Alert archive / Iowa / Tornado Warnings in 2004

Tornado Warning 4, NWS Des Moines, IA

April 20, 2004Polk County, Iowa

NWS Des Moines, IA issued this tornado warning at Apr 20, 2004, 5:56 PM CDT for Polk County, Iowa. It was in force for 34 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
Apr 20, 2004, 5:56 PM CDT (22:56 UTC)
Expired
Apr 20, 2004, 6:30 PM CDT
In force
34 min
Issued by
NWS Des Moines, IA
Area
Counties, with a storm outline in the text

County Polk County, IA

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 10.9 hours before the alert went out and 230 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 2004-04-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 13 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 12:00Z on 2004-04-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 74 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
13 J/kg
Mixed-layer CIN
-209 J/kg
Mixed-layer LCL
546 m above ground
0-6 km bulk shear
44 kt
0-1 km storm-relative helicity
74 m²/s²
0-3 km storm-relative helicity
105 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.2

Open this sounding in Storm Lab

The text

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

719 
WFUS53 KDMX 202256
TORDMX
IAC153-202330-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
556 PM CDT TUE APR 20 2004

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* TORNADO WARNING FOR...
  SOUTHERN POLK COUNTY IN CENTRAL IOWA
  THIS INCLUDES THE CITY OF DES MOINES

* UNTIL 630 PM CDT

* AT 554 PM...RADAR INDICATED A THUNDERSTORM CAPABLE OF PRODUCING A
  TORNADO 6 MILES SOUTHWEST OF WEST DES MOINES...OR ABOUT 12 MILES
  SOUTHWEST OF DES MOINES...MOVING EAST AT 40 MPH.

* THE STORM WILL BE...

  5 MILES SOUTH OF WEST DES MOINES AROUND 600 PM...
  NEAR DES MOINES INTERNATIONAL AIRPORT AROUND 605 PM...
  5 MILES SOUTH OF DES MOINES AROUND 610 PM...
  5 MILES SOUTH OF PLEASANT HILL AROUND 615 PM AND
  NEAR RUNNELLS AROUND 630 PM.

THIS IS A HAZARDOUS SITUATION. SEEK SHELTER IN A BASEMENT...OR IN AN
INTERIOR ROOM. STAY AWAY FROM WINDOWS. IF YOU ARE OUTSIDE OR IN A
CAR...SEEK SHELTER IN A REINFORCED BUILDING.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM TUESDAY
EVENING FOR SOUTHEASTERN IOWA.

LAT...LON 4159 9382 4150 9379 4150 9333 4162 9336


$$

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 20, 3:57 PM CDTSevere Thunderstorm WarningDMXAdair33 min
Apr 20, 4:15 PM CDTSevere Thunderstorm WarningDMXMadison45 min
Apr 20, 4:30 PM CDTSevere Thunderstorm WarningDMXAdair, Cass, Guthrie45 min
Apr 20, 5:18 PM CDTSevere Thunderstorm WarningDMXAdair, Dallas, Madison42 min

Nearby

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