Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 41, NWS Des Moines, IA

June 20, 2021Decatur County, Wayne County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jun 20, 2021, 6:15 PM CDT for Decatur County, Wayne County, Iowa. It was in force for 30 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: Jun 20, 2021, 6:15 PM CDT (23:15 UTC)
Expired: Jun 20, 2021, 6:45 PM CDT
In force: 30 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.5 in
Wind: 60.0 mph

Counties Decatur County, IA, Wayne County, IA

The radar

The Des Moines radar (KDMX), 107 km from the middle of the area, began a volume at 23:19 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 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, 11.3 hours before the alert went out and 238 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.

585 
WUUS53 KDMX 202315
SVRDMX
IAC053-185-202345-
/O.NEW.KDMX.SV.W.0041.210620T2315Z-210620T2345Z/

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

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Northern Decatur County in south central Iowa...
  Western Wayne County in south central Iowa...

* Until 645 PM CDT.

* At 615 PM CDT, a severe thunderstorm was located 11 miles west of
  Corydon, moving east at 35 mph.

  HAZARD...Ping pong ball size hail and 60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...People and animals outdoors will be injured. Expect hail 
           damage to roofs, siding, windows, and vehicles. Expect 
           wind damage to roofs, siding, and trees.

* Locations impacted include...
  Leon, Corydon, Allerton, Humeston, Garden Grove, Decatur City,
  Millerton and Le Roy.

This includes Interstate 35 between mile markers 13 and 20.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and damaging winds. People outside
should move immediately to shelter inside a strong building. Stay
away from windows.

&&

LAT...LON 4075 9394 4090 9371 4084 9323 4063 9333
TIME...MOT...LOC 2315Z 288DEG 32KT 4070 9353 

HAIL...1.50IN
WIND...60MPH
 
$$

Small

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, 6:20 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, 6:43 PM CDT	Severe Thunderstorm Warning	DMX	Decatur, Wayne	47 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.