Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 19, NWS Sioux Falls, SD

December 15, 2021Woodbury County, Iowa; Dakota County, Nebraska; Union County, South Dakota

NWS Sioux Falls, SD issued this tornado warning at Dec 15, 2021, 4:00 PM CST for Woodbury County, Iowa; Dakota County, Nebraska; Union County, South Dakota. It was in force for 45 min. 6 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, 4:00 PM CST (22:00 UTC)
Expired: Dec 15, 2021, 4:45 PM CST
In force: 45 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Woodbury County, IA, Dakota County, NE, Union County, SD

The radar

The Omaha radar (KOAX), 118 km from the middle of the area, began a volume at 22:01 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, 4:10 PM CST	TSTM WND DMG	Homer, NE	ELECTRIC POLE BLOWN DOWN. TIME ESTIMATED FROM RADAR.
Dec 15, 4:21 PM CST	TSTM WND DMG	2 E Sergeant Bluff, IA	ROOFS OFF A COUPLE OF HOMES BETWEEN SERGEANT BLUFF AND BRONSON. TIME ESTIMATED FROM RADAR.
Dec 15, 4:21 PM CST	TSTM WND DMG	5 Wnw Sioux City, IA	TREE UPROOTED. REPORT VIA SOCIAL MEDIA AND TIME ESTIMATED FROM RADAR.
Dec 15, 4:23 PM CST	TSTM WND GST 82	1 Wsw Sergeant Bluff, IA
Dec 15, 4:24 PM CST	TSTM WND DMG	4 Ene Sergeant Bluff, IA	DAMAGE TO BUILDING.
Dec 15, 4:25 PM CST	TSTM WND DMG	3 Se Sioux City, IA	POWER POLES LEARNING. REPORT RECEIVED VIA SOCIAL MEDIA. 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, 10.0 hours before the alert went out and 118 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.

419 
WFUS53 KFSD 152200
TORFSD
IAC193-NEC043-SDC127-152245-
/O.NEW.KFSD.TO.W.0019.211215T2200Z-211215T2245Z/

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

The National Weather Service in Sioux Falls has issued a

* Tornado Warning for...
  Northwestern Woodbury County in west central Iowa...
  Dakota County in northeastern Nebraska...
  Southeastern Union County in southeastern South Dakota...

* Until 445 PM CST.
    
* At 359 PM CST, a severe thunderstorm capable of producing a tornado
  was located near Pender, or 27 miles southwest of Sioux City,
  moving northeast at 50 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...
  Homer and Hubbard around 420 PM CST.
  Dakota City and Jackson In Dakota County around 425 PM CST.
  Sioux City, South Sioux City and Sergeant Bluff around 430 PM CST.
  North Sioux City around 435 PM CST.

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 4230 9673 4257 9662 4253 9619 4227 9639
      4228 9673
TIME...MOT...LOC 2159Z 208DEG 43KT 4215 9665 

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

$$

Chapman

2 follow-up statements

879 
WWUS53 KFSD 152224
SVSFSD

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

IAC193-NEC043-SDC127-152245-
/O.CON.KFSD.TO.W.0019.000000T0000Z-211215T2245Z/
Woodbury IA-Dakota NE-Union SD-
424 PM CST Wed Dec 15 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 445 PM CST FOR
NORTHWESTERN WOODBURY...NORTHERN DAKOTA AND SOUTHEASTERN UNION
COUNTIES...
    
At 423 PM CST, a severe thunderstorm capable of producing a tornado
was located over Dakota City, or near Sioux City, moving northeast at
50 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...
  Sioux City and North Sioux City.

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 4247 9666 4257 9662 4253 9619 4234 9634
      4244 9653
TIME...MOT...LOC 2223Z 208DEG 43KT 4241 9646 

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

$$

Chapman

603 
WWUS53 KFSD 152244
SVSFSD

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

IAC193-NEC043-SDC127-152253-
/O.EXP.KFSD.TO.W.0019.000000T0000Z-211215T2245Z/
Woodbury IA-Dakota NE-Union SD-
444 PM CST Wed Dec 15 2021

...THE TORNADO WARNING FOR NORTHWESTERN WOODBURY...NORTHERN DAKOTA
AND SOUTHEASTERN UNION COUNTIES WILL EXPIRE AT 445 PM CST...
    
The tornadic thunderstorm which prompted the warning has weakened 
and 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 west central
Iowa...northeastern Nebraska...and southeastern South Dakota.

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

LAT...LON 4247 9666 4257 9662 4253 9619 4234 9634
      4244 9653
TIME...MOT...LOC 2243Z 208DEG 43KT 4261 9631 

$$

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, 4:05 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, 4:42 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
Dec 15, 3:59 PM CST	Tornado Warning	FSD	Dakota, Dixon	31 min
Dec 15, 9:01 AM CST	Dense Fog Advisory	FSD	Beadle, Brookings, Davison, Hanson, Kingsbury, Lake and 4 more	119 min

Nearby

Tornado Warnings in Iowa, 2021 Tornado Warnings in Nebraska, 2021 Tornado Warnings in South Dakota, 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.