Alert archive / Iowa / Tornado Warnings in 1998

Tornado Warning 2, NWS Omaha, NE

April 6, 1998Mills County, Pottawattamie County, Iowa

NWS Omaha, NE issued this tornado warning at Apr 6, 1998, 8:06 PM CDT for Mills County, Pottawattamie County, Iowa. It was in force for 29 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Apr 6, 1998, 8:06 PM CDT (01:06 UTC)
Expired
Apr 6, 1998, 8:35 PM CDT
In force
29 min
Issued by
NWS Omaha, NE
Area
Whole counties

Counties Mills County, IA, Pottawattamie County, IA

The radar

The Omaha radar (KOAX), 67 km from the middle of the area, began a volume at 01:07 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.

IssuedProductOfficeLasted
Apr 6, 6:30 PM CDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.1 hours before the alert went out and 68 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 1998-04-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 25 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 1998-04-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 158 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
25 J/kg
Mixed-layer CIN
-306 J/kg
Mixed-layer LCL
711 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
158 m²/s²
0-3 km storm-relative helicity
414 m²/s²
Significant tornado parameter
0.0
Supercell composite
3.2

Open this sounding in Storm Lab

The text

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

700 
WFUS1 KOMA 070107 RRA
TOROMA
IAC129-155-070135-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
806 PM CDT MON APR 6 1998

* TORNADO WARNING FOR
  POTTAWATTAMIE COUNTY IN SOUTHWESTERN IOWA
  NORTHEASTERN MILLS COUNTY IN SOUTHWESTERN IOWA

* UNTIL 835 PM CDT
 
* SOME LOCATIONS AFFECTED
    HENDERSON                    NOW
    CARSON                       BY AROUND 815 PM CDT
    MACEDONIA                    BY AROUND 815 PM CDT

* AT 801 PM CDT...A POSSIBLE TORNADO WAS INDICATED BY DOPPLER RADAR
  32 MILES SOUTHEAST OF DOWNTOWN OMAHA OR 7 MILES NORTHWEST OF
  EMERSON MOVING NORTHEAST AT 15 MPH.
 
PERSONS IN THE WARNED AREA SHOULD TAKE SHELTER IN A BASEMENT IF
AVAILABLE.  OTHERWISE GO TO A SMALL INTERIOR ROOM ON THE LOWEST
FLOOR.  CARS AND MOBILE HOMES SHOULD BE ABANDONED.

CHERMOK

The office that day

Everything else NWS Omaha, NE issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 6, 7:05 PM CDTSevere Thunderstorm WarningOAXMills, Pottawattamie60 min
Apr 6, 7:32 PM CDTTornado WarningOAXMills33 min
Apr 6, 8:11 PM CDTSevere Thunderstorm WarningOAXMills49 min

Nearby

Tornado Warnings in Iowa, 1998Every tornado warning in 1998Tornadoes in 1998

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.