Alert archive / Iowa / Tornado Warnings in 2011

Tornado Warning 14, NWS Sioux Falls, SD

April 9, 2011Buena Vista County, Clay County, Iowa

NWS Sioux Falls, SD issued this tornado warning at Apr 9, 2011, 11:27 PM CDT for Buena Vista County, Clay County, Iowa. It was in force for 18 min. 1 report 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, 11:27 PM CDT (04:27 UTC)
Expired: Apr 9, 2011, 11:45 PM CDT
In force: 18 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon

Counties Buena Vista County, IA, Clay County, IA

The radar

The Sioux Falls radar (KFSD), 157 km from the middle of the area, began a volume at 04:27 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
Apr 9, 11:31 PM CDT	HAIL 1	3 Ssw Greenville, IA	COVERING APPROXIMATELY HALF OF THE GROUND

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.

Issued	Product	Office	Lasted
Apr 9, 5:48 PM CDT	Tornado Watch	SPC	7 hr
Apr 9, 11:01 PM CDT	Tornado Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 4.5 hours before the alert went out and 209 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: 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.

763 
WFUS53 KFSD 100427
TORFSD
IAC021-041-100445-
/O.NEW.KFSD.TO.W.0014.110410T0427Z-110410T0445Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1127 PM CDT SAT APR 9 2011

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* TORNADO WARNING FOR...
  NORTHEASTERN BUENA VISTA COUNTY IN NORTHWEST IOWA...
  SOUTHEASTERN CLAY COUNTY IN NORTHWEST IOWA...

* UNTIL 1145 PM CDT

* AT 1127 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS
  DANGEROUS STORM WAS LOCATED NEAR SIOUX RAPIDS...OR 17 MILES NORTH
  OF STORM LAKE...AND MOVING EAST AT 60 MPH.

* THIS TORNADIC STORM WILL AFFECT MAINLY RURAL AREAS OF NORTHEASTERN
  BUENA VISTA AND SOUTHEASTERN CLAY COUNTIES.

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.

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

&&

LAT...LON 4282 9516 4298 9521 4303 9492 4302 9491
      4287 9491 4285 9491
TIME...MOT...LOC 0427Z 258DEG 53KT 4291 9506

$$

CJ

1 follow-up statement

569 
WWUS53 KFSD 100435
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1135 PM CDT SAT APR 9 2011

IAC021-041-100445-
/O.CON.KFSD.TO.W.0014.000000T0000Z-110410T0445Z/
CLAY IA-BUENA VISTA IA-
1135 PM CDT SAT APR 9 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR EXTREME NORTHEASTERN BUENA
VISTA AND SOUTHEASTERN CLAY COUNTIES UNTIL 1145 PM CDT...

AT 1135 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS
DANGEROUS STORM WAS LOCATED NEAR SIOUX RAPIDS...OR 14 MILES SOUTH OF
SPENCER...MOVING NORTHEAST AT 40 MPH.

THIS DANGEROUS STORM WILL BE NEAR...
  WEBB AROUND 1140 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.

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

&&

LAT...LON 4293 9493 4290 9492 4289 9516 4298 9518
      4303 9492 4302 9491
TIME...MOT...LOC 0435Z 239DEG 34KT 4296 9506

$$

CJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 9, 7:09 PM CDT	Severe Thunderstorm Warning	FSD	Ida, Woodbury	36 min
Apr 9, 7:31 PM CDT	Tornado Warning	FSD	Ida	29 min
Apr 9, 7:44 PM CDT	Severe Thunderstorm Warning	FSD	Ida	31 min
Apr 9, 7:46 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Ida, Woodbury	29 min
Apr 9, 7:56 PM CDT	Tornado Warning	FSD	Ida	34 min
Apr 9, 8:08 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Ida, Woodbury	37 min
Apr 9, 8:11 PM CDT	Severe Thunderstorm Warning	FSD	Ida	34 min
Apr 9, 8:19 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Woodbury	41 min
Apr 9, 8:40 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee	35 min
Apr 9, 8:41 PM CDT	Severe Thunderstorm Warning	FSD	Ida	19 min
Apr 9, 8:49 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	41 min
Apr 9, 8:55 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Woodbury	35 min
Apr 9, 9:08 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee	37 min
Apr 9, 9:09 PM CDT	Tornado Warning	FSD	Buena Vista	36 min
Apr 9, 9:15 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Sioux	30 min
Apr 9, 9:17 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Woodbury	43 min
Apr 9, 9:24 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Plymouth, Woodbury	36 min
Apr 9, 9:25 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	20 min
Apr 9, 9:31 PM CDT	Tornado Warning	FSD	Plymouth, Woodbury	29 min
Apr 9, 9:36 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Clay	39 min
Apr 9, 9:46 PM CDT	Tornado Warning	FSD	Buena Vista	29 min
Apr 9, 9:48 PM CDT	Tornado Warning	FSD	Cherokee	27 min
Apr 9, 9:58 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth	32 min
Apr 9, 10:02 PM CDT	Tornado Warning	FSD	Buena Vista	28 min
Apr 9, 10:09 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	36 min
Apr 9, 10:13 PM CDT	Tornado Warning	FSD	Buena Vista, Cherokee	47 min
Apr 9, 10:24 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee, O'Brien, Plymouth, Sioux	36 min
Apr 9, 10:31 PM CDT	Tornado Warning	FSD	Cherokee	29 min
Apr 9, 10:35 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay	30 min
Apr 9, 10:50 PM CDT	Tornado Warning	FSD	Buena Vista, Cherokee	40 min
Apr 9, 11:11 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay	34 min
Apr 9, 11:39 PM CDT	Tornado Warning	FSD	Clay	21 min
Apr 10, 12:24 AM CDT	Severe Thunderstorm Warning	FSD	Woodbury	36 min
Apr 10, 12:47 AM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Ida	28 min

Nearby

Tornado Warnings in Iowa, 2011 Every tornado warning in 2011 Tornadoes 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.