Alert archive / Iowa / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 39, NWS Des Moines, IA

June 20, 1997Cass County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jun 20, 1997, 12:48 AM CDT for Cass County, Iowa. It was in force for 32 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Jun 20, 1997, 12:48 AM CDT (05:48 UTC)
Expired: Jun 20, 1997, 1:20 AM CDT
In force: 32 min
Issued by: NWS Des Moines, IA
Area: Whole counties

County Cass County, IA

The radar

The Des Moines radar (KDMX), 110 km from the middle of the area, began a volume at 05:52 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.

What was reported inside it

Time	Report	Where	Remark
Jun 20, 1:20 AM CDT	Hail 1	Cumberland, IA

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 5.8 hours before the alert went out and 120 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: 1320 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 2762 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 58 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.4

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KDSM 200547 RRA
SVRDSM
IAC029-200620-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
1248 AM CDT FRI JUN 20 1997

* SEVERE THUNDERSTORM WARNING FOR
  CASS COUNTY - SOUTHWESTERN IOWA

* UNTIL 120 AM CDT
 
* SOME AREAS AFFECTED
    ATLANTIC
    LEWIS
    GRISWOLD
    LYMAN

* AT 1245 AM CDT RADAR INDICATED A SEVERE THUNDERSTORM 40 MILES EAST
  OF COUNCIL BLUFFS MOVING SOUTHEAST AT 40 MPH.

* THE STORM WILL BE NEAR GRISWOLD BY 100 AM .

THIS IS A DANGEROUS STORM.  DO NOT GO OUTDOORS.

STARK

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 20, 1:20 AM CDT	Severe Thunderstorm Warning	DMX	Adair, Cass	50 min
Jun 20, 5:02 AM CDT	Severe Thunderstorm Warning	DMX	Webster	33 min
Jun 20, 5:17 AM CDT	Severe Thunderstorm Warning	DMX	Hamilton, Wright	33 min
Jun 20, 5:48 AM CDT	Severe Thunderstorm Warning	DMX	Franklin, Hardin	32 min
Jun 20, 6:09 AM CDT	Severe Thunderstorm Warning	DMX	Butler, Grundy	36 min
Jun 20, 6:45 AM CDT	Severe Thunderstorm Warning	DMX	Black Hawk	45 min
Jun 20, 7:25 AM CDT	Severe Thunderstorm Warning	DMX	Butler	35 min
Jun 20, 4:39 PM CDT	Severe Thunderstorm Warning	DMX	Warren	31 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1997 Every severe thunderstorm warning in 1997

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.