Alert archive / Delaware / Flash Flood Warnings in 2020

Flash Flood Warning 36, NWS Philadelphia/Mount Holly

August 4, 2020Kent County, New Castle County, Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 4, 2020, 8:58 AM EDT for Kent County, New Castle County, Sussex County, Delaware. It was in force for 3 hr. 3 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 4, 2020, 8:58 AM EDT (12:58 UTC)
Expired: Aug 4, 2020, 12:00 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Kent County, DE, New Castle County, DE, Sussex County, DE

The radar

The Dover AFB radar (KDOX), 40 km from the middle of the area, began a volume at 13:00 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 4, 10:45 AM EDT	COASTAL FLOOD	3 S Kitts Hummock, DE	TIDAL GAUGE ON THE MURDERKILL RIVER AT BOWERS BEACH CRESTED IN MINOR FLOOD STAGE AT 7.02 FT THIS MORNING.
Aug 4, 12:00 PM EDT	HEAVY RAIN 4.53	2 Nw Townsend, DE	MESONET STATION FW6355 TOWNSEND.
Aug 4, 12:09 PM EDT	HEAVY RAIN 4.54	2 Nne Delaney Corner, DE	MESONET STATION BLKD1 BLACKBIRD.

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, 1.0 hours before the alert went out and 139 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: 472 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 648 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 254 m²/s²
0-3 km storm-relative helicity: 273 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 2.9

Open this sounding in Storm Lab

The text

As transmitted.

211 
WGUS51 KPHI 041258
FFWPHI
DEC001-003-005-041600-
/O.NEW.KPHI.FF.W.0036.200804T1258Z-200804T1600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
858 AM EDT Tue Aug 4 2020

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Northern Sussex County in southern Delaware...
  Southwestern New Castle County in northern Delaware...
  Kent County in central Delaware...

* Until noon EDT.

* At 858 AM EDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Up to two inches of rain have
  already fallen. 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, Middletown, Smyrna, Camden, Clayton, Cheswold, Bowers,
  Woodside, Viola, Hartly, Rising Sun-Lebanon, Woodland Beach,
  Hazlettville, Delaney Corner, Dover Base Housing, Dover Speedway,
  Green Spring, Rising Sun, Big Stone Beach and Townsend.

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.

A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.

&&

LAT...LON 3907 7574 3947 7577 3938 7545 3885 7520

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...2-3 INCHES IN 1 HOUR

$$

Kruzdlo

1 follow-up statement

485 
WGUS71 KPHI 041555
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1155 AM EDT Tue Aug 4 2020

DEC001-003-005-041604-
/O.EXP.KPHI.FF.W.0036.000000T0000Z-200804T1600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex DE-New Castle DE-Kent DE-
1155 AM EDT Tue Aug 4 2020

...THE FLASH FLOOD WARNING FOR NORTHERN SUSSEX...SOUTHWESTERN NEW
CASTLE AND KENT COUNTIES WILL EXPIRE AT NOON EDT...

The heavy rain has ended. Water is receding. Please continue to heed 
any remaining road closures.

LAT...LON 3907 7574 3947 7577 3938 7545 3885 7520

$$

Kruzdlo

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 4, 4:50 AM EDT	Tornado Warning	PHI	Sussex	25 min
Aug 4, 5:17 AM EDT	Areal Flood Advisory	PHI	New Castle	4 hr
Aug 4, 7:28 AM EDT	Flash Flood Warning	PHI	New Castle	3 hr
Aug 4, 7:39 AM EDT	Tornado Warning	PHI	Sussex	36 min
Aug 4, 7:51 AM EDT	Tornado Warning	PHI	Sussex	24 min
Aug 4, 8:15 AM EDT	Tornado Warning	PHI	Kent	45 min
Aug 4, 8:18 AM EDT	Tornado Warning	PHI	Sussex	27 min
Aug 4, 8:27 AM EDT	Tornado Warning	PHI	Kent	33 min
Aug 4, 8:56 AM EDT	Tornado Warning	PHI	Kent, New Castle	34 min
Aug 4, 9:06 AM EDT	River Flood Warning	PHI	New Castle	11 hr
Aug 4, 9:23 AM EDT	Flash Flood Warning	PHI	New Castle	4 hr
Aug 4, 9:23 AM EDT	Tornado Warning Tornado observed	PHI	New Castle	22 min
Aug 4, 10:02 AM EDT	Flash Flood Warning	PHI	New Castle	4 hr
Aug 4, 10:38 AM EDT	River Flood Warning	PHI	New Castle	14 hr
Aug 4, 12:27 PM EDT	River Flood Warning	PHI	New Castle	10 hr
Aug 4, 12:48 PM EDT	River Flood Warning	PHI	New Castle	24 hr
Aug 4, 1:59 PM EDT	Areal Flood Warning	PHI	New Castle	9 hr

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.