Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 105, NWS Des Moines, IA

August 27, 2021Cerro Gordo County, Franklin County, Hancock County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Aug 27, 2021, 4:58 PM CDT for Cerro Gordo County, Franklin County, Hancock County, Iowa. It was in force for 32 min. 3 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 27, 2021, 4:58 PM CDT (21:58 UTC)
Expired: Aug 27, 2021, 5:30 PM CDT
In force: 32 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Cerro Gordo County, IA, Franklin County, IA, Hancock County, IA

The radar

The Des Moines radar (KDMX), 138 km from the middle of the area, began a volume at 21:59 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 27, 5:12 PM CDT	TSTM WND DMG	2 E Thornton, IA	TREES DOWN. NOT ALL TREES WERE COMPLETELY HEALTHY, SOME WERE. TIME ESTIMATED VIA RADAR.
Aug 27, 5:16 PM CDT	TSTM WND DMG	Swaledale, IA	EM REPORTS TREE DAMAGE SOUTH OF SWALEDALE AREA. TIME ESTIMATED VIA RADAR.
Aug 27, 5:27 PM CDT	FUNNEL CLOUD	3 S Rockwell, IA	FUNNEL CLOUD REPORTED NORTH OF SHEFFIELD. FUNNEL CLOUD WAS LOW, BUT UNCLEAR IF IN CONTACT WITH THE GROUND.

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

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 10.0 hours before the alert went out and 213 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: 487 J/kg
Mixed-layer CIN: -63 J/kg
Mixed-layer LCL: 644 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: -9 m²/s²
0-3 km storm-relative helicity: -16 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

290 
WUUS53 KDMX 272158
SVRDMX
IAC033-069-081-272230-
/O.NEW.KDMX.SV.W.0105.210827T2158Z-210827T2230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
458 PM CDT Fri Aug 27 2021

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Northwestern Franklin County in north central Iowa...
  Southeastern Hancock County in north central Iowa...
  Southern Cerro Gordo County in north central Iowa...

* Until 530 PM CDT.

* At 458 PM CDT, a severe thunderstorm was located 10 miles northeast
  of Belmond, or 12 miles southeast of Garner, moving northeast at 30
  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...
  Rockwell.

This includes Interstate 35 between mile markers 177 and 187.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4297 9306 4284 9350 4291 9350 4291 9358
      4294 9361 4305 9335
TIME...MOT...LOC 2158Z 232DEG 26KT 4295 9347 

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

$$

REV

1 follow-up statement

172 
WWUS53 KDMX 272217
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
517 PM CDT Fri Aug 27 2021

IAC069-081-272226-
/O.CAN.KDMX.SV.W.0105.000000T0000Z-210827T2230Z/
Franklin IA-Hancock IA-
517 PM CDT Fri Aug 27 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN FRANKLIN AND
SOUTHEASTERN HANCOCK COUNTIES IS CANCELLED...
    
The severe thunderstorm which prompted the warning has warned area. 
Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 1100 PM CDT for north central
Iowa.

LAT...LON 4297 9306 4291 9337 4291 9349 4299 9349
      4305 9335
TIME...MOT...LOC 2216Z 247DEG 18KT 4300 9334 

$$

IAC033-272230-
/O.CON.KDMX.SV.W.0105.000000T0000Z-210827T2230Z/
Cerro Gordo IA-
517 PM CDT Fri Aug 27 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM CDT
FOR SOUTHERN CERRO GORDO COUNTY...

At 516 PM CDT, a severe thunderstorm was located 7 miles west of
Rockwell, or 12 miles southwest of Mason City, moving northeast at 20
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...
Rockwell, Thornton, Meservey and Swaledale. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1100 PM CDT for north central
Iowa.

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

&&

LAT...LON 4297 9306 4291 9337 4291 9349 4299 9349
      4305 9335
TIME...MOT...LOC 2216Z 247DEG 18KT 4300 9334 

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

$$

REV

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 26, 7:02 PM CDT	Severe Thunderstorm Warning	DMX	Audubon, Carroll	28 min
Aug 26, 8:35 PM CDT	Special Weather Statement	DMX	Poweshiek	40 min
Aug 26, 8:47 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska, Poweshiek	58 min
Aug 26, 9:46 PM CDT	Special Weather Statement	DMX	Mahaska	44 min
Aug 26, 10:26 PM CDT	Special Weather Statement	DMX	Mahaska	34 min
Aug 26, 10:30 PM CDT	Severe Thunderstorm Warning	DMX	Emmet, Palo Alto	45 min
Aug 26, 10:52 PM CDT	Special Weather Statement	DMX	Wapello	38 min
Aug 26, 11:42 PM CDT	Severe Thunderstorm Warning	DMX	Emmet, Palo Alto	33 min
Aug 27, 12:13 AM CDT	Special Weather Statement	DMX	Emmet	32 min
Aug 27, 2:08 PM CDT	Special Weather Statement	DMX	Hancock	37 min
Aug 27, 2:59 PM CDT	Special Weather Statement	DMX	Cerro Gordo	16 min
Aug 27, 4:23 PM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Hancock	52 min
Aug 27, 4:48 PM CDT	Tornado Warning	DMX	Cerro Gordo, Hancock	57 min
Aug 27, 5:23 PM CDT	Tornado Warning Tornado observed	DMX	Cerro Gordo	37 min
Aug 27, 5:25 PM CDT	Tornado Warning	DMX	Cerro Gordo	35 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.