Alert archive / Pennsylvania / Flash Flood Warnings in 2023

Flash Flood Warning 80, NWS Philadelphia/Mount Holly

September 8, 2023Bucks County, Montgomery County, Pennsylvania; Hunterdon County, New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 8, 2023, 5:21 PM EDT for Bucks County, Montgomery County, Pennsylvania; Hunterdon County, New Jersey. It was in force for 4 hr. 3 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 8, 2023, 5:21 PM EDT (21:21 UTC)
Expired
Sep 8, 2023, 9:30 PM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Hunterdon County, NJ, Bucks County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 77 km from the middle of the area, began a volume at 21:25 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

TimeReportWhereRemark
Sep 8, 6:10 PM EDTFLASH FLOODDoylestown, PAEmergency manager reports flash flooding across the township of Doylestown. Time estimated.
Sep 8, 6:10 PM EDTFLASH FLOODPlumstead Twp, PAEmergency manager reports flash flooding across Plumstead Twp. Time estimated.
Sep 8, 6:20 PM EDTFLASH FLOODBuckingham Twp, PAEmergency manager reports flash flooding across Buckingham Township. Time estimated.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 9.4 hours before the alert went out and 198 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, Brookhaven, NY at 12:00Z on 2023-09-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2469 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, Brookhaven, NY at 12:00Z on 2023-09-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 92 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
2469 J/kg
Mixed-layer CIN
-23 J/kg
Mixed-layer LCL
566 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
92 m²/s²
0-3 km storm-relative helicity
87 m²/s²
Significant tornado parameter
0.7
Supercell composite
4.0

Open this sounding in Storm Lab

The text

As transmitted.

075 
WGUS51 KPHI 082121
FFWPHI
NJC019-PAC017-091-090130-
/O.NEW.KPHI.FF.W.0080.230908T2121Z-230909T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
521 PM EDT Fri Sep 8 2023

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Central Hunterdon County in northwestern New Jersey...
  Central Bucks County in southeastern Pennsylvania...
  Northeastern Montgomery County in southeastern Pennsylvania...

* Until 930 PM EDT.

* At 521 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1.5 inches of 
  rain have fallen. Additional rainfall amounts of 0.5 to 1.5 inches 
  are possible in the warned area. Flash flooding is 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...
  Lansdale, Doylestown, Byram, Souderton, Bedminster, Flemington, 
  Chalfont, Tinicum, Hatfield, Dublin, Frenchtown, and Stockton.

This includes the following highways...
	Northeast Extension between mile markers 29 and 31.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Motorists should not attempt to drive around barricades or drive 
cars through flooded areas.

&&

LAT...LON 4033 7531 4062 7501 4061 7492 4057 7481
      4040 7497 4031 7506 4024 7518 4021 7525
      4024 7537

FLASH FLOOD...RADAR INDICATED

$$

MLB
4 follow-up statements
377 
WGUS71 KPHI 082221
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
621 PM EDT Fri Sep 8 2023

NJC019-PAC017-091-090130-
/O.CON.KPHI.FF.W.0080.000000T0000Z-230909T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Bucks PA-Montgomery PA-
621 PM EDT Fri Sep 8 2023

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 930 PM EDT THIS 
EVENING FOR CENTRAL HUNTERDON, CENTRAL BUCKS, AND NORTHEASTERN 
MONTGOMERY COUNTIES...

At 621 PM EDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1 and 2.5 inches of rain have 
fallen. Additional rainfall amounts up to 0.5 inches are possible in 
the warned area. Flash flooding is ongoing or expected to begin 
shortly.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar.

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...
  Lansdale, Doylestown, Byram, Souderton, Bedminster, Flemington, 
  Chalfont, Tinicum, Hatfield, Dublin, Frenchtown, and Stockton.

This includes the following highways...
	Northeast Extension between mile markers 29 and 31.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Motorists should not attempt to drive around barricades or drive 
cars through flooded areas.

