Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 43, NWS Des Moines, IA

June 20, 2021Decatur County, Wayne County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jun 20, 2021, 6:43 PM CDT for Decatur County, Wayne County, Iowa. It was in force for 47 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: Jun 20, 2021, 6:43 PM CDT (23:43 UTC)
Expired: Jun 20, 2021, 7:30 PM CDT
In force: 47 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.25 in
Wind: 60.0 mph

Counties Decatur County, IA, Wayne County, IA

The radar

The Des Moines radar (KDMX), 121 km from the middle of the area, began a volume at 23:43 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
Jun 20, 6:43 PM CDT	HAIL 1.5	Davis City, IA	PUBLIC SENT VIDEO OF STORM NEAR AREA, WITH REPORT OF PEA TO PING PONG BALL SIZED HAIL.

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
Jun 20, 4:01 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 11.7 hours before the alert went out and 236 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: 9 J/kg
Mixed-layer CIN: -220 J/kg
Mixed-layer LCL: 932 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 60 m²/s²
0-3 km storm-relative helicity: 278 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

420 
WUUS53 KDMX 202343
SVRDMX
IAC053-185-210030-
/O.NEW.KDMX.SV.W.0043.210620T2343Z-210621T0030Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
643 PM CDT Sun Jun 20 2021

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Southeastern Decatur County in south central Iowa...
  Southern Wayne County in south central Iowa...

* Until 730 PM CDT.

* At 643 PM CDT, a severe thunderstorm was located near Mercer, or 14
  miles southwest of Corydon, moving east at 40 mph.

  HAZARD...60 mph wind gusts and half dollar size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Leon, Corydon, Lamoni, Seymour, Allerton, Lineville, Davis City,
  Decatur City, Clio, Pleasanton, South Lineville, Nine Eagles State
  Park and Lamoni Municipal Airport.

This includes Interstate 35 between mile markers 2 and 12.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4058 9402 4060 9402 4063 9401 4083 9369
      4070 9310 4058 9310
TIME...MOT...LOC 2343Z 289DEG 34KT 4057 9345 

HAIL...1.25IN
WIND...60MPH
 
$$

Small

3 follow-up statements

098 
WWUS53 KDMX 210004
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
704 PM CDT Sun Jun 20 2021

IAC053-185-210030-
/O.CON.KDMX.SV.W.0043.000000T0000Z-210621T0030Z/
Decatur IA-Wayne IA-
704 PM CDT Sun Jun 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM CDT
FOR SOUTHEASTERN DECATUR AND SOUTHERN WAYNE COUNTIES...

At 704 PM CDT, a severe thunderstorm was located 13 miles west of
Unionville, moving east at 35 mph.

HAZARD...60 mph wind gusts and half dollar size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Corydon, Seymour, Allerton, Lineville, Clio, Pleasanton, South
Lineville and Nine Eagles State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4058 9384 4081 9358 4070 9310 4058 9310
TIME...MOT...LOC 0004Z 288DEG 30KT 4052 9326 

HAIL...1.25IN
WIND...60MPH
 
$$

Krull

291 
WWUS53 KDMX 210015
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
715 PM CDT Sun Jun 20 2021

IAC053-210024-
/O.CAN.KDMX.SV.W.0043.000000T0000Z-210621T0030Z/
Decatur IA-
715 PM CDT Sun Jun 20 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN DECATUR COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 1100 PM CDT for
south central Iowa.

LAT...LON 4080 9356 4070 9310 4058 9310 4058 9356
TIME...MOT...LOC 0014Z 289DEG 34KT 4049 9313 

$$

IAC185-210030-
/O.CON.KDMX.SV.W.0043.000000T0000Z-210621T0030Z/
Wayne IA-
715 PM CDT Sun Jun 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM CDT
FOR SOUTHERN WAYNE COUNTY...

At 714 PM CDT, a severe thunderstorm was located near Unionville,
moving east at 40 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Corydon, Seymour, Allerton, Lineville, Clio and South Lineville. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4080 9356 4070 9310 4058 9310 4058 9356
TIME...MOT...LOC 0014Z 289DEG 34KT 4049 9313 

HAIL...1.00IN
WIND...60MPH
 
$$

Krull

712 
WWUS53 KDMX 210024
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
724 PM CDT Sun Jun 20 2021

IAC185-210034-
/O.EXP.KDMX.SV.W.0043.000000T0000Z-210621T0030Z/
Wayne IA-
724 PM CDT Sun Jun 20 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN WAYNE COUNTY WILL
EXPIRE AT 730 PM CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However heavy rain
is still possible with this thunderstorm.

A Severe Thunderstorm Watch remains in effect until 1100 PM CDT for
south central Iowa.

LAT...LON 4080 9356 4070 9310 4058 9310 4058 9356
TIME...MOT...LOC 0024Z 289DEG 34KT 4046 9302 

$$

Krull

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 20, 3:38 PM CDT	Special Weather Statement	DMX	Dallas	37 min
Jun 20, 4:20 PM CDT	Severe Thunderstorm Warning	DMX	Clarke, Madison, Union	55 min
Jun 20, 4:47 PM CDT	Severe Thunderstorm Warning	DMX	Jasper	43 min
Jun 20, 4:53 PM CDT	Severe Thunderstorm Warning	DMX	Clarke, Decatur, Ringgold, Union	52 min
Jun 20, 4:54 PM CDT	Severe Thunderstorm Warning	DMX	Bremer, Butler, Franklin	51 min
Jun 20, 5:33 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Poweshiek	42 min
Jun 20, 5:35 PM CDT	Severe Thunderstorm Warning	DMX	Clarke, Decatur, Lucas, Wayne	40 min
Jun 20, 5:55 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Mahaska, Marion	50 min
Jun 20, 5:59 PM CDT	Severe Thunderstorm Warning	DMX	Decatur, Wayne	46 min
Jun 20, 6:04 PM CDT	Tornado Warning	DMX	Decatur	26 min
Jun 20, 6:13 PM CDT	Severe Thunderstorm Warning	DMX	Poweshiek	62 min
Jun 20, 6:15 PM CDT	Severe Thunderstorm Warning	DMX	Decatur, Wayne	30 min
Jun 20, 6:20 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk	55 min
Jun 20, 6:37 PM CDT	Tornado Warning	DMX	Mahaska, Marion	23 min
Jun 20, 6:59 PM CDT	Tornado Warning	DMX	Mahaska, Marion	31 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2021 Every severe thunderstorm warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.