Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 34, NWS Des Moines, IA

August 27, 2021Cerro Gordo County, Iowa

NWS Des Moines, IA issued this tornado warning at Aug 27, 2021, 5:25 PM CDT for Cerro Gordo County, Iowa. It was in force for 35 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 27, 2021, 5:25 PM CDT (22:25 UTC)
Expired
Aug 27, 2021, 6:00 PM CDT
In force
35 min
Issued by
NWS Des Moines, IA
Area
Storm-based polygon
Tornado
Radar indicated
Hail
1.0 in

County Cerro Gordo County, IA

The radar

The Des Moines radar (KDMX), 145 km from the middle of the area, began a volume at 22:25 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

TimeReportWhereRemark
Aug 27, 5:27 PM CDTFUNNEL CLOUD3 S Rockwell, IAFUNNEL CLOUD REPORTED NORTH OF SHEFFIELD. FUNNEL CLOUD WAS LOW, BUT UNCLEAR IF IN CONTACT WITH THE GROUND.
Aug 27, 5:42 PM CDTFUNNEL CLOUDDougherty, IA2 MILES NW OF DOUGHERTY, NOT SURE WHETHER FUNNEL ACTUALLY TOUCHED GROUND.

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.

IssuedProductOfficeLasted
Aug 27, 5:15 PM CDTTornado WatchSPC6 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 10.4 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-pSkew-T log-p diagram, Minneapolis, MN at 12:00Z on 2021-08-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 487 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 12:00Z on 2021-08-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -9 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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.

055 
WFUS53 KDMX 272225
TORDMX
IAC033-272300-
/O.NEW.KDMX.TO.W.0034.210827T2225Z-210827T2300Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Des Moines IA
525 PM CDT Fri Aug 27 2021

The National Weather Service in Des Moines  has issued a

* Tornado Warning for...
  Southeastern Cerro Gordo County in north central Iowa...

* Until 600 PM CDT.
    
* At 524 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Sheffield, or 13 miles north of Hampton, moving
  northeast at 20 mph.

  HAZARD...Tornado and quarter size hail.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* This dangerous storm will be near...
  Rockwell around 535 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4291 9303 4291 9328 4301 9331 4306 9302
TIME...MOT...LOC 2224Z 246DEG 18KT 4294 9323 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN

$$

REV
3 follow-up statements
263 
WWUS53 KDMX 272235
SVSDMX

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

IAC033-272300-
/O.CON.KDMX.TO.W.0034.000000T0000Z-210827T2300Z/
Cerro Gordo IA-
535 PM CDT Fri Aug 27 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 600 PM CDT FOR
SOUTHEASTERN CERRO GORDO COUNTY...
    
At 535 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Rockwell, or 12 miles south of Mason City, moving
northeast at 25 mph.

HAZARD...Tornado and quarter size hail.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

This tornadic thunderstorm will remain over mainly rural areas of
southeastern Cerro Gordo County, including the following locations...
Dougherty.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4291 9303 4291 9328 4301 9331 4306 9302
TIME...MOT...LOC 2235Z 246DEG 20KT 4297 9311 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN

$$

REV
972 
WWUS53 KDMX 272242
SVSDMX

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

IAC033-272300-
/O.CON.KDMX.TO.W.0034.000000T0000Z-210827T2300Z/
Cerro Gordo IA-
542 PM CDT Fri Aug 27 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 600 PM CDT FOR
SOUTHEASTERN CERRO GORDO COUNTY...
    
At 542 PM CDT, a severe thunderstorm capable of producing a tornado
was located 7 miles east of Rockwell, or 15 miles southeast of Mason
City, moving east at 15 mph.

HAZARD...Tornado and quarter size hail.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

Locations impacted include...
Dougherty.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4291 9303 4291 9314 4303 9315 4306 9302
TIME...MOT...LOC 2242Z 259DEG 13KT 4295 9305 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN

$$

REV
759 
WWUS53 KDMX 272257
SVSDMX

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

IAC033-272307-
/O.EXP.KDMX.TO.W.0034.000000T0000Z-210827T2300Z/
Cerro Gordo IA-
557 PM CDT Fri Aug 27 2021

...THE TORNADO WARNING FOR SOUTHEASTERN CERRO GORDO COUNTY WILL
EXPIRE AT 600 PM CDT...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire.

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

LAT...LON 4291 9303 4291 9314 4303 9315 4306 9302
TIME...MOT...LOC 2257Z 246DEG 18KT 4298 9296 

$$

REV

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 26, 7:02 PM CDTSevere Thunderstorm WarningDMXAudubon, Carroll28 min
Aug 26, 8:35 PM CDTSpecial Weather StatementDMXPoweshiek40 min
Aug 26, 8:47 PM CDTSevere Thunderstorm WarningDMXMahaska, Poweshiek58 min
Aug 26, 9:46 PM CDTSpecial Weather StatementDMXMahaska44 min
Aug 26, 10:26 PM CDTSpecial Weather StatementDMXMahaska34 min
Aug 26, 10:30 PM CDTSevere Thunderstorm WarningDMXEmmet, Palo Alto45 min
Aug 26, 10:52 PM CDTSpecial Weather StatementDMXWapello38 min
Aug 26, 11:42 PM CDTSevere Thunderstorm WarningDMXEmmet, Palo Alto33 min
Aug 27, 12:13 AM CDTSpecial Weather StatementDMXEmmet32 min
Aug 27, 2:08 PM CDTSpecial Weather StatementDMXHancock37 min
Aug 27, 2:59 PM CDTSpecial Weather StatementDMXCerro Gordo16 min
Aug 27, 4:23 PM CDTSevere Thunderstorm WarningDMXCerro Gordo, Hancock52 min
Aug 27, 4:48 PM CDTTornado WarningDMXCerro Gordo, Hancock57 min
Aug 27, 4:58 PM CDTSevere Thunderstorm WarningDMXCerro Gordo, Franklin, Hancock32 min
Aug 27, 5:23 PM CDTTornado Warning Tornado observedDMXCerro Gordo37 min

Nearby

Tornado Warnings in Iowa, 2021Every tornado warning in 2021Tornadoes 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.