Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 13, NWS Des Moines, IA

April 6, 1998Guthrie County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Apr 6, 1998, 2:50 PM CDT for Guthrie County, Iowa. It was in force for 30 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, 2:50 PM CDT (19:50 UTC)
Expired: Apr 6, 1998, 3:20 PM CDT
In force: 30 min
Issued by: NWS Des Moines, IA
Area: Whole counties

County Guthrie County, IA

The radar

The Des Moines radar (KDMX), 65 km from the middle of the area, began a volume at 19:52 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 12:00Z, 7.8 hours before the alert went out and 161 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 2 J/kg
Mixed-layer CIN: -340 J/kg
Mixed-layer LCL: 961 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 34 m²/s²
0-3 km storm-relative helicity: 66 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

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

851 
WUUS1 KDSM 061951 RRA
SVRDSM
IAC077-062020-

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

* SEVERE THUNDERSTORM WARNING FOR
  GUTHRIE COUNTY - WEST CENTRAL IOWA

* UNTIL 320 PM CDT
 
* SOME AREAS AFFECTED
    GUTHRIE CENTER
    ADAIR
    CASEY

* AT 251 PM CDT RADAR INDICATED A SEVERE THUNDERSTORM 55 MILES WEST OF
  DES MOINES OR 10 MILES SOUTHWEST OF GUTHRIE CENTER  MOVING NORTHEAST
  30 MPH.

* THE STORM WILL BE THROUGH GUTHRIE CENTER BY 310 PM CDT.

THIS IS A DANGEROUS STORM.  DO NOT GO OUTDOORS.




DEROY

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, Apr 6, 12:45 PM CDT, 2 hours 5 minutes before

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-062345-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1245 PM CDT MON APR 6 1998

HAZARD--WIDELY SCATTERED THUNDERSTORMS WEST OF I35 THIS AFTERNOON AND
EVENING.  THE PRIMARY THREAT FROM THE THUNDERSTORMS WILL BE HAIL. IN
ADDITION...A FEW STORMS MAY PRODUCE BRIEF HEAVY RAIN AND GUSTY WINDS.

TIMING AND AREA OF CONCERN--BETWEEN 200 PM AND 800 PM OVER WESTERN
IOWA.  THE STORMS MAY MOVE INTO THE AREA FROM SOUTHEAST NEBRASKA.
THUNDERSTORM COVERAGE WILL BE WIDELY SCATTERED SO MOST AREAS WILL BE
DRY.

METEOROLOGICAL COMMENTS--THUNDERSTORMS INCREASED LATE THIS MORNING
ACROSS SOUTHEAST NEBRASKA JUST NORTH OF A WARM FRONT OVER KANSAS AND
MISSOURI.  THESE STORMS MAY MOVE NORTHEAST INTO IOWA THIS AFTERNOON.
THE LIMITING FACTOR FOR IOWA IS INSTABILITY.  THE AIRMASS MAY
DESTABALIZE THIS AFTERNOON AS LOW-LEVEL MOISTURE INCREASES.

PRECAUTIONS--THERE IS A SLIGHT CHANCE OF SPOTTER ACTIVATION OVER
WESTERN IOWA THIS AFTERNOON AND EVENING.  THE PRIMARY THREAT WOULD BE
HAIL.  EMERGENCY MANAGERS AND SPOTTERS OVER WESTERN IOWA SHOULD
MONITOR THE WEATHER THIS AFTERNOON.

JOHNSON

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 6, 4:16 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Dallas	34 min
Apr 6, 4:44 PM CDT	Severe Thunderstorm Warning	DMX	Boone	31 min
Apr 6, 5:09 PM CDT	Severe Thunderstorm Warning	DMX	Story	46 min
Apr 6, 6:24 PM CDT	Tornado Warning	DMX	Calhoun, Webster	31 min
Apr 6, 6:32 PM CDT	Tornado Warning	DMX	Greene	33 min
Apr 6, 6:56 PM CDT	Tornado Warning	DMX	Boone, Webster	34 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1998 Every 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.