Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 32, NWS Des Moines, IA

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

NWS Des Moines, IA issued this tornado warning at Aug 27, 2021, 4:48 PM CDT for Cerro Gordo County, Hancock County, Iowa. It was in force for 57 min. 5 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, 4:48 PM CDT (21:48 UTC)
Expired: Aug 27, 2021, 5:45 PM CDT
In force: 57 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.0 in

Counties Cerro Gordo County, IA, Hancock County, IA

The radar

The Des Moines radar (KDMX), 155 km from the middle of the area, began a volume at 21:48 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, 4:52 PM CDT	TSTM WND DMG	2 Ese Ventura, IA	DELAYED REPORT: SOME TREE DAMAGE REPORTED AROUND THE CLEAR LAKE AREA. POWER OUTAGES ALSO REPORTED. TIME ESTIMATED VIA RADAR.
Aug 27, 5:06 PM CDT	HAIL 0.7	Mason City, IA	NEAR MERCY HOSPITAL AND HWY 18.
Aug 27, 5:07 PM CDT	TORNADO	5 S Clear Lake, IA	TRAINED SPOTTER RELAYED REPORT TO EM OF BRIEF TORNADO TOUCH DOWN WEST OF BURCHINAL. TIME ESIMATED VIA RADAR.
Aug 27, 5:08 PM CDT	TSTM WND DMG	1 Sw Mason City, IA	EM REPORTS A FEW TREE LIMBS DOWN AROUND TOWN, SOME DAMAGE TO POWER LINES. TIME ESTIMATED VIA RADAR.
Aug 27, 5:15 PM CDT	TORNADO	5 Sse Clear Lake, IA	TRAINED SPOTTER RELAYED REPORT TO COUNTY LAW ENFORCEMENT OF BRIEF TORNADO ON THE GROUND SOUTHEAST OF CLEAR LAKE AND SOUTH OF MASON CITY. UNCLEAR OF DAMAGE AT THIS TIME.

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, 9.8 hours before the alert went out and 198 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.

625 
WFUS53 KDMX 272148
TORDMX
IAC033-081-272245-
/O.NEW.KDMX.TO.W.0032.210827T2148Z-210827T2245Z/

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

The National Weather Service in Des Moines  has issued a

* Tornado Warning for...
  East central Hancock County in north central Iowa...
  Central Cerro Gordo County in north central Iowa...

* Until 545 PM CDT.
    
* At 448 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Clear Lake, or 7 miles southeast of Garner, moving
  east 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 dangerous storm will be near...
  Clear Lake around 505 PM CDT.

Other locations in the path of this tornadic thunderstorm include
Mason City Municipal Airport and Mason City.

This includes Interstate 35 between mile markers 185 and 197.
 
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 4305 9302 4298 9352 4311 9361 4324 9319
TIME...MOT...LOC 2148Z 248DEG 23KT 4305 9348 

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

$$

REV

3 follow-up statements

907 
WWUS53 KDMX 272200
SVSDMX

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

IAC081-272210-
/O.CAN.KDMX.TO.W.0032.000000T0000Z-210827T2245Z/
Hancock IA-
500 PM CDT Fri Aug 27 2021

...THE TORNADO WARNING FOR EAST CENTRAL HANCOCK COUNTY IS
CANCELLED...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. Therefore, the warning has been cancelled.

LAT...LON 4305 9302 4299 9347 4313 9349 4324 9319
TIME...MOT...LOC 2200Z 248DEG 23KT 4308 9338 

$$

IAC033-272245-
/O.CON.KDMX.TO.W.0032.000000T0000Z-210827T2245Z/
Cerro Gordo IA-
500 PM CDT Fri Aug 27 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 545 PM CDT FOR CENTRAL
CERRO GORDO COUNTY...
    
At 500 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Clear Lake, or 10 miles southwest of Mason City,
moving east 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.

Locations impacted include...
  Mason City Municipal Airport and Mason City.

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 4305 9302 4299 9347 4313 9349 4324 9319
TIME...MOT...LOC 2200Z 248DEG 23KT 4308 9338 

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

$$

REV

494 
WWUS53 KDMX 272213
SVSDMX

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

IAC033-272245-
/O.CON.KDMX.TO.W.0032.000000T0000Z-210827T2245Z/
Cerro Gordo IA-
513 PM CDT Fri Aug 27 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 545 PM CDT FOR CENTRAL
CERRO GORDO COUNTY...
    
At 512 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Mason City Municipal Airport, or near Mason City, 
moving east at 25 mph. Rotation continues to be indicated on radar 
just south of Clear Lake, Iowa at 511 PM CDT.

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...
Mason City, Mason City Municipal Airport, Clear Lake, Ventura,
Burchinal, Portland, Clear Lake State Park and McIntosh Woods State
Park.

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 4305 9302 4300 9341 4314 9347 4324 9319
TIME...MOT...LOC 2212Z 248DEG 23KT 4311 9328 

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

$$

REV

377 
WWUS53 KDMX 272240
SVSDMX

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

IAC033-272248-
/O.EXP.KDMX.TO.W.0032.000000T0000Z-210827T2245Z/
Cerro Gordo IA-
540 PM CDT Fri Aug 27 2021

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

A Tornado Warning still remains in effect for portions of 
central and eastern Cerro Gordo County until 600 PM CDT.

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

LAT...LON 4305 9302 4300 9341 4314 9347 4324 9319
TIME...MOT...LOC 2238Z 248DEG 23KT 4317 9308 

$$

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, 4:58 PM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Franklin, Hancock	32 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

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