Alert archive / New Jersey / Flash Flood Warnings in 2021
Flash Flood Warning 75, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 1, 2021, 7:31 PM EDT for Hunterdon County, Mercer County, Somerset County, New Jersey; Bucks County, Pennsylvania. It was in force for 4 hr. 16 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
- Sep 1, 2021, 7:31 PM EDT (23:31 UTC)
- Expired
- Sep 2, 2021, 12:00 AM EDT
- In force
- 4 hr
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Emergency
- Flash flood emergency
- Damage threat
- Catastrophic
- Flood severity
- None
Counties Hunterdon County, NJ, Mercer County, NJ, Somerset County, NJ, Bucks County, PA
The radar
The Philadelphia radar (KDIX), 79 km from the middle of the area, began a volume at 23:29 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 |
|---|---|---|---|
| Sep 1, 7:56 PM EDT | FLASH FLOOD | 2 Nne Ewing, NJ | INTERSTATE 295 CLOSED FROM FLOODING BETWEEN EXITS 72 AND 73. TIME BASED ON DISPATCH REPORT. |
| Sep 1, 8:00 PM EDT | FLASH FLOOD | 2 W Stanton, NJ | THE GAUGE ON THE SOUTH BRANCH RARITAN RIVER AT STANTON (STTN4) REACHED FLOOD STAGE AT 800 PM 9/1, CRESTING AT 15.16 FEET (MAJOR FLOODING) AT 1130 PM 9/1. |
| Sep 1, 8:23 PM EDT | HEAVY RAIN 6.78 | Readington Twp, NJ | |
| Sep 1, 8:37 PM EDT | FLASH FLOOD | 1 Nw Trenton, NJ | FLOODING ON STATE ROUTE 29 NEAR CALHOUN STREET. ALL LANES CLOSED. TIME BASED ON DISPATCH REPORT. |
| Sep 1, 8:40 PM EDT | HEAVY RAIN 7.05 | Ringoes, NJ | |
| Sep 1, 9:00 PM EDT | FLASH FLOOD | 2 Sw Princeton, NJ | THE GAUGE ON STONY BROOK AT PRINCETON (PCTN4) REACHED FLOOD STAGE AT 900 PM 9/1, CRESTING AT 17.65 FEET (RECORD FLOODING) AT 345 AM 9/2. |
| Sep 1, 9:00 PM EDT | FLASH FLOOD | Flemington, NJ | PICTURE OF MULTIPLE VEHICLES SUBMERGED IN OVER A FOOT OF WATER. |
| Sep 1, 9:45 PM EDT | FLASH FLOOD | 1 Ne Trenton, NJ | THE GAUGE ON ASSUNPINK CREEK AT TRENTON (TACN4) REACHED FLOOD STAGE AT 945 PM 9/1, CRESTING AT 12.59 FEET (MAJOR FLOODING) AT 300 AM 9/2. |
| Sep 1, 9:45 PM EDT | FLASH FLOOD | 1 Nnw Hamilton Twp, NJ | THE GAUGE ON ASSUNPINK CREEK NEAR MERCERVILLE (MERN4) REACHED FLOOD STAGE AT 945 PM 9/1, CRESTING AT 15.82 FEET (MAJOR FLOODING) AT 245 PM 9/2. |
| Sep 1, 10:00 PM EDT | FLASH FLOOD | Washington Crossing, PA | THE GAUGE ON THE DELAWARE RIVER AT WASHINGTON CROSSING (WASN4) REACHED FLOOD STAGE AT 1000 PM 9/1, CRESTING AT 16.91 FEET (MINOR FLOODING) AT 1115 PM 9/1. |
| Sep 1, 10:26 PM EDT | HEAVY RAIN 6.42 | Whitehouse Station, NJ | |
| Sep 1, 10:30 PM EDT | FLASH FLOOD | 1 Nw Trenton, NJ | THE GAUGE ON THE DELAWARE RIVER AT TRENTON (TREN4) REACHED FLOOD STAGE AT 1030 PM 9/1, CRESTING AT 20.7 FEET (MINOR FLOODING) AT 1115 PM 9/1. |
| Sep 1, 11:00 PM EDT | FLASH FLOOD | 2 Sw Pennington, NJ | *** 2 FATAL *** DOZENS OF WATER RESCUES IN MERCER COUNTY DURING THE FLASH FLOODING SEPTEMBER 1-2, WITH TWO FATALITIES IN HOPEWELL TOWNSHIP. THREE POLICE OFFICERS WERE RESCUED AFTER BEING SWEPT AWAY BY FLOOD WATERS NEAR THE INTERSECTION OF ROUTES 518 AND 31. |
| Sep 1, 11:06 PM EDT | FLASH FLOOD | 1 Sse Raritan Twp, NJ | FLASH FLOODING OF THE NESHANIC RIVER FORCED THE CLOSURE OF U.S. HIGHWAY 202. TIME BASED ON DISPATCH REPORT. |
| Sep 1, 11:24 PM EDT | FLASH FLOOD | 1 Ene Prospect Park, NJ | U.S. HIGHWAY 206 SOUTH OF PRINCETON PIKE CLOSED FROM FLOODING. TIME BASED ON DISPATCH REPORT. |
| Sep 2, 12:00 AM EDT | FLASH FLOOD | Flemington, NJ | *** 6 FATAL *** OVER 300 WATER RESCUES WERE CONDUCTED IN HUNTERDON COUNTY DURING THE FLASH FLOODING SEPTEMBER 1-2 WITH SIX CONFIRMED FATALITIES AS OF SEPTEMBER 4. |
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, 11.5 hours before the alert went out and 184 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.
