Sioux Falls, SD

Weather Forecast Office

August 17th Severe Thunderstorms and Tornadoes

Overview

Severe thunderstorms formed across central South Dakota during the late afternoon. As these storms moved across southeastern South Dakota, they formed into a squall line and produced large hail and damaging winds. As the storms moved east of I-29, several tornadoes were produced by the storms. One EF-1 tornado went through Hadley, Minnesota and a second EF-1 tornado moved west and south of Rock Rapids, Iowa. Five EF-0 tornadoes also touched down in Nobles, Murray, and Cottonwood Counties in Minnesota. These tornadoes primarily did damage to crops and trees although a few homes and farm buildings were damaged. In addition, winds up to 90 mph moved through Okoboji Iowa causing tree damage as well as damage to a few homes and an office building.

Supercell which produced 2 inch hail near Lake Andes, SD.
(Julie Weddell)


Summary of Warnings Issued	Map of 24-hour Rainfall	Shelf Cloud near Mitchell, SD

Tornadoes
Photos & Video
Radar
Storm Reports

Tornadoes:

Tornado - Hadley, Minnesota
Murray County

Date	August 17, 2019
Time (Local)	10:54 - 11:01 PM CDT
EF Rating	EF-1
Est. Peak Winds	105 mph
Path Length	3.94 miles
Max Width	75 yards
Injuries/Deaths	0 injuries and deaths
Summary: The tornado touched down southwest of Hadley, Minnesota and reached the town around 10:57 PM CDT. The tornado had a width of around 75 yards as it moved through the town, lifting to the northeast. While a few buildings had damage, most of the damage was to trees. No injuries or deaths were reported.

Track Map

Downloadable KMZ File

Tornado - Rock Rapids, Iowa
Lyon County

Date	August 17, 2019
Time (Local)	10:34 - 10:43 PM CDT
EF Rating	EF-1
Est. Peak Winds	105
Path Length	6.92 miles
Max Width	75 yds
Injuries/Deaths	0 injuries or death
Summary: The tornado touched down west of Rock Rapids, IA and moved south of town before lifting southeast of town. At peak width, the tornado had a width of 75 yards. Outbuildings to four farmsteads were damaged west and south of Rock Rapids. Additional tree damage was observed south and southeast of Rock Rapids.

Track Map

Downloadable KMZ File

Tornado - Reading, MInnesota
Nobles County

Date	August 17, 2019
Time (Local)	10:59 - 11:03 PM CDT
EF Rating	EF-0
Est. Peak Winds	80 mph
Path Length	4.01 miles
Max Width	50 yds
Injuries/Deaths	0 injuries or death
Summary: The tornado touched down northwest of Reading, Minnesota. It primarily did damage to trees and crops north of Reading. One home had damage tts roof from the tornado.

Track Map

Downloadable KMZ File

Tornado - Iona, MInnesota
Murray County

Date	August 17, 2019
Time (Local)	10:59 - 11:01 PM CDT
EF Rating	EF-0
Est. Peak Winds	85 mph
Path Length	0.79 miles
Max Width	50 yds
Injuries/Deaths	0 injuries or death
Summary: The tornado touched south of Iona flattening corn in the area. As the tornado moved northeast, it hit a cemetery toppling some headstones and snapping a few trees. The tornado lifted as it moved northeast of the cemetery.

Track Map

Downloadable KMZ File

Tornado - Rural Murray County
Murray County

Date	August 17, 2019
Time (Local)	11:08 - 11:10 PM CDT
EF Rating	EF-0
Est. Peak Winds	75 mph
Path Length	0.93 miles
Max Width	50 yds
Injuries/Deaths	0 injuries or death
Summary: The tornado flattened corn along its entire path as it moved east. The tornado also moved across one property, snapping one tree which landed on a house and snapping numerous branches. A shed was also destroyed by the tornado with debris being blown at least 1/4 mile east of the shed.

Track Map

Downloadable KMZ File

Tornado - Lake Sarah
Murray County

Date	August 17, 2019
Time (Local)	11:14 - 11:16 PM CDT
EF Rating	EF-0
Est. Peak Winds	70 mph
Path Length	1.15 miles
Max Width	50 yds
Injuries/Deaths	0 injuries or death
Summary: The tornado touched a miles south of Lake Sarah and flattened corn along its path. As the tornado neared the southeast end of Lake Sarah, it move through a farmstead destroying one shed. The tornado lifted as it approached the water.

Track Map

Downloadable KMZ File

Tornado - Rural Cottonwood County
Cottonwood County

Date	August 17, 2019
Time (Local)	11:25 - 11:26 PM CDT
EF Rating	EF-0
Est. Peak Winds	70 mph
Path Length	0.51 miles
Max Width	50 yds
Injuries/Deaths	0 injuries or death
Summary: The tornado briefly touched down near Minnesota Highway 62 7 miles west of Windom. The tornado flattened corn along its path.

