Alert archive / New Jersey / Flash Flood Warnings in 2024

Flash Flood Warning 33, NWS Philadelphia/Mount Holly

August 6, 20244 counties in New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 6, 2024, 5:29 PM EDT for 4 counties in New Jersey. It was in force for 6 hr. 4 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
Aug 6, 2024, 5:29 PM EDT (21:29 UTC)
Expired
Aug 6, 2024, 11:22 PM EDT
In force
6 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Hunterdon County, NJ, Middlesex County, NJ, Morris County, NJ, Somerset County, NJ

The radar

The Philadelphia radar (KDIX), 77 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.

What was reported inside it

TimeReportWhereRemark
Aug 6, 8:45 PM EDTRAIN 3.41 N Pleasant Plains, NJMesonet station BKRN4 1.3 N Pleasant Plains.
Aug 6, 9:45 PM EDTRAIN 2.462 Ene Somerville, NJMesonet station FW7617 Bridgewater.
Aug 6, 9:49 PM EDTRAIN 2.133 Nnw Bridgewater, NJMesonet station FW8114 Bridgewater.
Aug 6, 9:50 PM EDTRAIN 2.282 Sse Readington, NJMesonet station CW6872 Branchburg.

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, 9.5 hours before the alert went out and 141 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 2024-08-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1440 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 2024-08-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 57 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
1440 J/kg
Mixed-layer CIN
-50 J/kg
Mixed-layer LCL
797 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
57 m²/s²
0-3 km storm-relative helicity
99 m²/s²
Significant tornado parameter
0.4
Supercell composite
3.2

Open this sounding in Storm Lab

The text

As transmitted.

451 
WGUS51 KPHI 062129
FFWPHI
NJC019-023-027-035-070130-
/O.NEW.KPHI.FF.W.0033.240806T2129Z-240807T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
529 PM EDT Tue Aug 6 2024

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  North Central Middlesex County in northern New Jersey...
  South Central Morris County in northern New Jersey...
  Somerset County in northern New Jersey...
  East Central Hunterdon County in northwestern New Jersey...

* Until 930 PM EDT.

* At 529 PM EDT, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain across the warned area. Between 
  1 and 2 inches of rain have fallen. The expected rainfall rate is 
  1 to 2 inches in 1 hour. 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 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...
  New Brunswick, Somerville, Somerset, Bridgewater, Middlesex, Bound 
  Brook, Manville, Mendham, Flemington, Peapack And Gladstone, Far 
  Hills and Millstone.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 4 and 32.
	Interstate 78 in New Jersey between mile markers 23 and 42.

This includes the following streams and drainages...
  Back Brook RARITAN, Primrose Brook HACKENSACK-PASSAIC, Black Brook 
  HACKENSACK-PASSAIC, Ireland Brook RARITAN, Simonson Brook RARITAN, 
  RARITAN, Wickecheoke Creek MIDDLE DELAWARE-MUSCONETCONG, Green 
  Brook RARITAN, Beden Brook RARITAN, Harrisons Brook 
  HACKENSACK-PASSAIC, West Branch Middle Brook RARITAN, Millstone 
  River RARITAN, Lamington River RARITAN, Bound Brook RARITAN, Penns 
  Brook HACKENSACK-PASSAIC, Indian Grove Brook HACKENSACK-PASSAIC, 
  Ambrose Brook RARITAN, Passaic River HACKENSACK-PASSAIC, Mill 
  Brook RARITAN, Oakeys Brook RARITAN, Plum Brook MIDDLE 
  DELAWARE-MUSCONETCONG, Royce Brook RARITAN, Third Neshanic River 
  RARITAN, Bonygutt Brook RARITAN, Holland Brook RARITAN, Cold Brook 
  RARITAN, North Branch Raritan River RARITAN, Pike Run RARITAN, 
  Roaring Brook RARITAN, HACKENSACK-PASSAIC, Middle Brook RARITAN, 
  Hoopstick Brook RARITAN, Dukes Brook RARITAN, Chambers Brook 
  RARITAN, East Branch Middle Brook RARITAN, First Neshanic River 
  RARITAN, Assiscong Creek RARITAN, Raritan River RARITAN, South 
  Branch Raritan River RARITAN and Sixmile Run RARITAN.

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 4074 7472 4077 7455 4070 7442 4070 7443
      4067 7446 4066 7445 4066 7443 4066 7442
      4067 7441 4066 7440 4062 7443 4060 7446
      4061 7433 4044 7450 4043 7465 4047 7496

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

$$

MJL
2 follow-up statements
884 
WGUS51 KPHI 070055
FFWPHI
NJC019-023-027-035-070330-
/O.EXT.KPHI.FF.W.0033.000000T0000Z-240807T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
855 PM EDT Tue Aug 6 2024

The National Weather Service in Mount Holly has extended the

* Flash Flood Warning for...
  North Central Middlesex County in northern New Jersey...
  South Central Morris County in northern New Jersey...
  Somerset County in northern New Jersey...
  East Central Hunterdon County in northwestern New Jersey...

* Until 1130 PM EDT.

* At 855 PM EDT, Doppler radar and automated rain gauges indicated 
  thunderstorms produced heavy rain across the warned area. Between 
  1 and 2 inches of rain have fallen. Another round of strong 
  thunderstorms with rainfall rates of 1 to 2 inches per hour is 
  expected. 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 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...
  New Brunswick, Somerville, Somerset, Bridgewater, Middlesex, Bound 
  Brook, Manville, Mendham, Flemington, Peapack And Gladstone, Far 
  Hills and Millstone.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 4 and 31.
	Interstate 78 in New Jersey between mile markers 23 and 42.

