Alert archive / Iowa / Tornado Warnings in 2012

Tornado Warning 15, NWS Sioux Falls, SD

May 1, 2012Clay County, O'Brien County, Iowa

NWS Sioux Falls, SD issued this tornado warning at May 1, 2012, 9:29 PM CDT for Clay County, O'Brien County, Iowa. It was in force for 46 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: May 1, 2012, 9:29 PM CDT (02:29 UTC)
Expired: May 1, 2012, 10:15 PM CDT
In force: 46 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon

Counties Clay County, IA, O'Brien County, IA

The radar

The Sioux Falls radar (KFSD), 113 km from the middle of the area, began a volume at 02:30 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 1, 9:40 PM CDT	TORNADO	3 S Everly, IA	SEVERAL POWER POLES LEANING ALONG 130TH AVENUE SOUTH OF EVERLY.
May 1, 9:40 PM CDT	TORNADO	3 Sw Everly, IA

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
May 1, 9:18 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 2.5 hours before the alert went out and 217 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: 1502 J/kg
Mixed-layer CIN: -30 J/kg
Mixed-layer LCL: 1477 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 75 m²/s²
0-3 km storm-relative helicity: 122 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 5.2

Open this sounding in Storm Lab

The text

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

164 
WFUS53 KFSD 020229
TORFSD
IAC041-141-020315-
/O.NEW.KFSD.TO.W.0015.120502T0229Z-120502T0315Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
929 PM CDT TUE MAY 1 2012

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* TORNADO WARNING FOR...
  NORTHWESTERN CLAY COUNTY IN NORTHWEST IOWA...
  NORTHEASTERN O'BRIEN COUNTY IN NORTHWEST IOWA...

* UNTIL 1015 PM CDT

* AT 929 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS
  DANGEROUS STORM WAS LOCATED NEAR PRIMGHAR...OR 22 MILES WEST OF
  SPENCER...AND MOVING NORTHEAST AT 40 MPH.

* THIS TORNADIC STORM WILL BE NEAR...
  HARTLEY AROUND 935 PM CDT...
  EVERLY AROUND 945 PM CDT...

OTHER LOCATIONS IMPACTED BY THIS TORNADIC THUNDERSTORM INCLUDE
MONETA.

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 4307 9559 4316 9562 4326 9535 4325 9533
      4312 9530
TIME...MOT...LOC 0229Z 242DEG 36KT 4313 9554

$$

CJ

1 follow-up statement

448 
WWUS53 KFSD 020237
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
937 PM CDT TUE MAY 1 2012

IAC041-141-020315-
/O.CON.KFSD.TO.W.0015.000000T0000Z-120502T0315Z/
O'BRIEN IA-CLAY IA-
937 PM CDT TUE MAY 1 2012

...A TORNADO WARNING REMAINS IN EFFECT FOR NORTHWESTERN CLAY AND EAST
CENTRAL O'BRIEN COUNTIES UNTIL 1015 PM CDT...

AT 937 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED NEAR HARTLEY...OR 15 MILES WEST OF SPENCER...MOVING
NORTHEAST AT 40 MPH.

THIS DANGEROUS STORM WILL BE NEAR...
  EVERLY AROUND 945 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 9545 4317 9548 4324 9534 4320 9533
      4312 9530
TIME...MOT...LOC 0237Z 242DEG 36KT 4314 9540

$$

CJ

The office that day

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

Issued	Product	Office	Counties	Lasted
May 1, 7:12 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Sioux	33 min
May 1, 7:27 PM CDT	Tornado Warning	FSD	Lyon, Sioux	33 min
May 1, 7:41 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Sioux	34 min
May 1, 7:57 PM CDT	Tornado Warning	FSD	Lyon	33 min
May 1, 8:09 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	36 min
May 1, 8:40 PM CDT	Flash Flood Warning	FSD	Lyon	3 hr
May 1, 9:15 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Clay, O'Brien, Plymouth, Sioux	30 min
May 1, 9:22 PM CDT	Severe Thunderstorm Warning	FSD	Dickinson, Osceola	38 min
May 1, 9:41 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Clay, Dickinson, O'Brien, Osceola	34 min
May 1, 9:44 PM CDT	Tornado Warning	FSD	Clay	31 min
May 1, 10:13 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay, Dickinson	17 min

Nearby

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