Alert archive / New Jersey / Areal Flood Advisories in 2021

Areal Flood Advisory 113, NWS Philadelphia/Mount Holly

August 11, 20215 counties in New Jersey; Monroe County, Northampton County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood advisory at Aug 11, 2021, 6:50 PM EDT for 5 counties in New Jersey; Monroe County, Northampton County, Pennsylvania. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Aug 11, 2021, 6:50 PM EDT (22:50 UTC)
Expired: Aug 11, 2021, 9:45 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Hunterdon County, NJ, Morris County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Monroe County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 114 km from the middle of the area, began a volume at 22:52 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.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 10.8 hours before the alert went out and 151 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: 977 J/kg
Mixed-layer CIN: -44 J/kg
Mixed-layer LCL: 711 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 29 m²/s²
0-3 km storm-relative helicity: 18 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

400 
WGUS81 KPHI 112250
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
650 PM EDT Wed Aug 11 2021

NJC019-027-035-037-041-PAC089-095-120145-
/O.NEW.KPHI.FA.Y.0113.210811T2250Z-210812T0145Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Morris NJ-Somerset NJ-Sussex NJ-Warren NJ-Monroe PA-
Northampton PA-
650 PM EDT Wed Aug 11 2021

The National Weather Service in Mount Holly has issued a

* Flood Advisory for...
  Morris County in northern New Jersey...
  North Central Somerset County in northern New Jersey...
  Northeastern Hunterdon County in northwestern New Jersey...
  Sussex County in northwestern New Jersey...
  Warren County in northwestern New Jersey...
  Northeastern Northampton County in eastern Pennsylvania...
  Southeastern Monroe County in northeastern Pennsylvania...

* Until 945 PM EDT.

* At 650 PM EDT, Doppler radar indicated heavy rain due to 
  thunderstorms. Around 1 inch of rain has fallen in some areas with 
  additional rainfall of around 1 inch expected. Minor flooding is 
  ongoing or expected to begin shortly in the advisory area.

* Some locations that will experience flooding include...
  Easton, Morristown, Newton, Dover, Madison, Hopatcong, Florham 
  Park, East Hanover, Lincoln Park, Kinnelon, East Stroudsburg, and 
  Hackettstown.

This includes the following highways...
	Interstate 80 in New Jersey between mile markers 0 and 48.
	Interstate 80 in Pennsylvania between mile markers 309 and 314.
	Interstate 287 in New Jersey between mile markers 30 and 53.

This includes the following DSS Events...
	New Jersey State Fair.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 4095 7540 4101 7513 4122 7465 4126 7449
      4120 7437 4109 7450 4108 7449 4104 7450
      4105 7445 4102 7443 4100 7430 4091 7427
      4091 7433 4086 7432 4076 7438 4076 7436
      4073 7446 4068 7501 4071 7519 4082 7541

$$

Robertson

3 follow-up statements

057 
WGUS81 KPHI 120033
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
833 PM EDT Wed Aug 11 2021

NJC019-027-035-037-041-PAC089-095-120145-
/O.CON.KPHI.FA.Y.0113.000000T0000Z-210812T0145Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Morris NJ-Somerset NJ-Sussex NJ-Warren NJ-Monroe PA-
Northampton PA-
833 PM EDT Wed Aug 11 2021

...FLOOD ADVISORY REMAINS IN EFFECT UNTIL 945 PM EDT THIS EVENING 
FOR MORRIS, NORTH CENTRAL SOMERSET, NORTHEASTERN HUNTERDON, SUSSEX, 
WARREN, NORTHEASTERN NORTHAMPTON, AND SOUTHEASTERN MONROE COUNTIES...

At 833 PM EDT, Doppler radar indicated heavy rain due to 
thunderstorms. Minor flooding is ongoing or expected to begin 
shortly in the advisory area. Between 1 and 2.5 inches of rain have 
fallen.

Some locations that will experience flooding include...
  Easton, Morristown, Newton, Dover, Madison, Hopatcong, Florham 
  Park, East Hanover, Lincoln Park, Kinnelon, East Stroudsburg, and 
  Hackettstown.

This includes the following highways...
	Interstate 80 in New Jersey between mile markers 0 and 48.
	Interstate 80 in Pennsylvania between mile markers 309 and 314.
	Interstate 287 in New Jersey between mile markers 30 and 53.

This includes the following DSS Events...
	New Jersey State Fair.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 4095 7540 4101 7513 4122 7465 4126 7449
      4120 7437 4109 7450 4108 7449 4104 7450
      4105 7445 4102 7443 4100 7430 4091 7427
      4091 7433 4086 7432 4076 7438 4076 7436
      4073 7446 4068 7501 4071 7519 4082 7541

$$

SFJ

131 
WGUS81 KPHI 120110
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
910 PM EDT Wed Aug 11 2021

NJC037-PAC089-095-120120-
/O.CAN.KPHI.FA.Y.0113.000000T0000Z-210812T0145Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex NJ-Monroe PA-Northampton PA-
910 PM EDT Wed Aug 11 2021

...FLOOD ADVISORY IS CANCELLED FOR SUSSEX, NORTHEASTERN NORTHAMPTON, 
AND SOUTHEASTERN MONROE COUNTIES...