- Mixed-layer CAPE
- 51 J/kg
- Mixed-layer CIN
- -80 J/kg
- Mixed-layer LCL
- 1274 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 31 m²/s²
- 0-3 km storm-relative helicity
- 201 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
As transmitted.
947
WGUS51 KPHI 012331
FFWPHI
NJC019-021-035-PAC017-020400-
/O.NEW.KPHI.FF.W.0075.210901T2331Z-210902T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
731 PM EDT Wed Sep 1 2021
...FLASH FLOOD EMERGENCY FOR PORTIONS OF SOUTHEAST HUNTERDON COUNTY
AND MUCH OF MERCER COUNTY INCLUDING TRENTON...
The National Weather Service in Mount Holly has issued a
* Flash Flood Warning for...
Mercer County in central New Jersey...
Southwestern Somerset County in northern New Jersey...
Hunterdon County in northwestern New Jersey...
Northeastern Bucks County in southeastern Pennsylvania...
* Until midnight EDT.
* At 731 PM EDT, local law enforcement reported flash flooding
across the warned area. Between 3 and 7 inches of rain have
fallen. Flash flooding is already occurring.
This is a FLASH FLOOD EMERGENCY for portions of southeast
Hunterdon County and much of Mercer County including Trenton. This
is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!
HAZARD...Life threatening flash flooding caused by heavy rain.
SOURCE...Law enforcement reported.
IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK
HIGHER GROUND NOW! Life threatening flash flooding of
low water crossings, small creeks and streams, urban
areas, highways, streets, and underpasses.
* Some locations that may experience flash flooding include...
Trenton, Ewing, Princeton, Byram, Flemington, Clinton, Pennington,
New Hope, Yardley, Hopewell, Ferndale, and Frenchtown.
This includes the following highways...
Interstate 78 in New Jersey near mile marker 16.
Interstate 295 in New Jersey between mile markers 62 and 76.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now! This is an extremely dangerous and
life-threatening situation. Do not attempt to travel unless you are
fleeing an area subject to flooding or under an evacuation order.
Turn around...don't drown when encountering flooded roads. Most
flood deaths occur in vehicles.
&&
LAT...LON 4058 7523 4059 7519 4059 7518 4060 7518
4060 7517 4064 7510 4062 7474 4057 7472
4033 7463 4019 7471 4024 7485 4041 7505
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC
$$
CMS1 follow-up statement
994
WGUS71 KPHI 020016
FFSPHI
Flash Flood Statement
National Weather Service Mount Holly NJ
816 PM EDT Wed Sep 1 2021
NJC019-021-035-PAC017-020400-
/O.CON.KPHI.FF.W.0075.000000T0000Z-210902T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Mercer NJ-Somerset NJ-Bucks PA-
816 PM EDT Wed Sep 1 2021
...FLASH FLOOD EMERGENCY FOR PORTIONS OF SOUTHEAST HUNTERDON COUNTY
AND MUCH OF MERCER COUNTY INCLUDING TRENTON...
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL MIDNIGHT EDT TONIGHT
FOR MERCER, SOUTHWESTERN SOMERSET, HUNTERDON, AND NORTHEASTERN BUCKS
COUNTIES...
At 816 PM EDT, local law enforcement reported flash flooding across
the warned area. Numerous water rescues are ongoing. Interstate 295
is closed in Hopewell Township from flooding. Between 3.5 and 8
inches of rain have fallen. Flash flooding is already occurring.
