Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 119, NWS Sioux Falls, SD

August 28, 2021Lyon County, Sioux County, Iowa; Lincoln County, Turner County, South Dakota

NWS Sioux Falls, SD issued this severe thunderstorm warning at Aug 28, 2021, 4:23 PM CDT for Lyon County, Sioux County, Iowa; Lincoln County, Turner County, South Dakota. It was in force for 37 min. 7 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: Aug 28, 2021, 4:23 PM CDT (21:23 UTC)
Expired: Aug 28, 2021, 5:00 PM CDT
In force: 37 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Possible
Damage threat: Considerable
Hail: 2.0 in
Wind: 70.0 mph

Counties Lyon County, IA, Sioux County, IA, Lincoln County, SD, Turner County, SD

The radar

The Sioux Falls radar (KFSD), 27 km from the middle of the area, began a volume at 21:24 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 28, 4:24 PM CDT	TSTM WND GST 72	Lennox, SD	DELAYED REPORT. PERSONAL WEATHER STATION REPORTED GUST OF 72 MPH.
Aug 28, 4:30 PM CDT	TSTM WND DMG	4 Nnw Worthing, SD	REPORT VIA SOCIAL MEDIA OF 2 SEMI TRUCKS FLIPPED OVER A LITTLE SOUTH OF I-29 EXIT 68.
Aug 28, 4:40 PM CDT	TSTM WND DMG	Canton, SD	SOCIAL MEDIA PICTURE OF LARGE TREE DOWN.
Aug 28, 4:40 PM CDT	TSTM WND DMG	Harrisburg, SD	REPORT VIA SOCIAL MEDIA OF TREE DAMAGE IN HARRISBURG.
Aug 28, 4:40 PM CDT	TSTM WND GST 61	1 Ssw Harrisburg, SD	CORRECTS PREVIOUS TSTM WND GST REPORT FROM 1 SSW HARRISBURG FOR INCORRECT TIME. DELAYED REPORT. PERSONAL WEATHER STATION REPORTED GUST OF 61 MPH.
Aug 28, 4:45 PM CDT	FUNNEL CLOUD	2 E Harrisburg, SD	ROTATION NOTICED IN CLOUDS OVERHEAD, AND SURFACE WINDS SEEMED TO BE BLOWING UPWARD.
Aug 28, 4:45 PM CDT	TSTM WND GST 70	2 E Harrisburg, SD	BRANCHES ON COTTONWOOD TREE BLOWN UPWARD AND OFF, LANDING ON ROOF OF HOUSE.

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
Aug 28, 3:57 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Aberdeen, SD (KABR), launched 12:00Z, 9.4 hours before the alert went out and 225 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: 9 J/kg
Mixed-layer CIN: -334 J/kg
Mixed-layer LCL: 1540 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: 25 m²/s²
0-3 km storm-relative helicity: 558 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

As transmitted.

813 
WUUS53 KFSD 282123
SVRFSD
IAC119-167-SDC083-125-282200-
/O.NEW.KFSD.SV.W.0119.210828T2123Z-210828T2200Z/

BULLETIN - EAS ACTIVATION REQUESTED
Severe Thunderstorm Warning
National Weather Service Sioux Falls SD
423 PM CDT Sat Aug 28 2021

The National Weather Service in Sioux Falls has issued a

* Severe Thunderstorm Warning for...
  Western Lyon County in northwestern Iowa...
  Northwestern Sioux County in northwestern Iowa...
  Lincoln County in southeastern South Dakota...
  Northeastern Turner County in southeastern South Dakota...

* Until 500 PM CDT.

* At 422 PM CDT, severe thunderstorms were located along a line
  extending from near Tea to near Davis, moving east at 50 mph.

  HAZARD...Two inch hail and 70 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...People and animals outdoors will be injured. Expect hail 
           damage to roofs, siding, windows, and vehicles. Expect 
           considerable tree damage. Wind damage is also likely to 
           mobile homes, roofs, and outbuildings.

* Severe thunderstorms will be near...
  Worthing around 430 PM CDT.
  Harrisburg around 435 PM CDT.
  Lake Alvin State Recreation Area around 440 PM CDT.
  Canton and Newton Hills State Park around 445 PM CDT.
  Larchwood, Inwood and Fairview around 450 PM CDT.
  Lester around 455 PM CDT.
  Rock Rapids, Rock Valley, Doon and Alvord around 500 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 900 PM CDT for southwestern
Minnesota.

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

A Tornado Watch remains in effect until 900 PM CDT for southwestern
Minnesota.

&&

LAT...LON 4350 9617 4312 9618 4319 9696 4345 9723
      4350 9660
TIME...MOT...LOC 2122Z 263DEG 43KT 4345 9688 4325 9691 

TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...2.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

APT

2 follow-up statements

593 
WWUS53 KFSD 282127
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
427 PM CDT Sat Aug 28 2021

IAC119-167-SDC083-125-282200-
/O.CON.KFSD.SV.W.0119.000000T0000Z-210828T2200Z/
Lyon IA-Sioux IA-Lincoln SD-Turner SD-
427 PM CDT Sat Aug 28 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 500 PM CDT
FOR WESTERN LYON...NORTHWESTERN SIOUX...LINCOLN AND NORTHEASTERN
TURNER COUNTIES...

