Alert archive / New Jersey / Flash Flood Warnings in 2026

Flash Flood Warning 105, NWS Philadelphia/Mount Holly

August 5, 2026Hunterdon County, Morris County, Somerset County, New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 5, 2026, 11:40 PM EDT for Hunterdon County, Morris County, Somerset County, New Jersey. It was in force for 4 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: Aug 5, 2026, 11:40 PM EDT (03:40 UTC)
Expired: Aug 6, 2026, 3:45 AM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

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

The radar

The Philadelphia radar (KDIX), 92 km from the middle of the area, began a volume at 03:41 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

Time	Report	Where	Remark
Aug 6, 12:16 AM EDT	FLASH FLOOD	Dover, NJ	Flooding on US 46 Both Directions East of NJ 15 in Dover. 2 right lanes of 4 lanes closed eastbound; 2 right lanes of 4 lanes closed westbound. Time included in report.
Aug 6, 1:34 AM EDT	FLASH FLOOD	2 Nne Dover, NJ	Flooding on I-80 Westbound At Exit 35 - Mount Hope Av (Rockaway Twp), All 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 00:00Z, 3.7 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: 94 J/kg
Mixed-layer CIN: -35 J/kg
Mixed-layer LCL: 462 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 83 m²/s²
0-3 km storm-relative helicity: 123 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

540 
WGUS51 KPHI 060340
FFWPHI
NJC019-027-035-060745-
/O.NEW.KPHI.FF.W.0105.260806T0340Z-260806T0745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
1140 PM EDT Wed Aug 5 2026

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Morris County in northern New Jersey...
  Northern Somerset County in northern New Jersey...
  Northeastern Hunterdon County in northwestern New Jersey...

* Until 345 AM EDT.

* At 1140 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1 inch of rain 
  has 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.

  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, Bridgewater, Dover, Madison, Florham Park, East 
  Hanover, Chatham, Boonton, Wharton, Rockaway, Morris Plains and 
  Mount Arlington.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 17 and 46.
	Interstate 78 in New Jersey between mile markers 17 and 38.
	Interstate 80 in New Jersey between mile markers 29 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.

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

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 4090 7434 4087 7433 4072 7439 4069 7445
      4067 7446 4046 7485 4068 7493 4074 7494
      4078 7490 4097 7452

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

$$

MPS

4 follow-up statements

949 
WGUS71 KPHI 060444
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1244 AM EDT Thu Aug 6 2026

NJC019-027-035-060745-
/O.CON.KPHI.FF.W.0105.000000T0000Z-260806T0745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Morris NJ-Somerset NJ-
1244 AM EDT Thu Aug 6 2026

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 345 AM EDT EARLY THIS 
MORNING FOR MORRIS, NORTHERN SOMERSET AND NORTHEASTERN HUNTERDON 
COUNTIES...

At 1244 AM EDT, local law enforcement reported thunderstorms 
producing heavy rain in Flooding on Route 46 east of NJ15 in Dover. 
Between 1 and 2 inches of rain have fallen. The expected rainfall 
rate is 0.5 to 1 inch in 1 hour. Additional rainfall amounts of 1 to 
2 inches are possible in the warned area. Flash flooding is already 
occurring.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Law enforcement 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, Bridgewater, Dover, Madison, Florham Park, East 
  Hanover, Chatham, Boonton, Wharton, Rockaway, Morris Plains and 
  Mount Arlington.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 17 and 46.
	Interstate 78 in New Jersey between mile markers 17 and 38.
	Interstate 80 in New Jersey between mile markers 29 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.

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

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 4090 7434 4087 7433 4072 7439 4069 7445
      4067 7446 4046 7485 4068 7493 4074 7494
      4078 7490 4097 7452

FLASH FLOOD...OBSERVED
EXPECTED RAINFALL RATE...0.5-1 INCH IN 1 HOUR

$$

MPS

887 
WGUS71 KPHI 060554
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
154 AM EDT Thu Aug 6 2026

NJC019-027-035-060745-
/O.CON.KPHI.FF.W.0105.000000T0000Z-260806T0745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Morris NJ-Somerset NJ-
154 AM EDT Thu Aug 6 2026

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 345 AM EDT EARLY THIS 
MORNING FOR MORRIS, NORTHERN SOMERSET AND NORTHEASTERN HUNTERDON 
COUNTIES...

