Alert archive / Minnesota / Tornado Warnings in 2021

Tornado Warning 2, NWS Sioux Falls, SD

August 8, 2021Nobles County, Minnesota; Osceola County, Iowa

NWS Sioux Falls, SD issued this tornado warning at Aug 8, 2021, 4:29 PM CDT for Nobles County, Minnesota; Osceola County, Iowa. It was in force for 31 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: Aug 8, 2021, 4:29 PM CDT (21:29 UTC)
Expired: Aug 8, 2021, 5:00 PM CDT
In force: 31 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.0 in

Counties Osceola County, IA, Nobles County, MN

The radar

The Sioux Falls radar (KFSD), 97 km from the middle of the area, began a volume at 21:32 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
Aug 8, 4:52 PM CDT	TORNADO	2 Sse Ocheyedan, IA	DAMAGE TO THE ROOF OF A CHICKEN BARN.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 9.5 hours before the alert went out and 224 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: 1659 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 542 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 11 m²/s²
0-3 km storm-relative helicity: 24 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

As transmitted.

079 
WFUS53 KFSD 082129
TORFSD
IAC143-MNC105-082200-
/O.NEW.KFSD.TO.W.0002.210808T2129Z-210808T2200Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Sioux Falls SD
429 PM CDT Sun Aug 8 2021

The National Weather Service in Sioux Falls has issued a

* Tornado Warning for...
  Central Osceola County in northwestern Iowa...
  South central Nobles County in southwestern Minnesota...

* Until 500 PM CDT.
    
* At 429 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Ocheyedan, or 9 miles south of Worthington, moving
  southeast at 20 mph.

  HAZARD...Tornado and quarter size hail.

  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...
  Ocheyedan around 445 PM CDT.

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 4331 9562 4351 9571 4352 9552 4341 9543
      4336 9539
TIME...MOT...LOC 2129Z 335DEG 17KT 4349 9559 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN

$$

Kalin

2 follow-up statements

383 
WWUS53 KFSD 082143
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
443 PM CDT Sun Aug 8 2021

MNC105-082152-
/O.CAN.KFSD.TO.W.0002.000000T0000Z-210808T2200Z/
Nobles MN-
443 PM CDT Sun Aug 8 2021

...THE TORNADO WARNING FOR SOUTH CENTRAL NOBLES COUNTY IS
CANCELLED...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. Therefore, the warning has been cancelled.

LAT...LON 4331 9562 4346 9564 4349 9550 4341 9543
      4336 9539
TIME...MOT...LOC 2142Z 329DEG 20KT 4342 9553 

$$

IAC143-082200-
/O.CON.KFSD.TO.W.0002.000000T0000Z-210808T2200Z/
Osceola IA-
443 PM CDT Sun Aug 8 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 500 PM CDT FOR
NORTHEASTERN OSCEOLA COUNTY...
    
At 442 PM CDT, a severe thunderstorm capable of producing a tornado
was located over Ocheyedan, or 10 miles east of Sibley, moving
southeast at 25 mph.

HAZARD...Tornado and half dollar size hail.

SOURCE...Radar indicated rotation. Law enforcement reported rotation 
         earlier near the Minnesota Iowa border. 

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
northeastern Osceola County.

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 4331 9562 4346 9564 4349 9550 4341 9543
      4336 9539
TIME...MOT...LOC 2142Z 329DEG 20KT 4342 9553 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.25 IN

$$

Kalin

107 
WWUS53 KFSD 082203
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
503 PM CDT Sun Aug 8 2021

IAC143-082212-
/O.EXP.KFSD.TO.W.0002.000000T0000Z-210808T2200Z/
Osceola IA-
503 PM CDT Sun Aug 8 2021

...THE TORNADO WARNING FOR NORTHEASTERN OSCEOLA COUNTY HAS EXPIRED...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning has been allowed to expire.  However hail is 
still possible with this thunderstorm.

Remember, a Severe Thunderstorm Warning still remains in effect for
southeastern Osceola County. 

LAT...LON 4331 9562 4346 9564 4349 9550 4341 9543
      4336 9539
TIME...MOT...LOC 2202Z 335DEG 17KT 4334 9548 

$$

Kalin

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 8, 4:10 PM CDT	Severe Thunderstorm Warning	FSD	Nobles	50 min
Aug 8, 4:50 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Clay, Dickinson, O'Brien, Osceola	55 min
Aug 8, 5:26 PM CDT	Tornado Warning	FSD	Clay, Dickinson, O'Brien	49 min
Aug 8, 6:31 PM CDT	Tornado Warning Tornado observed	FSD	Buena Vista, Clay	44 min

Nearby

Tornado Warnings in Minnesota, 2021 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.