Alert archive / Iowa / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 283, NWS Sioux Falls, SD

August 12, 2002Lyon County, Iowa; Rock County, Minnesota

NWS Sioux Falls, SD issued this severe thunderstorm warning at Aug 12, 2002, 1:08 AM CDT for Lyon County, Iowa; Rock County, Minnesota. It was in force for 37 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 12, 2002, 1:08 AM CDT (06:08 UTC)
Expired: Aug 12, 2002, 1:45 AM CDT
In force: 37 min
Issued by: NWS Sioux Falls, SD
Area: Counties, with a storm outline in the text

Counties Lyon County, IA, Rock County, MN

The radar

The Sioux Falls radar (KFSD), 27 km from the middle of the area, began a volume at 06:08 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
Aug 12, 1:12 AM CDT	Hail 0.75	Hills, MN

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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 11, 9:55 PM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Aberdeen, SD (KABR), launched 00:00Z, 6.1 hours before the alert went out and 221 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: 2317 J/kg
Mixed-layer CIN: -146 J/kg
Mixed-layer LCL: 2063 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 115 m²/s²
0-3 km storm-relative helicity: 92 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.5

Open this sounding in Storm Lab

The text

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

395 
WUUS53 KFSD 120608
SVRFSD
IAC119-MNC133-120645-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
107 AM CDT MON AUG 12 2002

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  WESTERN LYON COUNTY IN NORTHWEST IOWA
  ROCK COUNTY IN SOUTHWEST MINNESOTA

* UNTIL 145 AM CDT

* AT 107 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 5 MILES NORTHWEST OF LARCHWOOD...OR ABOUT 10
  MILES EAST OF SIOUX FALLS...MOVING EAST AT 25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  LARCHWOOD AROUND 115 AM CDT
  HILLS AROUND 125 AM CDT

THIS STORM HAS A HISTORY OF PRODUCING LARGE HAIL. GO INSIDE A STURDY
BUILDING AND STAY AWAY FROM WINDOWS.

LAT...LON 4357 9646 4350 9645 4349 9659 4342 9658
          4348 9608 4369 9616

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 11, 10:52 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	38 min
Aug 11, 11:14 PM CDT	Severe Thunderstorm Warning	FSD	Sioux	46 min
Aug 11, 11:32 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Osceola	43 min
Aug 12, 12:09 AM CDT	Severe Thunderstorm Warning	FSD	Dickinson	36 min
Aug 12, 12:40 AM CDT	Severe Thunderstorm Warning	FSD	Clay	35 min
Aug 12, 1:42 AM CDT	Severe Thunderstorm Warning	FSD	Sioux	33 min
Aug 12, 1:43 AM CDT	Severe Thunderstorm Warning	FSD	Lyon	32 min
Aug 12, 2:16 AM CDT	Severe Thunderstorm Warning	FSD	Sioux	29 min
Aug 12, 2:21 AM CDT	Severe Thunderstorm Warning	FSD	O'Brien	54 min
Aug 12, 2:25 AM CDT	Severe Thunderstorm Warning	FSD	Dickinson	50 min
Aug 12, 2:57 AM CDT	Severe Thunderstorm Warning	FSD	Clay	33 min
Aug 11, 10:59 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Murray, Pipestone	46 min
Aug 11, 11:13 PM CDT	Severe Thunderstorm Warning	FSD	Nobles	32 min
Aug 11, 11:42 PM CDT	Severe Thunderstorm Warning	FSD	Cottonwood, Jackson	48 min
Aug 11, 11:44 PM CDT	Severe Thunderstorm Warning	FSD	Nobles	46 min
Aug 11, 11:46 PM CDT	Severe Thunderstorm Warning	FSD	Nobles	14 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2002 Severe Thunderstorm Warnings in Minnesota, 2002 Every severe thunderstorm warning in 2002

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.