Alert archive / New Jersey / Flash Flood Warnings in 2023

Flash Flood Warning 84, NWS Philadelphia/Mount Holly

September 10, 2023Bucks County, Pennsylvania; Burlington County, Mercer County, New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 10, 2023, 7:55 PM EDT for Bucks County, Pennsylvania; Burlington County, Mercer County, New Jersey. 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
Sep 10, 2023, 7:55 PM EDT (23:55 UTC)
Expired
Sep 10, 2023, 11:00 PM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Burlington County, NJ, Mercer County, NJ, Bucks County, PA

The radar

The Philadelphia radar (KDIX), 35 km from the middle of the area, began a volume at 23:55 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 10, 9:20 PM EDTFLASH FLOOD1 Wnw Eastampton Twp, NJKnightsbridge Road in Eastampton Township was closed due to flooding.
Sep 10, 9:26 PM EDTFLOODBensalem, PATrained spotter reports Poquessing Creek overflowing its banks on social media.

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, 11.9 hours before the alert went out and 176 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 2023-09-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1034 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 2023-09-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 56 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
1034 J/kg
Mixed-layer CIN
-26 J/kg
Mixed-layer LCL
789 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
56 m²/s²
0-3 km storm-relative helicity
64 m²/s²
Significant tornado parameter
0.2
Supercell composite
1.9

Open this sounding in Storm Lab

The text

As transmitted.

534 
WGUS51 KPHI 102355
FFWPHI
NJC005-021-PAC017-110400-
/O.NEW.KPHI.FF.W.0084.230910T2355Z-230911T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
755 PM EDT Sun Sep 10 2023

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Southern Mercer County in central New Jersey...
  Northwestern Burlington County in southern New Jersey...
  Southeastern Bucks County in southeastern Pennsylvania...

* Until midnight EDT.

* At 755 PM EDT, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain across the warned area. Between 
  0.5 and 1.5 inches of rain have fallen. The expected rainfall rate 
  is 1 to 3 inches in 1 hour. Additional rainfall amounts up to 1 
  inch are possible in the warned area. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar and automated gauges.

  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, Trenton, Ewing, Willingboro, Florence, Burlington, 
  Bristol, Mount Holly, Riverside, Bordentown, Beverly, and Yardley.

This includes the following highways...
	New Jersey Turnpike between exits 5 and 8.
	Pennsylvania Turnpike between mile markers 354 and 359.
	Interstate 95 in Pennsylvania between mile markers 35 and 40.
	Interstate 295 in New Jersey between mile markers 45 and 66...and
	between mile markers 75 and 76.
	Interstate 195 in New Jersey between mile markers 0 and 7.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4014 7493 4023 7490 4029 7481 4024 7457
      4018 7459 4018 7460 4019 7460 4018 7461
      4017 7461 4016 7460 4008 7463 3998 7477
      4004 7498

FLASH FLOOD...RADAR AND GAUGE INDICATED
EXPECTED RAINFALL RATE...1-3 INCHES IN 1 HOUR

$$

MLB
1 follow-up statement
051 
WGUS71 KPHI 110300
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1100 PM EDT Sun Sep 10 2023

NJC005-021-PAC017-110310-
/O.CAN.KPHI.FF.W.0084.000000T0000Z-230911T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Burlington NJ-Mercer NJ-Bucks PA-
1100 PM EDT Sun Sep 10 2023

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHERN MERCER, 
NORTHWESTERN BURLINGTON, AND SOUTHEASTERN BUCKS COUNTIES...

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

LAT...LON 4014 7493 4023 7490 4029 7481 4024 7457
      4018 7459 4018 7460 4019 7460 4018 7461
      4017 7461 4016 7460 4008 7463 3998 7477
      4004 7498

$$

Iovino

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 9, 8:09 PM EDTAreal Flood AdvisoryPHIBerks20 min
Sep 9, 8:29 PM EDTFlash Flood WarningPHIBerks2 hr
Sep 9, 9:12 PM EDTAreal Flood AdvisoryPHIBerks, Carbon, Lehigh, Monroe116 min
Sep 10, 5:48 PM EDTAreal Flood AdvisoryPHIBucks, Montgomery, Philadelphia3 hr
Sep 10, 6:03 PM EDTFlash Flood WarningPHIBucks, Montgomery, Philadelphia3 hr
Sep 10, 7:11 PM EDTAreal Flood AdvisoryPHIBerks, Bucks, Lehigh, Montgomery, Northampton3 hr
Sep 10, 7:37 PM EDTAreal Flood AdvisoryPHIBucks3 hr
Sep 10, 9:37 AM EDTSpecial Weather StatementPHIAtlantic53 min
Sep 10, 10:14 AM EDTAreal Flood AdvisoryPHIMercer, Middlesex, Somerset107 min
Sep 10, 11:37 AM EDTAreal Flood AdvisoryPHIMonmouth85 min
Sep 10, 6:07 PM EDTSpecial Marine WarningPHI23 min

Nearby

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