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
617 PM EDT Sun Jul 9 2023

PAC029-045-091-101-100130-
/O.CON.KPHI.FF.W.0048.000000T0000Z-230710T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-Delaware PA-Montgomery PA-Philadelphia PA-
617 PM EDT Sun Jul 9 2023

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 930 PM EDT THIS 
EVENING FOR SOUTHEASTERN CHESTER, DELAWARE, SOUTHEASTERN MONTGOMERY, 
AND PHILADELPHIA COUNTIES...

At 617 PM EDT, local law enforcement reported thunderstorms 
producing heavy rain. At 6:14 PM,  law enforcement reported ongoing 
water rescue in Upper Dublin Township, PA. Between 1.5 and 2.5 
inches of rain have fallen. Additional rainfall amounts of 0.5 to 
1.5 inches are possible in the warned area. Flash flooding is 
already occurring.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Law enforcement reported.

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...
  Philadelphia, Camden, Chester, Yeadon, Westtown, Conshohocken, 
  Hatboro, Folcroft, Ambler, Swarthmore, Paulsboro, and Jenkintown.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 334 and 346.
	Interstate 95 in Pennsylvania between mile markers 0 and 33.
	Interstate 76 in Pennsylvania between mile markers 333 and 351.
	Interstate 676 in Pennsylvania between mile markers 0 and 1.
	Interstate 476 in Pennsylvania between mile markers 0 and 6...and
	between mile markers 18 and 19.

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 3985 7566 3997 7554 3995 7530 4000 7529
      4009 7531 4023 7517 4012 7497 4008 7496
      4006 7498 4005 7497 4001 7505 3998 7507
      3996 7513 3991 7513 3989 7515 3985 7525
      3985 7534 3980 7542 3984 7552 3983 7565

FLASH FLOOD...OBSERVED

$$

Hoeflich

941 
WGUS71 KPHI 100120
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
920 PM EDT Sun Jul 9 2023

PAC029-045-091-101-100130-
/O.EXP.KPHI.FF.W.0048.000000T0000Z-230710T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-Delaware PA-Montgomery PA-Philadelphia PA-
920 PM EDT Sun Jul 9 2023

...FLASH FLOOD WARNING WILL EXPIRE AT 930 PM EDT THIS EVENING FOR 
SOUTHEASTERN CHESTER, DELAWARE, SOUTHEASTERN MONTGOMERY, AND 
PHILADELPHIA COUNTIES...

Flood waters have receded. The heavy rain has ended. Flooding is no 
longer expected to pose a threat.

A Flood Watch remains in effect until 1200 AM EDT for portions of 
east central Pennsylvania...northeast Pennsylvania...and southeast 
Pennsylvania.

A Flood Watch remains in effect until 1200 AM EDT for portions of 
northern Delaware...northeast Maryland...southern New Jersey...and 
southeast Pennsylvania.

LAT...LON 3985 7566 3997 7554 3995 7530 4000 7529
      4009 7531 4023 7517 4012 7497 4008 7496
      4006 7498 4005 7497 4001 7505 3998 7507
      3996 7513 3991 7513 3989 7515 3985 7525
      3985 7534 3980 7542 3984 7552 3983 7565

$$

Hoeflich

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 9, 11:00 AM EDT	Special Weather Statement	PHI	Carbon	30 min
Jul 9, 11:33 AM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery	8 hr
Jul 9, 11:47 AM EDT	Special Weather Statement	PHI	Monroe	43 min
Jul 9, 11:49 AM EDT	Special Weather Statement	PHI	Montgomery	41 min
Jul 9, 11:54 AM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Lehigh, Montgomery	33 min
Jul 9, 12:14 PM EDT	Special Weather Statement	PHI	Bucks	46 min
Jul 9, 12:15 PM EDT	Special Weather Statement	PHI	Monroe	30 min
Jul 9, 12:22 PM EDT	Special Weather Statement	PHI	Lebanon	38 min
Jul 9, 12:27 PM EDT	Flash Flood Warning	PHI	Berks, Bucks, Lehigh, Montgomery	8 hr
Jul 9, 12:37 PM EDT	Areal Flood Advisory	PHI	Bucks, Lehigh, Northampton	2 hr
Jul 9, 12:43 PM EDT	Areal Flood Advisory	PHI	Berks	33 min
Jul 9, 12:51 PM EDT	Special Weather Statement	PHI	Northampton	24 min
Jul 9, 12:57 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	6 hr
Jul 9, 1:02 PM EDT	Flash Flood Warning	PHI	Bucks, Lehigh, Northampton	8 hr
Jul 9, 1:16 PM EDT	Flash Flood Warning	PHI	Berks	6 hr
Jul 9, 1:17 PM EDT	Special Weather Statement	PHI	Berks	28 min
Jul 9, 1:32 PM EDT	Areal Flood Advisory	PHI	Carbon, Lehigh, Monroe, Northampton	4 hr
Jul 9, 2:16 PM EDT	Areal Flood Advisory	PHI	Berks, Lehigh	30 min
Jul 9, 2:41 PM EDT	Flash Flood Warning	PHI	Berks	4 hr
Jul 9, 2:46 PM EDT	Flash Flood Warning	PHI	Berks, Lehigh, Northampton	6 hr
Jul 9, 3:01 PM EDT	Special Weather Statement	PHI	Berks	29 min
Jul 9, 3:03 PM EDT	Special Weather Statement	PHI	Chester	27 min
Jul 9, 3:15 PM EDT	Severe Thunderstorm Warning	PHI	Berks	30 min
Jul 9, 3:20 PM EDT	Special Weather Statement	PHI	Berks	25 min
Jul 9, 3:27 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester	33 min
Jul 9, 3:41 PM EDT	Special Weather Statement	PHI	Berks	34 min
Jul 9, 3:51 PM EDT	Flash Flood Warning Considerable damage threat	PHI	Berks, Chester, Lehigh, Montgomery	6 hr
Jul 9, 3:59 PM EDT	Special Weather Statement	PHI	Chester	31 min
Jul 9, 4:03 PM EDT	Severe Thunderstorm Warning	PHI	Montgomery	27 min
Jul 9, 4:19 PM EDT	Special Weather Statement	PHI	Chester	26 min
Jul 9, 4:31 PM EDT	Flash Flood Warning	PHI	Chester, Montgomery	4 hr
Jul 9, 5:10 PM EDT	Severe Thunderstorm Warning	PHI	Delaware	50 min
Jul 9, 5:12 PM EDT	Flash Flood Warning	PHI	Bucks, Montgomery	5 hr
Jul 9, 5:15 PM EDT	Special Weather Statement	PHI	Bucks, Delaware, Philadelphia	30 min
Jul 9, 5:35 PM EDT	Severe Thunderstorm Warning	PHI	Philadelphia	25 min
Jul 9, 5:59 PM EDT	Flash Flood Warning	PHI	Bucks, Montgomery	4 hr
Jul 9, 6:05 PM EDT	Special Weather Statement	PHI	Bucks	25 min
Jul 9, 7:04 PM EDT	Areal Flood Warning	PHI	Berks	9 hr
Jul 9, 7:11 PM EDT	Areal Flood Advisory	PHI	Bucks	3 hr
Jul 9, 7:27 PM EDT	River Flood Warning	PHI	Chester	4 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2023 Every flash flood warning in 2023

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.