Alert archive / Delaware / Flash Flood Warnings in 2018

Flash Flood Warning 84, NWS Philadelphia/Mount Holly

August 31, 2018Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 31, 2018, 12:54 PM EDT for Sussex County, Delaware. It was in force for 4 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 31, 2018, 12:54 PM EDT (16:54 UTC)
Expired: Aug 31, 2018, 4:45 PM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Sussex County, DE

The radar

The Dover AFB radar (KDOX), 15 km from the middle of the area, began a volume at 16:57 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 31, 4:44 PM EDT	HEAVY RAIN 6.88	5 Se Slaughter Beach, DE	AROUND 6 INCHES OF THIS RAINFALL OCCURRED IN 3-HR PERIOD ENDING AT 424 PM.

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, 4.9 hours before the alert went out and 90 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: 72 J/kg
Mixed-layer CIN: -177 J/kg
Mixed-layer LCL: 1245 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 15 m²/s²
0-3 km storm-relative helicity: 89 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

057 
WGUS51 KPHI 311654
FFWPHI
DEC005-312045-
/O.NEW.KPHI.FF.W.0084.180831T1654Z-180831T2045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
1254 PM EDT FRI AUG 31 2018

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Central Sussex County in southern Delaware...

* Until 445 PM EDT.

* At 1252 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Rainfall rates of several 
  inches per hour have been reported with some of these storms. 
  Flash flooding is expected in the areas of heaviest rain. Routes 1 
  and 13 will be adversely affected.

* Some locations that could experience flooding include...
  Georgetown, Seaford, Lewes, Milton, Bridgeville, Ellendale,
  Henlopen Acres, Cape Henlopen State Park, Sycamore, Blades,
  Greenwood, Dewey Beach and Bethel.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3857 7562 3881 7568 3889 7523 3881 7514
      3881 7509 3878 7505 3868 7505

$$

jjm

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 31, 1:37 AM EDT	Special Weather Statement	PHI	Sussex	53 min
Aug 31, 10:57 AM EDT	Areal Flood Advisory	PHI	Kent	107 min
Aug 31, 11:31 AM EDT	Flash Flood Warning	PHI	Kent	11 hr
Aug 31, 11:53 AM EDT	Special Weather Statement	PHI	Kent	37 min
Aug 31, 12:00 PM EDT	Severe Thunderstorm Warning	PHI	Kent	15 min
Aug 31, 12:15 PM EDT	Flash Flood Warning	PHI	Kent, Sussex	7 hr
Aug 31, 12:28 PM EDT	Special Weather Statement	PHI	Kent	32 min
Aug 31, 12:35 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	40 min
Aug 31, 1:09 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	51 min
Aug 31, 1:58 PM EDT	Special Weather Statement	PHI	Sussex	32 min
Aug 31, 4:27 PM EDT	Special Weather Statement	PHI	Sussex	18 min
Aug 31, 4:32 PM EDT	Flash Flood Warning	PHI	Sussex	4 hr
Aug 31, 4:41 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle	4 hr
Aug 31, 4:42 PM EDT	Special Weather Statement	PHI	Sussex	33 min
Aug 31, 5:00 PM EDT	Flash Flood Warning	PHI	New Castle	4 hr
Aug 31, 5:14 PM EDT	Special Weather Statement	PHI	Sussex	46 min
Aug 31, 5:38 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle, Sussex	4 hr
Aug 31, 5:48 PM EDT	Flash Flood Warning	PHI	Sussex	3 hr
Aug 31, 7:11 PM EDT	Areal Flood Warning	PHI	Kent, Sussex	4 hr
Aug 31, 7:37 PM EDT	Flash Flood Warning	PHI	Kent, New Castle	4 hr

Nearby

Flash Flood Warnings in Delaware, 2018 Every flash flood warning in 2018

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.