Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 27, NWS Des Moines, IA

August 8, 2021Calhoun County, Pocahontas County, Iowa

NWS Des Moines, IA issued this tornado warning at Aug 8, 2021, 9:02 PM CDT for Calhoun County, Pocahontas County, Iowa. It was in force for 31 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, 9:02 PM CDT (02:02 UTC)
Expired: Aug 8, 2021, 9:33 PM CDT
In force: 31 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.0 in

Counties Calhoun County, IA, Pocahontas County, IA

The radar

The Des Moines radar (KDMX), 122 km from the middle of the area, began a volume at 02:01 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, 9:09 PM CDT	FUNNEL CLOUD	5 Nnw Pomeroy, IA

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, 2.0 hours before the alert went out and 197 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.

450 
WFUS53 KDMX 090202
TORDMX
IAC025-151-090245-
/O.NEW.KDMX.TO.W.0027.210809T0202Z-210809T0245Z/

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

The National Weather Service in Des Moines  has issued a

* Tornado Warning for...
  South central Pocahontas County in northwestern Iowa...
  North central Calhoun County in west central Iowa...

* Until 945 PM CDT.
    
* At 901 PM CDT, a severe thunderstorm capable of producing a tornado
  was located 9 miles south of Pocahontas, 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...
  North Twin Lake and Manson.

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 4259 9481 4267 9473 4257 9447 4243 9459
TIME...MOT...LOC 0201Z 303DEG 12KT 4261 9474 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Cogil

3 follow-up statements

543 
WWUS53 KDMX 090213
SVSDMX

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

IAC025-151-090245-
/O.CON.KDMX.TO.W.0027.000000T0000Z-210809T0245Z/
Pocahontas IA-Calhoun IA-
913 PM CDT Sun Aug 8 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 945 PM CDT FOR SOUTH
CENTRAL POCAHONTAS AND NORTH CENTRAL CALHOUN COUNTIES...
    
At 912 PM CDT, a severe thunderstorm capable of producing a tornado
was located 9 miles northwest of North Twin Lake, or 9 miles south of
Pocahontas, 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...
Manson, North Twin Lake, Pomeroy, Twin Lakes and Twin Lakes 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 4260 9478 4266 9471 4257 9447 4243 9459
TIME...MOT...LOC 0212Z 301DEG 12KT 4260 9470 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Cogil

350 
WWUS53 KDMX 090226
SVSDMX

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

IAC025-151-090245-
/O.CON.KDMX.TO.W.0027.000000T0000Z-210809T0245Z/
Pocahontas IA-Calhoun IA-
926 PM CDT Sun Aug 8 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 945 PM CDT FOR SOUTH
CENTRAL POCAHONTAS AND NORTH CENTRAL CALHOUN COUNTIES...
    
At 926 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Manson, or 11 miles north of Rockwell City, 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...
Manson and Pomeroy. 

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 4258 9470 4264 9465 4257 9447 4246 9456
TIME...MOT...LOC 0226Z 300DEG 13KT 4257 9461 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Cogil

085 
WWUS53 KDMX 090233
SVSDMX

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

IAC025-151-090243-
/O.CAN.KDMX.TO.W.0027.000000T0000Z-210809T0245Z/
Pocahontas IA-Calhoun IA-
933 PM CDT Sun Aug 8 2021

...THE TORNADO WARNING FOR SOUTH CENTRAL POCAHONTAS AND NORTH CENTRAL
CALHOUN COUNTIES IS CANCELLED...
                
The storm which prompted the warning has weakened below severe 
limits, and no longer appears capable of producing a tornado. 
Therefore, the warning has been cancelled.

LAT...LON 4258 9470 4264 9465 4257 9447 4246 9456
TIME...MOT...LOC 0230Z 303DEG 12KT 4256 9458 

$$

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, 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, 11:30 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.