Alert archive / Pennsylvania / Areal Flood Warnings in 2024

Areal Flood Warning 93, NWS Philadelphia/Mount Holly

August 8, 2024Chester County, Pennsylvania; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this areal flood warning at Aug 8, 2024, 11:40 PM EDT for Chester County, Pennsylvania; New Castle County, Delaware. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 8, 2024, 11:40 PM EDT (03:40 UTC)
Expired: Aug 9, 2024, 3:30 AM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties New Castle County, DE, Chester County, PA

The radar

The Dover AFB radar (KDOX), 108 km from the middle of the area, began a volume at 03:42 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

Washington/Dulle, VA (KIAD), launched 00:00Z, 3.7 hours before the alert went out and 173 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: 886 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 607 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 70 m²/s²
0-3 km storm-relative helicity: 132 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.4

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this areal flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Philadelphia/Mount Holly wrote its last area forecast discussion before this areal flood warning went out at Aug 8, 11:03 PM EDT, 37 minutes earlier.

Area forecast discussion, Aug 8, 11:03 PM EDT, 37 minutes before

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In the hours before

Local storm report, Aug 8, 8:02 PM EDT, 3 hours 38 minutes before

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
802 PM EDT Thu Aug 8 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0747 PM     Rain             2 SW Glendale           39.61N 75.70W
08/08/2024  M6.29 Inch       New Castle         DE   Mesonet

            Mesonet station GW1337 BEAR.

0750 PM     Rain             1 WNW Camden            39.95N 75.13W
08/08/2024  M3.38 Inch       Camden             NJ   Mesonet

            Mesonet station 2549D Camden.

0745 PM     Rain             1 NE Kaolin             39.81N 75.71W
08/08/2024  M3.37 Inch       Chester            PA   Mesonet

            Mesonet station FW8290 Kennett Square.

0741 PM     Rain             1 NE South Coatesville  39.99N 75.79W
08/08/2024  M3.16 Inch       Chester            PA   Mesonet

            Mesonet station EW3013 Coatesville.

0745 PM     Rain             1 N Woodshade           39.67N 75.68W
08/08/2024  M3.06 Inch       New Castle         DE   Mesonet

            Mesonet station FW2774 Newark.

0700 PM     Rain             Brookside               39.67N 75.73W
08/08/2024  M3.02 Inch       New Castle         DE   CO-OP Observer

            CO-OP Observer station NEWD1 Brookside.

0750 PM     Rain             2 ENE Glasgow           39.62N 75.71W
08/08/2024  M3.00 Inch       New Castle         DE   Mesonet

            Mesonet station AR962 Newark.

&&

Gorse

Local storm report, Aug 8, 8:59 PM EDT, 2 hours 41 minutes before

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
859 PM EDT Thu Aug 8 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0709 PM     Tstm Wnd Dmg     Marshallton             39.73N 75.65W
08/08/2024                   New Castle         DE   Trained Spotter

            probable tornado. Roof damage to grocery
            store.

0711 PM     Tstm Wnd Dmg     Sherwood Park           39.74N 75.65W
08/08/2024                   New Castle         DE   Trained Spotter

            probable tornado- trees onto garage. Other
            large tree down nearby.

&&

Local storm report, Aug 8, 9:12 PM EDT, 2 hours 28 minutes before

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Local storm report, Aug 8, 9:26 PM EDT, 2 hours 14 minutes before

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Local storm report, Aug 8, 9:50 PM EDT, 1 hour 50 minutes before

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Local storm report, Aug 8, 10:09 PM EDT, 1 hour 31 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 3:31 PM EDT	Flash Flood Warning	PHI	Warren	108 min
Aug 9, 4:11 PM EDT	Flash Flood Warning	PHI	Warren	100 min
Aug 9, 5:30 PM EDT	Flash Flood Warning	PHI	Mercer	83 min
Aug 8, 8:52 PM EDT	Flash Flood Warning	PHI	Berks, Chester	3 hr
Aug 8, 9:06 PM EDT	River Flood Warning	PHI	Chester	9 hr
Aug 9, 12:12 AM EDT	River Flood Warning	PHI	Chester, Delaware	16 hr
Aug 9, 2:50 PM EDT	Flash Flood Warning	PHI	Lehigh, Northampton	2 hr
Aug 9, 3:50 PM EDT	Flash Flood Warning	PHI	Bucks, Montgomery	2 hr
Aug 9, 5:56 PM EDT	River Flood Warning	PHI	Chester	6 hr
Aug 9, 6:46 PM EDT	Areal Flood Warning	PHI	Berks, Bucks, Lehigh, Montgomery	4 hr
Aug 8, 9:56 PM EDT	River Flood Warning	PHI	New Castle	7 hr
Aug 8, 10:20 PM EDT	Areal Flood Warning	PHI	New Castle	11 hr

Nearby

Areal Flood Warnings in Pennsylvania, 2024 Areal Flood Warnings in Delaware, 2024 Every areal flood warning in 2024

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.