Alert archive / Delaware / Flash Flood Warnings in 2018

Flash Flood Warning 69, NWS Philadelphia/Mount Holly

August 11, 2018Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 11, 2018, 8:57 PM EDT for Sussex County, Delaware. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 11, 2018, 8:57 PM EDT (00:57 UTC)
Expired: Aug 11, 2018, 11:30 PM EDT
In force: 3 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), 14 km from the middle of the area, began a volume at 01:00 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.

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 00:00Z, 1.0 hours before the alert went out and 114 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: 2834 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 636 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 26 m²/s²
0-3 km storm-relative helicity: 66 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.1

Open this sounding in Storm Lab

The text

As transmitted.

154 
WGUS51 KPHI 120057
FFWPHI
DEC005-120400-
/O.NEW.KPHI.FF.W.0069.180812T0057Z-180812T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
857 PM EDT SAT AUG 11 2018

The National Weather Service in Mount Holly NJ has issued a

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

* Until midnight EDT.

* At 855 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain in northern Sussex County.  The rate of rainfall...one 
  to two inches per hour...will cause flash flooding within the 
  heavier rainbands as the storms move southeast through the county.

* Some locations that could experience flooding include...
  Dover, Georgetown, Milford, Seaford, Millsboro, Laurel, Lewes,
  Milton, Selbyville, Bridgeville, Delmar, Dagsboro, Millville,
  Ellendale, Bowers, Henlopen Acres, Gumboro, Cape Henlopen State
  Park, Sycamore and Big Stone Beach.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 3846 7569 3883 7572 3884 7555 3895 7539
      3923 7556 3924 7556 3908 7546 3925 7553
      3924 7552 3903 7542 3934 7551 3896 7539
      3895 7537 3931 7546 3892 7528 3881 7514
      3881 7506 3845 7505

$$

jjm

2 follow-up statements

976 
WGUS71 KPHI 120100
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
900 PM EDT SAT AUG 11 2018

DEC005-120400-
/O.CON.KPHI.FF.W.0069.000000T0000Z-180812T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex DE-
900 PM EDT SAT AUG 11 2018

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL MIDNIGHT EDT FOR
SUSSEX COUNTY...

At 859 PM EDT, Doppler radar indicated thunderstorms producing heavy 
rain in northern Sussex County.  The rate of rainfall...one to two 
inches per hour...will cause flash flooding within the heavier 
rainbands as the storms move southeast through the county.

Some locations that could experience flooding include...
Georgetown, Milford, Seaford, Millsboro, Laurel, Lewes, Milton,
Selbyville, Bridgeville, Delmar, Dagsboro, Millville, Ellendale,
Henlopen Acres, Gumboro, Cape Henlopen State Park, Sycamore, Long
Neck, Ocean View and Blades.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 3846 7569 3883 7572 3884 7555 3892 7544
      3892 7541 3896 7538 3892 7528 3881 7514
      3881 7506 3845 7505

$$

JJM

639 
WGUS71 KPHI 120330
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1130 PM EDT SAT AUG 11 2018

DEC005-120338-
/O.CAN.KPHI.FF.W.0069.000000T0000Z-180812T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex DE-
1130 PM EDT SAT AUG 11 2018

...THE FLASH FLOOD WARNING FOR SUSSEX COUNTY IS CANCELLED...

While rain continues in the area, the threat of heavy flooding rain 
has ended.

LAT...LON 3846 7569 3883 7572 3884 7555 3892 7544
      3892 7541 3896 7538 3892 7528 3881 7514
      3881 7506 3845 7505

$$

Iovino

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 11, 9:11 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle	81 min
Aug 12, 5:28 AM EDT	Coastal Flood Advisory	PHI	Kent, New Castle, Sussex	24 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.