Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 135, NWS Sioux Falls, SD

August 28, 2021Lyon County, Iowa; Lincoln County, South Dakota; Rock County, Minnesota

NWS Sioux Falls, SD issued this severe thunderstorm warning at Aug 28, 2021, 7:23 PM CDT for Lyon County, Iowa; Lincoln County, South Dakota; Rock County, Minnesota. It was in force for 52 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: Aug 28, 2021, 7:23 PM CDT (00:23 UTC)
Expired: Aug 28, 2021, 8:15 PM CDT
In force: 52 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Damage threat: Considerable
Hail: 1.75 in
Wind: 60.0 mph

Counties Lyon County, IA, Rock County, MN, Lincoln County, SD

The radar

The Sioux Falls radar (KFSD), 26 km from the middle of the area, began a volume at 00:22 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, 7:35 PM CDT	HAIL 1	5 Ssw Larchwood, IA	MOSTLY PEA-SIZED HAIL FOR ABOUT 5 MINUTES, LARGEST HAIL STONES WERE QUARTER SIZED.
Aug 28, 7:48 PM CDT	HAIL 2.5	1 Wnw Larchwood, IA
Aug 28, 7:48 PM CDT	HAIL 4	Larchwood, IA	MULTIPLE PICTURES FROM AROUND LARCHWOOD VIA SOCIAL MEDIA OF HAIL RANGING FROM TENNIS BALL SIZE TO AS LARGE AS 4 INCHES IN DIAMETER.
Aug 28, 7:53 PM CDT	HAIL 1	Lester, IA	VIA SOCIAL MEDIA.
Aug 28, 8:08 PM CDT	HAIL 1.75	Hills, MN	REPORT VIA SOCIAL MEDIA.
Aug 28, 8:12 PM CDT	TSTM WND DMG	3 Nnw Lester, IA	REPORT FROM MPING: 3-INCH TREE LIMBS BROKEN; POWER POLES BROKEN.

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
Aug 28, 3:44 PM CDT	Tornado Watch	SPC	5 hr

The nearest sounding before it

Aberdeen, SD (KABR), launched 00:00Z, 0.4 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: 143 J/kg
Mixed-layer CIN: -122 J/kg
Mixed-layer LCL: 1242 m above ground
0-6 km bulk shear: 71 kt
0-1 km storm-relative helicity: -15 m²/s²
0-3 km storm-relative helicity: 268 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.2

Open this sounding in Storm Lab

The text

As transmitted.

107 
WUUS53 KFSD 290023
SVRFSD
IAC119-MNC133-SDC083-290115-
/O.NEW.KFSD.SV.W.0135.210829T0023Z-210829T0115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Sioux Falls SD
723 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...
  Southwestern Rock County in southwestern Minnesota...
  Northeastern Lincoln County in southeastern South Dakota...

* Until 815 PM CDT.

* At 723 PM CDT, a severe thunderstorm was located near Canton,
  moving northeast at 20 mph.

  HAZARD...Golf ball size hail and 60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...People and animals outdoors will be injured. Expect hail 
           damage to roofs, siding, windows, and vehicles. Expect 
           wind damage to roofs, siding, and trees.

* This severe thunderstorm will be near...
  Inwood around 735 PM CDT.

Other locations in the path of this severe thunderstorm include
Larchwood, Alvord, Lester, Hills and Rock Rapids.

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 4339 9670 4350 9648 4350 9646 4352 9645
      4361 9628 4336 9609 4327 9660
TIME...MOT...LOC 0023Z 239DEG 16KT 4335 9655 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Kalin

3 follow-up statements

102 
WWUS53 KFSD 290031
SVSFSD

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

IAC119-MNC133-SDC083-290115-
/O.CON.KFSD.SV.W.0135.000000T0000Z-210829T0115Z/
Lyon IA-Rock MN-Lincoln SD-
731 PM CDT Sat Aug 28 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM CDT
FOR WESTERN LYON...SOUTHWESTERN ROCK AND NORTHEASTERN LINCOLN
COUNTIES...

At 731 PM CDT, a severe thunderstorm was located near Inwood, or near
Canton, moving northeast at 20 mph.

HAZARD...Two inch hail and 60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect wind 
         damage to roofs, siding, and trees.

This severe storm will be near...
  Inwood around 735 PM CDT.

Other locations in the path of this severe thunderstorm include
Larchwood, Alvord, Lester, Hills and Rock Rapids.

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.

&&

LAT...LON 4339 9670 4350 9648 4350 9646 4352 9645
      4361 9628 4336 9609 4327 9660
TIME...MOT...LOC 0031Z 239DEG 16KT 4337 9651 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...2.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Kalin

250 
WWUS53 KFSD 290040
SVSFSD

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

IAC119-MNC133-SDC083-290115-
/O.CON.KFSD.SV.W.0135.000000T0000Z-210829T0115Z/
Lyon IA-Rock MN-Lincoln SD-
740 PM CDT Sat Aug 28 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM CDT
FOR WESTERN LYON...SOUTHWESTERN ROCK AND NORTHEASTERN LINCOLN
COUNTIES...