&&

LAT...LON 4033 7531 4062 7501 4061 7492 4057 7481
      4040 7497 4031 7506 4024 7518 4021 7525
      4024 7537

FLASH FLOOD...RADAR INDICATED

$$

MLB
762 
WGUS71 KPHI 082237
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
637 PM EDT Fri Sep 8 2023

NJC019-PAC017-091-090130-
/O.CON.KPHI.FF.W.0080.000000T0000Z-230909T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Bucks PA-Montgomery PA-
637 PM EDT Fri Sep 8 2023

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 930 PM EDT THIS 
EVENING FOR CENTRAL HUNTERDON, CENTRAL BUCKS, AND NORTHEASTERN 
MONTGOMERY COUNTIES...

At 637 PM EDT, emergency management reported flash flooding 
occurring across Bucks County. Between 1 and 2.5 inches of rain have 
fallen. Additional rainfall amounts up to 0.5 inches are possible in 
the warned area. Flash flooding is already occurring.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Emergency management 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...
  Lansdale, Doylestown, Byram, Souderton, Bedminster, Flemington, 
  Chalfont, Tinicum, Hatfield, Dublin, Frenchtown, and Stockton.

This includes the following highways...
	Northeast Extension between mile markers 29 and 31.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Motorists should not attempt to drive around barricades or drive 
cars through flooded areas.

&&

LAT...LON 4033 7531 4062 7501 4061 7492 4057 7481
      4040 7497 4031 7506 4024 7518 4021 7525
      4024 7537

FLASH FLOOD...OBSERVED

$$

MLB
035 
WGUS71 KPHI 082326
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
726 PM EDT Fri Sep 8 2023

NJC019-PAC017-091-090130-
/O.CON.KPHI.FF.W.0080.000000T0000Z-230909T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Bucks PA-Montgomery PA-
726 PM EDT Fri Sep 8 2023

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 930 PM EDT THIS 
EVENING FOR CENTRAL HUNTERDON, CENTRAL BUCKS, AND NORTHEASTERN 
MONTGOMERY COUNTIES...

At 726 PM EDT, emergency management reported flash flooding 
occurring across Bucks County. Between 1 and 2.5 inches of rain have 
fallen. Flash flooding is already occurring.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Emergency management 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...
  Lansdale, Doylestown, Byram, Souderton, Bedminster, Flemington, 
  Chalfont, Tinicum, Hatfield, Dublin, Frenchtown, and Stockton.

This includes the following highways...
	Northeast Extension between mile markers 29 and 31.

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 4033 7531 4062 7501 4061 7492 4057 7481
      4040 7497 4031 7506 4024 7518 4021 7525
      4024 7537

FLASH FLOOD...OBSERVED

$$

MLB
857 
WGUS71 KPHI 090122
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
922 PM EDT Fri Sep 8 2023

NJC019-PAC017-091-090132-
/O.EXP.KPHI.FF.W.0080.000000T0000Z-230909T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Bucks PA-Montgomery PA-
922 PM EDT Fri Sep 8 2023

...FLASH FLOOD WARNING WILL EXPIRE AT 930 PM EDT THIS EVENING FOR 
CENTRAL HUNTERDON, CENTRAL BUCKS, AND NORTHEASTERN MONTGOMERY 
COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Do not drive around barricades.