Track Map

Downloadable KMZ File

The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:

EF0 Weak 65-85 mph	EF1 Moderate 86-110 mph	EF2 Significant 111-135 mph	EF3 Severe 136-165 mph	EF4 Extreme 166-200 mph	EF5 Catastrophic 200+ mph

Photos & Video

Tornado, Large Hail, and Wind Damage

Damage Photos from Rock Rapids, Tornado (EF-1)

Damaged silo near Rock Rapids (JD Hommes)	Tree damage near Rock Rapids (JD Hommes)	Damage to cow confinement near Rock Rapids	Grain bin damage near Rock Rapids (Anonymous)

Damage to hog confinement near Rock Rapids	One power pole was snapped and 4 others leaning near Rock Rapids.	Numerous shingles removed from roof near Rock Rapids.	Tree snapped near Rock Rapids.
Damage Photos from Hadley, Tornado (EF-1)

Roof damage to shed near Hadley. Several trusses were also broken.	Tree damage and numerous broken branches in Hadley	Trees uprooted in Hadley	Additional tree damage in Hadley

Garage destroyed with van remaining on concrete slab where the garage had been.	Trees snapped in foreground. Debris from destroyed garage can be seen on the grass.	Flattened corn near Hadley. Note the corn in the background turns right (southeast) toward the tornado track.	Outbuilding with door damaged.
Damage Photos from Reading, Minnesota Tornado (EF-0)		Damage Photo from Lake Sarah, Minnesota Tornado (EF-0)

Flattened corn near Reading, MN (James Joens)	Damage to roof near Reading, Minnesota	Damage to outbuilding near Lake Sarah, Minnesota (Parker McNeil)	Corn flattened south of Lake Sarah (Parker McNeil)
Damage Photos from Iona, Minnesota Tornado (EF-0)		Damage Photos from rural Murray County, Minnesota Tornado (EF-0)

Corn flattened. Photo was taken two days after tornado. (Brad Gass)	Pine tree snapped half way up and several headstones were toppled (Brad Gass)	Tree snapped and landing on house, damaging roof. (Timothy Moline)	Shed destroyed (Timothy Moline)
Wind damage photos from Wahpeton and Okoboji, Iowa

Barn roof partially taken off. (Mike Ehret)	Tin from barn roof wrapped around tree to the east of the barn. (Mike Ehret)	Roof to home damaged by fallen branch.	Tree snapped with other branches removed from trees in the background.

Garage door was partially blown in and 3 windows were blown in on the second floor.	North wall of warehouse blown out after west facing garage door gives way.	Second floor east wall blown out as a result of windows giving way on the west side of building.	Roof damaged by large limb falling on ti.
Other damage photos

Corn flattened by tornado 7 miles west of Windom, Minnesota (Paul Johnson)	Grain bin damaged by 80-85 mph winds near Sibley, Iowa (Rochelle Jacobsma)	Trees branches down in Pipestone, Minnesota (Pipestone Star newspaper)	Large hail near Lake Andes (Rachel Bergin Kaczor)

Radar

Squall line and tornadoes from August 17, 2019


Loop of Radar Reflectivity	Loop of Radar Velocity	Radar Image as Tornado was south of Hadley, Minnesota at 10:57 PM CDT	Radar Image as Tornado was south of Rock Rapids, Iowa at 10:39 PM CDT

Radar Image as the tornado was south of Iona, Minnesota at 10:59 PM CDT	Radar Image as the tornado was northwest of Reading, Minnesota at 10:59 PM CDT	Radar Image as the tornado was in rural Murray County west of Lake Shetek at 11:06 PM CDT	Radar Image as the tornado was south of Lake Sarah at 11:14 PM CDT

Radar Image as the tornado was in rural Cottonwood County west of Windom at 11:25 PM CDT

Storm Reports & Rainfall

Map of Storm Reports from the evening of August 17, 2019


Map showing the locations where damage to trees, homes and businesses were reported around Lake Okoboji.	Rainfall reports from volunteer observers	Rainfall reports from automated gauges

