Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 85, NWS Des Moines, IA

August 10, 2021Black Hawk County, Bremer County, Butler County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Aug 10, 2021, 1:48 PM CDT for Black Hawk County, Bremer County, Butler 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: Aug 10, 2021, 1:48 PM CDT (18:48 UTC)
Expired: Aug 10, 2021, 2:30 PM CDT
In force: 42 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Black Hawk County, IA, Bremer County, IA, Butler County, IA

The radar

The Des Moines radar (KDMX), 147 km from the middle of the area, began a volume at 18:49 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 10, 2:08 PM CDT	HAIL 1	2 Sw Frederika, IA	QUARTER INCH HAIL IN PROGRESS WITH HEAVY RAIN.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 6.8 hours before the alert went out and 207 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: 3755 J/kg
Mixed-layer CIN: -67 J/kg
Mixed-layer LCL: 819 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: -37 m²/s²
0-3 km storm-relative helicity: 4 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

568 
WUUS53 KDMX 101848
SVRDMX
IAC013-017-023-101930-
/O.NEW.KDMX.SV.W.0085.210810T1848Z-210810T1930Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
148 PM CDT Tue Aug 10 2021

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Northwestern Black Hawk County in northeastern Iowa...
  Bremer County in northeastern Iowa...
  Southeastern Butler County in north central Iowa...

* Until 230 PM CDT.

* At 147 PM CDT, a severe thunderstorm was located over Shell Rock,
  or 7 miles west of Waverly, moving northeast at 35 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...
  Waverly around 200 PM CDT.

Other locations in the path of this severe thunderstorm include
Tripoli.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4256 9276 4276 9277 4291 9251 4291 9221
      4258 9217
TIME...MOT...LOC 1847Z 244DEG 29KT 4272 9262 

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

$$

Krull

1 follow-up statement

668 
WWUS53 KDMX 101911
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
211 PM CDT Tue Aug 10 2021

IAC013-017-023-101930-
/O.CON.KDMX.SV.W.0085.000000T0000Z-210810T1930Z/
Black Hawk IA-Bremer IA-Butler IA-
211 PM CDT Tue Aug 10 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 230 PM CDT
FOR NORTHWESTERN BLACK HAWK...BREMER AND SOUTHEASTERN BUTLER
COUNTIES...

At 211 PM CDT, a severe thunderstorm was located near Tripoli, or
near Waverly, moving east at 30 mph.

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

SOURCE...Emergency management. Half to one inch hail reported north 
         of Waverly at 207 PM. 

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

Locations impacted include...
  Tripoli.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4256 9266 4278 9264 4291 9251 4291 9221
      4258 9217
TIME...MOT...LOC 1911Z 248DEG 28KT 4280 9238 

HAIL THREAT...OBSERVED
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 10, 12:50 PM CDT	Severe Thunderstorm Warning	DMX	Clarke	25 min
Aug 10, 12:56 PM CDT	Heat Advisory	DMX	Adair, Adams, Appanoose, Audubon, Cass, Clarke and 18 more	30 hr
Aug 10, 2:14 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Bremer	46 min
Aug 10, 2:57 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk	18 min
Aug 10, 3:00 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Poweshiek, Tama	60 min
Aug 10, 3:59 PM CDT	Special Weather Statement	DMX	Tama	46 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.