Alert archive / Iowa / Tornado Warnings in 2004

Tornado Warning 6, NWS Sioux Falls, SD

April 18, 2004Woodbury County, Iowa

NWS Sioux Falls, SD issued this tornado warning at Apr 18, 2004, 8:01 PM CDT for Woodbury County, Iowa. It was in force for 29 min. 3 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: Apr 18, 2004, 8:01 PM CDT (01:01 UTC)
Expired: Apr 18, 2004, 8:30 PM CDT
In force: 29 min
Issued by: NWS Sioux Falls, SD
Area: Counties, with a storm outline in the text

County Woodbury County, IA

The radar

The Omaha radar (KOAX), 117 km from the middle of the area, began a volume at 01:03 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

Time	Report	Where
Apr 18, 8:02 PM CDT	TORNADO	3 Nw Hornick, IA
Apr 18, 8:15 PM CDT	HAIL 0.88	Anthon, IA
Apr 18, 8:18 PM CDT	HAIL 0.75	3 Sw Correctionville, 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.

Issued	Product	Office	Lasted
Apr 18, 4:40 PM CDT	Tornado Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.0 hours before the alert went out and 117 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: 1099 J/kg
Mixed-layer CIN: -135 J/kg
Mixed-layer LCL: 1062 m above ground
0-6 km bulk shear: 64 kt
0-1 km storm-relative helicity: 334 m²/s²
0-3 km storm-relative helicity: 385 m²/s²
Significant tornado parameter: 1.2
Supercell composite: 5.0

Open this sounding in Storm Lab

The text

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

829 
WFUS53 KFSD 190101
TORFSD
IAC193-190130-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
801 PM CDT SUN APR 18 2004

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* TORNADO WARNING FOR...
  WOODBURY COUNTY IN NORTHWEST IOWA

* UNTIL 830 PM CDT

* AT 801 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 16 MILES
  SOUTHWEST OF ANTHON...OR ABOUT 19 MILES SOUTHEAST OF SIOUX CITY...
  MOVING EAST AT 40 MPH.

* THE TORNADO WILL BE NEAR...
  ANTHON AROUND 820 PM CDT
  OTO AROUND 822 PM CDT
  CORRECTIONVILLE AROUND 825 PM CDT

IF YOU ARE IN THE PATH OF THIS STORM...TAKE COVER IMMEDIATELY.

LAT...LON 4235 9626 4222 9618 4228 9573 4251 9577

$$

BOUSTEAD

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 18, 7:12 PM CDT	Severe Thunderstorm Warning	FSD	Clay	63 min
Apr 18, 7:54 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	36 min
Apr 18, 7:56 PM CDT	Severe Thunderstorm Warning	FSD	Woodbury	34 min
Apr 18, 8:19 PM CDT	Severe Thunderstorm Warning	FSD	Ida	26 min
Apr 18, 8:25 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee	50 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.