Alert archive / Iowa / Tornado Warnings in 2014

Tornado Warning 7, NWS Sioux Falls, SD

May 11, 2014O'Brien County, Sioux County, Iowa

NWS Sioux Falls, SD issued this tornado warning at May 11, 2014, 8:42 PM CDT for O'Brien County, Sioux County, Iowa. It was in force for 33 min. 6 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: May 11, 2014, 8:42 PM CDT (01:42 UTC)
Expired: May 11, 2014, 9:15 PM CDT
In force: 33 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties O'Brien County, IA, Sioux County, IA

The radar

The Sioux Falls radar (KFSD), 89 km from the middle of the area, began a volume at 01:42 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
May 11, 8:42 PM CDT	TORNADO	5 Wnw Hospers, IA	SEVERE STRUCTURAL DAMAGE TO DAIRY FARM. 500 CATTLE LOOSE.
May 11, 8:43 PM CDT	TORNADO	4 Wnw Hospers, IA	SIGNIFICANT DAMAGE TO OUTBUILDING. ALSO SOME DAMAGE TO HOME INCLUDING BROKEN WINDOWS.
May 11, 8:50 PM CDT	TORNADO	3 Nnw Hospers, IA
May 11, 8:51 PM CDT	TORNADO	2 Nnw Hospers, IA	VIDEO OF TORNADO OVER FIELDS
May 11, 8:52 PM CDT	TORNADO	3 N Hospers, IA	TORNADO ON THE GROUND.
May 11, 9:01 PM CDT	TORNADO	2 Ene Sheldon, IA	DAMAGE TO VEHICLE FROM FLYING DEBRIS.

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 00:00Z, 1.7 hours before the alert went out and 206 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: 2520 J/kg
Mixed-layer CIN: -40 J/kg
Mixed-layer LCL: 967 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 274 m²/s²
0-3 km storm-relative helicity: 254 m²/s²
Significant tornado parameter: 4.5
Supercell composite: 18.8

Open this sounding in Storm Lab

The text

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

050 
WFUS53 KFSD 120142
TORFSD
IAC141-167-120215-
/O.NEW.KFSD.TO.W.0007.140512T0142Z-140512T0215Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
842 PM CDT SUN MAY 11 2014

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* TORNADO WARNING FOR...
  WEST CENTRAL O'BRIEN COUNTY IN NORTHWEST IOWA...
  EAST CENTRAL SIOUX COUNTY IN NORTHWEST IOWA...

* UNTIL 915 PM CDT

* AT 837 PM CDT...A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A
  TORNADO WAS LOCATED NEAR HOSPERS...AND MOVING NORTHEAST AT 30 MPH.

  HAZARD...TORNADO.

  SOURCE...RADAR INDICATED ROTATION.

  IMPACT...FLYING DEBRIS WILL BE DANGEROUS TO THOSE CAUGHT WITHOUT
           SHELTER. MOBILE HOMES WILL BE DAMAGED OR DESTROYED. DAMAGE
           TO ROOFS...WINDOWS AND VEHICLES WILL OCCUR. TREE DAMAGE IS
           LIKELY.

* THIS DANGEROUS STORM WILL BE NEAR...
  ARCHER AROUND 900 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 4322 9572 4308 9565 4301 9602 4310 9605
TIME...MOT...LOC 0142Z 245DEG 26KT 4308 9594

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

CHAPMAN

1 follow-up statement

034 
WWUS53 KFSD 120155
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
855 PM CDT SUN MAY 11 2014

IAC141-167-120215-
/O.CON.KFSD.TO.W.0007.000000T0000Z-140512T0215Z/
SIOUX IA-O'BRIEN IA-
855 PM CDT SUN MAY 11 2014

...A TORNADO WARNING REMAINS IN EFFECT FOR WEST CENTRAL O'BRIEN AND
EAST CENTRAL SIOUX COUNTIES UNTIL 915 PM CDT...

AT 852 PM CDT...TRAINED WEATHER SPOTTERS REPORTED A TORNADO.  THIS 
TORNADO WAS LOCATED 3 MILES NORTH OF HOSPERS...OR 10 MILES NORTHEAST 
OF ORANGE CITY...MOVING NORTHEAST AT 25 MPH.  A SECOND ROTATION ON
RADAR WAS INDICATED 3 MILES NORTHEAST OF HOSPERS...MOVING EAST 
AT 30 MPH.

THE TORNADO WILL BE NEAR...
  SOUTH OF SHELDON AROUND 905 PM...
  ARCHER AROUND 915 PM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORNADOES ARE DIFFICULT TO SEE AT NIGHT. TAKE COVER NOW.

&&

LAT...LON 4305 9593 4312 9598 4322 9572 4308 9565
      4306 9575
TIME...MOT...LOC 0154Z 238DEG 19KT 4313 9592

$$

CHAPMAN

The office that day

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

Issued	Product	Office	Counties	Lasted
May 11, 7:55 PM CDT	Severe Thunderstorm Warning	FSD	Sioux	35 min
May 11, 8:14 PM CDT	Tornado Warning	FSD	Sioux	31 min
May 11, 9:10 PM CDT	Tornado Warning Tornado observed	FSD	O'Brien, Sioux	35 min

Nearby

Tornado Warnings in Iowa, 2014 Every tornado warning in 2014 Tornadoes in 2014

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.