Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 23, NWS Sioux Falls, SD

December 15, 20217 counties in Iowa

NWS Sioux Falls, SD issued this tornado warning at Dec 15, 2021, 4:42 PM CST for 7 counties in Iowa. It was in force for 33 min. 8 reports 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, 4:42 PM CST (22:42 UTC)
Expired: Dec 15, 2021, 5:15 PM CST
In force: 33 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Ida County, IA, O'Brien County, IA, Plymouth County, IA, Woodbury County, IA

The radar

The Sioux Falls radar (KFSD), 130 km from the middle of the area, began a volume at 22:40 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, 4:43 PM CST	TSTM WND DMG	2 Nw Battle Creek, IA	MACHINE SHED DAMAGED. TIME ESTIMATED FROM RADAR.
Dec 15, 4:52 PM CST	TSTM WND DMG	6 Ssw Cleghorn, IA	MACHINE SHED DESTROYED AND GRAVITY WAGON TIPPED OVER. REPORT VIA SOCIAL MEDIA.
Dec 15, 4:56 PM CST	TSTM WND DMG	1 Ssw Marcus, IA	ROOFS WERE BLOWN OFF OF A FEW BUILDINGS AND SEMI WAS BLOWN OFF THE ROAD. TIME ESTIMATED FROM RADAR.
Dec 15, 5:03 PM CST	TSTM WND DMG	Aurelia, IA	SILO DAMAGED, TREES DOWN AND SHEET METAL FROM BUILDINGS ON ROAD. POWER OUT IN TOWN. TIME ESTIMATED FROM RADAR.
Dec 15, 5:03 PM CST	TSTM WND DMG	Aurelia, IA	UPDATES PREVIOUS TSTM WND DMG REPORT FROM AURELIA. SILO DAMAGED, TREES DOWN AND SHEET METAL FROM BUILDINGS ON ROAD. 3 RAIL CARS BLOWN OVER, AND A HOME DESTROYED. POWER OUT IN TOWN. TIME ESTIMATED FROM RADAR.
Dec 15, 5:04 PM CST	TSTM WND DMG	Larrabee, IA	DAMAGE TO MACHINE SHEDS AND SOME ROOFS DAMAGE. TIME ESTIMATED FROM RADAR.
Dec 15, 5:10 PM CST	TSTM WND DMG	2 Sse Sutherland, IA	DESTROYED BUILDING BLOCKING HIGHWAY 10 SOUTH OF SUTHERLAND. TIME ESTIMATED FROM RADAR.
Dec 15, 5:11 PM CST	TSTM WND DMG	Sutherland, IA	LARGE TREE BRANCH DOWN IN TOWN. TIME ESTIMATED FROM RADAR.

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, 10.7 hours before the alert went out and 158 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.

015 
WFUS53 KFSD 152242
TORFSD
IAC021-035-041-093-141-149-193-152315-
/O.NEW.KFSD.TO.W.0023.211215T2242Z-211215T2315Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Sioux Falls SD
442 PM CST Wed Dec 15 2021

The National Weather Service in Sioux Falls has issued a

* Tornado Warning for...
  Cherokee County in northwestern Iowa...
  Northeastern Woodbury County in west central Iowa...
  Eastern Plymouth County in northwestern Iowa...
  Northwestern Buena Vista County in northwestern Iowa...
  Southwestern Clay County in northwestern Iowa...
  Southern O'Brien County in northwestern Iowa...
  Western Ida County in west central Iowa...

* Until 515 PM CST.

* At 442 PM CST, severe thunderstorms capable of producing both
  tornadoes and extensive straight line wind damage were located near
  Pierson, or 17 miles southwest of Cherokee, moving northeast at 75
  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.

* These dangerous storms will be near...
  Cherokee, Marcus and Cleghorn around 455 PM CST.
  Larrabee around 500 PM CST.
  Sutherland around 510 PM CST.

Other locations impacted by this tornadic thunderstorm include
Calumet and Meriden.

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.

This cluster of thunderstorms is capable of producing tornadoes and
widespread significant wind damage. Do not wait to see or hear the
tornado. For your protection move to an interior room on the lowest
floor of a building.

