Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 28, NWS Des Moines, IA

August 8, 2021Webster County, Iowa

NWS Des Moines, IA issued this tornado warning at Aug 8, 2021, 11:00 PM CDT for Webster County, Iowa. It was in force for 30 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 8, 2021, 11:00 PM CDT (04:00 UTC)
Expired: Aug 8, 2021, 11:30 PM CDT
In force: 30 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

County Webster County, IA

The radar

The Des Moines radar (KDMX), 84 km from the middle of the area, began a volume at 04:00 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 8, 11:23 PM CDT	TORNADO	3 Ssw Otho, IA	PAST WITHIN 50 YARDS OF CHASER. REPORT VIA SOCIAL MEDIA.

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

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 4.0 hours before the alert went out and 214 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: 1733 J/kg
Mixed-layer CIN: -130 J/kg
Mixed-layer LCL: 1356 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 104 m²/s²
0-3 km storm-relative helicity: 137 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 6.0

Open this sounding in Storm Lab

The text

As transmitted.

945 
WFUS53 KDMX 090400
TORDMX
IAC187-090430-
/O.NEW.KDMX.TO.W.0028.210809T0400Z-210809T0430Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Des Moines IA
1100 PM CDT Sun Aug 8 2021

The National Weather Service in Des Moines  has issued a

* Tornado Warning for...
  Central Webster County in central Iowa...

* Until 1130 PM CDT.
    
* At 1100 PM CDT, a severe thunderstorm capable of producing a
  tornado was located 8 miles southwest of Fort Dodge, moving
  southeast at 10 mph.

  HAZARD...Tornado.

  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
  central Webster County, including the following locations...
  Dolliver Memorial State Park, Moorland, Otho, Woodman Hollow State
  Park, Lehigh and Coalville.

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 4241 9435 4247 9430 4241 9400 4225 9412
TIME...MOT...LOC 0400Z 296DEG 11KT 4241 9428 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

Cogil

2 follow-up statements

881 
WWUS53 KDMX 090408
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
1108 PM CDT Sun Aug 8 2021

IAC187-090430-
/O.CON.KDMX.TO.W.0028.000000T0000Z-210809T0430Z/
Webster IA-
1108 PM CDT Sun Aug 8 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1130 PM CDT FOR CENTRAL
WEBSTER COUNTY...
    
At 1108 PM CDT, a severe thunderstorm capable of producing a tornado
was located 7 miles southwest of Fort Dodge, moving east at 10 mph.

HAZARD...Tornado.

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...
Coalville, Otho, Lehigh, Moorland, Dolliver Memorial State Park and
Woodman Hollow 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 4242 9431 4246 9425 4241 9400 4228 9410
TIME...MOT...LOC 0408Z 283DEG 10KT 4242 9425 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

Cogil

092 
WWUS53 KDMX 090417
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
1117 PM CDT Sun Aug 8 2021

IAC187-090430-
/O.CON.KDMX.TO.W.0028.000000T0000Z-210809T0430Z/
Webster IA-
1117 PM CDT Sun Aug 8 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1130 PM CDT FOR
SOUTHEASTERN WEBSTER COUNTY...
    
At 1116 PM CDT, a severe thunderstorm capable of producing a tornado
was located 8 miles south of Fort Dodge, moving east at 15 mph.

HAZARD...Tornado.

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...
Otho, Lehigh and Dolliver Memorial 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 4238 9425 4242 9418 4241 9400 4228 9410
TIME...MOT...LOC 0416Z 288DEG 13KT 4239 9418 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

Cogil

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 8, 8:36 PM CDT	Tornado Warning	DMX	Pocahontas	24 min
Aug 8, 9:02 PM CDT	Tornado Warning	DMX	Calhoun, Pocahontas	31 min
Aug 8, 10:39 PM CDT	Special Weather Statement	DMX	Webster	51 min
Aug 8, 11:30 PM CDT	Tornado Warning Tornado observed	DMX	Webster	30 min
Aug 8, 11:52 PM CDT	Tornado Warning	DMX	Boone, Webster	38 min
Aug 9, 12:23 AM CDT	Tornado Warning	DMX	Butler, Franklin	20 min
Aug 9, 12:29 AM CDT	Severe Thunderstorm Warning	DMX	Boone, Hamilton, Webster	46 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.