Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 175, NWS Sioux Falls, SD

December 15, 20214 counties in Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Dec 15, 2021, 4:56 PM CST for 4 counties in Iowa. It was in force for 46 min. 10 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, 4:56 PM CST (22:56 UTC)
Expired: Dec 15, 2021, 5:42 PM CST
In force: 46 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Possible
Damage threat: Destructive
Hail: 0.75 in
Wind: 80.0 mph

Counties Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Ida County, IA

The radar

The Sioux Falls radar (KFSD), 149 km from the middle of the area, began a volume at 22:54 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, 4:56 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, 4:57 PM CST	TSTM WND DMG	2 Nnw Galva, IA	HOUSE DAMAGED WITH ROOF TORN OFF. HOOP BARN DESTROYED AND 100 YEAR OLD MARCHINE SHED DESTOYED. TIME ESTIMATED FROM RADAR.
Dec 15, 5:01 PM CST	TSTM WND DMG	5 Sw Alta, IA	NUMEROUS TREES AND BRANCHES DOWN. REPORT RECEIVED VIA SOCIAL MEDIA. 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 GST 51	4 Wsw Lakeside, IA	TIME ESTIMATED FROM RADAR.
Dec 15, 5:25 PM CST	TSTM WND DMG	3 E Royal, IA	LARGE PINE TREE BLOW DOWN. TIME ESTIMATED FROM RADAR.
Dec 15, 5:31 PM CST	TSTM WND DMG	1 Sse Spencer, IA	TREES DOWN IN TOWN. TIME ESTIMATED FROM RADAR.
Dec 15, 5:33 PM CST	TSTM WND GST 54	3 Wnw Spencer, IA

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, 10.9 hours before the alert went out and 161 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.

781 
WUUS53 KFSD 152256
SVRFSD
IAC021-035-041-093-160000-
/O.NEW.KFSD.SV.W.0175.211215T2256Z-211216T0000Z/

BULLETIN - EAS ACTIVATION REQUESTED
Severe Thunderstorm Warning
National Weather Service Sioux Falls SD
456 PM CST Wed Dec 15 2021

The National Weather Service in Sioux Falls has issued a

* Severe Thunderstorm Warning for...
  Cherokee County in northwestern Iowa...
  Buena Vista County in northwestern Iowa...
  Clay County in northwestern Iowa...
  Ida County in west central Iowa...

* Until 600 PM CST.

* At 455 PM CST, severe thunderstorms were located along a line
  extending from near Paullina to Cherokee to near Galva, moving
  northeast at 70 mph.

  HAZARD...80 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be heavily damaged. Expect 
           considerable damage to roofs, windows, and vehicles. 
           Extensive tree damage and power outages are likely.

* Severe thunderstorms will be near...
  Larrabee around 500 PM CST.
  Storm Lake, Alta, Lakeside, Peterson and Linn Grove around 510 PM 
  CST.
  Royal and Truesdale around 515 PM CST.

Other locations in the path of these severe thunderstorms include
Everly, Greenville, Spencer In Clay County, Albert City, Marathon,
Fostoria, Webb and Lost Island Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

For your protection move to an interior room on the lowest floor of a
building.

This is a DANGEROUS SITUATION. These storms are producing widespread 
wind damage across parts of Nebraska and Woodbury county. SEEK 
SHELTER NOW inside a sturdy structure and stay away from windows! A 
Tornado Watch remains in effect until 800 PM CST for northwestern 
and west central Iowa.

&&

LAT...LON 4222 9567 4246 9567 4248 9574 4256 9574
      4257 9577 4291 9586 4291 9539 4325 9539
      4326 9491 4256 9492 4256 9539 4248 9539
      4247 9532 4221 9533
TIME...MOT...LOC 2255Z 223DEG 59KT 4296 9577 4277 9556 4247 9546 

TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...DESTRUCTIVE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...80 MPH

$$

Weisser

2 follow-up statements

453 
WWUS53 KFSD 152338
SVSFSD

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

IAC035-093-152347-
/O.CAN.KFSD.SV.W.0175.000000T0000Z-211216T0000Z/
Cherokee IA-Ida IA-
538 PM CST Wed Dec 15 2021

...THE SEVERE THUNDERSTORM WARNING FOR CHEROKEE AND IDA COUNTIES IS
CANCELLED...

The storms which prompted the warning have moved 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 4256 9492 4256 9539 4325 9539 4326 9491
      4325 9491
TIME...MOT...LOC 2337Z 223DEG 59KT 4346 9513 4327 9492 4297 9482 

$$

IAC021-041-160000-
/O.CON.KFSD.SV.W.0175.000000T0000Z-211216T0000Z/
Buena Vista IA-Clay IA-
538 PM CST Wed Dec 15 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM CST
FOR BUENA VISTA AND CLAY COUNTIES...

At 537 PM CST, severe thunderstorms were located along a line
extending from Orleans to near Terril to near Rush Lake, moving
northeast at 70 mph.

HAZARD...80 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be heavily damaged. Expect 
         considerable damage to roofs, windows, and vehicles. 
         Extensive tree damage and power outages are likely.

These severe thunderstorms will remain over mainly rural areas of
Buena Vista and Clay Counties, including the following locations...
Gillett Grove, Dickens, Rossie and Rembrandt.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4256 9492 4256 9539 4325 9539 4326 9491
      4325 9491
TIME...MOT...LOC 2337Z 223DEG 59KT 4346 9513 4327 9492 4297 9482 

TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...DESTRUCTIVE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...80 MPH

$$

Weisser

517 
WWUS53 KFSD 152342 RRA
SVSFSD

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

IAC021-041-152352-
/O.CAN.KFSD.SV.W.0175.000000T0000Z-211216T0000Z/
Buena Vista IA-Clay IA-
542 PM CST Wed Dec 15 2021

...THE SEVERE THUNDERSTORM WARNING FOR BUENA VISTA AND CLAY COUNTIES
IS CANCELLED...
    
The storms which prompted the warning have moved out of the area.
Therefore, the warning has been cancelled.  However gusty winds are
still possible with these thunderstorms.

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

LAT...LON 4256 9492 4256 9539 4325 9539 4326 9491
      4325 9491
TIME...MOT...LOC 2342Z 223DEG 59KT 4352 9505 4333 9484 4303 9474 

$$

Weisser

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, 4:42 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, 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

Severe Thunderstorm Warnings in Iowa, 2021 Every severe thunderstorm warning 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.