Alert archive / New Jersey / Flash Flood Warnings in 2024

Flash Flood Warning 56, NWS Philadelphia/Mount Holly

August 9, 2024Mercer County, New Jersey; Bucks County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 9, 2024, 5:30 PM EDT for Mercer County, New Jersey; Bucks County, Pennsylvania. It was in force for 83 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 9, 2024, 5:30 PM EDT (21:30 UTC)
Expired
Aug 9, 2024, 6:53 PM EDT
In force
83 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Mercer County, NJ, Bucks County, PA

The radar

The Philadelphia radar (KDIX), 39 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.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 9.5 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-pSkew-T log-p diagram, Brookhaven, NY at 12:00Z on 2024-08-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 988 joules per kilogram.LCLEL10008507005003002001001 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 2024-08-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 223 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
988 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
536 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
223 m²/s²
0-3 km storm-relative helicity
245 m²/s²
Significant tornado parameter
0.8
Supercell composite
13.0

Open this sounding in Storm Lab

The text

As transmitted.

285 
WGUS51 KPHI 092130
FFWPHI
NJC021-PAC017-100030-
/O.NEW.KPHI.FF.W.0056.240809T2130Z-240810T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
530 PM EDT Fri Aug 9 2024

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Central Mercer County in central New Jersey...
  Southeastern Bucks County in southeastern Pennsylvania...

* Until 830 PM EDT.

* At 530 PM EDT, Doppler radar indicated heavy rain across the 
  warned area. Up to 1 inch of rain has fallen. The expected 
  rainfall rate is 1 to 2 inches in 1 hour. 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...
  Trenton, Ewing, Burlington, Bristol, Hightstown, Tullytown, 
  Langhorne, White Horse, Mercerville-Hamilton Square, 
  Florence-Roebling, Levittown and Edinburg.

This includes the following highways...
	Interstate 295 in New Jersey between mile markers 58 and 68.
	Interstate 195 in New Jersey between mile markers 0 and 4.
	Interstate 95 in Pennsylvania between mile markers 39 and 40.
	Pennsylvania Turnpike between mile markers 355 and 359.

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 4035 7463 4032 7462 4029 7456 4028 7450
      4018 7469 4018 7471 4016 7471 4013 7474
      4012 7479 4013 7482 4010 7484 4008 7487
      4016 7495 4027 7475

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL RATE...1-2 INCHES IN 1 HOUR

$$

MJL
1 follow-up statement
165 
WGUS71 KPHI 092253
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
653 PM EDT Fri Aug 9 2024

NJC021-PAC017-092303-
/O.CAN.KPHI.FF.W.0056.000000T0000Z-240810T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mercer NJ-Bucks PA-
653 PM EDT Fri Aug 9 2024

...FLASH FLOOD WARNING IS CANCELLED FOR CENTRAL MERCER AND 
SOUTHEASTERN BUCKS 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.

&&

LAT...LON 4035 7463 4032 7462 4029 7456 4028 7450
      4018 7469 4018 7471 4016 7471 4013 7474
      4012 7479 4013 7482 4010 7484 4008 7487
      4016 7495 4027 7475

$$

MJL

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 9, 3:31 PM EDTFlash Flood WarningPHIWarren108 min
Aug 9, 4:11 PM EDTFlash Flood WarningPHIWarren100 min
Aug 8, 8:52 PM EDTFlash Flood WarningPHIBerks, Chester3 hr
Aug 8, 9:06 PM EDTRiver Flood WarningPHIChester9 hr
Aug 8, 11:40 PM EDTAreal Flood WarningPHIChester4 hr
Aug 9, 12:12 AM EDTRiver Flood WarningPHIChester, Delaware16 hr
Aug 9, 2:50 PM EDTFlash Flood WarningPHILehigh, Northampton2 hr
Aug 9, 3:50 PM EDTFlash Flood WarningPHIBucks, Montgomery2 hr
Aug 9, 5:56 PM EDTRiver Flood WarningPHIChester6 hr
Aug 9, 6:46 PM EDTAreal Flood WarningPHIBerks, Bucks, Lehigh, Montgomery4 hr

Nearby

Flash Flood Warnings in New Jersey, 2024Flash Flood Warnings in Pennsylvania, 2024Every flash flood warning in 2024

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.