Alert archive / New Jersey / Flash Flood Warnings in 2024

Flash Flood Warning 63, NWS Philadelphia/Mount Holly

August 18, 20245 counties in New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 18, 2024, 6:01 PM EDT for 5 counties in New Jersey. It was in force for 6 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, 6:01 PM EDT (22:01 UTC)
Expired
Aug 18, 2024, 11:52 PM EDT
In force
6 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Hunterdon County, NJ, Morris County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ

The radar

The Philadelphia radar (KDIX), 107 km from the middle of the area, began a volume at 22:01 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, 6:30 PM EDTFLASH FLOODDenville Twp, NJFlooding on US 46. All lanes closed. Time estimated from radar.
Aug 18, 7:00 PM EDTFLASH FLOOD1 N Randolph, NJAll lanes closed on NJ 10 due to flooding.
Aug 18, 7:00 PM EDTFLASH FLOOD1 Sse Butler, NJNJ 23 Southbound, sough of CR 511/Boonton Ave flooded. 2 of 3 lanes closed.

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, 10.0 hours before the alert went out and 144 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.

856 
WGUS51 KPHI 182201
FFWPHI
NJC019-027-035-037-041-190200-
/O.NEW.KPHI.FF.W.0063.240818T2201Z-240819T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Morris County in northern New Jersey...
  North Central Somerset County in northern New Jersey...
  Northeastern Hunterdon County in northwestern New Jersey...
  Southeastern Sussex County in northwestern New Jersey...
  East Central Warren County in northwestern New Jersey...

* Until 1000 PM EDT.

* At 601 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 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, Dover, Hopatcong, Lincoln Park, Kinnelon, 
  Hackettstown, Boonton, Butler, Wharton, Washington, Rockaway and 
  Morris Plains.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 40 and 52.
	Interstate 78 in New Jersey between mile markers 16 and 17.
	Interstate 80 in New Jersey between mile markers 12 and 47.

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 4079 7505 4094 7497 4094 7481 4099 7466
      4110 7450 4103 7450 4105 7445 4102 7443
      4101 7434 4096 7428 4093 7429 4091 7427
      4090 7428 4091 7433 4087 7433 4082 7448
      4072 7466 4062 7494 4073 7496

FLASH FLOOD...RADAR INDICATED

$$

Hoeflich
3 follow-up statements
548 
WGUS71 KPHI 182305
FFSPHI

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

NJC019-027-035-037-041-190200-
/O.CON.KPHI.FF.W.0063.000000T0000Z-240819T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Morris NJ-Somerset NJ-Sussex NJ-Warren NJ-
705 PM EDT Sun Aug 18 2024

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 10 PM EDT THIS 
EVENING FOR MORRIS, NORTH CENTRAL SOMERSET, NORTHEASTERN HUNTERDON, 
SOUTHEASTERN SUSSEX AND EAST CENTRAL WARREN COUNTIES...

At 705 PM EDT, emergency management reported thunderstorms producing 
heavy rain with Route 46 in Denville Township closed due to high 
water, with multiple water rescues reported in portions of Morris 
County. Between 2 and 3 inches of rain have fallen. Additional 
rainfall amounts of 0.5 to 1 inch 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...
  Morristown, Dover, Hopatcong, Lincoln Park, Kinnelon, 
  Hackettstown, Boonton, Butler, Wharton, Washington, Rockaway and 
  Morris Plains.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 40 and 52.
	Interstate 78 in New Jersey between mile markers 15 and 17.
	Interstate 80 in New Jersey between mile markers 12 and 47.

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 4079 7505 4094 7497 4094 7481 4099 7466
      4110 7450 4103 7450 4105 7445 4102 7443
      4101 7434 4096 7428 4093 7429 4091 7427
      4090 7428 4091 7433 4087 7433 4082 7448
      4072 7466 4062 7494 4073 7496

FLASH FLOOD...OBSERVED

$$

Hoeflich
883 
WGUS51 KPHI 190155
FFWPHI
NJC019-027-035-037-041-190400-
/O.EXT.KPHI.FF.W.0063.000000T0000Z-240819T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Mount Holly has extended the

* Flash Flood Warning for...
  Morris County in northern New Jersey...
  North Central Somerset County in northern New Jersey...
  Northeastern Hunterdon County in northwestern New Jersey...
  Southeastern Sussex County in northwestern New Jersey...
  East Central Warren County in northwestern New Jersey...

* Until midnight EDT tonight.

* At 955 PM EDT, emergency management reported thunderstorms 
  producing heavy rain with flooding/high water reported around 
  Morris County, most notably within the Boonton area, with more 
  rain moving into the warned area. Between 2 and 4 inches of rain 
  have fallen. Additional rainfall amounts of 0.5 to 1 inch 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...
  Morristown, Dover, Hopatcong, Lincoln Park, Kinnelon, 
  Hackettstown, Boonton, Butler, Wharton, Washington, Rockaway and 
  Morris Plains.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 40 and 52.
	Interstate 78 in New Jersey between mile markers 15 and 17.
	Interstate 80 in New Jersey between mile markers 12 and 47.

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 4079 7505 4094 7497 4094 7481 4099 7466
      4110 7450 4103 7450 4105 7445 4102 7443
      4101 7434 4096 7428 4093 7429 4091 7427
      4090 7428 4091 7433 4087 7433 4082 7448
      4072 7466 4062 7494 4073 7496

FLASH FLOOD...OBSERVED

$$

Hoeflich
631 
WGUS71 KPHI 190352
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1152 PM EDT Sun Aug 18 2024

NJC019-027-035-037-041-190402-
/O.CAN.KPHI.FF.W.0063.000000T0000Z-240819T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Morris NJ-Somerset NJ-Sussex NJ-Warren NJ-
1152 PM EDT Sun Aug 18 2024

...FLASH FLOOD WARNING FOR MORRIS, NORTH CENTRAL SOMERSET, 
NORTHEASTERN HUNTERDON, SOUTHEASTERN SUSSEX AND EAST CENTRAL WARREN 
COUNTIES HAS BEEN REPLACED WITH A FLOOD WARNING...

&&

LAT...LON 4079 7505 4094 7497 4094 7481 4099 7466
      4110 7450 4103 7450 4105 7445 4102 7443
      4101 7434 4096 7428 4093 7429 4091 7427
      4090 7428 4091 7433 4087 7433 4082 7448
      4072 7466 4062 7494 4073 7496

$$

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, 6:24 PM EDTSevere Thunderstorm WarningPHIMiddlesex, Morris, Somerset66 min
Aug 18, 6:36 PM EDTFlash Flood WarningPHIMorris, Somerset5 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.