Alert archive / Iowa / Severe Thunderstorm Warnings in 2004

Severe Thunderstorm Warning 430, NWS Sioux Falls, SD

July 31, 2004Plymouth County, Sioux County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Jul 31, 2004, 9:49 PM CDT for Plymouth County, Sioux County, Iowa. It was in force for 41 min. 2 reports 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
Jul 31, 2004, 9:49 PM CDT (02:49 UTC)
Expired
Jul 31, 2004, 10:30 PM CDT
In force
41 min
Issued by
NWS Sioux Falls, SD
Area
Counties, with a storm outline in the text

Counties Plymouth County, IA, Sioux County, IA

The radar

The Sioux Falls radar (KFSD), 75 km from the middle of the area, began a volume at 02:49 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

TimeReportWhereRemark
Jul 31, 9:59 PM CDTHAIL 0.751 N Hawarden, IA
Jul 31, 10:38 PM CDTHAIL 1Hawarden, IA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Jul 31, 9:45 PM CDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 2.8 hours before the alert went out and 182 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 00:00Z on 2004-08-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1429 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 00:00Z on 2004-08-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 94 square meters per square second.1939Sfc1 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
1429 J/kg
Mixed-layer CIN
-97 J/kg
Mixed-layer LCL
1769 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
94 m²/s²
0-3 km storm-relative helicity
282 m²/s²
Significant tornado parameter
0.2
Supercell composite
6.7

Open this sounding in Storm Lab

The text

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

000 
WUUS53 KFSD 010249
SVRFSD
IAC149-167-010330-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
948 PM CDT SAT JUL 31 2004

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHWEST PLYMOUTH COUNTY IN NORTHWEST IOWA
  SOUTHWEST SIOUX COUNTY IN NORTHWEST IOWA

* UNTIL 1030 PM CDT

* AT 945 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING DIME SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED 9 MILES
  WEST OF HAWARDEN...OR ABOUT 7 MILES SOUTHEAST OF BERESFORD...MOVING
  SOUTHEAST AT 25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  HAWARDEN AROUND 1005 PM CDT
  IRETON AROUND 1020 PM CDT
  CRAIG AROUND 1030 PM CDT

SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES WITH LITTLE OR NO ADVANCE
WARNING. PREPARE TO MOVE TO A PLACE OF SAFETY IN A STURDY STRUCTURE
SUCH AS A BASEMENT OR SMALL INTERIOR ROOM IF A TORNADO IS SPOTTED.

LAT...LON 4312 9638 4304 9652 4270 9655 4280 9624

$$
RSR

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 31, 7:59 PM CDTTornado WarningFSDLyon31 min
Jul 31, 8:01 PM CDTTornado WarningFSDLyon29 min
Jul 31, 8:11 PM CDTSevere Thunderstorm WarningFSDOsceola34 min
Jul 31, 8:30 PM CDTTornado WarningFSDLyon30 min
Jul 31, 8:58 PM CDTSevere Thunderstorm WarningFSDLyon, Osceola32 min
Jul 31, 9:48 PM CDTSevere Thunderstorm WarningFSDLyon, Osceola27 min
Jul 31, 10:08 PM CDTSevere Thunderstorm WarningFSDClay, O'Brien22 min
Jul 31, 10:30 PM CDTSevere Thunderstorm WarningFSDBuena Vista, Clay, O'Brien30 min
Jul 31, 10:44 PM CDTSevere Thunderstorm WarningFSDCherokee, Sioux31 min
Jul 31, 10:56 PM CDTFlash Flood WarningFSDO'Brien2 hr
Jul 31, 11:01 PM CDTSevere Thunderstorm WarningFSDBuena Vista, Clay, O'Brien14 min
Jul 31, 11:03 PM CDTSevere Thunderstorm WarningFSDBuena Vista, Clay, O'Brien27 min
Jul 31, 11:13 PM CDTSevere Thunderstorm WarningFSDCherokee32 min
Jul 31, 11:32 PM CDTSevere Thunderstorm WarningFSDPlymouth28 min
Jul 31, 11:43 PM CDTSevere Thunderstorm WarningFSDBuena Vista, Cherokee32 min
Aug 1, 12:16 AM CDTSevere Thunderstorm WarningFSDCherokee, Ida44 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2004Every severe thunderstorm 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.