Alert archive / New Jersey / Flash Flood Warnings in 2021

Flash Flood Warning 54, NWS Philadelphia/Mount Holly

August 22, 2021Hunterdon County, Warren County, New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 22, 2021, 6:07 AM EDT for Hunterdon County, Warren County, New Jersey. It was in force for 67 min. 3 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 22, 2021, 6:07 AM EDT (10:07 UTC)
Expired: Aug 22, 2021, 7:14 AM EDT
In force: 67 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Hunterdon County, NJ, Warren County, NJ

The radar

The Philadelphia radar (KDIX), 89 km from the middle of the area, began a volume at 10:10 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 22, 7:00 AM EDT	HEAVY RAIN 1.07	3 W Holland Twp, NJ	CO-OP OBSERVER STATION RGLN4 RIEGELSVILLE.
Aug 22, 7:00 AM EDT	HEAVY RAIN 1.7	5 S Frenchtown, NJ	COCORAHS STATION NJ-HN-65 FRENCHTOWN 4.8 S.
Aug 22, 7:00 AM EDT	HEAVY RAIN 2.45	2 Nnw Rosemont, NJ	COCORAHS STATION NJ-HN-52 STOCKTON 3.8 NNW.

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, 10.1 hours before the alert went out and 191 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: 1163 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 543 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 75 m²/s²
0-3 km storm-relative helicity: 85 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 1.7

Open this sounding in Storm Lab

The text

As transmitted.

713 
WGUS51 KPHI 221007
FFWPHI
NJC019-041-221300-
/O.NEW.KPHI.FF.W.0054.210822T1007Z-210822T1300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
607 AM EDT Sun Aug 22 2021

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Central Hunterdon County in northwestern New Jersey...
  Southwestern Warren County in northwestern New Jersey...

* Until 900 AM EDT.

* At 607 AM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have already fallen in parts of the area. Additional rainfall 
  amounts of 1 to 1.5 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 will experience flash flooding include...
  Byram, High Bridge, Clinton, Harmony, New Hope, Alpha, Glen 
  Gardner, Hampton, Frenchtown, Milford, Bloomsbury, and 
  Riegelsville.

This includes the following highways...
	Interstate 78 in New Jersey between mile markers 0 and 17.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4076 7519 4071 7489 4034 7493 4034 7494
      4040 7497 4041 7499 4040 7503 4042 7506
      4046 7507 4049 7506 4054 7507 4057 7512
      4056 7517 4058 7519 4062 7520 4063 7519
      4065 7520 4067 7518 4069 7520 4073 7518

FLASH FLOOD...RADAR INDICATED

$$

Iovino

1 follow-up statement

641 
WGUS71 KPHI 221114
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
714 AM EDT Sun Aug 22 2021

NJC019-041-221124-
/O.CAN.KPHI.FF.W.0054.000000T0000Z-210822T1300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Warren NJ-
714 AM EDT Sun Aug 22 2021

...FLASH FLOOD WARNING IS CANCELLED FOR CENTRAL HUNTERDON AND 
SOUTHWESTERN WARREN COUNTIES...

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

A Flood Watch remains in effect until 800 AM Monday.

LAT...LON 4076 7519 4071 7489 4034 7493 4034 7494
      4040 7497 4041 7499 4040 7503 4042 7506
      4046 7507 4049 7506 4054 7507 4057 7512
      4056 7517 4058 7519 4062 7520 4063 7519
      4065 7520 4067 7518 4069 7520 4073 7518

$$

Iovino

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 21, 9:35 PM EDT	Areal Flood Advisory	PHI	Mercer, Middlesex, Monmouth, Ocean	3 hr
Aug 21, 10:47 PM EDT	Areal Flood Advisory	PHI	Morris	3 hr
Aug 21, 11:38 PM EDT	Areal Flood Advisory	PHI	Atlantic, Burlington, Monmouth, Ocean	3 hr
Aug 22, 12:04 AM EDT	Areal Flood Advisory	PHI	Atlantic, Burlington, Camden, Monmouth, Ocean	3 hr
Aug 22, 12:24 AM EDT	Flash Flood Warning	PHI	Morris	3 hr
Aug 22, 1:30 AM EDT	Areal Flood Advisory	PHI	Middlesex, Monmouth	4 hr
Aug 22, 1:35 AM EDT	Areal Flood Advisory	PHI	Morris, Somerset	3 hr
Aug 22, 2:04 AM EDT	Flash Flood Warning	PHI	Middlesex, Monmouth	9 hr
Aug 22, 2:09 AM EDT	Flash Flood Warning	PHI	Burlington, Ocean	5 hr
Aug 22, 2:40 AM EDT	Flash Flood Warning	PHI	Hunterdon, Morris, Somerset	5 hr
Aug 22, 3:10 AM EDT	Flash Flood Warning	PHI	Burlington, Hunterdon, Mercer, Monmouth, Ocean	8 hr
Aug 22, 4:21 AM EDT	Flash Flood Warning	PHI	Monmouth, Ocean	3 hr
Aug 22, 5:36 AM EDT	Flash Flood Warning Considerable damage threat	PHI	Mercer, Middlesex, Monmouth, Somerset	5 hr
Aug 22, 7:52 AM EDT	Areal Flood Warning	PHI	Hunterdon, Somerset	15 hr
Aug 22, 10:43 AM EDT	Special Marine Warning	PHI		62 min
Aug 22, 10:49 AM EDT	Areal Flood Warning	PHI	Middlesex, Monmouth, Somerset	13 hr
Aug 22, 10:52 AM EDT	Areal Flood Warning	PHI	Hunterdon, Mercer, Monmouth	13 hr
Aug 22, 11:06 AM EDT	Special Marine Warning	PHI		54 min
Aug 22, 1:35 PM EDT	Coastal Flood Advisory	PHI	Cape May	10 hr
Aug 22, 1:53 PM EDT	Areal Flood Advisory	PHI	Morris	6 hr
Aug 22, 3:21 PM EDT	River Flood Warning	PHI	Somerset	54 hr
Aug 22, 5:07 PM EDT	Areal Flood Advisory	PHI	Morris, Sussex, Warren	6 hr
Aug 22, 5:48 PM EDT	Flash Flood Warning	PHI	Morris, Sussex, Warren	6 hr

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.