Alert archive / New Jersey / Flash Flood Warnings in 2021

Flash Flood Warning 35, NWS Philadelphia/Mount Holly

August 11, 2021Morris County, Warren County, New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 11, 2021, 7:28 PM EDT for Morris County, Warren County, New Jersey. It was in force for 3 hr. 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 11, 2021, 7:28 PM EDT (23:28 UTC)
Expired: Aug 11, 2021, 10:54 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Morris County, NJ, Warren County, NJ

The radar

The Philadelphia radar (KDIX), 102 km from the middle of the area, began a volume at 23:28 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, 11.5 hours before the alert went out and 145 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 977 J/kg
Mixed-layer CIN: -44 J/kg
Mixed-layer LCL: 711 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 29 m²/s²
0-3 km storm-relative helicity: 18 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

672 
WGUS51 KPHI 112328
FFWPHI
NJC027-041-120330-
/O.NEW.KPHI.FF.W.0035.210811T2328Z-210812T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
728 PM EDT Wed Aug 11 2021

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Morris County in northern New Jersey...
  East Central Warren County in northwestern New Jersey...

* Until 1130 PM EDT.

* At 728 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to 2 inches of rain have 
  fallen. 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.

  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 will experience flash flooding include...
  Morristown, Dover, Madison, Hopatcong, Florham Park, East Hanover, 
  Lincoln Park, Hackettstown, Boonton, Wharton, Rockaway, and Morris 
  Plains.

This includes the following highways...
	Interstate 80 in New Jersey between mile markers 25 and 48.
	Interstate 287 in New Jersey between mile markers 34 and 48.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Motorists should not attempt to drive around barricades or drive 
cars through flooded areas.

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 4078 7495 4085 7500 4090 7498 4091 7472
      4090 7471 4092 7467 4094 7452 4093 7429
      4091 7427 4090 7428 4091 7433 4087 7434
      4086 7432 4082 7433 4080 7436 4078 7437
      4075 7463 4077 7486 4079 7489

FLASH FLOOD...RADAR INDICATED

$$

Robertson

2 follow-up statements

575 
WGUS71 KPHI 120141
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
941 PM EDT Wed Aug 11 2021

NJC027-041-120330-
/O.CON.KPHI.FF.W.0035.000000T0000Z-210812T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris NJ-Warren NJ-
941 PM EDT Wed Aug 11 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1130 PM EDT THIS 
EVENING FOR MORRIS AND EAST CENTRAL WARREN COUNTIES...

At 941 PM EDT, Doppler radar indicated the heaviest rain has left 
the warned area. Between 2 and 3.5 inches of rain have fallen. 
However, additional light rain is possible and could exacerbate 
flooding that is already occuring. Additional rainfall amounts up to 
0.5 inches are possible in the warned area. 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 will experience flash flooding include...
  Morristown, Dover, Madison, Hopatcong, Florham Park, East Hanover, 
  Lincoln Park, Hackettstown, Boonton, Wharton, Rockaway, and Morris 
  Plains.

This includes the following highways...
	Interstate 80 in New Jersey between mile markers 25 and 48.
	Interstate 287 in New Jersey between mile markers 34 and 48.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4078 7495 4085 7500 4090 7498 4091 7472
      4090 7471 4092 7467 4094 7452 4093 7429
      4091 7427 4090 7428 4091 7433 4087 7434
      4086 7432 4082 7433 4080 7436 4078 7437
      4075 7463 4077 7486 4079 7489

FLASH FLOOD...RADAR INDICATED

$$

SFJ

429 
WGUS71 KPHI 120254
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1054 PM EDT Wed Aug 11 2021

NJC027-041-120304-
/O.CAN.KPHI.FF.W.0035.000000T0000Z-210812T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris NJ-Warren NJ-
1054 PM EDT Wed Aug 11 2021

...FLASH FLOOD WARNING FOR MORRIS AND EAST CENTRAL WARREN COUNTIES 
HAS BEEN REPLACED WITH A FLOOD WARNING...

LAT...LON 4078 7495 4085 7500 4090 7498 4091 7472
      4090 7471 4092 7467 4094 7452 4093 7429
      4091 7427 4090 7428 4091 7433 4087 7434
      4086 7432 4082 7433 4080 7436 4078 7437
      4075 7463 4077 7486 4079 7489

$$

Fitzsimmons

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 10, 8:02 PM EDT	Severe Thunderstorm Warning	PHI	Camden, Gloucester	43 min
Aug 10, 8:18 PM EDT	Severe Thunderstorm Warning	PHI	Gloucester, Salem	42 min
Aug 10, 8:23 PM EDT	Special Marine Warning	PHI		79 min
Aug 10, 8:36 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Burlington, Camden, Cumberland, Gloucester, Salem	39 min
Aug 10, 8:43 PM EDT	Areal Flood Advisory	PHI	Burlington, Camden, Gloucester	2 hr
Aug 10, 9:07 PM EDT	Special Weather Statement	PHI	Burlington, Camden, Cumberland	23 min
Aug 11, 2:56 PM EDT	Excessive Heat Watch	PHI	Hunterdon, Morris, Warren	12 hr
Aug 11, 5:57 PM EDT	Special Weather Statement	PHI	Sussex	48 min
Aug 11, 6:32 PM EDT	Special Weather Statement	PHI	Morris, Sussex, Warren	28 min
Aug 11, 6:50 PM EDT	Areal Flood Advisory	PHI	Hunterdon, Morris, Somerset, Sussex, Warren	3 hr
Aug 11, 7:04 PM EDT	Areal Flood Advisory	PHI	Gloucester, Hunterdon, Salem	2 hr
Aug 11, 7:04 PM EDT	Severe Thunderstorm Warning	PHI	Morris, Sussex, Warren	41 min
Aug 11, 7:11 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Camden, Gloucester	49 min
Aug 11, 7:45 PM EDT	Special Weather Statement	PHI	Morris	45 min
Aug 11, 7:52 PM EDT	Special Weather Statement	PHI	Atlantic, Burlington, Camden, Gloucester, Mercer	53 min
Aug 11, 7:57 PM EDT	Special Weather Statement	PHI	Hunterdon, Middlesex, Somerset	48 min

Nearby

Flash Flood Warnings in New Jersey, 2021 Every flash flood warning in 2021

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.