Alert archive / Pennsylvania / Flash Flood Warnings in 2023

Flash Flood Warning 65, NWS Philadelphia/Mount Holly

July 16, 20235 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 16, 2023, 9:40 AM EDT for 5 counties in 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
Jul 16, 2023, 9:40 AM EDT (13:40 UTC)
Expired
Jul 16, 2023, 12:29 PM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

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

The radar

The Philadelphia radar (KDIX), 76 km from the middle of the area, began a volume at 13:43 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 12:00Z, 1.7 hours before the alert went out and 220 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-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2023-07-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 275 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2023-07-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 30 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
275 J/kg
Mixed-layer CIN
-48 J/kg
Mixed-layer LCL
570 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
97 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

As transmitted.

948 
WGUS51 KPHI 161340
FFWPHI
PAC017-029-045-091-101-161645-
/O.NEW.KPHI.FF.W.0065.230716T1340Z-230716T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
940 AM EDT Sun Jul 16 2023

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  South Central Bucks County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...
  Northeastern Delaware County in southeastern Pennsylvania...
  Southeastern Montgomery County in southeastern Pennsylvania...
  Northwestern Philadelphia County in southeastern Pennsylvania...

* Until 1245 PM EDT.

* At 940 AM EDT, Doppler radar indicated heavy rain across the 
  warned area. Between 0.5 and 1.5 inches of rain have fallen. 
  Additional rainfall amounts of 1 to 1.5 inches are possible in the 
  warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by heavy rain.

  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, Norristown, West Norriton, East Norriton, 
  Conshohocken, Hatboro, Ambler, Jenkintown, Narberth, Rockledge, 
  Abington, and Bryn Athyn.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 324 and 348.
	Interstate 76 in Pennsylvania between mile markers 327 and 342.
	Interstate 476 in Pennsylvania between mile markers 7 and 19.
	Northeast Extension between mile markers 21 and 22.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4007 7548 4016 7528 4025 7509 4014 7502
      4013 7501 4007 7509 3998 7521 3994 7537
      3998 7546 3999 7545 4004 7541 4006 7539

FLASH FLOOD...RADAR INDICATED

$$

MJL
2 follow-up statements
308 
WGUS71 KPHI 161524
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1124 AM EDT Sun Jul 16 2023

PAC029-161534-
/O.CAN.KPHI.FF.W.0065.000000T0000Z-230716T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-
1124 AM EDT Sun Jul 16 2023

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHEASTERN CHESTER 
COUNTY...

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

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

LAT...LON 4007 7536 4012 7534 4016 7528 4025 7509
      4018 7505 4013 7507 4007 7509 4005 7512
      3998 7521 3998 7527 3998 7528 3998 7533
      4003 7538 4006 7536

$$

PAC017-045-091-101-161645-
/O.CON.KPHI.FF.W.0065.000000T0000Z-230716T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Bucks PA-Delaware PA-Montgomery PA-Philadelphia PA-
1124 AM EDT Sun Jul 16 2023

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1245 PM EDT THIS 
AFTERNOON FOR SOUTH CENTRAL BUCKS, NORTHEASTERN DELAWARE, 
SOUTHEASTERN MONTGOMERY, AND NORTHWESTERN PHILADELPHIA COUNTIES...

At 1124 AM EDT, Doppler radar indicated 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 heavy rain.

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, Norristown, East Norriton, Conshohocken, Hatboro, 
  Ambler, Jenkintown, Narberth, Rockledge, Abington, Bryn Athyn, and 
  Ivyland.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 330 and 346.
	Interstate 76 in Pennsylvania between mile markers 330 and 342.
	Interstate 476 in Pennsylvania between mile markers 11 and 19.
	Northeast Extension between mile markers 21 and 22.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4007 7536 4012 7534 4016 7528 4025 7509
      4018 7505 4013 7507 4007 7509 4005 7512
      3998 7521 3998 7527 3998 7528 3998 7533
      4003 7538 4006 7536

FLASH FLOOD...RADAR INDICATED

$$

MJL
943 
WGUS71 KPHI 161629
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1229 PM EDT Sun Jul 16 2023

PAC017-045-091-101-161639-
/O.CAN.KPHI.FF.W.0065.000000T0000Z-230716T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Bucks PA-Delaware PA-Montgomery PA-Philadelphia PA-
1229 PM EDT Sun Jul 16 2023

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTH CENTRAL BUCKS, 
NORTHEASTERN DELAWARE, SOUTHEASTERN MONTGOMERY, AND NORTHWESTERN 
PHILADELPHIA COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat.

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

LAT...LON 4007 7536 4012 7534 4016 7528 4025 7509
      4018 7505 4013 7507 4007 7509 4005 7512
      3998 7521 3998 7527 3998 7528 3998 7533
      4003 7538 4006 7536

$$

MJL

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 15, 8:37 PM EDTAreal Flood AdvisoryPHICarbon19 min
Jul 15, 8:44 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe30 min
Jul 15, 8:56 PM EDTFlash Flood WarningPHICarbon95 min
Jul 16, 12:50 AM EDTSpecial Weather StatementPHIBerks25 min
Jul 16, 1:41 AM EDTSpecial Weather StatementPHICarbon, Lehigh34 min
Jul 16, 2:12 AM EDTSpecial Weather StatementPHICarbon, Lehigh, Monroe33 min
Jul 16, 2:43 AM EDTFlash Flood WarningPHICarbon, Lehigh, Monroe, Northampton4 hr
Jul 16, 2:47 AM EDTSpecial Weather StatementPHIChester, Delaware28 min
Jul 16, 3:40 AM EDTFlash Flood WarningPHIMonroe, Northampton7 hr
Jul 16, 4:05 AM EDTFlash Flood WarningPHIBerks, Bucks, Chester, Lehigh, Montgomery, Northampton6 hr
Jul 16, 4:14 AM EDTSpecial Weather StatementPHIBucks31 min
Jul 16, 4:38 AM EDTTornado WarningPHIBucks37 min
Jul 16, 9:12 AM EDTFlash Flood WarningPHIChester2 hr
Jul 16, 9:53 AM EDTTornado WarningPHIMontgomery, Philadelphia37 min
Jul 16, 10:54 AM EDTAreal Flood WarningPHIMonroe, Northampton5 hr
Jul 16, 11:08 AM EDTFlash Flood WarningPHIDelaware, Philadelphia3 hr
Jul 16, 12:22 PM EDTAreal Flood AdvisoryPHIBucks, Philadelphia3 hr
Jul 16, 12:26 PM EDTAreal Flood AdvisoryPHIPhiladelphia3 hr
Jul 16, 1:47 PM EDTAreal Flood AdvisoryPHIDelaware, Philadelphia80 min
Jul 16, 6:44 PM EDTAreal Flood AdvisoryPHIBucks90 min

Nearby

Flash Flood Warnings in Pennsylvania, 2023Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.