Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 21, NWS Sioux Falls, SD

December 15, 2021Ida County, Plymouth County, Woodbury County, Iowa

NWS Sioux Falls, SD issued this tornado warning at Dec 15, 2021, 4:31 PM CST for Ida County, Plymouth County, Woodbury County, Iowa. It was in force for 29 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, 4:31 PM CST (22:31 UTC)
Expired: Dec 15, 2021, 5:00 PM CST
In force: 29 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Ida County, IA, Plymouth County, IA, Woodbury County, IA

The radar

The Omaha radar (KOAX), 134 km from the middle of the area, began a volume at 22:36 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, 4:34 PM CST	TSTM WND DMG	1 W Anthon, IA	CATTLE BARN AND GARAGE DAMAGED. 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, 10.5 hours before the alert went out and 135 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.

878 
WFUS53 KFSD 152231
TORFSD
IAC093-149-193-152300-
/O.NEW.KFSD.TO.W.0021.211215T2231Z-211215T2300Z/

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

The National Weather Service in Sioux Falls has issued a

* Tornado Warning for...
  Eastern Woodbury County in west central Iowa...
  Southeastern Plymouth County in northwestern Iowa...
  Northwestern Ida County in west central Iowa...

* Until 500 PM CST.

* At 430 PM CST, severe thunderstorms capable of producing both
  tornadoes and extensive straight line wind damage were located over
  Smithland, or 23 miles west of Ida Grove, moving north 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.

* These dangerous storms will be near...
  Anthon around 440 PM CST.
  Correctionville around 445 PM CST.
  Pierson and Cushing around 450 PM CST.

Other locations impacted by this tornadic thunderstorm include Oto.

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 4262 9586 4256 9586 4256 9554 4221 9578
      4222 9617
TIME...MOT...LOC 2230Z 202DEG 60KT 4223 9591 

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

$$

SG

1 follow-up statement

675 
WWUS53 KFSD 152301
SVSFSD

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

IAC093-149-193-152309-
/O.EXP.KFSD.TO.W.0021.000000T0000Z-211215T2300Z/
Woodbury IA-Plymouth IA-Ida IA-
501 PM CST Wed Dec 15 2021

...THE TORNADO WARNING FOR EASTERN WOODBURY...SOUTHEASTERN PLYMOUTH
AND NORTHWESTERN IDA COUNTIES WILL EXPIRE AT 500 PM CST...
    
The tornado threat has diminished and the Tornado Warning has 
expired. However, large hail and damaging winds remain likely and a 
Severe Thunderstorm Warning remains in effect for Ida county.

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

Remember, a Tornado Warning still remains in effect for northern Ida 
county until 515 PM.

LAT...LON 4262 9586 4256 9586 4256 9554 4221 9578
      4222 9617
TIME...MOT...LOC 2259Z 202DEG 60KT 4266 9567 

$$

SG

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, 4:32 PM CST	Tornado Warning	FSD	Plymouth, Woodbury	28 min
Dec 15, 4:42 PM CST	Tornado Warning	FSD	Buena Vista, Cherokee, Clay, Ida, O'Brien, Plymouth and 1 more	33 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.