Alert archive / Iowa / Tornado Warnings in 2004

Tornado Warning 51, NWS Sioux Falls, SD

July 31, 2004Lyon County, Iowa

NWS Sioux Falls, SD issued this tornado warning at Jul 31, 2004, 7:59 PM CDT for Lyon County, Iowa. It was in force for 31 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 31, 2004, 7:59 PM CDT (00:59 UTC)
Expired: Jul 31, 2004, 8:30 PM CDT
In force: 31 min
Issued by: NWS Sioux Falls, SD
Area: Counties, with a storm outline in the text

County Lyon County, IA

The radar

The Sioux Falls radar (KFSD), 64 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 watch it was issued in

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

Issued	Product	Office	Lasted
Jul 31, 3:00 PM CDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.0 hours before the alert went out and 235 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: 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 
WFUS53 KFSD 010059
TORFSD
IAC119-010130-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
758 PM CDT SAT JUL 31 2004

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* TORNADO WARNING FOR...
  EASTERN LYON COUNTY IN NORTHWEST IOWA

* UNTIL 830 PM CDT

* AT 756 PM CDT...LOCAL LAW ENFORCEMENT REPORTED A TORNADO 1 MILE
  NORTH OF ELLSWORTH MINNESOTA...MOVING SOUTHEAST AROUND 15 MPH.

* THE TORNADO WILL BE NEAR...
  LITTLE ROCK AROUND 815 PM CDT
  GEORGE AROUND 830 PM CDT

A TORNADO HAS BEEN CONFIRMED BY LAW ENFORCEMENT. TAKE COVER IN A 
STURDY BUILDING NOW. MOBILE HOMES AND VEHICLES ARE NOT SAFE.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 1000 PM CDT SATURDAY EVENING
FOR NORTHWEST IOWA AND SOUTHWEST MINNESOTA AND SOUTHEASTERN SOUTH
DAKOTA.

LAT...LON 4350 9588 4350 9610 4328 9610 4328 9588

$$
 JH

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 31, 8:01 PM CDT	Tornado Warning	FSD	Lyon	29 min
Jul 31, 8:11 PM CDT	Severe Thunderstorm Warning	FSD	Osceola	34 min
Jul 31, 8:30 PM CDT	Tornado Warning	FSD	Lyon	30 min
Jul 31, 8:58 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Osceola	32 min
Jul 31, 9:48 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Osceola	27 min
Jul 31, 9:49 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Sioux	41 min
Jul 31, 10:08 PM CDT	Severe Thunderstorm Warning	FSD	Clay, O'Brien	22 min
Jul 31, 10:30 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay, O'Brien	30 min
Jul 31, 10:44 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Sioux	31 min
Jul 31, 10:56 PM CDT	Flash Flood Warning	FSD	O'Brien	2 hr
Jul 31, 11:01 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay, O'Brien	14 min
Jul 31, 11:03 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay, O'Brien	27 min
Jul 31, 11:13 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee	32 min
Jul 31, 11:32 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth	28 min
Jul 31, 11:43 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee	32 min
Aug 1, 12:16 AM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Ida	44 min

Nearby

Tornado Warnings in Iowa, 2004 Every tornado warning in 2004 Tornadoes 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.