At 426 PM CDT, severe thunderstorms were located along a line
extending from Tea to 6 miles southwest of Worthing, moving east at
50 mph.

HAZARD...Two inch hail and 70 mph wind gusts.

SOURCE...At 4:19 pm, emergency management reported quarter-sized 
         hail and winds gusting up to 70 mph in Hurley.

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect 
         considerable tree damage. Wind damage is also likely to 
         mobile homes, roofs, and outbuildings.

These severe storms will be near...
  Harrisburg and Worthing around 435 PM CDT.
  Lake Alvin State Recreation Area around 440 PM CDT.
  Canton and Newton Hills State Park around 445 PM CDT.
  Larchwood and Fairview around 450 PM CDT.
  Inwood and Lester around 455 PM CDT.
  Rock Rapids, Rock Valley, Doon and Alvord around 500 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 900 PM CDT for southwestern
Minnesota.

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

Prepare immediately for large hail and damaging winds. People outside
should move to a shelter, inside a strong building and away from
windows.

&&

LAT...LON 4350 9617 4312 9618 4319 9696 4345 9723
      4350 9660
TIME...MOT...LOC 2126Z 263DEG 43KT 4346 9682 4326 9685 

TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...OBSERVED
MAX HAIL SIZE...2.00 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH

$$

APT

698 
WWUS53 KFSD 282154
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
454 PM CDT Sat Aug 28 2021

SDC125-282204-
/O.CAN.KFSD.SV.W.0119.000000T0000Z-210828T2200Z/
Turner SD-
454 PM CDT Sat Aug 28 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN TURNER COUNTY 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 900 PM CDT for southwestern
Minnesota.

A Severe Thunderstorm Watch remains in effect until 900 PM CDT for
northwestern Iowa...and southeastern South Dakota.

LAT...LON 4319 9693 4347 9693 4350 9660 4350 9617
      4312 9618
TIME...MOT...LOC 2154Z 263DEG 43KT 4350 9637 4330 9640 

$$

IAC119-167-SDC083-282200-
/O.CON.KFSD.SV.W.0119.000000T0000Z-210828T2200Z/
Lyon IA-Sioux IA-Lincoln SD-
454 PM CDT Sat Aug 28 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 500 PM CDT
FOR WESTERN LYON...NORTHWESTERN SIOUX AND LINCOLN COUNTIES...

At 454 PM CDT, severe thunderstorms were located along a line
extending from Hills to Inwood, moving east at 50 mph.

HAZARD...70 mph wind gusts and ping pong ball size hail.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect 
         considerable tree damage. Wind damage is also likely to 
         mobile homes, roofs, and outbuildings.

Locations impacted include...
  Doon and Rock Rapids.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 900 PM CDT for southwestern
Minnesota.

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

Prepare immediately for large hail and damaging winds. People outside
should move to a shelter, inside a strong building and away from
windows.

&&

LAT...LON 4319 9693 4347 9693 4350 9660 4350 9617
      4312 9618
TIME...MOT...LOC 2154Z 263DEG 43KT 4350 9637 4330 9640 

TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.50 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

APT

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 28, 4:39 PM CDT	Tornado Warning Tornado observed	FSD	Lyon	36 min
Aug 28, 4:45 PM CDT	Tornado Warning	FSD	Lyon	30 min
Aug 28, 5:00 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Lyon, Sioux	45 min
Aug 28, 5:26 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Lyon, Osceola	34 min
Aug 28, 5:29 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Lyon, Osceola	31 min
Aug 28, 5:34 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	17 min
Aug 28, 6:44 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	46 min
Aug 28, 6:53 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	52 min
Aug 28, 3:21 PM CDT	Severe Thunderstorm Warning	FSD	Lake, McCook, Miner, Minnehaha, Moody	24 min
Aug 28, 3:56 PM CDT	Severe Thunderstorm Warning	FSD	Lincoln, Turner, Yankton	49 min
Aug 28, 4:23 PM CDT	Tornado Warning	FSD	Lincoln, Turner	37 min
Aug 28, 4:33 PM CDT	Severe Thunderstorm Warning	FSD	Lincoln, Minnehaha	42 min
Aug 28, 6:14 PM CDT	Severe Thunderstorm Warning	FSD	Hanson, Lake, McCook	31 min
Aug 28, 6:15 PM CDT	Severe Thunderstorm Warning	FSD	Minnehaha, Moody	45 min
Aug 28, 6:17 PM CDT	Severe Thunderstorm Warning	FSD	Hutchinson, McCook, Turner	43 min
Aug 28, 6:44 PM CDT	Severe Thunderstorm Warning	FSD	Davison, Hanson, Lake, McCook, Miner, Sanborn	46 min
Aug 28, 6:48 PM CDT	Severe Thunderstorm Warning	FSD	Hanson, Lake, McCook, Minnehaha	42 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2021 Severe Thunderstorm Warnings in South Dakota, 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.