Alert archive / Delaware / Flash Flood Warnings in 2020

Flash Flood Warning 56, NWS Philadelphia/Mount Holly

August 12, 2020Kent County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 12, 2020, 3:31 PM EDT for Kent County, Delaware. It was in force for 3 hr. 1 report 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 12, 2020, 3:31 PM EDT (19:31 UTC)
Expired: Aug 12, 2020, 6:03 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Kent County, DE

The radar

The Dover AFB radar (KDOX), 33 km from the middle of the area, began a volume at 19:31 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 12, 4:10 PM EDT	HEAVY RAIN 3.06	1 Ese Frederica, DE	3.06 INCHES OF RAIN WITHIN AN HOUR AT THE FREDERICA DEOS STATION.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 7.5 hours before the alert went out and 133 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: 1590 J/kg
Mixed-layer CIN: -21 J/kg
Mixed-layer LCL: 729 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 3 m²/s²
0-3 km storm-relative helicity: 17 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

064 
WGUS51 KPHI 121931
FFWPHI
DEC001-122230-
/O.NEW.KPHI.FF.W.0056.200812T1931Z-200812T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
331 PM EDT Wed Aug 12 2020

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Central Kent County in central Delaware...

* Until 630 PM EDT.

* At 331 PM EDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Flash flooding is ongoing or
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar indicated.

  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 could experience flooding include...
  Dover, Camden, Bowers, Woodside, Viola, Hartly, Rising Sun-Lebanon,
  Rising Sun, Hazlettville, Dover Base Housing, Dover Speedway,
  Wyoming, Felton, Frederica, Magnolia, Little Creek, Rodney Village,
  Kent Acres, Riverview and Highland Acres.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 3921 7537 3898 7537 3900 7571 3920 7571

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR

$$

JJM

1 follow-up statement

087 
WGUS71 KPHI 122203
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
603 PM EDT Wed Aug 12 2020

DEC001-122212-
/O.CAN.KPHI.FF.W.0056.000000T0000Z-200812T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent DE-
603 PM EDT Wed Aug 12 2020

...THE FLASH FLOOD WARNING FOR CENTRAL KENT COUNTY IS CANCELLED...

Heavy rain has moved out of the area, and water is receeding. The 
Flash Flood Warning has therefore been cancelled. However, please 
continue to heed any remaining road closures.

LAT...LON 3921 7537 3898 7537 3900 7571 3920 7571

$$

JJM

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 12, 12:43 PM EDT	Areal Flood Advisory	PHI	New Castle	3 hr
Aug 12, 12:55 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle	3 hr
Aug 12, 12:55 PM EDT	Special Weather Statement	PHI	Kent	35 min
Aug 12, 1:06 PM EDT	Flash Flood Warning	PHI	Kent, New Castle	3 hr
Aug 12, 1:37 PM EDT	Areal Flood Advisory	PHI	New Castle	3 hr
Aug 12, 1:54 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	51 min
Aug 12, 2:38 PM EDT	Severe Thunderstorm Warning	PHI	Kent	52 min
Aug 12, 2:40 PM EDT	Flash Flood Warning	PHI	New Castle	3 hr
Aug 12, 3:06 PM EDT	Areal Flood Advisory	PHI	Kent, Sussex	3 hr
Aug 12, 3:15 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	45 min
Aug 12, 3:20 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	29 min
Aug 12, 3:46 PM EDT	Flash Flood Warning	PHI	Kent, Sussex	3 hr
Aug 12, 4:00 PM EDT	Special Weather Statement	PHI	Kent	30 min

Nearby

Flash Flood Warnings in Delaware, 2020 Every flash flood warning in 2020

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.