Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 90, NWS Des Moines, IA

May 20, 1998Carroll County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at May 20, 1998, 4:31 AM CDT for Carroll County, Iowa. It was in force for 49 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
May 20, 1998, 4:31 AM CDT (09:31 UTC)
Expired
May 20, 1998, 5:20 AM CDT
In force
49 min
Issued by
NWS Des Moines, IA
Area
Whole counties

County Carroll County, IA

The radar

The Des Moines radar (KDMX), 100 km from the middle of the area, began a volume at 09:31 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
May 20, 1:45 AM CDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 9.5 hours before the alert went out and 148 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 1998-05-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2454 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 1998-05-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 21 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
2454 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
1962 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
21 m²/s²
0-3 km storm-relative helicity
64 m²/s²
Significant tornado parameter
0.0
Supercell composite
3.4

Open this sounding in Storm Lab

The text

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

557 
WUUS1 KDSM 200932 RRA
SVRDSM
IAC027-201020-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
431 AM CDT WED MAY 20 1998

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  CARROLL COUNTY IN WEST CENTRAL IOWA

* UNTIL 520 AM CDT

* AT 429 AM CDT... DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM 60
  MILES NORTHEAST OF OMAHA OR 6 MILES WEST NORTHWEST OF MANNING
  MOVING EAST NORTHEAST AT 35 MPH.

* THIS STORM CAN BE EXPECTED NEAR...
   MANNING            BY 434 AM CDT
   ARCADIA            BY 439 AM CDT
   TEMPLETON          BY 443 AM CDT
   HALBUR             BY 444 AM CDT
   CARROLL            BY 455 AM CDT

DAMAGING WINDS AND HEAVY RAIN ARE LIKELY. GO INSIDE A STURDY
BUILDING AND STAY AWAY FROM WINDOWS

COGIL

The office that day

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

IssuedProductOfficeCountiesLasted
May 19, 7:23 PM CDTSevere Thunderstorm WarningDMXAppanoose47 min
May 19, 7:31 PM CDTSevere Thunderstorm WarningDMXWarren34 min
May 19, 7:59 PM CDTSevere Thunderstorm WarningDMXLucas36 min
May 20, 3:46 AM CDTSevere Thunderstorm WarningDMXCrawford49 min
May 20, 3:53 AM CDTSevere Thunderstorm WarningDMXAudubon, Cass62 min
May 20, 5:20 AM CDTSevere Thunderstorm WarningDMXDallas, Madison, Polk, Warren60 min
May 20, 5:47 AM CDTSevere Thunderstorm WarningDMXJasper, Marion48 min
May 20, 10:19 AM CDTSevere Thunderstorm WarningDMXMarion36 min
May 20, 10:21 AM CDTSevere Thunderstorm WarningDMXMarion34 min
May 20, 10:50 AM CDTSevere Thunderstorm WarningDMXMonroe35 min
May 20, 11:05 AM CDTSevere Thunderstorm WarningDMXWapello35 min
May 20, 11:45 AM CDTSevere Thunderstorm WarningDMXMahaska20 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.