Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 45, NWS Des Moines, IA

December 15, 2021Calhoun County, Pocahontas County, Webster County, Iowa

NWS Des Moines, IA issued this tornado warning at Dec 15, 2021, 5:45 PM CST for Calhoun County, Pocahontas County, 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
Dec 15, 2021, 5:45 PM CST (23:45 UTC)
Expired
Dec 15, 2021, 6:15 PM CST
In force
30 min
Issued by
NWS Des Moines, IA
Area
Storm-based polygon
Tornado
Radar indicated
Hail
0.75 in

Counties Calhoun County, IA, Pocahontas County, IA, Webster County, IA

The radar

The Des Moines radar (KDMX), 107 km from the middle of the area, began a volume at 23:48 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

TimeReportWhereRemark
Dec 15, 5:48 PM CSTTSTM WND DMGKnierim, IAMACHINE SHED DAMAGED 1 MILE NORTH OF SOMERS AND STOP SIGNS/HIGHWAY SIGNS BLOWN OVER HWY 20 AT KNIERIM.

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
Dec 15, 1:23 PM CSTTornado WatchSPC7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 11.8 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, Omaha, NE at 12:00Z on 2021-12-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Omaha, NE at 12:00Z on 2021-12-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 346 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2165 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
346 m²/s²
0-3 km storm-relative helicity
384 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

360 
WFUS53 KDMX 152345
TORDMX
IAC025-151-187-160015-
/O.NEW.KDMX.TO.W.0045.211215T2345Z-211216T0015Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Des Moines IA
545 PM CST Wed Dec 15 2021

The National Weather Service in Des Moines  has issued a

* Tornado Warning for...
  Northwestern Webster County in central Iowa...
  Southeastern Pocahontas County in northwestern Iowa...
  Northeastern Calhoun County in west central Iowa...

* Until 615 PM CST.
    
* At 544 PM CST, a severe thunderstorm capable of producing a tornado
  was located 8 miles east of Rockwell City, moving northeast at 70
  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
  northwestern Webster, southeastern Pocahontas and northeastern
  Calhoun Counties, including the following locations... Knierim,
  Clare, Rinard, Barnum and Somers.

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 4264 9448 4265 9431 4265 9423 4264 9422
      4230 9450 4235 9461
TIME...MOT...LOC 2344Z 210DEG 62KT 4240 9447 

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

$$

Cogil
2 follow-up statements
589 
WWUS53 KDMX 160000 RRA
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
600 PM CST Wed Dec 15 2021

IAC025-151-160010-
/O.CAN.KDMX.TO.W.0045.000000T0000Z-211216T0015Z/
Pocahontas IA-Calhoun IA-
600 PM CST Wed Dec 15 2021

...THE TORNADO WARNING FOR SOUTHEASTERN POCAHONTAS AND NORTHEASTERN
CALHOUN COUNTIES IS CANCELLED...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 800 PM CST for central and
north central Iowa.

LAT...LON 4265 9431 4265 9423 4264 9422 4246 9439
      4257 9438 4264 9440
TIME...MOT...LOC 0000Z 213DEG 50KT 4260 9431 

$$

IAC187-160015-
/O.CON.KDMX.TO.W.0045.000000T0000Z-211216T0015Z/
Webster IA-
600 PM CST Wed Dec 15 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 615 PM CST FOR
NORTHWESTERN WEBSTER COUNTY...
    
At 600 PM CST, a severe thunderstorm capable of producing a tornado
was located near Fort Dodge Regional Airport, or 9 miles northwest of
Fort Dodge, moving northeast at 55 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...
Barnum and Clare. 

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 4265 9431 4265 9423 4264 9422 4246 9439
      4257 9438 4264 9440
TIME...MOT...LOC 0000Z 213DEG 50KT 4260 9431 

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

$$

Cogil
683 
WWUS53 KDMX 160009
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
609 PM CST Wed Dec 15 2021

IAC187-160019-
/O.EXP.KDMX.TO.W.0045.000000T0000Z-211216T0015Z/
Webster IA-
609 PM CST Wed Dec 15 2021

...THE TORNADO WARNING FOR NORTHWESTERN WEBSTER COUNTY WILL EXPIRE AT
615 PM CST...
        
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 800 PM CST for central and
north central Iowa.

LAT...LON 4265 9431 4265 9423 4264 9422 4246 9439
      4257 9438 4264 9440
TIME...MOT...LOC 0009Z 210DEG 62KT 4273 9421 

$$

Cogil

The office that day

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

IssuedProductOfficeCountiesLasted
Dec 15, 4:13 PM CSTSevere Thunderstorm Warning Destructive damage threatDMXAdair, Adams, Audubon, Cass, Guthrie, Ringgold and 2 more77 min
Dec 15, 4:16 PM CSTSevere Thunderstorm Warning Destructive damage threatDMXCarroll, Crawford, Sac74 min
Dec 15, 4:37 PM CSTTornado Warning Tornado observedDMXCass23 min
Dec 15, 4:44 PM CSTTornado WarningDMXCrawford36 min
Dec 15, 4:53 PM CSTTornado WarningDMXAdair, Audubon, Cass, Guthrie33 min
Dec 15, 5:07 PM CSTTornado WarningDMXSac27 min
Dec 15, 5:10 PM CSTSevere Thunderstorm Warning Destructive damage threatDMXAdair, Audubon, Boone, Dallas, Greene, Guthrie and 4 more80 min
Dec 15, 5:10 PM CSTTornado WarningDMXCarroll, Crawford35 min
Dec 15, 5:14 PM CSTTornado WarningDMXAudubon, Calhoun, Carroll, Greene, Guthrie31 min
Dec 15, 5:15 PM CSTTornado WarningDMXCalhoun, Carroll, Crawford, Sac30 min
Dec 15, 5:18 PM CSTTornado Warning Tornado observedDMXAdair, Boone, Dallas, Greene, Guthrie42 min
Dec 15, 5:19 PM CSTSevere Thunderstorm Warning Destructive damage threatDMXBoone, Calhoun, Carroll, Emmet, Greene, Humboldt and 5 more71 min
Dec 15, 5:22 PM CSTSevere Thunderstorm Warning Destructive damage threatDMXCarroll, Crawford, Sac23 min
Dec 15, 5:22 PM CSTSevere Thunderstorm Warning Considerable damage threatDMXAdair, Adams, Clarke, Decatur, Madison, Ringgold and 3 more68 min
Dec 15, 5:36 PM CSTTornado WarningDMXCalhoun, Humboldt, Kossuth, Palo Alto, Pocahontas24 min
Dec 15, 5:38 PM CSTTornado Warning Tornado observedDMXBoone, Calhoun, Greene, Hamilton, Webster37 min
Dec 15, 5:52 PM CSTSevere Thunderstorm Warning Destructive damage threatDMXBoone, Franklin, Hamilton, Hancock, Hardin, Humboldt and 6 more53 min
Dec 15, 5:58 PM CSTTornado WarningDMXHancock, Humboldt, Kossuth, Palo Alto, Pocahontas32 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.