Alert archive / Iowa / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 339, NWS Sioux Falls, SD

August 17, 2002Clay County, O'Brien County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Aug 17, 2002, 1:15 AM CDT for Clay County, O'Brien County, Iowa. It was in force for 45 min. 2 reports 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 17, 2002, 1:15 AM CDT (06:15 UTC)
Expired
Aug 17, 2002, 2:00 AM CDT
In force
45 min
Issued by
NWS Sioux Falls, SD
Area
Counties, with a storm outline in the text

Counties Clay County, IA, O'Brien County, IA

The radar

The Sioux Falls radar (KFSD), 125 km from the middle of the area, began a volume at 06:19 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.

What was reported inside it

TimeReportWhereRemark
Aug 17, 1:27 AM CDTHail 0.75Spencer, IA
Aug 17, 1:30 AM CDTThunderstorm Wind 52 ESutherland, IAThunderstorm winds blew down tree branches, and at least one power line.

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.

IssuedProductOfficeLasted
Aug 17, 1:05 AM CDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 6.3 hours before the alert went out and 216 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 2002-08-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3070 joules per kilogram.LCLLFCEL10008507005003002001001 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 2002-08-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 229 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
3070 J/kg
Mixed-layer CIN
-50 J/kg
Mixed-layer LCL
1356 m above ground
0-6 km bulk shear
55 kt
0-1 km storm-relative helicity
229 m²/s²
0-3 km storm-relative helicity
597 m²/s²
Significant tornado parameter
3.9
Supercell composite
18.4

Open this sounding in Storm Lab

The text

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

799 
WUUS53 KFSD 170615
SVRFSD
IAC041-141-170700-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
115 AM CDT SAT AUG 17 2002

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  CLAY COUNTY IN NORTHWEST IOWA
  OBRIEN COUNTY IN NORTHWEST IOWA

* UNTIL 200 AM CDT

* AT 115 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 5 MILES EAST OF SUTHERLAND...OR ABOUT 17 MILES
  SOUTHWEST OF SPENCER...MOVING EAST AT 35 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  ROYAL...EVERLY AROUND 125 AM CDT
  GREENVILLE AROUND 135 AM CDT
  SPENCER...WEBB AROUND 140 AM CDT

THIS STORM WILL PRODUCE LARGE HAIL AND DAMAGING WIND. GO INSIDE A
STURDY BUILDING AND STAY AWAY FROM WINDOWS.

LAT...LON 4322 9546 4292 9586 4293 9494 4323 9494

BOUSTEAD

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 16, 9:23 PM CDTSevere Thunderstorm WarningFSDPlymouth52 min
Aug 16, 9:45 PM CDTSevere Thunderstorm WarningFSDSioux45 min
Aug 16, 10:15 PM CDTSevere Thunderstorm WarningFSDPlymouth45 min
Aug 16, 11:03 PM CDTSevere Thunderstorm WarningFSDO'Brien37 min
Aug 16, 11:25 PM CDTSevere Thunderstorm WarningFSDClay35 min
Aug 17, 12:49 AM CDTSevere Thunderstorm WarningFSDPlymouth26 min
Aug 17, 1:06 AM CDTSevere Thunderstorm WarningFSDWoodbury39 min
Aug 17, 1:08 AM CDTSevere Thunderstorm WarningFSDCherokee37 min
Aug 17, 1:13 AM CDTSevere Thunderstorm WarningFSDPlymouth32 min
Aug 17, 1:35 AM CDTSevere Thunderstorm WarningFSDBuena Vista40 min
Aug 17, 1:39 AM CDTSevere Thunderstorm WarningFSDIda, Woodbury36 min
Aug 17, 1:45 AM CDTSevere Thunderstorm WarningFSDCherokee30 min
Aug 17, 2:15 AM CDTSevere Thunderstorm WarningFSDIda45 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2002Every 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.