Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 36, NWS Des Moines, IA

June 20, 2021Jasper County, Poweshiek County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jun 20, 2021, 5:33 PM CDT for Jasper County, Poweshiek County, Iowa. It was in force for 42 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, 5:33 PM CDT (22:33 UTC)
Expired: Jun 20, 2021, 6:15 PM CDT
In force: 42 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

Counties Jasper County, IA, Poweshiek County, IA

The radar

The Des Moines radar (KDMX), 77 km from the middle of the area, began a volume at 22:37 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, 5:41 PM CDT	HAIL 1.25	4 Ese Oakland Acres, 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
Jun 20, 4:01 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 10.6 hours before the alert went out and 191 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2060 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 102 m²/s²
0-3 km storm-relative helicity: 84 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

915 
WUUS53 KDMX 202233
SVRDMX
IAC099-157-202315-
/O.NEW.KDMX.SV.W.0036.210620T2233Z-210620T2315Z/

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

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Southwestern Poweshiek County in central Iowa...
  Northeastern Jasper County in central Iowa...

* Until 615 PM CDT.

* At 533 PM CDT, a severe thunderstorm was located near Rock Creek
  Lake, or 7 miles west of Grinnell, moving east at 25 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.

* This severe thunderstorm will be near...
  Grinnell around 550 PM CDT.

This includes Interstate 80 between mile markers 170 and 193.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4164 9298 4179 9295 4174 9250 4155 9257
TIME...MOT...LOC 2233Z 286DEG 22KT 4170 9287 

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

REV

2 follow-up statements

231 
WWUS53 KDMX 202245
SVSDMX

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

IAC099-157-202315-
/O.CON.KDMX.SV.W.0036.000000T0000Z-210620T2315Z/
Poweshiek IA-Jasper IA-
545 PM CDT Sun Jun 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM CDT
FOR SOUTHWESTERN POWESHIEK AND EAST CENTRAL JASPER COUNTIES...

At 544 PM CDT, a severe thunderstorm was located near Grinnell,
moving east at 25 mph.

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

SOURCE...Trained weather spotters reported half dollar sized hail 
         near Oakland Acres at 5:41 pm.

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

This severe thunderstorm will remain over mainly rural areas of
southwestern Poweshiek and east central Jasper Counties, including
the following locations... Grinnell Regional Airport, Malcom, Oakland
Acres, Rock Creek State Park and Searsboro.

This includes Interstate 80 between mile markers 175 and 193.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4162 9289 4178 9285 4174 9250 4155 9257
TIME...MOT...LOC 2244Z 286DEG 22KT 4168 9278 

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

REV

362 
WWUS53 KDMX 202306
SVSDMX

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

IAC099-157-202315-
/O.CON.KDMX.SV.W.0036.000000T0000Z-210620T2315Z/
Poweshiek IA-Jasper IA-
606 PM CDT Sun Jun 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM CDT
FOR SOUTHWESTERN POWESHIEK AND EAST CENTRAL JASPER COUNTIES...

At 606 PM CDT, a severe thunderstorm was located near Montezuma,
moving east at 25 mph.

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

SOURCE...Trained weather spotters.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Grinnell, Rock Creek Lake, Malcom, Oakland Acres, Searsboro, Grinnell
Regional Airport and Rock Creek State Park.

This includes Interstate 80 between mile markers 175 and 193.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4162 9289 4178 9285 4174 9250 4155 9257
TIME...MOT...LOC 2306Z 286DEG 22KT 4164 9261 

TORNADO...POSSIBLE
HAIL...0.88IN
WIND...60MPH
 
$$

REV

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, 5:35 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, 6:43 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.