This is a FLASH FLOOD EMERGENCY for portions of southeast Hunterdon
County and much of Mercer County including Trenton. This is a
PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!
HAZARD...Life threatening flash flooding caused by heavy rain.
SOURCE...Law enforcement reported.
IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER
GROUND NOW! Life threatening flash flooding of low water
crossings, small creeks and streams, urban areas,
highways, streets, and underpasses.
Some locations that may experience flash flooding include...
Trenton, Ewing, Princeton, Byram, Flemington, Clinton, Pennington,
New Hope, Yardley, Hopewell, Ferndale, and Frenchtown.
This includes the following highways...
Interstate 295 in New Jersey between mile markers 61 and 76.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now! This is an extremely dangerous and
life-threatening situation. Do not attempt to travel unless you are
fleeing an area subject to flooding or under an evacuation order.
Turn around...don't drown when encountering flooded roads. Most
flood deaths occur in vehicles.
&&
LAT...LON 4058 7523 4059 7519 4059 7518 4060 7518
4060 7517 4064 7510 4062 7474 4057 7472
4033 7463 4019 7471 4024 7485 4041 7505
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC
$$
CMSThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 1, 3:23 AM EDT | Gale Warning | PHI | 32 hr | |
| Sep 1, 3:23 AM EDT | Small Craft Advisory | PHI | 41 hr | |
| Sep 1, 4:34 AM EDT | Rip Current Statement | PHI | Atlantic, Cape May, Monmouth, Ocean | 39 hr |
| Sep 1, 7:58 AM EDT | Severe Thunderstorm Warning | PHI | Burlington, Ocean | 47 min |
| Sep 1, 8:39 AM EDT | Severe Thunderstorm Warning | PHI | Monmouth, Ocean | 39 min |
| Sep 1, 9:11 AM EDT | Special Marine Warning | PHI | 64 min | |
| Sep 1, 11:24 AM EDT | Areal Flood Advisory | PHI | Sussex, Warren | 3 hr |
| Sep 1, 4:04 PM EDT | Areal Flood Warning | PHI | Warren | 24 hr |
| Sep 1, 4:12 PM EDT | Flash Flood Warning | PHI | Hunterdon, Warren | 7 hr |
| Sep 1, 4:27 PM EDT | River Flood Warning | PHI | Morris, Somerset | 6 days |
| Sep 1, 4:27 PM EDT | River Flood Warning | PHI | Essex, Morris, Passaic | 8 days |
| Sep 1, 4:27 PM EDT | River Flood Warning | PHI | Essex, Morris, Passaic | 6 days |
| Sep 1, 4:27 PM EDT | River Flood Warning | PHI | Essex, Passaic | 21 days |
| Sep 1, 4:33 PM EDT | River Flood Warning | PHI | Morris, Passaic | 46 hr |
| Sep 1, 4:40 PM EDT | River Flood Warning | PHI | Hunterdon, Somerset | 36 hr |
| Sep 1, 4:40 PM EDT | River Flood Warning | PHI | Somerset | 22 hr |
| Sep 1, 4:40 PM EDT | River Flood Warning | PHI | Middlesex, Somerset | 42 hr |
| Sep 1, 4:40 PM EDT | River Flood Warning | PHI | Middlesex, Somerset | 48 hr |
| Sep 1, 4:41 PM EDT | River Flood Warning | PHI | Somerset | 61 hr |
| Sep 1, 5:13 PM EDT | Severe Thunderstorm Warning | PHI | Hunterdon, Mercer | 47 min |
| Sep 1, 5:26 PM EDT | Flash Flood Warning | PHI | Burlington, Camden, Gloucester, Salem | 9 hr |
| Sep 1, 5:33 PM EDT | Special Marine Warning | PHI | 27 min | |
| Sep 1, 5:34 PM EDT | Tornado Warning | PHI | Mercer | 26 min |
| Sep 1, 5:35 PM EDT | Tornado Warning | PHI | Cumberland, Salem | 25 min |
| Sep 1, 5:42 PM EDT | Flash Flood Warning | PHI | Hunterdon, Mercer, Morris, Somerset, Warren | 10 hr |