This includes the following streams and drainages...
  Back Brook RARITAN, Primrose Brook HACKENSACK-PASSAIC, Black Brook 
  HACKENSACK-PASSAIC, Ireland Brook RARITAN, Simonson Brook RARITAN, 
  RARITAN, Wickecheoke Creek MIDDLE DELAWARE-MUSCONETCONG, Green 
  Brook RARITAN, Beden Brook RARITAN, Harrisons Brook 
  HACKENSACK-PASSAIC, West Branch Middle Brook RARITAN, Millstone 
  River RARITAN, Lamington River RARITAN, Bound Brook RARITAN, Penns 
  Brook HACKENSACK-PASSAIC, Indian Grove Brook HACKENSACK-PASSAIC, 
  Ambrose Brook RARITAN, Passaic River HACKENSACK-PASSAIC, Mill 
  Brook RARITAN, Oakeys Brook RARITAN, Plum Brook MIDDLE 
  DELAWARE-MUSCONETCONG, Royce Brook RARITAN, Third Neshanic River 
  RARITAN, Bonygutt Brook RARITAN, Holland Brook RARITAN, Cold Brook 
  RARITAN, North Branch Raritan River RARITAN, Pike Run RARITAN, 
  Roaring Brook RARITAN, HACKENSACK-PASSAIC, Middle Brook RARITAN, 
  Hoopstick Brook RARITAN, Dukes Brook RARITAN, Chambers Brook 
  RARITAN, East Branch Middle Brook RARITAN, First Neshanic River 
  RARITAN, Assiscong Creek RARITAN, Raritan River RARITAN, South 
  Branch Raritan River RARITAN and Sixmile Run RARITAN.

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.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 4074 7472 4077 7455 4070 7442 4070 7443
      4067 7446 4066 7445 4066 7443 4066 7442
      4067 7441 4066 7440 4062 7443 4060 7446
      4061 7433 4044 7450 4043 7465 4047 7496

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

$$

MJL
660 
WGUS71 KPHI 070322
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1122 PM EDT Tue Aug 6 2024

NJC019-023-027-035-070332-
/O.CAN.KPHI.FF.W.0033.000000T0000Z-240807T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Middlesex NJ-Morris NJ-Somerset NJ-
1122 PM EDT Tue Aug 6 2024

...FLASH FLOOD WARNING FOR NORTH CENTRAL MIDDLESEX, SOUTH CENTRAL 
MORRIS, SOMERSET AND EAST CENTRAL HUNTERDON COUNTIES HAS BEEN 
REPLACED WITH A FLOOD WARNING...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

A Flood Watch remains in effect until 1200 PM EDT Wednesday for 
portions of northern Delaware, New Jersey, and Pennsylvania.

&&

LAT...LON 4074 7472 4077 7455 4070 7442 4070 7443
      4067 7446 4066 7445 4066 7443 4066 7442
      4067 7441 4066 7440 4062 7443 4060 7446
      4061 7433 4044 7450 4043 7465 4047 7496

$$

MPS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 6, 9:37 AM EDTHeat AdvisoryPHIBurlington, Camden, Gloucester, Hunterdon, Mercer, Middlesex and 5 more9 hr
Aug 6, 9:39 AM EDTSmall Craft AdvisoryPHI10 hr
Aug 6, 2:04 PM EDTSpecial Marine WarningPHI56 min
Aug 6, 2:41 PM EDTSevere Thunderstorm WarningPHIOcean19 min
Aug 6, 2:55 PM EDTSpecial Marine WarningPHI65 min
Aug 6, 3:15 PM EDTSpecial Marine WarningPHI60 min
Aug 6, 3:18 PM EDTSevere Thunderstorm WarningPHIMonmouth27 min
Aug 6, 3:21 PM EDTSevere Thunderstorm WarningPHIBurlington23 min
Aug 6, 3:23 PM EDTSevere Thunderstorm WarningPHIMercer, Middlesex, Monmouth37 min
Aug 6, 3:45 PM EDTFlash Flood WarningPHIMiddlesex, Monmouth2 hr
Aug 6, 3:49 PM EDTSevere Thunderstorm WarningPHIMercer, Middlesex, Monmouth56 min
Aug 6, 4:10 PM EDTSpecial Marine WarningPHI65 min
Aug 6, 4:13 PM EDTFlash Flood WarningPHIMercer, Middlesex, Monmouth8 hr
Aug 6, 4:32 PM EDTSevere Thunderstorm WarningPHIHunterdon, Middlesex, Somerset43 min
Aug 6, 4:37 PM EDTSevere Thunderstorm WarningPHIHunterdon, Mercer, Middlesex, Somerset40 min
Aug 6, 4:55 PM EDTFlash Flood Warning Considerable damage threatPHIMonmouth6 hr
Aug 6, 4:56 PM EDTSevere Thunderstorm WarningPHIOcean49 min
Aug 6, 5:06 PM EDTSevere Thunderstorm WarningPHIHunterdon, Middlesex, Morris, Somerset54 min
Aug 6, 5:36 PM EDTFlash Flood WarningPHIMonmouth, Ocean8 hr
Aug 6, 6:37 PM EDTFlash Flood WarningPHIWarren3 hr
Aug 6, 6:39 PM EDTFlash Flood WarningPHIBurlington, Camden, Gloucester5 hr
Aug 6, 6:46 PM EDTFlash Flood WarningPHIMorris, Somerset4 hr
Aug 6, 6:57 PM EDTFlash Flood WarningPHIWarren3 hr
Aug 6, 7:04 PM EDTFlash Flood WarningPHIBurlington5 hr
Aug 6, 7:24 PM EDTFlash Flood WarningPHIBurlington, Mercer, Middlesex, Monmouth, Ocean5 hr

Nearby

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