Alert archive / Delaware / Flash Flood Warnings in 2009

Flash Flood Warning 36, NWS Philadelphia/Mount Holly

August 12, 2009Kent County, New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 12, 2009, 4:39 PM EDT for Kent County, New Castle 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 12, 2009, 4:39 PM EDT (20:39 UTC)
Expired
Aug 12, 2009, 7:25 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

The radar

The Dover AFB radar (KDOX), 50 km from the middle of the area, began a volume at 20:42 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

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 8.7 hours before the alert went out and 48 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-pSkew-T log-p diagram, Phillips Aaf/Abe, MD at 12:00Z on 2009-08-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 402 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phillips Aaf/Abe, MD at 12:00Z on 2009-08-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 39 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
402 J/kg
Mixed-layer CIN
-103 J/kg
Mixed-layer LCL
1048 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
39 m²/s²
0-3 km storm-relative helicity
111 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.3

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 122039
FFWPHI
DEC001-003-130045-
/O.NEW.KPHI.FF.W.0036.090812T2039Z-090813T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
439 PM EDT WED AUG 12 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTH CENTRAL KENT COUNTY IN CENTRAL DELAWARE...
  SOUTH CENTRAL NEW CASTLE COUNTY IN NORTHERN DELAWARE...

* UNTIL 845 PM EDT

* AT 436 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
SLOW MOVING THUNDERSTORMS WITH TORRENTIAL RAIN ACROSS PORTIONS OF 
THE WARNED AREA. RAINFALL AMOUNTS OF ONE TO THREE INCHES ARE 
POSSIBLE WITH RAINFALL RATES APPROACHING SIX INCHES PER HOUR.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO GREEN
  SPRING...SMYRNA AND CLAYTON

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE 
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS 
SAFELY. MOVE TO HIGHER GROUND.

&&

LAT...LON 3910 7562 3928 7571 3934 7572 3940 7559
      3928 7543

$$

KRUZDLO
1 follow-up statement
000 
WGUS71 KPHI 122325
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
725 PM EDT WED AUG 12 2009

DEC001-003-122335-
/O.CAN.KPHI.FF.W.0036.000000T0000Z-090813T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
KENT DE-NEW CASTLE DE-
725 PM EDT WED AUG 12 2009

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR SOUTH CENTRAL NEW
CASTLE AND NORTH CENTRAL KENT COUNTIES...

THE HEAVY RAIN HAS MOVED OUT OF THE AREA. THE FLASH FLOOD WARNING  
HAS BEEN CANCELLED.

LAT...LON 3910 7562 3928 7571 3934 7572 3940 7559
      3928 7543

$$

KRUZDLO

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 12, 4:16 PM EDTAreal Flood AdvisoryPHIKent3 hr
Aug 12, 4:55 PM EDTFlash Flood WarningPHINew Castle3 hr
Aug 12, 5:55 PM EDTFlash Flood WarningPHINew Castle100 min

Nearby

Flash Flood Warnings in Delaware, 2009Every flash flood warning in 2009

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.