Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 14, NWS Des Moines, IA

April 6, 1998Boone County, Dallas County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Apr 6, 1998, 4:16 PM CDT for Boone County, Dallas County, Iowa. It was in force for 34 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, 4:16 PM CDT (21:16 UTC)
Expired: Apr 6, 1998, 4:50 PM CDT
In force: 34 min
Issued by: NWS Des Moines, IA
Area: Whole counties

Counties Boone County, IA, Dallas County, IA

The radar

The Des Moines radar (KDMX), 26 km from the middle of the area, began a volume at 21:19 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, 9.3 hours before the alert went out and 207 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.

000 
TTAA00 KDSM 062116 RRA
SVRDSM
IAC015-049-062150-

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

* SEVERE THUNDERSTORM WARNING FOR
  BOONE COUNTY - CENTRAL IOWA
  NORTHERN DALLAS COUNTY - CENTRAL IOWA

* UNTIL 450 PM CDT
 
* SOME AREAS AFFECTED
    PERRY
    WOODWARD
    MADRID

* AT 415 PM CDT RADAR INDICATED A SEVERE THUNDERSTORM JUST SW OF PERRY
  OR 30 MILES NW OF DES MOINES MOVING NORTHEAST AT 30 MPH.

* THE STORM WILL BE NEAR MADRID AT 430 PM CDT.

THIS IS A DANGEROUS STORM.  DO NOT GO OUTDOORS.




FAB

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, 3 hours 31 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, 2:50 PM CDT	Severe Thunderstorm Warning	DMX	Guthrie	30 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.