&&

LAT...LON 4251 9609 4315 9574 4292 9518 4222 9570
TIME...MOT...LOC 2242Z 210DEG 65KT 4259 9582 

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

$$

SG

1 follow-up statement

895 
WWUS53 KFSD 152300
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
500 PM CST Wed Dec 15 2021

IAC149-193-152309-
/O.CAN.KFSD.TO.W.0023.000000T0000Z-211215T2315Z/
Woodbury IA-Plymouth IA-
500 PM CST Wed Dec 15 2021

...THE TORNADO WARNING FOR NORTHEASTERN WOODBURY AND EASTERN PLYMOUTH
COUNTIES IS CANCELLED...
    
The tornadic thunderstorm which prompted the warning hasmoved out of 
the warned area. Therefore, the warning has been cancelled.

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

LAT...LON 4272 9584 4292 9586 4315 9574 4292 9518
      4247 9551 4267 9567
TIME...MOT...LOC 2259Z 210DEG 65KT 4287 9560 

$$

IAC021-035-041-093-141-152315-
/O.CON.KFSD.TO.W.0023.000000T0000Z-211215T2315Z/
Cherokee IA-Buena Vista IA-Clay IA-O'Brien IA-Ida IA-
500 PM CST Wed Dec 15 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 515 PM CST FOR
CHEROKEE...NORTHWESTERN BUENA VISTA...SOUTHWESTERN CLAY...SOUTHERN
O'BRIEN AND NORTH CENTRAL IDA COUNTIES...

At 459 PM CST, a severe squall line capable of producing both
tornadoes and extensive straight line wind damage was located over
Larrabee, or 8 miles north of Cherokee, moving northeast at 75 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.

These dangerous storms will be near...
  Sutherland around 505 PM CST.

Other locations impacted by this tornadic thunderstorm include
Calumet and Meriden.

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.

This cluster of thunderstorms is capable of producing tornadoes and
widespread significant wind damage. Do not wait to see or hear the
tornado. For your protection move to an interior room on the lowest
floor of a building.

&&

LAT...LON 4272 9584 4292 9586 4315 9574 4292 9518
      4247 9551 4267 9567
TIME...MOT...LOC 2259Z 210DEG 65KT 4287 9560 

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

$$

Chapman

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 15, 2:56 AM CST	Dense Fog Advisory	FSD	Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 5 more	6 hr
Dec 15, 3:23 PM CST	Severe Thunderstorm Warning Considerable damage threat	FSD	Plymouth, Woodbury	67 min
Dec 15, 4:00 PM CST	Tornado Warning	FSD	Woodbury	45 min
Dec 15, 4:05 PM CST	Severe Thunderstorm Warning Considerable damage threat	FSD	Buena Vista, Cherokee, Ida, Plymouth, Woodbury	55 min
Dec 15, 4:17 PM CST	Tornado Warning	FSD	Plymouth, Woodbury	28 min
Dec 15, 4:26 PM CST	Severe Thunderstorm Warning Considerable damage threat	FSD	Plymouth, Woodbury	34 min
Dec 15, 4:31 PM CST	Tornado Warning	FSD	Ida, Plymouth, Woodbury	29 min
Dec 15, 4:32 PM CST	Tornado Warning	FSD	Plymouth, Woodbury	28 min
Dec 15, 4:51 PM CST	Severe Thunderstorm Warning Considerable damage threat	FSD	O'Brien, Sioux	39 min
Dec 15, 4:56 PM CST	Severe Thunderstorm Warning Destructive damage threat	FSD	Buena Vista, Cherokee, Clay, Ida	46 min
Dec 15, 5:08 PM CST	Tornado Warning	FSD	Buena Vista, Cherokee, Clay	37 min
Dec 15, 5:15 PM CST	Tornado Warning	FSD	Buena Vista, Cherokee, Clay, O'Brien	30 min
Dec 15, 5:29 PM CST	Severe Thunderstorm Warning Considerable damage threat	FSD	Dickinson	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.