Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 22, NWS Sioux Falls, SD

December 15, 2021Plymouth County, Woodbury County, Iowa

NWS Sioux Falls, SD issued this tornado warning at Dec 15, 2021, 4:32 PM CST for Plymouth County, Woodbury County, Iowa. It was in force for 28 min. 2 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, 4:32 PM CST (22:32 UTC)
Expired: Dec 15, 2021, 5:00 PM CST
In force: 28 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Plymouth County, IA, Woodbury County, IA

The radar

The Sioux Falls radar (KFSD), 121 km from the middle of the area, began a volume at 22:33 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, 4:33 PM CST	TORNADO	3 Ene Lawton, IA	REPORT OF POWER FLASHES FROM POWER LINES.
Dec 15, 4:35 PM CST	TSTM WND DMG	Kingsley, IA	ROOF TOWN OFF OF BUILDING. 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 147 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.

625 
WFUS53 KFSD 152232
TORFSD
IAC149-193-152300-
/O.NEW.KFSD.TO.W.0022.211215T2232Z-211215T2300Z/

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

The National Weather Service in Sioux Falls has issued a

* Tornado Warning for...
  North central Woodbury County in west central Iowa...
  Eastern Plymouth County in northwestern Iowa...

* Until 500 PM CST.
    
* At 431 PM CST, a severe thunderstorm capable of producing a tornado
  was located near Lawton, or 8 miles east of Sioux City, 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.

* This dangerous storm will be near...
  Hinton around 440 PM CST.
  Merrill around 445 PM CST.

Other locations in the path of this tornadic thunderstorm include Le
Mars and Remsen.

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 4238 9604 4255 9634 4291 9617 4286 9587
      4262 9586
TIME...MOT...LOC 2231Z 202DEG 49KT 4252 9623 

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

$$

Chapman

3 follow-up statements

771 
WWUS53 KFSD 152237
SVSFSD

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

IAC149-193-152300-
/O.CON.KFSD.TO.W.0022.000000T0000Z-211215T2300Z/
Woodbury IA-Plymouth IA-
437 PM CST Wed Dec 15 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 500 PM CST FOR NORTH
CENTRAL WOODBURY AND EASTERN PLYMOUTH COUNTIES...
    
At 433 PM CST, a confirmed tornado was located 3 miles east 
northeast of lawton, or 15 miles south southeast of Le Mars, moving 
north at 60 mph. Power flashes were noted with this tornado.

HAZARD...Damaging tornado.

SOURCE...Weather spotters 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...
  Le Mars around 450 PM CST.
  Remsen around 455 PM CST.

Other locations impacted by this tornadic thunderstorm include Oyens.

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 4238 9604 4255 9634 4291 9617 4286 9587
      4262 9586
TIME...MOT...LOC 2236Z 202DEG 53KT 4261 9612 

TORNADO...OBSERVED
MAX HAIL SIZE...<.75 IN

$$

Chapman

203 
WWUS53 KFSD 152241
SVSFSD

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

IAC149-193-152300-
/O.CON.KFSD.TO.W.0022.000000T0000Z-211215T2300Z/
Woodbury IA-Plymouth IA-
441 PM CST Wed Dec 15 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 500 PM CST FOR NORTH
CENTRAL WOODBURY AND EASTERN PLYMOUTH COUNTIES...
    
At 440 PM CST, a confirmed tornado was located near Kingsley, or 18 
miles southeast of Le Mars, moving northeast at 70 mph.

HAZARD...Damaging tornado.

SOURCE...Weather spotters 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 thunderstorm will remain over mainly rural areas of
north central Woodbury and eastern Plymouth Counties, including the
following locations... Oyens.

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 4238 9604 4255 9634 4291 9617 4286 9587
      4262 9586
TIME...MOT...LOC 2240Z 207DEG 60KT 4259 9593 

TORNADO...OBSERVED
MAX HAIL SIZE...<.75 IN

$$

Chapman

432 
WWUS53 KFSD 152257
SVSFSD

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

IAC149-193-152307-
/O.EXP.KFSD.TO.W.0022.000000T0000Z-211215T2300Z/
Woodbury IA-Plymouth IA-
457 PM CST Wed Dec 15 2021

...THE TORNADO WARNING FOR NORTH CENTRAL WOODBURY AND EASTERN
PLYMOUTH COUNTIES WILL EXPIRE AT 500 PM CST...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. Therefore, the warning will be allowed to 
expire. However, gusty winds are still possible with this 
thunderstorm.

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

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Sioux Falls.

LAT...LON 4238 9604 4255 9634 4291 9617 4286 9587
      4262 9586
TIME...MOT...LOC 2257Z 201DEG 48KT 4279 9583 

$$

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, 4:42 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.