Alert archive / New Jersey / Areal Flood Warnings in 2021

Areal Flood Warning 19, NWS Philadelphia/Mount Holly

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

NWS Philadelphia/Mount Holly issued this areal flood warning at Aug 22, 2021, 7:52 AM EDT for Hunterdon County, Somerset County, New Jersey. It was in force for 15 hr. 6 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, 7:52 AM EDT (11:52 UTC)
Expired: Aug 22, 2021, 11:15 PM EDT
In force: 15 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Hunterdon County, NJ, Somerset County, NJ

The radar

The Philadelphia radar (KDIX), 70 km from the middle of the area, began a volume at 11:53 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, 9:00 AM EDT	HEAVY RAIN 3.72	Cloverhill, NJ	COCORAHS STATION NJ-HN-59 FLEMINGTON 4.2 ESE.
Aug 22, 11:30 AM EDT	FLOOD	1 Ese Branchburg Twp, NJ	THE NORTH BRANCH RARITAN RIVER AT SOUTH BRANCH (SBRN4) REACHED MINOR FLOOD STAGE.
Aug 22, 11:30 AM EDT	HEAVY RAIN 1.38	1 Wsw Branchburg Twp, NJ	MESONET STATION FW4161 BRANCHBURG.
Aug 22, 11:55 AM EDT	HEAVY RAIN 1.38	2 Sse Readington, NJ	MESONET STATION CW6872 BRANCHBURG.
Aug 22, 4:45 PM EDT	FLOOD	2 Sse Millstone, NJ	BKWN4 USGS GAUGE AT BLACKWELLS MILLS HAS RISEN TO MINOR FLOOD STAGE.
Aug 22, 7:30 PM EDT	FLOOD	Millstone, NJ	THE MILLSTONE RIVER AT MILLSTONE (MITN4) REACHED FLOOD STAGE. CURRENTLY IN MODERATE FLOOD.

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, 11.9 hours before the alert went out and 152 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.

555 
WGUS41 KPHI 221152
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
752 AM EDT Sun Aug 22 2021

NJC019-035-221800-
/O.NEW.KPHI.FA.W.0019.210822T1152Z-210822T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Somerset NJ-
752 AM EDT Sun Aug 22 2021

The National Weather Service in Mount Holly has issued a

* Flood Warning for...
  Somerset County in northern New Jersey...
  Eastern Hunterdon County in northwestern New Jersey...

* Until 200 PM EDT Sunday.

* At 752 AM EDT, local law enforcement reported flooding in the 
  warned area. Flooding is ongoing south of Neshanic Station and in 
  Montgomery Township. Between 2 and 4 inches of rain have fallen.

* Some locations that will experience flooding include...
  New Brunswick, Somerville, Somerset, Bridgewater, Middlesex, Bound 
  Brook, Manville, Mendham, Flemington, High Bridge, Clinton, and 
  Peapack And Gladstone.

This includes the following highways...
	Interstate 78 in New Jersey between mile markers 17 and 42.
	Interstate 287 in New Jersey between mile markers 11 and 30.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4047 7492 4078 7490 4072 7473 4076 7456
      4070 7451 4067 7453 4065 7452 4067 7446
      4066 7445 4066 7440 4062 7443 4057 7452
      4049 7446 4042 7458 4039 7459 4038 7461
      4039 7465 4038 7472 4042 7475 4042 7480

$$

CMS

5 follow-up statements

671 
WGUS81 KPHI 221629
FLSPHI

Flood Statement
National Weather Service Mount Holly NJ
1229 PM EDT Sun Aug 22 2021

NJC019-035-221800-
/O.CON.KPHI.FA.W.0019.000000T0000Z-210822T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Somerset NJ-
1229 PM EDT Sun Aug 22 2021

...FLOOD WARNING REMAINS IN EFFECT UNTIL 2 PM EDT THIS AFTERNOON FOR 
SOMERSET AND EASTERN HUNTERDON COUNTIES...

At 1229 PM EDT, gauge reports indicated flooding was continuing in 
several creeks and streams across the warning area. The gauges on 
the Neshanic River at Reaville and the North Branch Raritan River at 
South Branch were both in minor flood stage at this time and will 
likely remain so for the next couple of hours. The Millstone River 
is rapidly rising, with moderate flooding already occurring in 
Griggstown. Do not drive through flooded roadways!

For Millstone River at Blackwells Mills:
At 11:15am the stage was 6.33 feet.
Flood Stage is 9 feet.