| Sep 1, 5:57 PM EDT | Tornado Warning | PHI | Gloucester, Salem | 33 min |
| Sep 1, 5:57 PM EDT | Tornado Warning | PHI | Hunterdon, Mercer, Somerset | 33 min |
| Sep 1, 6:05 PM EDT | Flash Flood Warning | PHI | Hunterdon, Mercer, Middlesex, Morris, Somerset | 10 hr |
| Sep 1, 6:08 PM EDT | Flash Flood Warning | PHI | Hunterdon, Morris, Somerset, Sussex, Warren | 6 hr |
| Sep 1, 6:14 PM EDT | Special Marine Warning | PHI | 61 min | |
| Sep 1, 6:20 PM EDT | Tornado Warning | PHI | Hunterdon, Mercer, Somerset | 40 min |
| Sep 1, 6:22 PM EDT | Tornado Warning | PHI | Burlington, Camden, Gloucester | 23 min |
| Sep 1, 6:42 PM EDT | Tornado Warning | PHI | Burlington, Camden | 33 min |
| Sep 1, 6:59 PM EDT | Severe Thunderstorm Warning | PHI | Hunterdon, Mercer, Middlesex, Monmouth, Morris, Somerset | 61 min |
| Sep 1, 7:04 PM EDT | Tornado Warning | PHI | Burlington, Mercer | 26 min |
| Sep 1, 7:22 PM EDT | Tornado Warning | PHI | Hunterdon, Mercer | 11 min |
| Sep 1, 7:28 PM EDT | Tornado Warning | PHI | Mercer, Middlesex, Morris, Somerset | 47 min |
| Sep 1, 7:44 PM EDT | Special Marine Warning | PHI | 61 min | |
| Sep 1, 6:19 AM EDT | Areal Flood Advisory | PHI | Chester, Delaware | 116 min |
| Sep 1, 6:49 AM EDT | Flash Flood Warning | PHI | Chester, Delaware, Philadelphia | 86 min |
| Sep 1, 12:07 PM EDT | Flash Flood Warning | PHI | Carbon, Monroe | 4 hr |
| Sep 1, 1:29 PM EDT | Flash Flood Warning | PHI | Berks, Lehigh | 6 hr |
| Sep 1, 2:53 PM EDT | Flash Flood Warning | PHI | Berks, Chester, Delaware, Montgomery | 9 hr |
| Sep 1, 3:55 PM EDT | River Flood Warning | PHI | Montgomery | 36 hr |
| Sep 1, 3:55 PM EDT | River Flood Warning | PHI | Chester, Montgomery, Philadelphia | 43 hr |
| Sep 1, 3:55 PM EDT | River Flood Warning | PHI | Montgomery, Philadelphia | 41 hr |
| Sep 1, 3:55 PM EDT | River Flood Warning | PHI | Philadelphia | 39 hr |
| Sep 1, 3:55 PM EDT | River Flood Warning | PHI | Berks | 24 hr |
| Sep 1, 4:02 PM EDT | River Flood Warning | PHI | Monroe | 24 hr |
| Sep 1, 4:10 PM EDT | River Flood Warning | PHI | Monroe | 19 hr |
| Sep 1, 4:12 PM EDT | River Flood Warning | PHI | Lehigh, Northampton | 25 hr |
| Sep 1, 4:12 PM EDT | River Flood Warning | PHI | Lehigh, Northampton | 24 hr |
| Sep 1, 4:12 PM EDT | River Flood Warning | PHI | Carbon | 15 hr |
| Sep 1, 4:13 PM EDT | Tornado Warning | PHI | Chester | 32 min |
| Sep 1, 4:20 PM EDT | River Flood Warning | PHI | Montgomery | 22 hr |
| Sep 1, 4:21 PM EDT | River Flood Warning | PHI | Bucks | 29 hr |
| Sep 1, 4:42 PM EDT | Flash Flood Warning | PHI | Chester, Delaware, Montgomery | 6 hr |
| Sep 1, 5:07 PM EDT | River Flood Warning | PHI | Chester | 17 hr |
| Sep 1, 5:15 PM EDT | Tornado Warning | PHI | Delaware, Montgomery, Philadelphia | 30 min |
| Sep 1, 6:38 PM EDT | River Flood Warning | PHI | Chester, Delaware | 26 hr |
| Sep 1, 7:05 PM EDT | Flash Flood Warning | PHI | Bucks | 8 hr |
| Sep 1, 7:23 PM EDT | Areal Flood Warning | PHI | Berks, Lehigh | 14 hr |
| Sep 1, 7:53 PM EDT | River Flood Warning | PHI | Delaware | 13 hr |
Nearby
Flash Flood Warnings in New Jersey, 2021Flash Flood Warnings in Pennsylvania, 2021Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.