Alert archive / Iowa / Tornado Warnings in 2011

Tornado Warning 4, NWS Sioux Falls, SD

April 9, 2011Ida County, Iowa

NWS Sioux Falls, SD issued this tornado warning at Apr 9, 2011, 7:56 PM CDT for Ida County, Iowa. It was in force for 34 min. 4 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
Apr 9, 2011, 7:56 PM CDT (00:56 UTC)
Expired
Apr 9, 2011, 8:30 PM CDT
In force
34 min
Issued by
NWS Sioux Falls, SD
Area
Storm-based polygon

County Ida County, IA

The radar

The Omaha radar (KOAX), 131 km from the middle of the area, began a volume at 00:59 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
Apr 9, 8:02 PM CDTTSTM WND DMG5 Sse Ida Grove, IAROOF DAMAGE TO OUTBUILDING.
Apr 9, 8:02 PM CDTTSTM WND DMG6 S Ida Grove, IADAMAGE TO FARMBUILDINGS.
Apr 9, 8:05 PM CDTTSTM WND GST 636 Sse Ida Grove, IA
Apr 9, 8:20 PM CDTTORNADO6 Sw Arthur, IASTOVE PIPE SHAPED TORNADO REPORTED BY STORM CHASER

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
Apr 9, 5:48 PM CDTTornado WatchSPC7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 0.9 hours before the alert went out and 132 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 2011-04-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3327 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 2011-04-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 270 square meters per square second.19395878Sfc1 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
3327 J/kg
Mixed-layer CIN
-24 J/kg
Mixed-layer LCL
1533 m above ground
0-6 km bulk shear
56 kt
0-1 km storm-relative helicity
270 m²/s²
0-3 km storm-relative helicity
403 m²/s²
Significant tornado parameter
3.7
Supercell composite
19.0

Open this sounding in Storm Lab

The text

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

135 
WFUS53 KFSD 100056
TORFSD
IAC093-100130-
/O.NEW.KFSD.TO.W.0004.110410T0056Z-110410T0130Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
756 PM CDT SAT APR 9 2011

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* TORNADO WARNING FOR...
  SOUTHEASTERN IDA COUNTY IN NORTHWEST IOWA...

* UNTIL 830 PM CDT

* AT 757 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS
  DANGEROUS STORM WAS LOCATED 7 MILES SOUTH OF IDA GROVE...AND MOVING
  NORTHEAST AT 25 MPH.

* THIS TORNADIC STORM WILL BE NEAR...
  ARTHUR AROUND 820 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 4229 9558 4237 9535 4237 9533 4222 9533
      4221 9534 4221 9557
TIME...MOT...LOC 0057Z 234DEG 22KT 4225 9549

$$

CJ
2 follow-up statements
944 
WWUS53 KFSD 100119
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
819 PM CDT SAT APR 9 2011

IAC093-100130-
/O.CON.KFSD.TO.W.0004.000000T0000Z-110410T0130Z/
IDA IA-
819 PM CDT SAT APR 9 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR SOUTHEASTERN IDA COUNTY
UNTIL 830 PM CDT...

AT 819 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED NEAR ARTHUR...OR 7 MILES EAST OF IDA GROVE...MOVING
NORTHEAST AT 25 MPH.

THIS TORNADO WILL AFFECT MAINLY RURAL AREAS OF SOUTHEASTERN IDA
COUNTY.

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 4223 9541 4233 9544 4237 9535 4237 9533
      4222 9533
TIME...MOT...LOC 0119Z 232DEG 23KT 4234 9532

$$

CJ
252 
WWUS53 KFSD 100125
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
825 PM CDT SAT APR 9 2011

IAC093-100135-
/O.EXP.KFSD.TO.W.0004.000000T0000Z-110410T0130Z/
IDA IA-
825 PM CDT SAT APR 9 2011

...THE TORNADO WARNING FOR SOUTHEASTERN IDA COUNTY WILL EXPIRE AT 830
PM CDT...

