Alert archive / New Jersey / Flash Flood Warnings in 2024

Flash Flood Warning 64, NWS Philadelphia/Mount Holly

August 18, 2024Morris County, Somerset County, New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 18, 2024, 6:36 PM EDT for Morris County, Somerset County, New Jersey. It was in force for 5 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
Aug 18, 2024, 6:36 PM EDT (22:36 UTC)
Expired
Aug 18, 2024, 11:55 PM EDT
In force
5 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Morris County, NJ, Somerset County, NJ

The radar

The Philadelphia radar (KDIX), 85 km from the middle of the area, began a volume at 22:39 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 18, 7:40 PM EDTFLASH FLOOD2 N Manville, NJAdamsville Road between Union Ave and US 22 is closed due to flooding.
Aug 18, 7:45 PM EDTFLASH FLOOD2 Wnw Martinsville, NJWest Branch Middle Brook at Martinsville reached flood stage.
Aug 18, 11:45 PM EDTRAIN 4.51 Wsw Madison, NJA lot of ponding of water in the area and a lot of water flowing down the streets.

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, 10.6 hours before the alert went out and 133 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 2024-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 109 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 2024-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 187 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
109 J/kg
Mixed-layer CIN
-20 J/kg
Mixed-layer LCL
582 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
187 m²/s²
0-3 km storm-relative helicity
205 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

As transmitted.

314 
WGUS51 KPHI 182236
FFWPHI
NJC027-035-190245-
/O.NEW.KPHI.FF.W.0064.240818T2236Z-240819T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
636 PM EDT Sun Aug 18 2024

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Southeastern Morris County in northern New Jersey...
  Northeastern Somerset County in northern New Jersey...

* Until 1045 PM EDT.

* At 636 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1.5 and 2.5 inches of 
  rain have fallen. 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.

  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...
  Morristown, Somerville, Bridgewater, Madison, Middlesex, Florham 
  Park, East Hanover, Bound Brook, Manville, Chatham, Morris Plains 
  and Mendham.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 11 and 40.
	Interstate 78 in New Jersey between mile markers 29 and 42.
	Interstate 80 in New Jersey between mile markers 46 and 48.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 4091 7427 4086 7432 4080 7436 4076 7438
      4075 7436 4069 7443 4069 7445 4067 7446
      4066 7445 4066 7440 4065 7440 4062 7443
      4058 7451 4056 7453 4053 7450 4054 7460
      4056 7465 4073 7471 4088 7434 4087 7434

FLASH FLOOD...RADAR INDICATED

$$

Hoeflich
4 follow-up statements
848 
WGUS71 KPHI 182254
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
654 PM EDT Sun Aug 18 2024

NJC027-035-190245-
/O.CON.KPHI.FF.W.0064.000000T0000Z-240819T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris NJ-Somerset NJ-
654 PM EDT Sun Aug 18 2024

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1045 PM EDT THIS 
EVENING FOR SOUTHEASTERN MORRIS AND NORTHEASTERN SOMERSET COUNTIES...

At 654 PM EDT, gauge reports indicated thunderstorms producing heavy 
rain in the  Morristown area as the Whippany River went into flood 
stage. Between 2.5 and 4 inches of rain have fallen. Additional 
rainfall amounts of 0.5 to 1.5 inches are possible in the warned 
area. Flash flooding is already occurring.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Gauges reported.

IMPACT...Flooding of small creeks and streams, urban areas,
         highways, streets, and underpasses as well as other
         drainage and low lying areas.

For Whippany River at Morristown:
At 6:35pm the stage was 6.18 feet.
Flood Stage is 6 feet.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 11 and 40.
	Interstate 78 in New Jersey between mile markers 30 and 42.
	Interstate 80 in New Jersey between mile markers 46 and 48.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 4091 7427 4086 7432 4080 7436 4076 7438
      4075 7436 4069 7443 4069 7445 4067 7446
      4066 7445 4066 7440 4065 7440 4062 7443
      4058 7451 4056 7453 4053 7450 4054 7460
      4056 7465 4073 7471 4088 7434 4087 7434

FLASH FLOOD...GAUGE INDICATED

$$

Hoeflich
880 
WGUS71 KPHI 182258
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
658 PM EDT Sun Aug 18 2024

NJC027-035-190245-
/O.CON.KPHI.FF.W.0064.000000T0000Z-240819T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris NJ-Somerset NJ-
658 PM EDT Sun Aug 18 2024

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1045 PM EDT THIS 
EVENING FOR SOUTHEASTERN MORRIS AND NORTHEASTERN SOMERSET COUNTIES...

At 658 PM EDT, gauge reports indicated thunderstorms producing heavy 
rain as the Whippany River at Morristown went into flood stage. 
Between 2.5 and 4 inches of rain have fallen. Additional rainfall 
amounts of 0.5 to 1.5 inches are possible in the warned area. Flash 
flooding is already occurring.

HAZARD...Life threatening flash flooding caused by thunderstorms.

