Alert archive / New Jersey / Flash Flood Warnings in 2021

Flash Flood Warning 78, NWS Philadelphia/Mount Holly

September 1, 2021Morris County, Somerset County, New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 1, 2021, 10:05 PM EDT for Morris County, Somerset County, New Jersey. It was in force for 4 hr. 1 report 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, 10:05 PM EDT (02:05 UTC)
Expired
Sep 2, 2021, 1:52 AM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Morris County, NJ, Somerset County, NJ

The radar

The Philadelphia radar (KDIX), 106 km from the middle of the area, began a volume at 02:09 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
Sep 2, 12:58 AM EDTHEAVY RAIN 5.8Butler, NJ

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, 2.1 hours before the alert went out and 136 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 00:00Z on 2021-09-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 123 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 00:00Z on 2021-09-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 279 square meters per square second.19395878Sfc1 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
123 J/kg
Mixed-layer CIN
-47 J/kg
Mixed-layer LCL
512 m above ground
0-6 km bulk shear
53 kt
0-1 km storm-relative helicity
279 m²/s²
0-3 km storm-relative helicity
456 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.2

Open this sounding in Storm Lab

The text

As transmitted.

108 
WGUS51 KPHI 020205
FFWPHI
NJC027-035-020600-
/O.NEW.KPHI.FF.W.0078.210902T0205Z-210902T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
1005 PM EDT Wed Sep 1 2021

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...

* Until 200 AM EDT.

* At 1005 PM EDT, local law enforcement reported flash flooding 
  across the warned area. Several roads are closed in Morris County. 
  Avoid travel in this area. Between 3.5 and 7 inches of rain have 
  fallen. Flash flooding is already occurring.

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

  SOURCE...Law enforcement reported.

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

* Some locations that may experience flash flooding include...
  Morristown, Dover, Madison, Hopatcong, Florham Park, East Hanover, 
  Lincoln Park, Kinnelon, Chatham, Boonton, Butler, and Wharton.

This includes the following highways...
	Interstate 80 in New Jersey between mile markers 27 and 48.
	Interstate 287 in New Jersey between mile markers 30 and 53.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4074 7477 4077 7485 4091 7470 4092 7465
      4096 7464 4108 7450 4103 7450 4105 7445
      4104 7443 4102 7443 4100 7430 4097 7428
      4090 7429 4091 7433 4087 7434 4086 7432
      4079 7437 4076 7438 4076 7436 4072 7439

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

CMS
1 follow-up statement
297 
WGUS71 KPHI 020552
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
152 AM EDT Thu Sep 2 2021

NJC027-035-020602-
/O.CAN.KPHI.FF.W.0078.000000T0000Z-210902T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Morris NJ-Somerset NJ-
152 AM EDT Thu Sep 2 2021

...FLASH FLOOD WARNING FOR MORRIS AND NORTH CENTRAL SOMERSET 
COUNTIES HAS BEEN REPLACED WITH A FLOOD WARNING...

Please continue to heed road closures.

LAT...LON 4074 7477 4077 7485 4091 7470 4092 7465
      4096 7464 4108 7450 4103 7450 4105 7445
      4104 7443 4102 7443 4100 7430 4097 7428
      4090 7429 4091 7433 4087 7434 4086 7432
      4079 7437 4076 7438 4076 7436 4072 7439

$$

CMS

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 1, 8:02 PM EDTFlash Flood Warning EmergencyCatastrophic damage threatPHIMiddlesex, Morris, Somerset5 hr
Sep 1, 9:01 PM EDTFlash Flood WarningPHIBurlington, Mercer, Middlesex, Monmouth, Ocean5 hr
Sep 1, 9:43 PM EDTRiver Flood WarningPHIMercer33 hr
Sep 1, 10:23 PM EDTCoastal Flood StatementPHIOcean13 hr
Sep 1, 10:24 PM EDTFlash Flood WarningPHIBurlington, Camden, Gloucester4 hr
Sep 1, 10:29 PM EDTRiver Flood WarningPHIHunterdon, Mercer49 hr
Sep 1, 10:32 PM EDTRiver Flood WarningPHIMercer31 hr
Sep 1, 10:35 PM EDTRiver Flood WarningPHIBergen, Morris, Passaic30 hr
Sep 1, 10:37 PM EDTRiver Flood WarningPHIMorris, Passaic41 hr
Sep 1, 10:38 PM EDTRiver Flood WarningPHIMorris, Somerset21 days
Sep 1, 10:47 PM EDTAreal Flood WarningPHIWarren23 hr
Sep 1, 10:52 PM EDTAreal Flood WarningPHIHunterdon, Warren12 hr
Sep 2, 12:01 AM EDTAreal Flood WarningPHIHunterdon, Morris, Sussex, Warren40 hr
Sep 2, 12:28 AM EDTAreal Flood AdvisoryPHIAtlantic, Burlington, Camden, Gloucester3 hr
Sep 2, 12:31 AM EDTAreal Flood AdvisoryPHIMonmouth, Ocean2 hr
Sep 2, 1:38 AM EDTAreal Flood WarningPHIBurlington, Mercer, Middlesex, Monmouth, Ocean4 hr
Sep 2, 1:52 AM EDTAreal Flood WarningPHIMorris, Somerset13 hr
Sep 2, 2:23 AM EDTAreal Flood WarningPHIBurlington, Camden, Gloucester, Salem9 hr
Sep 2, 2:29 AM EDTAreal Flood WarningPHIBurlington, Camden, Gloucester5 hr
Sep 2, 3:52 AM EDTAreal Flood WarningPHIHunterdon, Mercer, Morris, Somerset, Warren8 hr
Sep 2, 3:53 AM EDTAreal Flood WarningPHIHunterdon, Mercer, Middlesex, Morris, Somerset8 hr
Sep 2, 4:00 AM EDTRiver Flood WarningPHIMorris48 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHIHunterdon, Mercer37 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHIHunterdon, Warren37 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHIHunterdon37 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHIHunterdon33 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHIHunterdon, Mercer34 hr
Sep 2, 4:45 AM EDTRiver Flood WarningPHISussex, Warren5 hr
Sep 2, 6:05 AM EDTCoastal Flood WarningPHIBurlington, Camden, Gloucester, Mercer6 hr
Sep 2, 1:20 PM EDTAreal Flood WarningPHIMiddlesex21 hr
Sep 2, 6:44 PM EDTCoastal Flood AdvisoryPHIBurlington, Camden, Gloucester7 hr

Nearby

Flash Flood Warnings in New Jersey, 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.