Alert archive / Iowa / Tornado Warnings in 2001

Tornado Warning 59, NWS Des Moines, IA

September 6, 2001Polk County, Iowa

NWS Des Moines, IA issued this tornado warning at Sep 6, 2001, 3:40 PM CDT for Polk County, Iowa. It was in force for 30 min. 1 report came from inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties, with what was reported inside it.

The facts

Issued
Sep 6, 2001, 3:40 PM CDT (20:40 UTC)
Expired
Sep 6, 2001, 4:10 PM CDT
In force
30 min
Issued by
NWS Des Moines, IA
Area
Whole counties; the outline is the Mesonet’s reconstruction

County Polk County, IA

What was reported inside it

TimeReportWhereRemark
Sep 6, 3:50 PM CDTThunderstorm Wind 50 EJohnston, IA

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 8.7 hours before the alert went out and 223 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 2001-09-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 64 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 2001-09-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 46 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
64 J/kg
Mixed-layer CIN
-66 J/kg
Mixed-layer LCL
1147 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
46 m²/s²
0-3 km storm-relative helicity
32 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

140 
WFUS53 KDMX 062040
TORDSM
IAC153-062110-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
340 PM CDT THU SEP 6 2001

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

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

* UNTIL 410 PM CDT

* AT 335 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  TORNADO OVER WEST DES MOINES...OR ABOUT 8 MILES WEST OF DES
  MOINES...MOVING NORTHEAST AT 25 MPH.

* THE TORNADO WILL BE...
  NEAR URBANDALE...JOHNSTON...6 MILES NORTHWEST OF DES MOINES AROUND
     350 PM

LAT...LON 4156 9382 4156 9357 4169 9356 4168 9381

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 6, 2:43 PM CDTSevere Thunderstorm WarningDMXBoone, Story47 min
Sep 6, 3:50 PM CDTTornado WarningDMXPolk30 min
Sep 6, 4:18 PM CDTSevere Thunderstorm WarningDMXStory42 min
Sep 6, 5:07 PM CDTSevere Thunderstorm WarningDMXGrundy38 min
Sep 6, 5:14 PM CDTSevere Thunderstorm WarningDMXBlack Hawk26 min
Sep 6, 6:10 PM CDTSevere Thunderstorm WarningDMXBremer25 min

Nearby

Tornado Warnings in Iowa, 2001Every tornado warning in 2001Tornadoes in 2001

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive.