Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 17, NWS Des Moines, IA

April 6, 1998Boone County, Story County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Apr 6, 1998, 9:13 PM CDT for Boone County, Story County, Iowa. It was in force for 32 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, 9:13 PM CDT (02:13 UTC)
Expired
Apr 6, 1998, 9:45 PM CDT
In force
32 min
Issued by
NWS Des Moines, IA
Area
Whole counties

Counties Boone County, IA, Story County, IA

The radar

The Des Moines radar (KDMX), 34 km from the middle of the area, began a volume at 02:14 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, 2.2 hours before the alert went out and 236 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.

084 
WUUS1 KDSM 070214 RRA
SVRDSM
IAC015-169-070245-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
913 PM CDT MON APR 6 1998

* SEVERE THUNDERSTORM WARNING FOR
  EASTERN BOONE COUNTY - CENTRAL IOWA
  WESTERN STORY COUNTY - CENTRAL IOWA

* UNTIL 945 PM CDT
 
* SOME AREAS AFFECTED
    NAPIER
    AMES
    GILBERT

* AT 915 PM CDT RADAR INDICATED A SEVERE THUNDERSTORM JUST SOUTHWEST OF
  BOONE OR 35 MILES NORTHWEST OF DES MOINES MOVING EAST AT 30 MPH.

* THE STORM WILL BE NEAR AMES BY 930 PM CDT.

THIS IS A DANGEROUS STORM.  DO NOT GO OUTDOORS.

FAB

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 6, 7:36 PM CDTTornado WarningDMXBoone, Hamilton, Webster34 min
Apr 6, 8:13 PM CDTTornado WarningDMXBoone, Greene32 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1998Every severe thunderstorm warning 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.