Alert archive / Pennsylvania / Flash Flood Warnings in 2023

Flash Flood Warning 76, NWS Philadelphia/Mount Holly

July 25, 2023Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 25, 2023, 3:34 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 3 hr. 2 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 25, 2023, 3:34 PM EDT (19:34 UTC)
Expired: Jul 25, 2023, 6:47 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 93 km from the middle of the area, began a volume at 19:37 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
Jul 25, 4:00 PM EDT	FLASH FLOOD	East Whiteland Twp, PA	911 Call Center reports water rescue in East Whiteland Township.
Jul 25, 5:00 PM EDT	RAIN 3.21	2 Se Exton, PA	Storm Total as of 5:00pm.

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, 7.6 hours before the alert went out and 216 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: 591 J/kg
Mixed-layer CIN: -87 J/kg
Mixed-layer LCL: 1068 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 17 m²/s²
0-3 km storm-relative helicity: 52 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

As transmitted.

720 
WGUS51 KPHI 251934
FFWPHI
PAC029-091-252345-
/O.NEW.KPHI.FF.W.0076.230725T1934Z-230725T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
334 PM EDT Tue Jul 25 2023

The National Weather Service in Mount Holly has issued a

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

* Until 745 PM EDT.

* At 334 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 3 inches of rain 
  have fallen. 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.

  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...
  Norristown, Phoenixville, Lansdale, West Norriton, East Norriton, 
  Collegeville, Royersford, Trappe, Schwenksville, Valley Forge, 
  King Of Prussia, and Spring Mount.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 316 and 327.
	Northeast Extension between mile markers 26 and 31.

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 4031 7546 4025 7528 4011 7534 4000 7560
      4013 7560

FLASH FLOOD...RADAR INDICATED

$$

RCM

1 follow-up statement

113 
WGUS71 KPHI 252247
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
647 PM EDT Tue Jul 25 2023

PAC029-091-252257-
/O.CAN.KPHI.FF.W.0076.000000T0000Z-230725T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-Montgomery PA-
647 PM EDT Tue Jul 25 2023

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHEASTERN CHESTER AND 
CENTRAL MONTGOMERY COUNTIES...

The heavy rain has ended and flood waters have receded. While local 
creeks and streams will continue to run high, flooding is no longer 
expected to pose a threat.

LAT...LON 4031 7546 4025 7528 4011 7534 4000 7560
      4013 7560

$$

Robertson

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 25, 11:58 AM EDT	Special Weather Statement	PHI	Montgomery	32 min
Jul 25, 12:07 PM EDT	Special Weather Statement	PHI	Berks	23 min
Jul 25, 12:16 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Lehigh, Montgomery	44 min
Jul 25, 12:31 PM EDT	Special Weather Statement	PHI	Berks	29 min
Jul 25, 12:33 PM EDT	Special Weather Statement	PHI	Berks	27 min
Jul 25, 12:37 PM EDT	Special Weather Statement	PHI	Carbon	38 min
Jul 25, 12:47 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery	33 min
Jul 25, 12:56 PM EDT	Special Weather Statement	PHI	Northampton	34 min
Jul 25, 1:00 PM EDT	Special Weather Statement	PHI	Berks	30 min
Jul 25, 1:03 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery	42 min
Jul 25, 1:06 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Monroe, Northampton	39 min
Jul 25, 1:10 PM EDT	Special Weather Statement	PHI	Delaware	35 min
Jul 25, 1:12 PM EDT	Special Weather Statement	PHI	Monroe	33 min
Jul 25, 1:20 PM EDT	Flash Flood Warning	PHI	Bucks, Montgomery	5 hr
Jul 25, 1:27 PM EDT	Areal Flood Advisory	PHI	Berks	3 hr
Jul 25, 1:27 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	48 min
Jul 25, 1:37 PM EDT	Areal Flood Advisory	PHI	Carbon	3 hr
Jul 25, 1:38 PM EDT	Flash Flood Warning	PHI	Delaware	4 hr
Jul 25, 1:41 PM EDT	Areal Flood Advisory	PHI	Lehigh, Northampton	3 hr
Jul 25, 1:42 PM EDT	Special Weather Statement	PHI	Philadelphia	33 min
Jul 25, 1:49 PM EDT	Special Weather Statement	PHI	Chester	26 min
Jul 25, 1:54 PM EDT	Flash Flood Warning	PHI	Delaware, Philadelphia	4 hr
Jul 25, 1:55 PM EDT	Areal Flood Advisory	PHI	Monroe	2 hr
Jul 25, 2:06 PM EDT	Severe Thunderstorm Warning	PHI	Monroe	39 min
Jul 25, 2:14 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Montgomery	46 min
Jul 25, 2:21 PM EDT	Areal Flood Advisory	PHI	Berks, Chester, Montgomery	2 hr
Jul 25, 2:36 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Montgomery, Philadelphia	39 min
Jul 25, 2:51 PM EDT	Flash Flood Warning	PHI	Chester, Montgomery	3 hr
Jul 25, 2:57 PM EDT	Areal Flood Advisory	PHI	Chester	3 hr
Jul 25, 3:06 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Montgomery	95 min
Jul 25, 3:13 PM EDT	Flash Flood Warning	PHI	Chester	4 hr
Jul 25, 3:16 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	44 min
Jul 25, 3:21 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	39 min
Jul 25, 3:58 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	30 min
Jul 25, 4:04 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	3 hr
Jul 25, 4:55 PM EDT	Flash Flood Warning	PHI	Chester	118 min
Jul 25, 5:07 PM EDT	River Flood Warning	PHI	Chester	6 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.