THE TORNADO HAS EXITED THE COUNTY...THEREFORE THE TORNADO 
WARNING HAS EXPIRED. HOWEVER...A SEVERE THUNDERSTORM WARNING REMAINS 
IN EFFECT FOR THE AREA.


LAT...LON 4223 9541 4233 9544 4237 9535 4237 9533
      4222 9533
TIME...MOT...LOC 0125Z 232DEG 23KT 4236 9528

$$

CJ

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 9, 7:09 PM CDTSevere Thunderstorm WarningFSDIda, Woodbury36 min
Apr 9, 7:31 PM CDTTornado WarningFSDIda29 min
Apr 9, 7:44 PM CDTSevere Thunderstorm WarningFSDIda31 min
Apr 9, 7:46 PM CDTSevere Thunderstorm WarningFSDCherokee, Ida, Woodbury29 min
Apr 9, 8:08 PM CDTSevere Thunderstorm WarningFSDBuena Vista, Cherokee, Ida, Woodbury37 min
Apr 9, 8:11 PM CDTSevere Thunderstorm WarningFSDIda34 min
Apr 9, 8:19 PM CDTSevere Thunderstorm WarningFSDPlymouth, Woodbury41 min
Apr 9, 8:40 PM CDTSevere Thunderstorm WarningFSDCherokee35 min
Apr 9, 8:41 PM CDTSevere Thunderstorm WarningFSDIda19 min
Apr 9, 8:49 PM CDTSevere Thunderstorm WarningFSDBuena Vista41 min
Apr 9, 8:55 PM CDTSevere Thunderstorm WarningFSDPlymouth, Woodbury35 min
Apr 9, 9:08 PM CDTSevere Thunderstorm WarningFSDCherokee37 min
Apr 9, 9:09 PM CDTTornado WarningFSDBuena Vista36 min
Apr 9, 9:15 PM CDTSevere Thunderstorm WarningFSDPlymouth, Sioux30 min
Apr 9, 9:17 PM CDTSevere Thunderstorm WarningFSDPlymouth, Woodbury43 min
Apr 9, 9:24 PM CDTSevere Thunderstorm WarningFSDCherokee, Plymouth, Woodbury36 min
Apr 9, 9:25 PM CDTSevere Thunderstorm WarningFSDBuena Vista20 min
Apr 9, 9:31 PM CDTTornado WarningFSDPlymouth, Woodbury29 min
Apr 9, 9:36 PM CDTSevere Thunderstorm WarningFSDBuena Vista, Cherokee, Clay39 min
Apr 9, 9:46 PM CDTTornado WarningFSDBuena Vista29 min
Apr 9, 9:48 PM CDTTornado WarningFSDCherokee27 min
Apr 9, 9:58 PM CDTSevere Thunderstorm WarningFSDPlymouth32 min
Apr 9, 10:02 PM CDTTornado WarningFSDBuena Vista28 min
Apr 9, 10:09 PM CDTSevere Thunderstorm WarningFSDBuena Vista36 min
Apr 9, 10:13 PM CDTTornado WarningFSDBuena Vista, Cherokee47 min
Apr 9, 10:24 PM CDTSevere Thunderstorm WarningFSDCherokee, O'Brien, Plymouth, Sioux36 min
Apr 9, 10:31 PM CDTTornado WarningFSDCherokee29 min
Apr 9, 10:35 PM CDTSevere Thunderstorm WarningFSDBuena Vista, Clay30 min
Apr 9, 10:50 PM CDTTornado WarningFSDBuena Vista, Cherokee40 min
Apr 9, 11:11 PM CDTSevere Thunderstorm WarningFSDBuena Vista, Clay34 min
Apr 9, 11:27 PM CDTTornado WarningFSDBuena Vista, Clay18 min
Apr 9, 11:39 PM CDTTornado WarningFSDClay21 min
Apr 10, 12:24 AM CDTSevere Thunderstorm WarningFSDWoodbury36 min
Apr 10, 12:47 AM CDTSevere Thunderstorm WarningFSDCherokee, Ida28 min

Nearby

Tornado Warnings in Iowa, 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.