Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 35, NWS Des Moines, IA

December 15, 2021Cass County, Iowa

NWS Des Moines, IA issued this tornado warning at Dec 15, 2021, 4:37 PM CST for Cass County, Iowa. It was in force for 23 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, 4:37 PM CST (22:37 UTC)
Expired: Dec 15, 2021, 5:00 PM CST
In force: 23 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Observed
Hail: 0.0 in

County Cass County, IA

The radar

The Des Moines radar (KDMX), 112 km from the middle of the area, began a volume at 22:38 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
Dec 15, 5:02 PM CST	TORNADO	1 Nw Atlantic, IA	STORM CHASER REPORTED TORNADO ON THE WEST SIDE OF ATLANTIC.

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.

Issued	Product	Office	Lasted
Dec 15, 1:23 PM CST	Tornado Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 10.6 hours before the alert went out and 117 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: 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.

749 
WFUS53 KDMX 152237
TORDMX
IAC029-152300-
/O.NEW.KDMX.TO.W.0035.211215T2237Z-211215T2300Z/

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

The National Weather Service in Des Moines  has issued a

* Tornado Warning for...
  Cass County in southwestern Iowa...

* Until 500 PM CST.
    
* At 437 PM CST, a tornado producing storm was located near
  Macedonia, or 21 miles southwest of Atlantic, moving northeast at
  80 mph.

  HAZARD...Damaging tornado.

  SOURCE...Radar 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 storm will be near...
  Griswold around 445 PM CST.
  Atlantic around 455 PM CST.

This includes Interstate 80 between mile markers 50 and 73.
 
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 4150 9515 4150 9470 4133 9470 4116 9494
      4116 9516
TIME...MOT...LOC 2237Z 231DEG 68KT 4120 9534 

TORNADO...OBSERVED
MAX HAIL SIZE...0.00 IN

$$

Martin

1 follow-up statement

244 
WWUS53 KDMX 152247
SVSDMX

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

IAC029-152300-
/O.CON.KDMX.TO.W.0035.000000T0000Z-211215T2300Z/
Cass IA-
447 PM CST Wed Dec 15 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 500 PM CST FOR CASS
COUNTY...
        
At 446 PM CST, a confirmed tornado was located 8 miles northwest of
Griswold, or 12 miles west of Atlantic, moving northeast at 80 mph.

HAZARD...Damaging tornado.

SOURCE...Radar 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 tornado will be near...
  Marne around 455 PM CST.  
  Atlantic around 455 PM CST.

Other locations impacted by this tornadic thunderstorm include Wiota,
Lake Anita State Park, Lewis, Cumberland, Griswold Park, Cold Springs
State Park, Atlantic Municipal Airport, Anita Municipal Airport,
Anita and Marne.

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 4150 9515 4150 9470 4133 9470 4116 9494
      4116 9516
TIME...MOT...LOC 2246Z 221DEG 59KT 4133 9523 

TORNADO...OBSERVED
MAX HAIL SIZE...0.00 IN

$$

Martin

The office that day

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

Issued	Product	Office	Counties	Lasted
Dec 15, 4:13 PM CST	Severe Thunderstorm Warning Destructive damage threat	DMX	Adair, Adams, Audubon, Cass, Guthrie, Ringgold and 2 more	77 min
Dec 15, 4:16 PM CST	Severe Thunderstorm Warning Destructive damage threat	DMX	Carroll, Crawford, Sac	74 min
Dec 15, 4:44 PM CST	Tornado Warning	DMX	Crawford	36 min
Dec 15, 4:53 PM CST	Tornado Warning	DMX	Adair, Audubon, Cass, Guthrie	33 min
Dec 15, 5:07 PM CST	Tornado Warning	DMX	Sac	27 min
Dec 15, 5:10 PM CST	Severe Thunderstorm Warning Destructive damage threat	DMX	Adair, Audubon, Boone, Dallas, Greene, Guthrie and 4 more	80 min
Dec 15, 5:10 PM CST	Tornado Warning	DMX	Carroll, Crawford	35 min
Dec 15, 5:14 PM CST	Tornado Warning	DMX	Audubon, Calhoun, Carroll, Greene, Guthrie	31 min
Dec 15, 5:15 PM CST	Tornado Warning	DMX	Calhoun, Carroll, Crawford, Sac	30 min
Dec 15, 5:18 PM CST	Tornado Warning Tornado observed	DMX	Adair, Boone, Dallas, Greene, Guthrie	42 min
Dec 15, 5:19 PM CST	Severe Thunderstorm Warning Destructive damage threat	DMX	Boone, Calhoun, Carroll, Emmet, Greene, Humboldt and 5 more	71 min
Dec 15, 5:22 PM CST	Severe Thunderstorm Warning Destructive damage threat	DMX	Carroll, Crawford, Sac	23 min
Dec 15, 5:22 PM CST	Severe Thunderstorm Warning Considerable damage threat	DMX	Adair, Adams, Clarke, Decatur, Madison, Ringgold and 3 more	68 min
Dec 15, 5:36 PM CST	Tornado Warning	DMX	Calhoun, Humboldt, Kossuth, Palo Alto, Pocahontas	24 min
Dec 15, 5:38 PM CST	Tornado Warning Tornado observed	DMX	Boone, Calhoun, Greene, Hamilton, Webster	37 min
Dec 15, 5:45 PM CST	Tornado Warning	DMX	Calhoun, Pocahontas, Webster	30 min
Dec 15, 5:52 PM CST	Severe Thunderstorm Warning Destructive damage threat	DMX	Boone, Franklin, Hamilton, Hancock, Hardin, Humboldt and 6 more	53 min
Dec 15, 5:58 PM CST	Tornado Warning	DMX	Hancock, Humboldt, Kossuth, Palo Alto, Pocahontas	32 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.