Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 31, NWS Des Moines, IA

August 9, 2021Butler County, Franklin County, Iowa

NWS Des Moines, IA issued this tornado warning at Aug 9, 2021, 12:23 AM CDT for Butler County, Franklin County, Iowa. It was in force for 20 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 9, 2021, 12:23 AM CDT (05:23 UTC)
Expired: Aug 9, 2021, 12:43 AM CDT
In force: 20 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Butler County, IA, Franklin County, IA

The radar

The Des Moines radar (KDMX), 123 km from the middle of the area, began a volume at 05:25 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.

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 5.4 hours before the alert went out and 242 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: 47 J/kg
Mixed-layer CIN: -48 J/kg
Mixed-layer LCL: 1001 m above ground
0-6 km bulk shear: 4 kt
0-1 km storm-relative helicity: -21 m²/s²
0-3 km storm-relative helicity: 29 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

674 
WFUS53 KDMX 090523
TORDMX
IAC023-069-090600-
/O.NEW.KDMX.TO.W.0031.210809T0523Z-210809T0600Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Des Moines IA
1223 AM CDT Mon Aug 9 2021

The National Weather Service in Des Moines  has issued a

* Tornado Warning for...
  East central Franklin County in north central Iowa...
  Southwestern Butler County in north central Iowa...

* Until 100 AM CDT.
    
* At 1223 AM CDT, a severe thunderstorm capable of producing a
  tornado was located near Hampton, moving east at 25 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* This tornadic thunderstorm will remain over mainly rural areas of
  east central Franklin and southwestern Butler Counties, including
  the following locations... Dumont, Hansell and Bristow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4269 9314 4277 9314 4279 9291 4263 9292
TIME...MOT...LOC 0523Z 270DEG 20KT 4273 9311 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

Ansorge

1 follow-up statement

050 
WWUS53 KDMX 090543
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
1243 AM CDT Mon Aug 9 2021

IAC023-069-090552-
/O.CAN.KDMX.TO.W.0031.000000T0000Z-210809T0600Z/
Franklin IA-Butler IA-
1243 AM CDT Mon Aug 9 2021

...THE TORNADO WARNING FOR EAST CENTRAL FRANKLIN AND SOUTHWESTERN
BUTLER COUNTIES IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore, the warning has been cancelled.

LAT...LON 4269 9314 4277 9314 4279 9291 4263 9292
TIME...MOT...LOC 0540Z 270DEG 20KT 4273 9296 

$$

Ansorge

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 8, 8:36 PM CDT	Tornado Warning	DMX	Pocahontas	24 min
Aug 8, 9:02 PM CDT	Tornado Warning	DMX	Calhoun, Pocahontas	31 min
Aug 8, 10:39 PM CDT	Special Weather Statement	DMX	Webster	51 min
Aug 8, 11:00 PM CDT	Tornado Warning	DMX	Webster	30 min
Aug 8, 11:30 PM CDT	Tornado Warning Tornado observed	DMX	Webster	30 min
Aug 8, 11:52 PM CDT	Tornado Warning	DMX	Boone, Webster	38 min
Aug 9, 12:29 AM CDT	Severe Thunderstorm Warning	DMX	Boone, Hamilton, Webster	46 min

Nearby

Tornado Warnings in Iowa, 2021 Every tornado warning in 2021 Tornadoes in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.