Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 96, NWS Des Moines, IA

August 24, 20214 counties in Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Aug 24, 2021, 3:28 PM CDT for 4 counties in Iowa. It was in force for 47 min. 2 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: Aug 24, 2021, 3:28 PM CDT (20:28 UTC)
Expired: Aug 24, 2021, 4:15 PM CDT
In force: 47 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Hamilton County, IA, Hardin County, IA, Marshall County, IA, Story County, IA

The radar

The Des Moines radar (KDMX), 77 km from the middle of the area, began a volume at 20:30 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
Aug 24, 3:36 PM CDT	TSTM WND DMG	Story City, IA	DELAYED REPORT. TIME ESTIMATED VIA RADAR. LARGE TREE LIMBS BROKEN AND HEAVY WOODEN PEN SHIFTED.
Aug 24, 3:38 PM CDT	HAIL 0.88	Story City, IA	SUSTAINED 30MPH WIND REPORT WITH THE 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
Aug 24, 1:52 PM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 8.5 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: 1809 J/kg
Mixed-layer CIN: -127 J/kg
Mixed-layer LCL: 1284 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 9 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

921 
WUUS53 KDMX 242028
SVRDMX
IAC079-083-127-169-242115-
/O.NEW.KDMX.SV.W.0096.210824T2028Z-210824T2115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
328 PM CDT Tue Aug 24 2021

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Northern Story County in central Iowa...
  Northwestern Marshall County in central Iowa...
  Hardin County in central Iowa...
  Eastern Hamilton County in central Iowa...

* Until 415 PM CDT.

* At 328 PM CDT, a severe thunderstorm was located 9 miles east of
  Jewell Junction, or 15 miles southwest of Iowa Falls, moving east
  at 45 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...
  Eldora.

This includes Interstate 35 between mile markers 122 and 147.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4202 9306 4218 9370 4251 9372 4254 9303
      4247 9303 4247 9300 4223 9300
TIME...MOT...LOC 2028Z 269DEG 40KT 4234 9345 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Krull

2 follow-up statements

095 
WWUS53 KDMX 242045
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
345 PM CDT Tue Aug 24 2021

IAC079-083-127-169-242115-
/O.CON.KDMX.SV.W.0096.000000T0000Z-210824T2115Z/
Story IA-Marshall IA-Hardin IA-Hamilton IA-
345 PM CDT Tue Aug 24 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 415 PM CDT
FOR NORTHEASTERN STORY...NORTHWESTERN MARSHALL...HARDIN AND EASTERN
HAMILTON COUNTIES...

At 344 PM CDT, a severe thunderstorm was located 9 miles southwest of
Eldora, moving east at 40 mph.

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

SOURCE...Radar indicated. Spotters reported nickel size hail in 
         Story City.

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

Locations impacted include...
Iowa Falls, Eldora, Story City, Ackley, Roland, Hubbard, Alden,
Zearing, Radcliffe, Ellsworth, Union, Williams, McCallsburg,
Steamboat Rock, Liscomb, New Providence, Randall, Whitten, Clemons
and Buckeye.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4202 9306 4216 9361 4251 9362 4254 9303
      4247 9303 4247 9300 4223 9300
TIME...MOT...LOC 2044Z 274DEG 36KT 4230 9327 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Krull

384 
WWUS53 KDMX 242105
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
405 PM CDT Tue Aug 24 2021

IAC079-242115-
/O.CAN.KDMX.SV.W.0096.000000T0000Z-210824T2115Z/
Hamilton IA-
405 PM CDT Tue Aug 24 2021

...THE SEVERE THUNDERSTORM WARNING FOR EASTERN HAMILTON 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 700 PM CDT for
central Iowa.

LAT...LON 4202 9306 4216 9361 4220 9361 4220 9346
      4245 9334 4253 9329 4254 9303 4247 9303
      4247 9300 4223 9300
TIME...MOT...LOC 2105Z 267DEG 37KT 4231 9300 

$$

IAC083-127-169-242115-
/O.CON.KDMX.SV.W.0096.000000T0000Z-210824T2115Z/
Story IA-Marshall IA-Hardin IA-
405 PM CDT Tue Aug 24 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 415 PM CDT
FOR NORTHEASTERN STORY...NORTHWESTERN MARSHALL AND HARDIN COUNTIES...

At 405 PM CDT, a severe thunderstorm was located near Eldora, moving
east at 45 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...
Iowa Falls, Eldora, Story City, Ackley, Roland, Hubbard, Zearing,
Union, McCallsburg, Steamboat Rock, Liscomb, New Providence, Whitten,
Clemons, St. Anthony, Garden City, Owasa, Pine Lake State Park, Iowa
Falls Municipal Airport and Eldora Municipal Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4202 9306 4216 9361 4220 9361 4220 9346
      4245 9334 4253 9329 4254 9303 4247 9303
      4247 9300 4223 9300
TIME...MOT...LOC 2105Z 267DEG 37KT 4231 9300 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Krull

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 24, 11:06 AM CDT	Special Weather Statement	DMX	Emmet	24 min
Aug 24, 11:30 AM CDT	Special Weather Statement	DMX	Kossuth, Winnebago	45 min
Aug 24, 12:07 PM CDT	Special Weather Statement	DMX	Cerro Gordo, Hancock, Worth	68 min
Aug 24, 12:26 PM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Hancock	49 min
Aug 24, 12:51 PM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Franklin, Hancock, Wright	54 min
Aug 24, 1:18 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Butler	57 min
Aug 24, 1:44 PM CDT	Severe Thunderstorm Warning	DMX	Butler	31 min
Aug 24, 1:53 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Bremer	67 min
Aug 24, 2:17 PM CDT	Special Weather Statement	DMX	Butler	28 min
Aug 24, 3:00 PM CDT	Special Weather Statement	DMX	Black Hawk, Bremer	30 min
Aug 24, 4:03 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Grundy, Hardin, Marshall, Poweshiek, Tama	57 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.