Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 29, NWS Des Moines, IA

August 8, 2021Webster County, Iowa

NWS Des Moines, IA issued this tornado warning at Aug 8, 2021, 11:30 PM CDT for Webster County, Iowa. It was in force for 30 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 8, 2021, 11:30 PM CDT (04:30 UTC)
Expired: Aug 9, 2021, 12:00 AM CDT
In force: 30 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Observed
Hail: 0.75 in

County Webster County, IA

The radar

The Des Moines radar (KDMX), 79 km from the middle of the area, began a volume at 04:33 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.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 4.5 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: 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.

337 
WFUS53 KDMX 090430
TORDMX
IAC187-090500-
/O.NEW.KDMX.TO.W.0029.210809T0430Z-210809T0500Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Des Moines IA
1130 PM CDT Sun Aug 8 2021

The National Weather Service in Des Moines  has issued a

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

* Until midnight CDT.

* At 1130 PM CDT, a confirmed tornado was located 7 miles north of
  Gowrie, or 9 miles southwest of Fort Dodge, moving southeast at 20
  mph.

  HAZARD...Damaging tornado.

  SOURCE...Weather spotters confirmed tornado.

  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
  southern Webster County, including the following locations...
  Callender, Dolliver Memorial State Park, Lehigh, Brushy Creek St
  Recreation Area, Dayton and Otho.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. 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 4235 9433 4243 9429 4240 9397 4223 9408
TIME...MOT...LOC 0430Z 306DEG 18KT 4239 9426 

TORNADO...OBSERVED
MAX HAIL SIZE...<.75 IN

$$

Cogil

1 follow-up statement

562 
WWUS53 KDMX 090444
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
1144 PM CDT Sun Aug 8 2021

IAC187-090500-
/O.CON.KDMX.TO.W.0029.000000T0000Z-210809T0500Z/
Webster IA-
1144 PM CDT Sun Aug 8 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL MIDNIGHT CDT FOR
SOUTHERN WEBSTER COUNTY...
    
At 1144 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Gowrie, or 12 miles south of Fort Dodge, moving
southeast 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...
Dayton, Otho, Lehigh, Callender, Dolliver Memorial State Park and
Brushy Creek St Recreation Area.

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 4235 9433 4242 9419 4240 9397 4223 9408
TIME...MOT...LOC 0444Z 320DEG 14KT 4234 9421 

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, 11:00 PM CDT	Tornado Warning	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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.