Alert archive / Iowa / Severe Thunderstorm Warnings in 1997
Severe Thunderstorm Warning 31, NWS Sioux Falls, SD
NWS Sioux Falls, SD issued this severe thunderstorm warning at Jun 20, 1997, 9:00 PM CDT for Woodbury County, Iowa. It was in force for 45 min. 2 reports 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, 9:00 PM CDT (02:00 UTC)
- Expired
- Jun 20, 1997, 9:45 PM CDT
- In force
- 45 min
- Issued by
- NWS Sioux Falls, SD
- Area
- Whole counties
County Woodbury County, IA
The radar
The Omaha radar (KOAX), 122 km from the middle of the area, began a volume at 02:03 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, 9:10 PM CDT | Hail 2.5 | Hornick, IA | |
| Jun 20, 9:25 PM CDT | Hail 1.75 | Smithland, 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, 2.0 hours before the alert went out and 122 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.
- 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
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KFSD 210200 RRA SVRFSD IAC193-210245- BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE SIOUX FALLS SD 900 PM CDT FRI JUN 20 1997 * SEVERE THUNDERSTORM WARNING FOR WOODBURY COUNTY - IN NORTHWESTERN IOWA * UNTIL 945 PM CDT * SOME AREAS AFFECTED SLOAN AROUND 905 PM CDT HORNICK AROUND 915 PM CDT HOLLY SPRINGS AROUND 920 PM CDT CLIMBING HILL AROUND 930 PM CDT OTO AROUND 930 PM CDT * AT 857 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM 27 MILES SOUTH OF SIOUX CITY OR 7 MILES SOUTH OF SLOAN MOVING NORTHEAST AT 30 MPH. STRONG GUSTY WINDS...FREQUENT LIGHTNING...VERY HEAVY RAINFALL AND SMALL HAIL MAY ACCOMPANY THE STRONGER STORMS.
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.
NWS Sioux Falls, SD wrote its last area forecast discussion before this severe thunderstorm warning went out at Jun 20, 10:03 AM CDT, 10 hours 57 minutes earlier.
Area forecast discussion, Jun 20, 10:03 AM CDT, 10 hours 57 minutes before
SOUTH DAKOTA/NORTHWEST IOWA/SOUTHWEST MINNESOTA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SIOUX FALLS SD 1000 AM CDT FRI JUN 20 1997 AS PREDICTED YESTERDAY NGM/FWC POPS WOEFULLY INADEQUATE WITH THIS CONVECTIVE PATTERN. LUKS LK ANOTHER SHORT WV WITH SCT SHWRS AND TSTMS WL DVLP EWD INTO MUCH OF THE CWA THIS AFTN AND TNGT AGAIN...WITH THIS TIME THE MAIN THREAT OF SVR NR THE NEB AND IOWA BORDERS. ALREADY CLEANED UP AND FINE TUNED PREV FCST. .FSD...NONE RYRHOLM
The office that day
Everything else NWS Sioux Falls, SD issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 20, 9:38 PM CDT | Severe Thunderstorm Warning | FSD | Ida | 47 min |
| Jun 20, 9:45 PM CDT | Severe Thunderstorm Warning | FSD | Woodbury | 35 min |
| Jun 20, 10:27 PM CDT | Severe Thunderstorm Warning | FSD | Plymouth | 33 min |
| Jun 20, 10:34 PM CDT | Severe Thunderstorm Warning | FSD | Lyon | 31 min |
| Jun 20, 11:02 PM CDT | Severe Thunderstorm Warning | FSD | Lyon | 33 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.