Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 98, NWS Des Moines, IA

May 21, 1998Taylor County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at May 21, 1998, 6:36 AM CDT for Taylor 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 21, 1998, 6:36 AM CDT (11:36 UTC)
Expired
May 21, 1998, 7:25 AM CDT
In force
49 min
Issued by
NWS Des Moines, IA
Area
Whole counties

County Taylor County, IA

The radar

The Des Moines radar (KDMX), 137 km from the middle of the area, began a volume at 11:36 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 nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 11.6 hours before the alert went out and 155 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 1998-05-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 365 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 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 1998-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 34 square meters per square second.193958Sfc1 km3 km6 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
365 J/kg
Mixed-layer CIN
-316 J/kg
Mixed-layer LCL
1026 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
34 m²/s²
0-3 km storm-relative helicity
-17 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.

626 
WUUS1 KDSM 211137 RRA
SVRDSM
IAC173-211225-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
636 AM CDT THU MAY 21 1998

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  TAYLOR COUNTY IN SOUTHWESTERN IOWA

* UNTIL 725 AM CDT

* AT 634 AM CDT... DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM 62
  MILES EAST SOUTHEAST OF OMAHA OR 6 MILES NORTH OF NEW MARKET
  MOVING EAST SOUTHEAST AT 30 MPH.

* THIS STORM CAN BE EXPECTED NEAR...
   GRAVITY            BY 644 AM CDT
   SHARPSBURG         BY 650 AM CDT
   BEDFORD            BY 653 AM CDT
   CLEARFIELD         BY 706 AM CDT

DAMAGING WINDS AND LARGE HAIL ARE LIKELY. GO INSIDE A STURDY
BUILDING AND STAY AWAY FROM WINDOWS

GF

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

In the hours before

Special weather statement, May 21, 6:00 AM CDT, 36 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-211500-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
600 AM CDT THU MAY 21 1998

HAZARD--SCATTERED THUNDERSTORMS CAPABLE OF PRODUCING STRONG WINDS
...LARGE HAIL AND HEAVY RAINFALL.

AREA OF CONCERN AND TIMING DETAILS--SOUTHWESTERN HALF OF IOWA...ALONG
AND SOUTHWEST OF A FORT DODGE TO MARSHALLTOWN TO JUST NORTH OF OTTUMWA
LINE BETWEEN 300 PM CDT AND 900 PM CDT.

METEOROLOGICAL COMMENTS--DAYTIME HEATING WILL CONTINUE TO DESTABILIZE
THE AIRMASS OVER IOWA JUST NORTH OF A STATIONARY FRONTAL BOUNDARY DURING
THE AFTERNOON AND INTO THE EVENING.  UPPER AIR FIELDS FAVOR THE
CONVECTION ORGANIZING INTO A BOW ECHO LINE WITH STRONG WINDS.

PRECAUTIONS--SPOTTER ACTIVATION IS NOT ANTICIPATED UNTIL LATE AFTERNOON.
HOWEVER...EMERGENCY MANAGERS AND SPOTTER GROUPS SHOULD KEEP ABREAST
OF UPDATED CENTRAL IOWA THUNDERSTORM OUTLOOKS DURING THE DAY TODAY.

FORSTER

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.