For Millstone River at Griggstown:
At 12:15pm the stage was 12.21 feet.
Flood Stage is 10 feet.

For Millstone River at Millstone:
At 11:15am the stage was 6.63 feet.
Flood Stage is 10 feet.

For Neshanic at Reaville:
At 12:15pm the stage was 8.85 feet.
Flood Stage is 6.5 feet.

For North Branch Raritan River at South Branch:
At 12:00pm the stage was 8.16 feet.
Flood Stage is 8 feet.

This includes the following highways...
	Interstate 78 in New Jersey between mile markers 17 and 42.
	Interstate 287 in New Jersey between mile markers 11 and 30.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4047 7492 4078 7490 4072 7473 4076 7456
      4070 7451 4067 7453 4065 7452 4067 7446
      4066 7445 4066 7440 4062 7443 4057 7452
      4049 7446 4042 7458 4039 7459 4038 7461
      4039 7465 4038 7472 4042 7475 4042 7480

$$

CMS

997 
WGUS41 KPHI 221721
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
121 PM EDT Sun Aug 22 2021

NJC019-035-222200-
/O.EXT.KPHI.FA.W.0019.000000T0000Z-210822T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Somerset NJ-
121 PM EDT Sun Aug 22 2021

The National Weather Service in Mount Holly has extended the

* Flood Warning for...
  Somerset County in northern New Jersey...
  Eastern Hunterdon County in northwestern New Jersey...

* Until 600 PM EDT.

* At 121 PM EDT, gauge reports indicated flooding was continuing in 
  several creeks and streams across the warning area. The gauges on 
  the Neshanic River at Reaville and the North Branch Raritan River 
  at South Branch were both in minor flood stage at this time and 
  will likely remain so for the next couple of hours. The Millstone 
  River continues to rise rapidly, with moderate flooding already 
  occurring in Griggstown and major flooding likely to occur. Do not 
  drive through flooded roadways!

* For Millstone River at Blackwells Mills:
  At 12:15pm the stage was 6.66 feet.
  Flood Stage is 9 feet.
  ...
  For Millstone River at Griggstown:
  At 1:00pm the stage was 13.81 feet.
  Flood Stage is 10 feet.
  ...
  For Millstone River at Millstone:
  At 12:15pm the stage was 6.86 feet.
  Flood Stage is 10 feet.
  ...
  For Neshanic at Reaville:
  At 1:00pm the stage was 7.97 feet.
  Flood Stage is 6.5 feet.
  ...
  For North Branch Raritan River at South Branch:
  At 12:00pm the stage was 8.16 feet.
  Flood Stage is 8 feet.
  ...
  For North Branch Raritan River at Raritan:
  At 12:15pm the stage was 6.48 feet.
  Flood Stage is 10 feet.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4047 7492 4078 7490 4072 7473 4076 7456
      4070 7451 4067 7453 4065 7452 4067 7446
      4066 7445 4066 7440 4062 7443 4057 7452
      4049 7446 4042 7458 4039 7459 4038 7461
      4039 7465 4038 7472 4042 7475 4042 7480

$$

CMS

389 
WGUS81 KPHI 221938
FLSPHI

Flood Statement
National Weather Service Mount Holly NJ
338 PM EDT Sun Aug 22 2021

NJC019-221948-
/O.CAN.KPHI.FA.W.0019.000000T0000Z-210822T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-
338 PM EDT Sun Aug 22 2021

...FLOOD WARNING IS CANCELLED FOR EASTERN HUNTERDON COUNTY...

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 EDT Monday for portions 
of northern Delaware...New Jersey...and Pennsylvania.

LAT...LON 4076 7456 4070 7451 4065 7452 4067 7446
      4066 7445 4066 7440 4062 7443 4057 7452
      4049 7446 4042 7458 4038 7461 4039 7465
      4038 7472 4051 7480 4050 7478 4058 7471
      4060 7472 4062 7470 4063 7473 4072 7473

$$

NJC035-222200-
/O.CON.KPHI.FA.W.0019.000000T0000Z-210822T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Somerset NJ-
338 PM EDT Sun Aug 22 2021

...FLOOD WARNING REMAINS IN EFFECT UNTIL 6 PM EDT THIS EVENING FOR 
SOMERSET COUNTY...

At 338 PM EDT, gauge reports indicated flooding continuing in 
Somerset County, with the North Branch Raritan River in minor flood 
at South Branch and the Millstone River in major flood at 
Griggstown. Several road closures remain. Never drive across flooded 
roadways!

