Alert archive / New Jersey / Flash Flood Warnings in 2026

Flash Flood Warning 100, NWS Philadelphia/Mount Holly

August 5, 2026Hunterdon County, Mercer County, New Jersey; Bucks County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 5, 2026, 2:50 PM EDT for Hunterdon County, Mercer County, New Jersey; Bucks County, Pennsylvania. 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, 2:50 PM EDT (18:50 UTC)
Expired
Aug 5, 2026, 6:22 PM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Hunterdon County, NJ, Mercer County, NJ, Bucks County, PA

The radar

The Philadelphia radar (KDIX), 65 km from the middle of the area, began a volume at 18:50 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 5, 3:00 PM EDTFLASH FLOOD3 Nw Washington Crossin, NJFlooding on River Road.
Aug 5, 3:15 PM EDTFLASH FLOOD2 Nnw Wrightstown Twp, PAPine Lane is flooded and impassable.

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, 6.8 hours before the alert went out and 186 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 2026-08-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2026-08-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -20 square meters per square second.1939Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1372 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
-20 m²/s²
0-3 km storm-relative helicity
-42 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

248 
WGUS51 KPHI 051850
FFWPHI
NJC019-021-PAC017-052300-
/O.NEW.KPHI.FF.W.0100.260805T1850Z-260805T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Northwestern Mercer County in central New Jersey...
  Southeastern Hunterdon County in northwestern New Jersey...
  Central Bucks County in southeastern Pennsylvania...

* Until 700 PM EDT.

* At 250 PM EDT, Doppler radar indicated heavy rainfall producing 
  heavy rain across the warned area. Between 0.5 and 1 inch of rain 
  has fallen. The expected rainfall rate is 0.5 to 1 inch in 30 
  minutes. Additional rainfall amounts up to 2 inches are possible 
  in the warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Life threatening flash flooding caused by heavy
           rainfall.

  SOURCE...Radar.

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

* Some locations that may experience flash flooding include...
  Trenton, Ewing, Doylestown, Byram, Bedminster, Flemington, 
  Chalfont, Tinicum, Pennington, New Hope, Yardley and Newtown.

This includes Interstate 295 in New Jersey between mile markers 65 
and 76.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Move to higher ground now. Act quickly to protect your life.

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

&&

LAT...LON 4041 7474 4039 7473 4038 7472 4025 7465
      4020 7485 4026 7521 4026 7522 4027 7523
      4027 7524 4028 7525 4028 7526 4036 7527
      4047 7516 4052 7480 4045 7476 4044 7476
      4042 7475

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL RATE...0.5-1 INCH IN 30 MINUTES

$$

Fitzsimmons
2 follow-up statements
438 
WGUS71 KPHI 052109
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
509 PM EDT Wed Aug 5 2026

NJC019-021-PAC017-052300-
/O.CON.KPHI.FF.W.0100.000000T0000Z-260805T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Mercer NJ-Bucks PA-
509 PM EDT Wed Aug 5 2026

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 7 PM EDT THIS EVENING 
FOR NORTHWESTERN MERCER, SOUTHEASTERN HUNTERDON AND CENTRAL BUCKS 
COUNTIES...

At 509 PM EDT, Doppler radar and automated rain gauges indicate 1 to 
2 inches of rainfall have fallen across the warned area from heavy 
showers and embedded thunderstorms. Additional rainfall amounts up 
to 1 inch are possible in the warned area. Flash flooding has 
already been occuring.

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...
  Trenton, Ewing, Doylestown, Byram, Bedminster, Flemington, 
  Chalfont, Tinicum, Pennington, New Hope, Yardley and Newtown.

This includes Interstate 295 in New Jersey between mile markers 65 
and 76.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Move to higher ground now. Act quickly to protect your life.

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

&&

LAT...LON 4041 7474 4039 7473 4038 7472 4025 7465
      4020 7485 4026 7521 4026 7522 4027 7523
      4027 7524 4028 7525 4028 7526 4036 7527
      4047 7516 4052 7480 4045 7476 4044 7476
      4042 7475

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

Fitzsimmons
551 
WGUS71 KPHI 052222
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
622 PM EDT Wed Aug 5 2026

NJC019-021-PAC017-052232-
/O.CAN.KPHI.FF.W.0100.000000T0000Z-260805T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Mercer NJ-Bucks PA-
622 PM EDT Wed Aug 5 2026

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN MERCER, 
SOUTHEASTERN HUNTERDON AND CENTRAL BUCKS COUNTIES...

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

&&

LAT...LON 4041 7474 4039 7473 4038 7472 4025 7465
      4020 7485 4026 7521 4026 7522 4027 7523
      4027 7524 4028 7525 4028 7526 4036 7527
      4047 7516 4052 7480 4045 7476 4044 7476
      4042 7475

$$

Fitzsimmons

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 5, 12:58 PM EDTFlash Flood WarningPHIBurlington, Camden, Gloucester6 hr
Aug 5, 1:13 PM EDTFlash Flood WarningPHIGloucester5 hr
Aug 5, 1:23 PM EDTFlash Flood WarningPHIBurlington, Mercer4 hr
Aug 5, 1:50 PM EDTHeat AdvisoryPHIBurlington, Camden, Gloucester, Hunterdon, Mercer, Middlesex and 6 more3 days
Aug 5, 3:33 PM EDTFlash Flood WarningPHIHunterdon, Warren86 min
Aug 5, 5:29 PM EDTFlash Flood WarningPHIMiddlesex3 hr
Aug 5, 2:17 PM EDTFlash Flood WarningPHIBucks, Montgomery4 hr

Nearby

Flash Flood Warnings in New Jersey, 2026Flash Flood Warnings in Pennsylvania, 2026Every 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.