LAT...LON 4033 7531 4062 7501 4061 7492 4057 7481
      4040 7497 4031 7506 4024 7518 4021 7525
      4024 7537

$$

MLB

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 7, 8:08 PM EDTSpecial Weather StatementPHIChester, Lehigh37 min
Sep 7, 8:42 PM EDTSpecial Weather StatementPHIBucks33 min
Sep 7, 9:19 PM EDTSpecial Weather StatementPHIBerks26 min
Sep 7, 9:37 PM EDTSevere Thunderstorm WarningPHIBerks18 min
Sep 7, 10:07 PM EDTSpecial Weather StatementPHIBerks38 min
Sep 7, 10:38 PM EDTAreal Flood AdvisoryPHIBerks76 min
Sep 7, 10:44 PM EDTSpecial Weather StatementPHIBerks, Lehigh61 min
Sep 8, 4:24 PM EDTSevere Thunderstorm WarningPHIBucks51 min
Sep 8, 5:12 PM EDTAreal Flood AdvisoryPHIBucks3 hr
Sep 8, 5:14 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery46 min
Sep 8, 5:16 PM EDTAreal Flood AdvisoryPHIChester, Montgomery3 hr
Sep 8, 5:29 PM EDTSpecial Weather StatementPHIMontgomery31 min
Sep 8, 5:34 PM EDTSevere Thunderstorm WarningPHIMonroe, Northampton41 min
Sep 8, 6:00 PM EDTSpecial Weather StatementPHIBucks30 min
Sep 8, 6:16 PM EDTSpecial Weather StatementPHINorthampton29 min
Sep 8, 6:24 PM EDTSpecial Weather StatementPHIMonroe36 min
Sep 8, 6:29 PM EDTSpecial Weather StatementPHIBucks31 min
Sep 8, 6:34 PM EDTAreal Flood AdvisoryPHIMonroe3 hr
Sep 7, 9:46 PM EDTSpecial Weather StatementPHISussex29 min
Sep 8, 6:02 AM EDTSpecial Marine WarningPHI40 min
Sep 8, 1:36 PM EDTSpecial Weather StatementPHIBurlington24 min
Sep 8, 1:37 PM EDTSpecial Weather StatementPHIMonmouth23 min
Sep 8, 1:46 PM EDTSevere Thunderstorm WarningPHIBurlington, Ocean44 min
Sep 8, 1:50 PM EDTSpecial Marine WarningPHI115 min
Sep 8, 1:54 PM EDTSevere Thunderstorm WarningPHIMonmouth, Ocean51 min
Sep 8, 2:27 PM EDTSevere Thunderstorm WarningPHIMiddlesex, Monmouth48 min
Sep 8, 2:30 PM EDTSevere Thunderstorm WarningPHIBurlington, Middlesex, Monmouth, Ocean45 min
Sep 8, 2:33 PM EDTAreal Flood AdvisoryPHIBurlington, Monmouth, Ocean3 hr
Sep 8, 2:44 PM EDTSpecial Marine WarningPHI18 min
Sep 8, 2:45 PM EDTSevere Thunderstorm WarningPHIBurlington, Ocean45 min
Sep 8, 2:53 PM EDTSevere Thunderstorm WarningPHIBurlington, Mercer, Middlesex, Monmouth, Somerset52 min
Sep 8, 3:17 PM EDTSpecial Marine WarningPHI58 min
Sep 8, 3:27 PM EDTSevere Thunderstorm WarningPHIBurlington, Mercer, Monmouth, Ocean63 min
Sep 8, 3:29 PM EDTFlash Flood WarningPHIBurlington, Ocean4 hr
Sep 8, 3:31 PM EDTSevere Thunderstorm WarningPHICumberland, Salem44 min
Sep 8, 3:36 PM EDTSevere Thunderstorm WarningPHIMorris30 min
Sep 8, 3:43 PM EDTSpecial Weather StatementPHIMiddlesex32 min
Sep 8, 3:58 PM EDTSpecial Weather StatementPHISomerset32 min
Sep 8, 4:27 PM EDTSevere Thunderstorm WarningPHIBurlington, Ocean51 min
Sep 8, 4:30 PM EDTSevere Thunderstorm WarningPHIBurlington, Mercer, Monmouth, Ocean60 min
Sep 8, 4:50 PM EDTSevere Thunderstorm WarningPHIHunterdon, Morris, Somerset, Sussex, Warren40 min
Sep 8, 5:49 PM EDTSevere Thunderstorm WarningPHISussex41 min
Sep 8, 6:11 PM EDTSpecial Weather StatementPHIWarren34 min

Nearby

Flash Flood Warnings in Pennsylvania, 2023Flash Flood Warnings in New Jersey, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.