SOURCE...Gauges reported.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets, and underpasses.

For Whippany River at Morristown:
At 6:35pm the stage was 6.18 feet and rising. 
Flood Stage is 6 feet.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 11 and 40.
	Interstate 78 in New Jersey between mile markers 30 and 42.
	Interstate 80 in New Jersey between mile markers 46 and 48.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 4091 7427 4086 7432 4080 7436 4076 7438
      4075 7436 4069 7443 4069 7445 4067 7446
      4066 7445 4066 7440 4065 7440 4062 7443
      4058 7451 4056 7453 4053 7450 4054 7460
      4056 7465 4073 7471 4088 7434 4087 7434

FLASH FLOOD...GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Hoeflich
293 
WGUS51 KPHI 190238
FFWPHI
NJC027-035-190445-
/O.EXT.KPHI.FF.W.0064.000000T0000Z-240819T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
1038 PM EDT Sun Aug 18 2024

The National Weather Service in Mount Holly has extended the

* Flash Flood Warning for...
  Southeastern Morris County in northern New Jersey...
  Northeastern Somerset County in northern New Jersey...

* Until 1245 AM EDT.

* At 1038 PM EDT, emergency management reported thunderstorms 
  producing heavy rain with flooding around Morristown, with more 
  rain coming into the warned area. Between 2.5 and 4 inches of rain 
  have fallen. Additional rainfall amounts up to 1 inch is 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...
  Morristown, Somerville, Bridgewater, Madison, Middlesex, Florham 
  Park, East Hanover, Bound Brook, Manville, Chatham, Morris Plains 
  and Mendham.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 11 and 40.
	Interstate 78 in New Jersey between mile markers 30 and 42.
	Interstate 80 in New Jersey between mile markers 46 and 48.

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.

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 4091 7427 4086 7432 4080 7436 4076 7438
      4075 7436 4069 7443 4069 7445 4067 7446
      4066 7445 4066 7440 4065 7440 4062 7443
      4058 7451 4056 7453 4053 7450 4054 7460
      4056 7465 4073 7471 4088 7434 4087 7434

FLASH FLOOD...OBSERVED

$$

Hoeflich
832 
WGUS71 KPHI 190355
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1155 PM EDT Sun Aug 18 2024

NJC027-035-190405-
/O.CAN.KPHI.FF.W.0064.000000T0000Z-240819T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris NJ-Somerset NJ-
1155 PM EDT Sun Aug 18 2024

...FLASH FLOOD WARNING FOR SOUTHEASTERN MORRIS AND NORTHEASTERN 
SOMERSET COUNTIES HAS BEEN REPLACED WITH A FLOOD WARNING...

&&

LAT...LON 4091 7427 4086 7432 4080 7436 4076 7438
      4075 7436 4069 7443 4069 7445 4067 7446
      4066 7445 4066 7440 4065 7440 4062 7443
      4058 7451 4056 7453 4053 7450 4054 7460
      4056 7465 4073 7471 4088 7434 4087 7434

$$

Staarmann

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 18, 3:09 AM EDTFlash Flood WarningPHIBurlington, Camden93 min
Aug 18, 4:41 AM EDTFlash Flood WarningPHIBurlington, Camden, Mercer2 hr
Aug 18, 2:17 PM EDTSpecial Marine WarningPHI58 min
Aug 18, 2:42 PM EDTSpecial Marine WarningPHI93 min
Aug 18, 3:55 PM EDTSpecial Marine WarningPHI95 min
Aug 18, 4:04 PM EDTSevere Thunderstorm WarningPHIWarren41 min
Aug 18, 4:41 PM EDTSevere Thunderstorm WarningPHISussex, Warren34 min
Aug 18, 4:56 PM EDTFlash Flood WarningPHIWarren6 hr
Aug 18, 5:10 PM EDTSevere Thunderstorm WarningPHIHunterdon, Morris, Warren29 min
Aug 18, 5:21 PM EDTSevere Thunderstorm WarningPHIBurlington, Camden39 min
Aug 18, 5:31 PM EDTFlash Flood WarningPHIHunterdon, Warren6 hr
Aug 18, 5:38 PM EDTFlash Flood WarningPHISussex, Warren4 hr
Aug 18, 5:47 PM EDTSevere Thunderstorm WarningPHIMorris, Sussex43 min
Aug 18, 5:47 PM EDTSevere Thunderstorm WarningPHIBurlington, Mercer, Middlesex, Monmouth58 min
Aug 18, 5:51 PM EDTSevere Thunderstorm WarningPHIMorris, Somerset24 min
Aug 18, 5:59 PM EDTSevere Thunderstorm WarningPHIMorris, Sussex18 min
Aug 18, 6:01 PM EDTFlash Flood WarningPHIHunterdon, Morris, Somerset, Sussex, Warren6 hr
Aug 18, 6:24 PM EDTSevere Thunderstorm WarningPHIMiddlesex, Morris, Somerset66 min

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.