At 739 PM CDT, a severe thunderstorm was located south of Larchwood, 
or 8 miles northeast of Canton, moving northeast at 20 mph.

THIS IS A DESTRUCTIVE STORM FOR NORTHERN LYON COUNTY.

HAZARD...Baseball size hail and 60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be severely injured. 
         Expect shattered windows, extensive damage to roofs, 
         siding, and vehicles.

Locations impacted include...
  Larchwood, Alvord, Lester, Hills and Rock Rapids.

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.

&&

LAT...LON 4342 9664 4350 9648 4350 9646 4352 9645
      4361 9628 4336 9609 4329 9656
TIME...MOT...LOC 0039Z 239DEG 16KT 4339 9647 

THUNDERSTORM DAMAGE THREAT...DESTRUCTIVE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...2.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Kalin

704 
WWUS53 KFSD 290052
SVSFSD

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

SDC083-290100-
/O.CAN.KFSD.SV.W.0135.000000T0000Z-210829T0115Z/
Lincoln SD-
752 PM CDT Sat Aug 28 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN LINCOLN COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has 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 4345 9656 4350 9648 4350 9646 4352 9645
      4361 9628 4336 9609 4331 9645
TIME...MOT...LOC 0050Z 238DEG 19KT 4344 9641 

$$

IAC119-MNC133-290115-
/O.CON.KFSD.SV.W.0135.000000T0000Z-210829T0115Z/
Lyon IA-Rock MN-
752 PM CDT Sat Aug 28 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM CDT
FOR WESTERN LYON AND SOUTHWESTERN ROCK COUNTIES...

At 750 PM CDT, a severe thunderstorm was located over Larchwood, or
12 miles west of Rock Rapids, moving northeast at 20 mph.

THIS IS A DESTRUCTIVE STORM FOR NEAR LARCHWOOD.

HAZARD...Baseball size hail and 60 mph wind gusts.

SOURCE...Trained weather spotters reported tennis ball size hail in 
         Larchwood at 750 pm.

IMPACT...People and animals outdoors will be severely injured. 
         Expect shattered windows, extensive damage to roofs, 
         siding, and vehicles.

Locations impacted include...
Rock Rapids, Larchwood, Inwood, Hills, Lester, Alvord and Steen. 

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.

&&

LAT...LON 4345 9656 4350 9648 4350 9646 4352 9645
      4361 9628 4336 9609 4331 9645
TIME...MOT...LOC 0050Z 238DEG 19KT 4344 9641 

THUNDERSTORM DAMAGE THREAT...DESTRUCTIVE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...2.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Kalin

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 28, 8:52 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Osceola, Sioux	23 min
Aug 28, 9:13 PM CDT	Severe Thunderstorm Warning	FSD	Dickinson, Lyon, O'Brien, Osceola, Sioux	47 min
Aug 28, 9:29 PM CDT	Flash Flood Warning	FSD	Lyon	3 hr
Aug 28, 10:04 PM CDT	Flash Flood Warning	FSD	Lyon, Osceola	4 hr
Aug 28, 10:24 PM CDT	Flash Flood Warning	FSD	Dickinson, Osceola	5 hr
Aug 28, 7:25 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Hanson, Lake, McCook, Miner, Minnehaha, Moody	50 min
Aug 28, 7:27 PM CDT	Severe Thunderstorm Warning	FSD	Bon Homme, Hutchinson, Turner, Yankton	48 min
Aug 28, 7:48 PM CDT	Severe Thunderstorm Warning	FSD	Lake, McCook, Minnehaha, Moody, Turner	31 min
Aug 28, 7:50 PM CDT	Severe Thunderstorm Warning	FSD	Bon Homme, Clay, Hutchinson, Lincoln, Turner, Yankton	40 min
Aug 28, 9:20 PM CDT	Flash Flood Warning	FSD	Lincoln, Minnehaha	85 min
Aug 28, 10:36 PM CDT	Flash Flood Warning	FSD	Lincoln, Minnehaha	114 min
Aug 28, 11:46 PM CDT	River Flood Warning	FSD	Lincoln, Minnehaha	8 hr
Aug 29, 7:44 AM CDT	River Flood Warning	FSD	Lincoln	15 hr
Aug 28, 7:00 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Lincoln, Lyon, Murray, Pipestone	45 min
Aug 28, 7:34 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Murray, Pipestone	56 min
Aug 28, 8:03 PM CDT	Flash Flood Warning	FSD	Murray, Pipestone	6 hr
Aug 28, 8:06 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Nobles, Rock	54 min
Aug 28, 8:17 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Cottonwood, Lyon, Murray	58 min

Nearby

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