Alert archive / Iowa / Tornado Warnings in 2011

Tornado Warning 19, NWS Des Moines, IA

April 9, 2011Sac County, Iowa

NWS Des Moines, IA issued this tornado warning at Apr 9, 2011, 8:23 PM CDT for Sac County, Iowa. It was in force for 22 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: Apr 9, 2011, 8:23 PM CDT (01:23 UTC)
Expired: Apr 9, 2011, 8:45 PM CDT
In force: 22 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon

County Sac County, IA

The radar

The Des Moines radar (KDMX), 137 km from the middle of the area, began a volume at 01:26 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, 8:41 PM CDT	HAIL 1.75	Wnw Early, IA
Apr 9, 8:44 PM CDT	TORNADO	2 Sw Early, IA
Apr 9, 8:48 PM CDT	TSTM WND DMG	4 Se Schaller, IA	AROUND A DOZEN FOOT DIAMETER TREES DOWN AND/OR UPROOTED NEAR THE VICINITY OF HIGHWAY 20 AND COUNTY ROAD M43. MULTIPLE POWER POLES DOWN.
Apr 9, 8:48 PM CDT	TSTM WND DMG	Early, IA	MAJOR DAMAGE TO BUILDINGS IN TOWN. COMMERCIAL AND RESIDENTIAL. LARGE TREES DOWN. TIME ESTIMATED. NO INJURIES REPORTED IN EARLY AS OF YET.
Apr 9, 8:48 PM CDT	HAIL 1.25	Early, 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
Apr 9, 5:48 PM CDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.4 hours before the alert went out and 172 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.

673 
WFUS53 KDMX 100123
TORDMX
IAC161-100145-
/O.NEW.KDMX.TO.W.0019.110410T0123Z-110410T0145Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
823 PM CDT SAT APR 9 2011

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* TORNADO WARNING FOR...
  NORTHERN SAC COUNTY IN WEST CENTRAL IOWA...

* UNTIL 845 PM CDT

* AT 818 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
  STORM WAS LOCATED NEAR ARTHUR...OR 21 MILES SOUTH OF STORM LAKE...
  AND MOVING EAST AT 40 MPH.

* LOCATIONS IMPACTED INCLUDE...
  SAC CITY...EARLY AND NEMAHA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IMMEDIATELY SEEK SHELTER IN A BASEMENT...
OR IN AN INTERIOR ROOM OF A REINFORCED BUILDING. STAY AWAY FROM
WINDOWS.

IF YOU ARE OUTSIDE...IN A MOBILE HOME...OR IN A VEHICLE...SEEK
SHELTER IN A NEARBY REINFORCED BUILDING. AS A LAST RESORT...FIND THE
LOWEST SPOT AVAILABLE AND COVER YOUR HEAD.

&&

LAT...LON 4257 9501 4257 9493 4256 9492 4248 9492
      4248 9488 4243 9486 4237 9532 4246 9533
TIME...MOT...LOC 0123Z 248DEG 33KT 4237 9527

$$

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 9, 7:09 PM CDT	Tornado Warning	DMX	Crawford	51 min
Apr 9, 7:58 PM CDT	Tornado Warning	DMX	Sac	47 min
Apr 9, 8:41 PM CDT	Tornado Warning	DMX	Sac	34 min
Apr 9, 8:57 PM CDT	Severe Thunderstorm Warning	DMX	Kossuth, Palo Alto	33 min
Apr 9, 9:11 PM CDT	Tornado Warning	DMX	Calhoun, Pocahontas, Sac	49 min
Apr 9, 9:19 PM CDT	Severe Thunderstorm Warning	DMX	Sac	26 min
Apr 9, 9:48 PM CDT	Severe Thunderstorm Warning	DMX	Hancock, Kossuth, Winnebago	42 min
Apr 9, 9:55 PM CDT	Tornado Warning	DMX	Palo Alto, Pocahontas	35 min
Apr 9, 10:12 PM CDT	Tornado Warning	DMX	Hancock, Kossuth	33 min
Apr 9, 10:18 PM CDT	Tornado Warning	DMX	Cerro Gordo, Hancock, Winnebago, Worth	42 min
Apr 9, 10:22 PM CDT	Tornado Warning	DMX	Pocahontas	38 min
Apr 9, 10:28 PM CDT	Tornado Warning	DMX	Humboldt, Kossuth, Palo Alto, Pocahontas	47 min
Apr 9, 10:54 PM CDT	Tornado Warning	DMX	Humboldt, Kossuth, Palo Alto, Pocahontas	51 min
Apr 9, 10:58 PM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Worth	25 min
Apr 9, 11:11 PM CDT	Tornado Warning	DMX	Kossuth, Palo Alto	12 min
Apr 9, 11:24 PM CDT	Severe Thunderstorm Warning	DMX	Emmet, Kossuth, Palo Alto	36 min
Apr 9, 11:29 PM CDT	Tornado Warning	DMX	Hancock, Kossuth, Winnebago	33 min
Apr 9, 11:36 PM CDT	Tornado Warning	DMX	Emmet, Palo Alto	39 min
Apr 9, 11:41 PM CDT	Severe Thunderstorm Warning	DMX	Kossuth, Winnebago	49 min
Apr 9, 11:55 PM CDT	Tornado Warning	DMX	Kossuth, Palo Alto	35 min
Apr 9, 11:58 PM CDT	Severe Thunderstorm Warning	DMX	Winnebago, Worth	32 min
Apr 10, 12:24 AM CDT	Severe Thunderstorm Warning	DMX	Hancock, Kossuth, Winnebago, Worth	31 min
Apr 10, 12:53 AM CDT	Severe Thunderstorm Warning	DMX	Worth	22 min
Apr 10, 1:07 AM CDT	Severe Thunderstorm Warning	DMX	Sac	38 min
Apr 10, 1:38 AM CDT	Severe Thunderstorm Warning	DMX	Calhoun, Humboldt, Pocahontas, Webster	52 min
Apr 10, 3:54 AM CDT	Wind Advisory	DMX	Adair, Adams, Appanoose, Audubon, Black Hawk, Boone and 33 more	15 hr

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.