Alert archive / Delaware / Flash Flood Warnings in 2011

Flash Flood Warning 57, NWS Philadelphia/Mount Holly

September 8, 2011Kent County, Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 8, 2011, 3:26 AM EDT for Kent County, Sussex County, Delaware. It was in force for 5 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: Sep 8, 2011, 3:26 AM EDT (07:26 UTC)
Expired: Sep 8, 2011, 8:39 AM EDT
In force: 5 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Kent County, DE, Sussex County, DE

The radar

The Dover AFB radar (KDOX), 12 km from the middle of the area, began a volume at 07:29 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, 7.4 hours before the alert went out and 110 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: 791 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 740 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 72 m²/s²
0-3 km storm-relative helicity: 109 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

507 
WGUS51 KPHI 080726
FFWPHI
DEC001-005-081330-
/O.NEW.KPHI.FF.W.0057.110908T0726Z-110908T1330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
326 AM EDT THU SEP 8 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  KENT COUNTY...
  SUSSEX COUNTY...

* UNTIL 930 AM EDT...

* AT 320 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR             
  INDICATED A LONG LINE OF SHOWERS AND THUNDERSTORMS ORIENTED 
  FROM SOUTH TO NORTH THROUGH CENTRAL AND EASTERN SUSSEX AND KENT    
  COUNTIES. THIS LINE EXTENDS SOUTH TO THE VIRGINIA BORDER. WITH     
  RAINFALL RATES UP TO ONE INCH PER HOUR...AND GIVEN THE ALREADY     
  SATURATED CONDITIONS...RAPID RUNOFF IS OCCURRING. EXPECTED ROADWAY 
  AND POOR DRAINAGE FLOODING. SMALL STREAMS WILL ALSO RISE RAPIDLY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER ELEVATIONS TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

&&

LAT...LON 3846 7569 3929 7570 3931 7559 3937 7551
      3932 7543 3924 7538 3916 7540 3909 7540
      3898 7529 3893 7530 3880 7516 3861 7511
      3860 7514 3860 7510 3845 7506

$$

FORECASTER: JJM

1 follow-up statement

529 
WGUS71 KPHI 081239
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
839 AM EDT THU SEP 8 2011

DEC001-005-081249-
/O.CAN.KPHI.FF.W.0057.000000T0000Z-110908T1330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
KENT DE-SUSSEX DE-
839 AM EDT THU SEP 8 2011

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR SUSSEX AND KENT
COUNTIES...

THE WATERS FROM THE EARLIER HEAVY RAINS ARE RECEDING AND FLOOD WATERS
NO LONGER POSE A THREAT TO LIFE OR PROPERTY. THEREFORE...THE FLASH
FLOOD WARNING HAS BEEN CANCELLED.

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO DOVER AND
GEORGETOWN.

LAT...LON 3846 7569 3929 7570 3931 7559 3937 7551
      3932 7543 3924 7538 3916 7540 3909 7540
      3898 7529 3893 7530 3880 7516 3861 7511
      3860 7514 3860 7510 3845 7506

$$

KRUZDLO

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 8, 1:29 AM EDT	Areal Flood Advisory	PHI	Kent, Sussex	4 hr
Sep 8, 3:41 AM EDT	River Flood Warning	PHI	New Castle	14 hr
Sep 8, 5:30 AM EDT	Coastal Flood Advisory	PHI	Kent, New Castle	17 hr
Sep 8, 9:23 AM EDT	Areal Flood Advisory	PHI	Kent, New Castle, Sussex	4 hr
Sep 8, 9:56 AM EDT	Special Weather Statement	PHI	Kent	64 min
Sep 8, 1:51 PM EDT	Areal Flood Advisory	PHI	Kent, Sussex	6 hr
Sep 8, 3:53 PM EDT	Flash Flood Warning	PHI	Kent, Sussex	4 hr
Sep 8, 7:41 PM EDT	Areal Flood Warning	PHI	Kent, Sussex	14 hr

Nearby

Flash Flood Warnings in Delaware, 2011 Every flash flood warning in 2011

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.