Alert archive / South Dakota / Tornado Warnings in 2011

Tornado Warning 39, NWS Sioux Falls, SD

August 18, 2011Bon Homme County, Charles Mix County, South Dakota

NWS Sioux Falls, SD issued this tornado warning at Aug 18, 2011, 6:57 PM CDT for Bon Homme County, Charles Mix County, South Dakota. It was in force for 33 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 18, 2011, 6:57 PM CDT (23:57 UTC)
Expired
Aug 18, 2011, 7:30 PM CDT
In force
33 min
Issued by
NWS Sioux Falls, SD
Area
Storm-based polygon

Counties Bon Homme County, SD, Charles Mix County, SD

The radar

The Sioux Falls radar (KFSD), 136 km from the middle of the area, began a volume at 23:58 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 18, 7:06 PM CDTHAIL 17 S Avon, SD
Aug 18, 7:15 PM CDTHAIL 0.888 W Springfield, SD

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 12.0 hours before the alert went out and 218 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 12:00Z on 2011-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1181 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 12:00Z on 2011-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 234 square meters per square second.1939587897Sfc1 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
1181 J/kg
Mixed-layer CIN
-126 J/kg
Mixed-layer LCL
683 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
234 m²/s²
0-3 km storm-relative helicity
385 m²/s²
Significant tornado parameter
0.0
Supercell composite
11.7

Open this sounding in Storm Lab

The text

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

256 
WFUS53 KFSD 182357
TORFSD
SDC009-023-190030-
/O.NEW.KFSD.TO.W.0039.110818T2357Z-110819T0030Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
657 PM CDT THU AUG 18 2011

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* TORNADO WARNING FOR...
  SOUTHWESTERN BON HOMME COUNTY IN SOUTHEAST SOUTH DAKOTA...
  SOUTHEASTERN CHARLES MIX COUNTY IN SOUTH CENTRAL SOUTH DAKOTA...

* UNTIL 730 PM CDT

* AT 656 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS
  DANGEROUS STORM WAS LOCATED 9 MILES SOUTHWEST OF AVON...OR 22 MILES
  SOUTHEAST OF PICKSTOWN...AND MOVING SOUTHEAST AT 25 MPH.

* THIS TORNADIC STORM WILL BE NEAR...
  RURAL AREAS OF EXTREME SOUTHEAST CHARLES MIX COUNTY THROUGH
   715 PM CDT...
  RURAL AREAS OF SOUTHWEST BON HOMME COUNTY THROUGH 730 PM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 4278 9807 4284 9815 4283 9820 4286 9824
      4289 9832 4298 9825 4288 9781 4286 9783
      4286 9787 4280 9789 4276 9794 4276 9802
TIME...MOT...LOC 2356Z 306DEG 21KT 4289 9815

$$

CHAPMAN
2 follow-up statements
688 
WWUS53 KFSD 190012
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
712 PM CDT THU AUG 18 2011

SDC023-190022-
/O.CAN.KFSD.TO.W.0039.000000T0000Z-110819T0030Z/
CHARLES MIX SD-
712 PM CDT THU AUG 18 2011

...THE TORNADO WARNING FOR SOUTHEASTERN CHARLES MIX COUNTY IS
CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE WARNED 
AREA.

LAT...LON 4278 9807 4285 9816 4287 9812 4290 9811
      4291 9813 4292 9811 4295 9811 4288 9781
      4286 9783 4286 9787 4280 9789 4276 9794
      4276 9799
TIME...MOT...LOC 0012Z 309DEG 19KT 4283 9807

$$

SDC009-190030-
/O.CON.KFSD.TO.W.0039.000000T0000Z-110819T0030Z/
BON HOMME SD-
712 PM CDT THU AUG 18 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR SOUTHWESTERN BON HOMME
COUNTY UNTIL 730 PM CDT...

AT 712 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED 6 MILES NORTH OF NIOBRARA...OR 28 MILES SOUTHEAST
OF PICKSTOWN...MOVING SOUTHEAST AT 20 MPH.

THIS DANGEROUS STORM WILL BE NEAR...
  SPRINGFIELD AROUND 725 PM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 4278 9807 4285 9816 4287 9812 4290 9811
      4291 9813 4292 9811 4295 9811 4288 9781
      4286 9783 4286 9787 4280 9789 4276 9794
      4276 9799
TIME...MOT...LOC 0012Z 309DEG 19KT 4283 9807

$$

CHAPMAN
079 
WWUS53 KFSD 190029
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
729 PM CDT THU AUG 18 2011

SDC009-190039-
/O.EXP.KFSD.TO.W.0039.000000T0000Z-110819T0030Z/
BON HOMME SD-
729 PM CDT THU AUG 18 2011

...THE TORNADO WARNING FOR SOUTHWESTERN BON HOMME COUNTY WILL EXPIRE
AT 730 PM CDT...

THE STORM WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE WARNED
AREA...HOWEVER HEAVY RAIN IS STILL POSSIBLE WITH THIS THUNDERSTORM.

LAT...LON 4278 9807 4285 9816 4287 9812 4290 9811
      4291 9813 4292 9811 4295 9811 4288 9781
      4286 9783 4286 9787 4280 9789 4276 9794
      4276 9799
TIME...MOT...LOC 0029Z 309DEG 19KT 4277 9798

$$
CHAPMAN

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 18, 11:39 AM CDTSevere Thunderstorm WarningFSDCharles Mix, Gregory25 min
Aug 18, 11:55 AM CDTSevere Thunderstorm WarningFSDBon Homme, Charles Mix35 min
Aug 18, 12:25 PM CDTSevere Thunderstorm WarningFSDBon Homme, Yankton35 min
Aug 18, 1:49 PM CDTFlash Flood WarningFSDAurora, Brule, Jerauld4 hr
Aug 18, 1:53 PM CDTSevere Thunderstorm WarningFSDBon Homme, Douglas, Hutchinson37 min
Aug 18, 2:28 PM CDTSevere Thunderstorm WarningFSDBon Homme, Clay, Hutchinson, Yankton47 min
Aug 18, 3:06 PM CDTSevere Thunderstorm WarningFSDClay, Yankton39 min
Aug 18, 3:42 PM CDTSevere Thunderstorm WarningFSDClay, Union, Yankton48 min
Aug 18, 4:26 PM CDTSevere Thunderstorm WarningFSDUnion49 min
Aug 18, 4:34 PM CDTSevere Thunderstorm WarningFSDBon Homme, Hutchinson, Yankton26 min
Aug 18, 5:17 PM CDTSevere Thunderstorm WarningFSDClay, Yankton28 min
Aug 18, 5:22 PM CDTSevere Thunderstorm WarningFSDUnion23 min
Aug 18, 5:46 PM CDTSevere Thunderstorm WarningFSDUnion29 min
Aug 18, 5:47 PM CDTSevere Thunderstorm WarningFSDClay, Yankton28 min
Aug 18, 5:57 PM CDTSevere Thunderstorm WarningFSDClay, Union33 min
Aug 18, 6:26 PM CDTSevere Thunderstorm WarningFSDUnion34 min
Aug 18, 6:43 PM CDTSevere Thunderstorm WarningFSDBon Homme, Charles Mix47 min

Nearby

Tornado Warnings in South Dakota, 2011Every tornado warning in 2011Tornadoes in 2011

Sources

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