At 154 AM EDT, local law enforcement reported flooding on Route 46 
east of NJ15 in Dover and flooding on I-80 Westbound at Exit 35. 
Between 1.5 and 2.5 inches of rain have fallen. Additional rainfall 
amounts up to 0.5 inches are possible in the warned area. Flash 
flooding is already occurring.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Law enforcement 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, Bridgewater, Dover, Madison, Florham Park, East 
  Hanover, Chatham, Boonton, Wharton, Rockaway, Morris Plains and 
  Mount Arlington.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 17 and 46.
	Interstate 78 in New Jersey between mile markers 17 and 38.
	Interstate 80 in New Jersey between mile markers 29 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.

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

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 4090 7434 4087 7433 4072 7439 4069 7445
      4067 7446 4046 7485 4068 7493 4074 7494
      4078 7490 4097 7452

FLASH FLOOD...OBSERVED

$$

MPS

944 
WGUS71 KPHI 060705
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
305 AM EDT Thu Aug 6 2026

NJC019-035-060715-
/O.CAN.KPHI.FF.W.0105.000000T0000Z-260806T0745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Somerset NJ-
305 AM EDT Thu Aug 6 2026

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHERN SOMERSET AND 
NORTHEASTERN HUNTERDON COUNTIES...

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

&&

LAT...LON 4079 7437 4078 7437 4077 7437 4072 7439
      4073 7455 4075 7455 4076 7456 4074 7463
      4075 7472 4084 7478 4097 7452 4090 7434
      4087 7434 4087 7433 4080 7436

$$

NJC027-060745-
/O.CON.KPHI.FF.W.0105.000000T0000Z-260806T0745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris NJ-
305 AM EDT Thu Aug 6 2026

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 345 AM EDT EARLY THIS 
MORNING FOR CENTRAL MORRIS COUNTY...

At 305 AM EDT, local law enforcement reported thunderstorms 
producing heavy rain in Flooding on Route 46 east of NJ15 in Dover. 
Flooding on I-80 Westbound at Exit 35. Between 1.5 and 2.5 inches of 
rain have fallen. Flooding impacts will continue, but no additional 
rainfall is expected. Flash flooding is already occurring.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Law enforcement 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, Madison, Florham Park, East Hanover, Chatham, 
  Boonton, Wharton, Rockaway, Morris Plains, Mount Arlington and 
  Mendham.

This includes the following highways...
	Interstate 287 in New Jersey between mile markers 31 and 46.
	Interstate 80 in New Jersey between mile markers 29 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.

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

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 7437 4078 7437 4077 7437 4072 7439
      4073 7455 4075 7455 4076 7456 4074 7463
      4075 7472 4084 7478 4097 7452 4090 7434
      4087 7434 4087 7433 4080 7436

FLASH FLOOD...OBSERVED

$$

Staarmann

711 
WGUS71 KPHI 060745
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
345 AM EDT Thu Aug 6 2026

NJC027-060755-
/O.EXP.KPHI.FF.W.0105.000000T0000Z-260806T0745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris NJ-
345 AM EDT Thu Aug 6 2026

...FLASH FLOOD WARNING HAS EXPIRED FOR CENTRAL MORRIS COUNTY...

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

&&

LAT...LON 4079 7437 4078 7437 4077 7437 4072 7439
      4073 7455 4075 7455 4076 7456 4074 7463
      4075 7472 4084 7478 4097 7452 4090 7434
      4087 7434 4087 7433 4080 7436

$$

Staarmann

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 6, 12:31 AM EDT	Flash Flood Warning	PHI	Morris	4 hr

Nearby

Flash Flood Warnings in New Jersey, 2026 Every flash flood warning in 2026

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.