Alert archive / Iowa / Flash Flood Warnings in 2004

Flash Flood Warning 35, NWS Sioux Falls, SD

September 17, 2004Clay County, Iowa

NWS Sioux Falls, SD issued this flash flood warning at Sep 17, 2004, 4:14 PM CDT for Clay County, Iowa. It was in force for 2 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 17, 2004, 4:14 PM CDT (21:14 UTC)
Expired
Sep 17, 2004, 6:15 PM CDT
In force
2 hr
Issued by
NWS Sioux Falls, SD
Area
Counties, with a storm outline in the text

County Clay County, IA

The radar

The Sioux Falls radar (KFSD), 134 km from the middle of the area, began a volume at 21:15 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

Omaha, NE (KOAX), launched 12:00Z, 9.2 hours before the alert went out and 222 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, Omaha, NE at 12:00Z on 2004-09-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Omaha, NE at 12:00Z on 2004-09-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 204 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2346 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
204 m²/s²
0-3 km storm-relative helicity
267 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1

Open this sounding in Storm Lab

The text

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

000 
WGUS53 KFSD 172114
FFWFSD
IAC041-172315-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
414 PM CDT FRI SEP 17 2004

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CLAY COUNTY IN NORTHWEST IOWA

* UNTIL 615 PM CDT

* AT 412 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  FLASH FLOODING FROM CONTINUOUS THUNDERSTORM ACTIVITY.

WHILE THE EXCESSIVE RAINFALL HAS ENDED...RUNOFF AND STANDING WATER 
WILL CONTINUE FOR THE NEXT COUPLE OF HOURS.

EXCESSIVE RUNOFF FROM 3 TO 4 INCHES OF RAIN THAT FELL LATE THIS 
MORNING AND EARLY THIS AFTERNOON WILL CAUSE FLOODING OF SMALL CREEKS 
AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS 
WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

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.

FLOODING IS OCCURRING. IT IS IMPORTANT TO KNOW WHERE YOU ARE 
RELATIVE TO STREAMS...RIVERS...OR CREEKS WHICH CAN BECOME KILLERS IN 
HEAVY RAINS. CAMPERS AND HIKERS SHOULD AVOID STREAMS OR CREEKS.

LAT...LON 4325 9538 4294 9538 4293 9493 4325 9494

$$

08
3 follow-up statements
000 
WGUS73 KFSD 172217
FFSFSD
IAC041-172315-

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
516 PM CDT FRI SEP 17 2004

...A FLASH FLOOD WARNING CONTINUES UNTIL 615 PM CDT FOR CLAY COUNTY 
IN NORTHWEST IOWA...

AT 516 PM CDT...RAINFALL HAD ENDED OVER THE AREA...BUT RUNOFF AND 
STANDING WATER CONTINUE TO BE A PROBLEM. NATIONAL WEATHER SERVICE 
DOPPLER RADAR CONTINUED TO INDICATE A THUNDERSTORM PRODUCING FLASH 
FLOODING.  THIS STORM WAS LOCATED 4 MILES SOUTH OF SPENCER  THE 
THUNDERSTORM WITH EXCESSIVE RAIN WAS NEARLY STATIONARY.

EXCESSIVE RUNOFF FROM 3 TO 4 INCHES OF RAIN THAT FELL LATE THIS 
MORNING AND EARLY THIS AFTERNOON WILL CAUSE FLOODING OF SMALL CREEKS 
AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS 
WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

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.

LAT...LON 4325 9538 4294 9538 4293 9493 4325 9494

$$
WILLIAMS
000 
WGUS73 KFSD 172229 CCA
FFSFSD
IAC041-172315-

FLASH FLOOD STATEMENT...CORRECTION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
530 PM CDT FRI SEP 17 2004

...A FLASH FLOOD WARNING CONTINUES UNTIL 615 PM CDT FOR CLAY COUNTY 
IN NORTHWEST IOWA...

AT 516 PM CDT...RAINFALL HAD ENDED OVER THE AREA...BUT RUNOFF AND 
STANDING WATER CONTINUE TO BE A PROBLEM.

EXCESSIVE RUNOFF FROM 3 TO 4 INCHES OF RAIN THAT FELL LATE THIS 
MORNING AND EARLY THIS AFTERNOON WILL CAUSE FLOODING OF SMALL CREEKS 
AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS 
WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

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.

LAT...LON 4325 9538 4294 9538 4293 9493 4325 9494

$$
WILLIAMS
000 
WGUS73 KFSD 172316
FFSFSD
IAC041-172321-

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
615 PM CDT FRI SEP 17 2004

...THE FLASH FLOOD WARNING FOR CLAY COUNTY EXPIRED AT 615 PM CDT...

RAINFALL HAS ENDED OVER THE AREA AND NO NEW FLASH FLOODING IS 
EXPECTED. HOWEVER...WATER CONTINUES TO COVER MANY LOW AREAS 
INCLUDING SOME ROADS...AS IT SLOWLY RECEDES.  

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.

LAT...LON 4325 9538 4294 9538 4293 9493 4325 9494

$$
WILLIAMS

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 17, 8:56 AM CDTSevere Thunderstorm WarningFSDSioux34 min
Sep 17, 1:12 PM CDTFlash Flood WarningFSDClay3 hr
Sep 17, 1:49 PM CDTSevere Thunderstorm WarningFSDClay26 min

Nearby

Flash Flood Warnings in Iowa, 2004Every flash flood warning in 2004

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.