Alert archive / New Jersey / Areal Flood Advisories in 2021

Areal Flood Advisory 103, NWS Philadelphia/Mount Holly

August 9, 2021Chester County, Delaware County, Pennsylvania; 5 counties in New Jersey; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this areal flood advisory at Aug 9, 2021, 4:36 PM EDT for Chester County, Delaware County, Pennsylvania; 5 counties in New Jersey; New Castle County, Delaware. It was in force for 104 min.

The area

The outline as issued.

The facts

Issued: Aug 9, 2021, 4:36 PM EDT (20:36 UTC)
Expired: Aug 9, 2021, 6:20 PM EDT
In force: 104 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties New Castle County, DE, Atlantic County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Salem County, NJ, Chester County, PA, Delaware County, PA

The radar

The Dover AFB radar (KDOX), 77 km from the middle of the area, began a volume at 20:36 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

Wallops Is Stn, VA (KWAL), launched 12:00Z, 8.6 hours before the alert went out and 176 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: 927 J/kg
Mixed-layer CIN: -47 J/kg
Mixed-layer LCL: 869 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: 25 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.

316 
WGUS81 KPHI 092036
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
436 PM EDT Mon Aug 9 2021

DEC003-NJC001-009-011-015-033-PAC029-045-092345-
/O.NEW.KPHI.FA.Y.0103.210809T2036Z-210809T2345Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Atlantic NJ-Cape May NJ-Cumberland NJ-Gloucester NJ-
Salem NJ-Chester PA-Delaware PA-
436 PM EDT Mon Aug 9 2021

The National Weather Service in Mount Holly has issued a

* Flood Advisory for...
  New Castle County in northern Delaware...
  Southwestern Atlantic County in southern New Jersey...
  Northern Cape May County in southern New Jersey...
  Central Cumberland County in southern New Jersey...
  Central Gloucester County in southern New Jersey...
  Salem County in southern New Jersey...
  South Central Chester County in southeastern Pennsylvania...
  Southwestern Delaware County in southeastern Pennsylvania...

* Until 745 PM EDT.

* At 436 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 inches of rain have 
  fallen for some areas.

* Some locations that will experience flooding include...
  Wilmington, Vineland, Newark, Millville, Bridgeton, Middletown, 
  Ocean City, Cumberland, Chester, Glassboro, Pennsville, and Somers 
  Point.

This includes the following highways...
	New Jersey Turnpike between exits 1 and 2.
	Interstate 95 in Pennsylvania between mile markers 0 and 2.
	Interstate 95 in Delaware between mile markers 2 and 23.
	Interstate 295 in New Jersey between mile markers 0 and 12.
	Garden State Parkway between mile markers 17 and 27...and
	between mile markers 29 and 30.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3989 7575 3994 7557 3922 7439 3910 7462
      3945 7527 3940 7538 3935 7544 3940 7577

$$

Robertson

1 follow-up statement

628 
WGUS81 KPHI 092220
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
620 PM EDT Mon Aug 9 2021

DEC003-NJC001-009-011-015-033-PAC029-045-092230-
/O.CAN.KPHI.FA.Y.0103.000000T0000Z-210809T2345Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Atlantic NJ-Cape May NJ-Cumberland NJ-Gloucester NJ-
Salem NJ-Chester PA-Delaware PA-
620 PM EDT Mon Aug 9 2021

...FLOOD ADVISORY IS CANCELLED FOR NEW CASTLE, SOUTHWESTERN 
ATLANTIC, NORTHERN CAPE MAY, CENTRAL CUMBERLAND, CENTRAL GLOUCESTER, 
SALEM, SOUTH CENTRAL CHESTER, AND SOUTHWESTERN DELAWARE COUNTIES...

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

LAT...LON 3989 7575 3994 7557 3922 7439 3910 7462
      3945 7527 3940 7538 3935 7544 3940 7577

$$

Robertson

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 3:43 PM EDT	Excessive Heat Watch	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	12 hr
Aug 9, 5:12 PM EDT	Areal Flood Advisory	PHI	Chester, Delaware	85 min
Aug 9, 5:34 PM EDT	Special Weather Statement	PHI	Philadelphia	26 min
Aug 9, 5:40 PM EDT	Areal Flood Advisory	PHI	Philadelphia	82 min
Aug 9, 6:10 PM EDT	Special Weather Statement	PHI	Philadelphia	35 min
Aug 9, 6:24 PM EDT	Special Weather Statement	PHI	Lehigh	36 min
Aug 9, 6:29 PM EDT	Areal Flood Advisory	PHI	Berks, Montgomery	70 min
Aug 9, 6:49 PM EDT	Special Weather Statement	PHI	Montgomery	26 min
Aug 9, 7:14 PM EDT	Special Weather Statement	PHI	Carbon	31 min
Aug 9, 4:45 PM EDT	Special Weather Statement	PHI	Atlantic	30 min
Aug 9, 6:37 PM EDT	Special Weather Statement	PHI	Mercer	38 min
Aug 9, 2:10 PM EDT	Special Weather Statement	PHI	Sussex	50 min
Aug 9, 2:41 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle, Sussex	3 hr
Aug 9, 3:01 PM EDT	Flash Flood Warning	PHI	Kent, Sussex	2 hr
Aug 9, 4:35 PM EDT	Severe Thunderstorm Warning	PHI	Kent	40 min
Aug 9, 4:59 PM EDT	Flash Flood Warning	PHI	Kent	79 min
Aug 9, 5:12 PM EDT	Severe Thunderstorm Warning	PHI	Kent	20 min

Nearby

Areal Flood Advisories in New Jersey, 2021 Areal Flood Advisories in Pennsylvania, 2021 Areal Flood Advisories in Delaware, 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.