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

LAT...LON 4072 7519 4073 7518 4075 7520 4077 7513
      4086 7505 4095 7490 4091 7477 4091 7472
      4090 7471 4097 7454 4098 7431 4091 7427
      4091 7433 4088 7434 4086 7432 4076 7438
      4076 7437 4073 7446 4068 7501

$$

NJC019-027-035-041-120145-
/O.CON.KPHI.FA.Y.0113.000000T0000Z-210812T0145Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Morris NJ-Somerset NJ-Warren NJ-
910 PM EDT Wed Aug 11 2021

...FLOOD ADVISORY REMAINS IN EFFECT UNTIL 945 PM EDT THIS EVENING 
FOR MORRIS, NORTH CENTRAL SOMERSET, NORTHEASTERN HUNTERDON, AND 
CENTRAL WARREN COUNTIES...

At 910 PM EDT, Doppler radar indicated heavy rain due to 
thunderstorms. Minor flooding is ongoing or expected to begin 
shortly in the advisory area. Between 1 and 2.5 inches of rain have 
fallen.

Some locations that will experience flooding include...
  Morristown, Dover, Madison, Hopatcong, Florham Park, East Hanover, 
  Lincoln Park, Hackettstown, Boonton, Wharton, Washington, and 
  Rockaway.

This includes the following highways...
	Interstate 80 in New Jersey between mile markers 13 and 20...and
	between mile markers 25 and 48.
	Interstate 287 in New Jersey between mile markers 30 and 52.

LAT...LON 4072 7519 4073 7518 4075 7520 4077 7513
      4086 7505 4095 7490 4091 7477 4091 7472
      4090 7471 4097 7454 4098 7431 4091 7427
      4091 7433 4088 7434 4086 7432 4076 7438
      4076 7437 4073 7446 4068 7501

$$

SFJ

161 
WGUS81 KPHI 120138
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
938 PM EDT Wed Aug 11 2021

NJC019-027-035-041-120148-
/O.EXP.KPHI.FA.Y.0113.000000T0000Z-210812T0145Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Morris NJ-Somerset NJ-Warren NJ-
938 PM EDT Wed Aug 11 2021

...FLOOD ADVISORY WILL EXPIRE AT 945 PM EDT THIS EVENING FOR MORRIS, 
NORTH CENTRAL SOMERSET, NORTHEASTERN HUNTERDON, AND CENTRAL WARREN 
COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat for the entire advisory area. However...a small portion of 
the area is now under a flash flood warning. It will take time for 
water to recede in the warning area. Please continue to heed 
remaining road closures.

LAT...LON 4072 7519 4073 7518 4075 7520 4077 7513
      4086 7505 4095 7490 4091 7477 4091 7472
      4090 7471 4097 7454 4098 7431 4091 7427
      4091 7433 4088 7434 4086 7432 4076 7438
      4076 7437 4073 7446 4068 7501

$$

SFJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 10, 8:02 PM EDT	Severe Thunderstorm Warning	PHI	Camden, Gloucester	43 min
Aug 10, 8:18 PM EDT	Severe Thunderstorm Warning	PHI	Gloucester, Salem	42 min
Aug 10, 8:23 PM EDT	Special Marine Warning	PHI		79 min
Aug 10, 8:36 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Burlington, Camden, Cumberland, Gloucester, Salem	39 min
Aug 10, 8:43 PM EDT	Areal Flood Advisory	PHI	Burlington, Camden, Gloucester	2 hr
Aug 10, 9:07 PM EDT	Special Weather Statement	PHI	Burlington, Camden, Cumberland	23 min
Aug 11, 2:56 PM EDT	Excessive Heat Watch	PHI	Hunterdon, Morris, Warren	12 hr
Aug 11, 5:57 PM EDT	Special Weather Statement	PHI	Sussex	48 min
Aug 11, 6:32 PM EDT	Special Weather Statement	PHI	Morris, Sussex, Warren	28 min
Aug 11, 7:04 PM EDT	Areal Flood Advisory	PHI	Gloucester, Hunterdon, Salem	2 hr
Aug 11, 7:04 PM EDT	Severe Thunderstorm Warning	PHI	Morris, Sussex, Warren	41 min
Aug 11, 7:11 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Camden, Gloucester	49 min
Aug 11, 7:28 PM EDT	Flash Flood Warning	PHI	Morris, Warren	3 hr
Aug 11, 7:45 PM EDT	Special Weather Statement	PHI	Morris	45 min
Aug 11, 7:52 PM EDT	Special Weather Statement	PHI	Atlantic, Burlington, Camden, Gloucester, Mercer	53 min
Aug 11, 7:57 PM EDT	Special Weather Statement	PHI	Hunterdon, Middlesex, Somerset	48 min
Aug 11, 4:46 PM EDT	Special Weather Statement	PHI	Monroe	44 min
Aug 11, 4:58 PM EDT	Special Weather Statement	PHI	Berks	47 min
Aug 11, 5:20 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	57 min
Aug 11, 5:48 PM EDT	Severe Thunderstorm Warning	PHI	Berks	57 min
Aug 11, 6:16 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh, Montgomery	44 min
Aug 11, 6:26 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Delaware, Montgomery	49 min
Aug 11, 6:48 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Lehigh, Montgomery, Northampton	42 min

Nearby

Areal Flood Advisories in New Jersey, 2021 Areal Flood Advisories in Pennsylvania, 2021 Every areal flood advisory 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.