Alert archive / Iowa / Tornado Warnings in 2012

Tornado Warning 23, NWS Sioux Falls, SD

May 4, 2012Clay County, Iowa

NWS Sioux Falls, SD issued this tornado warning at May 4, 2012, 4:06 PM CDT for Clay County, Iowa. It was in force for 24 min. 5 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 4, 2012, 4:06 PM CDT (21:06 UTC)
Expired
May 4, 2012, 4:30 PM CDT
In force
24 min
Issued by
NWS Sioux Falls, SD
Area
Storm-based polygon

County Clay County, IA

The radar

The Sioux Falls radar (KFSD), 128 km from the middle of the area, began a volume at 21:06 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
May 4, 4:10 PM CDTTSTM WND GST 601 E Everly, IA
May 4, 4:22 PM CDTTSTM WND GST 693 Wnw Spencer, IAMEASURED AT THE SPENCER AIRPORT.
May 4, 4:24 PM CDTTSTM WND DMGSpencer, IAWIDESPREAD TREE DAMAGE AND SOME STRUCTURE DAMAGE.
May 4, 4:24 PM CDTTSTM WND GST 65N Spencer, IATREES DOWNED JUST NORTH OF SPENCER.
May 4, 4:24 PM CDTNON-TSTM WND GST 65N Spencer, IATREES DOWNED JUST NORTH OF SPENCER.

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

The watch it was issued in

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

IssuedProductOfficeLasted
May 4, 2:00 PM CDTSevere Thunderstorm WatchSPC9 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 9.1 hours before the alert went out and 227 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 2012-05-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2705 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 2012-05-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 10 square meters per square second.1939Sfc1 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
2705 J/kg
Mixed-layer CIN
-17 J/kg
Mixed-layer LCL
584 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
10 m²/s²
0-3 km storm-relative helicity
98 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

205 
WFUS53 KFSD 042106
TORFSD
IAC041-042130-
/O.NEW.KFSD.TO.W.0023.120504T2106Z-120504T2130Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
406 PM CDT FRI MAY 4 2012

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* TORNADO WARNING FOR...
  NORTHERN CLAY COUNTY IN NORTHWEST IOWA...

* UNTIL 430 PM CDT

* AT 407 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS
  DANGEROUS STORM WAS LOCATED NEAR HARTLEY...OR 18 MILES WEST OF
  SPENCER...AND MOVING EAST AT 30 MPH.

* THIS TORNADIC STORM WILL BE NEAR...
  EVERLY AROUND 420 PM CDT...
  FOSTORIA AND SPENCER AROUND 430 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 4310 9539 4319 9540 4325 9539 4326 9511
      4326 9505 4312 9503
TIME...MOT...LOC 2107Z 269DEG 28KT 4321 9544

$$

SCHUMACHER
2 follow-up statements
318 
WWUS53 KFSD 042119
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
419 PM CDT FRI MAY 4 2012

IAC041-042130-
/O.CON.KFSD.TO.W.0023.000000T0000Z-120504T2130Z/
CLAY IA-
419 PM CDT FRI MAY 4 2012

...A TORNADO WARNING REMAINS IN EFFECT FOR NORTHERN CLAY COUNTY UNTIL
430 PM CDT...

AT 418 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED NEAR EVERLY...OR 8 MILES NORTHWEST OF SPENCER...
MOVING EAST AT 45 MPH.

IN ADDITION...WINDS UP TO 80 MPH ARE POSSIBLE WITH THIS STORM AS IT 
MOVES TOWARD SPENCER...FOSTORIA AND DICKENS.

THIS DANGEROUS STORM WILL BE NEAR...
  FOSTORIA AND SPENCER AROUND 425 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 4310 9539 4319 9540 4325 9539 4326 9511
      4326 9505 4312 9503
TIME...MOT...LOC 2118Z 269DEG 38KT 4321 9525

$$

SCHUMACHER
438 
WWUS53 KFSD 042131
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
431 PM CDT FRI MAY 4 2012

IAC041-042141-
/O.EXP.KFSD.TO.W.0023.000000T0000Z-120504T2130Z/
CLAY IA-
431 PM CDT FRI MAY 4 2012

...THE TORNADO WARNING FOR NORTHERN CLAY COUNTY HAS EXPIRED...

THE STORM WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE WARNED 
AREA...HOWEVER GUSTY WINDS TO 50 MPH ARE STILL POSSIBLE WITH THIS 
THUNDERSTORM.

LAT...LON 4310 9539 4319 9540 4325 9539 4326 9511
      4326 9505 4312 9503
TIME...MOT...LOC 2119Z 269DEG 38KT 4321 9523

$$

SCHUMACHER

The office that day

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

IssuedProductOfficeCountiesLasted
May 3, 7:57 PM CDTSevere Thunderstorm WarningFSDCherokee33 min
May 3, 8:05 PM CDTFlash Flood WarningFSDCherokee93 min
May 3, 8:37 PM CDTSevere Thunderstorm WarningFSDBuena Vista, Cherokee38 min
May 4, 3:00 PM CDTSevere Thunderstorm WarningFSDSioux30 min
May 4, 3:14 PM CDTSevere Thunderstorm WarningFSDPlymouth, Sioux31 min
May 4, 3:18 PM CDTSevere Thunderstorm WarningFSDO'Brien, Osceola, Sioux42 min
May 4, 3:20 PM CDTTornado WarningFSDO'Brien, Sioux25 min
May 4, 3:39 PM CDTSevere Thunderstorm WarningFSDPlymouth36 min
May 4, 3:43 PM CDTTornado WarningFSDO'Brien, Sioux32 min
May 4, 4:01 PM CDTSevere Thunderstorm WarningFSDCherokee, O'Brien29 min
May 4, 4:09 PM CDTSevere Thunderstorm WarningFSDDickinson, Osceola51 min
May 4, 4:12 PM CDTSevere Thunderstorm WarningFSDClay, O'Brien33 min
May 4, 4:25 PM CDTSevere Thunderstorm WarningFSDClay35 min

Nearby

Tornado Warnings in Iowa, 2012Every tornado warning in 2012Tornadoes in 2012

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.