For Millstone River at Blackwells Mills:
At 3:15pm the stage was 7.85 feet.
Flood Stage is 9 feet.

For Millstone River at Griggstown:
At 3:30pm the stage was 15.36 feet.
Flood Stage is 10 feet.

For North Branch Raritan River at South Branch:
At 3:00pm the stage was 8.33 feet.
Flood Stage is 8 feet.

For Millstone River at Millstone:
At 3:30pm the stage was 7.78 feet.
Flood Stage is 10 feet.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4076 7456 4070 7451 4065 7452 4067 7446
      4066 7445 4066 7440 4062 7443 4057 7452
      4049 7446 4042 7458 4038 7461 4039 7465
      4038 7472 4051 7480 4050 7478 4058 7471
      4060 7472 4062 7470 4063 7473 4072 7473

$$

CMS

440 
WGUS41 KPHI 222156
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
556 PM EDT Sun Aug 22 2021

NJC035-230000-
/O.EXT.KPHI.FA.W.0019.000000T0000Z-210823T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Somerset NJ-
556 PM EDT Sun Aug 22 2021

The National Weather Service in Mount Holly has extended the

* Flood Warning for...
  Somerset County in northern New Jersey...

* Until 800 PM EDT.

* At 556 PM EDT, gauge reports indicated flooding continuing in 
  Somerset County, with the North Branch Raritan River in minor 
  flood at South Branch and the Millstone River in major flood at 
  Griggstown and minor flood at Blackwells Mills. Several road 
  closures remain. Never drive across flooded roadways!

* For Millstone River at Blackwells Mills:
  At 5:15pm the stage was 9.51 feet.
  Flood Stage is 9 feet.
  ...
  For Millstone River at Griggstown:
  At 5:45pm the stage was 15.59 feet.
  Flood Stage is 10 feet.
  ...
  For North Branch Raritan River at South Branch:
  At 5:00pm the stage was 8.08 feet.
  Flood Stage is 8 feet.
  ...
  For Millstone River at Millstone:
  At 5:30pm the stage was 8.87 feet.
  Flood Stage is 10 feet.

This includes the following highways...
	Interstate 78 in New Jersey between mile markers 27 and 42.
	Interstate 287 in New Jersey between mile markers 11 and 30.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4076 7456 4070 7451 4065 7452 4067 7446
      4066 7445 4066 7440 4062 7443 4057 7452
      4049 7446 4042 7458 4038 7461 4039 7465
      4038 7472 4051 7480 4050 7478 4058 7471
      4060 7472 4062 7470 4063 7473 4072 7473

$$

Meola

249 
WGUS41 KPHI 222354
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
754 PM EDT Sun Aug 22 2021

NJC035-230315-
/O.EXT.KPHI.FA.W.0019.000000T0000Z-210823T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Somerset NJ-
754 PM EDT Sun Aug 22 2021

The National Weather Service in Mount Holly has extended the

* Flood Warning for...
  Somerset County in northern New Jersey...

* Until 1115 PM EDT.

* At 754 PM EDT, gauge reports indicated flooding continuing in 
  Somerset County, with the Millstone River in major flood at 
  Griggstown, moderate flood at Blackwells Mills, and minor flood at 
  Millstone. Several road closures remain. Never drive across 
  flooded roadways!

* For Millstone River at Blackwells Mills:
  At 7:15pm the stage was 10.53 feet.
  Flood Stage is 9 feet.
  ...
  For Millstone River at Griggstown:
  At 7:45pm the stage was 16.01 feet.
  Flood Stage is 10 feet.
  ...
  For Millstone River at Millstone:
  At 7:45pm the stage was 10.26 feet.
  Flood Stage is 10 feet.

This includes the following highways...
	Interstate 78 in New Jersey between mile markers 27 and 42.
	Interstate 287 in New Jersey between mile markers 11 and 30.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4076 7456 4070 7451 4065 7452 4067 7446
      4066 7445 4066 7440 4062 7443 4057 7452
      4049 7446 4042 7458 4038 7461 4039 7465
      4038 7472 4051 7480 4050 7478 4058 7471
      4060 7472 4062 7470 4063 7473 4072 7473

$$

Meola

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, 6:07 AM EDT	Flash Flood Warning	PHI	Hunterdon, Warren	67 min
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

Areal Flood Warnings in New Jersey, 2021 Every areal 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.