Alert archive / Iowa / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 39, NWS Sioux Falls, SD

June 20, 1997Lyon County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Jun 20, 1997, 11:02 PM CDT for Lyon County, Iowa. It was in force for 33 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
Jun 20, 1997, 11:02 PM CDT (04:02 UTC)
Expired
Jun 20, 1997, 11:35 PM CDT
In force
33 min
Issued by
NWS Sioux Falls, SD
Area
Whole counties

County Lyon County, IA

The radar

The Sioux Falls radar (KFSD), 48 km from the middle of the area, began a volume at 04:06 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, 4.0 hours before the alert went out and 230 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 1997-06-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 5994 joules per kilogram.LCLEL10008507005003002001001 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 1997-06-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 89 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
5994 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
1151 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
89 m²/s²
0-3 km storm-relative helicity
186 m²/s²
Significant tornado parameter
4.8
Supercell composite
25.7

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KFSD 210402 RRA
SVRFSD
IAC119-210435-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1102 PM CDT FRI JUN 20 1997

* SEVERE THUNDERSTORM WARNING FOR
  EASTERN LYON COUNTY - IN NORTHWESTERN IOWA

* UNTIL 1135 PM CDT
 
* SOME AREAS AFFECTED
  EDNA                     AROUND 1105 PM CDT
  GEORGE                   AROUND 1115 PM CDT

* AT 1059 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  A SEVJERE THUNDERSTORM 20 MILES WEST OF SIBLEY  OR 6 MILES
  SOUTHWEST OF EDNA MOVING EAST AT 25 MPH.
 
THIS IS A DANGEROUS STORM.  IF THREATENING WEATHER APPROACHES SEEK
SHELTER IN A SAFE PLACE SUCH AS A BUILDING OR A DITCH

HARMON

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 20, 9:00 PM CDTSevere Thunderstorm WarningFSDWoodbury45 min
Jun 20, 9:38 PM CDTSevere Thunderstorm WarningFSDIda47 min
Jun 20, 9:45 PM CDTSevere Thunderstorm WarningFSDWoodbury35 min
Jun 20, 10:27 PM CDTSevere Thunderstorm WarningFSDPlymouth33 min
Jun 20, 10:34 PM CDTSevere Thunderstorm WarningFSDLyon31 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1997Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.