Local Storm Reports (timestamps are UTC)
Report Time	County	Location	ST	Event Type	Mag.	Remark
Sat Aug 17 2019 23:10:00	Charles Mix	2 SSW Geddes	SD	HAIL	1.75	lots of rain, and hail occurred for 40 minutes.
Sat Aug 17 2019 23:28:00	Charles Mix	Pickstown	SD	HAIL	0.7
Sat Aug 17 2019 23:30:00	Charles Mix	Pickstown	SD	HAIL	1.5	picture received via social media.
Sun Aug 18 2019 00:14:00	Gregory	6 NNW Dixon	SD	HAIL	1.5
Sun Aug 18 2019 00:16:00	Charles Mix	2 N Lake Andes	SD	HAIL	0.88
Sun Aug 18 2019 00:17:00	Beadle	2 SSE Wessington	SD	HAIL	0.88	dime to nickel sized hail with heavy rain.
Sun Aug 18 2019 00:19:00	Beadle	3 SSE Wessington	SD	HAIL	1.25	car dented due to the hail.
Sun Aug 18 2019 00:30:00	Charles Mix	2 N Lake Andes	SD	HAIL	2
Sun Aug 18 2019 00:35:00	Brule	Chamberlain	SD	TSTM WND GST	56
Sun Aug 18 2019 00:46:00	Aurora	White Lake	SD	TSTM WND GST	61	sdsu station.
Sun Aug 18 2019 00:47:00	Brule	5 WNW White Lake	SD	HAIL	1.75
Sun Aug 18 2019 00:50:00	Charles Mix	14 W Platte	SD	TSTM WND GST	51	rwis station.
Sun Aug 18 2019 00:52:00	Charles Mix	4 ENE Lake Andes	SD	HAIL	1.25	report via social media.
Sun Aug 18 2019 00:53:00	Charles Mix	6 N Ravinia	SD	HAIL	1.5
Sun Aug 18 2019 00:55:00	Charles Mix	6 S Armour	SD	HAIL	1.25	report via mping.
Sun Aug 18 2019 01:10:00	Aurora	Plankinton	SD	TSTM WND GST	65	rwis station.
Sun Aug 18 2019 01:35:00	Davison	2 N Mitchell	SD	TSTM WND GST	53
Sun Aug 18 2019 01:38:00	Charles Mix	Platte	SD	HAIL	1.25	report via social media.
Sun Aug 18 2019 01:40:00	Sanborn	Forestburg	SD	TSTM WND GST	55	rwis station.
Sun Aug 18 2019 01:45:00	Davison	2 N Mitchell	SD	TSTM WND GST	61
Sun Aug 18 2019 02:02:00	Kingsbury	7 W Erwin	SD	HAIL	0.75
Sun Aug 18 2019 02:25:00	Miner	Canova	SD	TSTM WND GST	58	cwop station.
Sun Aug 18 2019 02:48:00	Moody	10 N Colman	SD	HAIL	0.5
Sun Aug 18 2019 02:53:00	Lake	Madison	SD	TSTM WND GST	59
Sun Aug 18 2019 03:10:00	Moody	5 ESE Egan	SD	TSTM WND DMG		severe damage to farm outbuilding. winds estimated 75 mph.
Sun Aug 18 2019 03:12:00	Moody	Flandreau	SD	TSTM WND GST	54	sdsu station.
Sun Aug 18 2019 03:16:00	Hutchinson	Tripp	SD	HAIL	1	mping station.
Sun Aug 18 2019 03:27:00	Pipestone	Pipestone	MN	TSTM WND GST	60	some power outages reported around town.
Sun Aug 18 2019 03:32:00	Pipestone	Pipestone	MN	TSTM WND GST	60	some power outages reported around town.
Sun Aug 18 2019 03:35:00	Rock	Luverne	MN	TSTM WND GST	54
Sun Aug 18 2019 03:35:00	Brookings	Volga	SD	HEAVY RAIN	1.31	rain fell in approx 45 minutes.
Sun Aug 18 2019 03:41:00	Lyon	1 SE Rock Rapids	IA	TORNADO		time estimated based on radar. additional detail from storm survey will be complied monday, 8-19-2019.
Sun Aug 18 2019 03:48:00	Nobles	6 NNW Lismore	MN	TSTM WND DMG		garage blown off of foundation. numerous large tree limbs down.
Sun Aug 18 2019 03:53:00	Nobles	Wilmont	MN	TSTM WND DMG		power lines down in wilmont. picture via social media.
Sun Aug 18 2019 03:56:00	Murray	Hadley	MN	TSTM WND DMG		structural damage to a pair of garages in town. one garage blown off its foundation with cinder blocks from foundation rolled northeast. additional damage to trees in the city.
Sun Aug 18 2019 03:57:00	Murray	Hadley	MN	TORNADO		time estimated based on radar. additional detail from storm survey will be compiled monday, 8-19-2019.
Sun Aug 18 2019 03:59:00	Nobles	5 SE Wilmont	MN	TORNADO		start of damage path. trees uprooted with several large branches down.
Sun Aug 18 2019 03:59:00	Murray	1 S Iona	MN	TORNADO		start of damage path. corn flattened.
Sun Aug 18 2019 04:01:00	Osceola	Sibley	IA	TSTM WND DMG		damage to metal shed and many trees down. report via social media.
Sun Aug 18 2019 04:01:00	Osceola	1 SSW Sibley	IA	TSTM WND DMG		several grain bins damaged. road signs bent over on the south exit to sibley from highway 60.
Sun Aug 18 2019 04:02:00	Osceola	2 SE Sibley	IA	TSTM WND DMG		damage to grain bins. bolts holding empty bin in place broken with bin lifted/shifted from original position. top collapsed in on northwest side. wind estimated 85 mph.
Sun Aug 18 2019 04:03:00	Nobles	8 NNW Worthington	MN	TORNADO		end of 4 mile damage path.
Sun Aug 18 2019 04:07:00	Nobles	2 NE Worthington	MN	TSTM WND GST	56
Sun Aug 18 2019 04:08:00	Murray	6 WNW Currie	MN	TORNADO		start of nearly mile long damage path. over the path, corn was flattened, several trees damaged and an old barn destroyed.
Sun Aug 18 2019 04:14:00	Murray	6 S Garvin	MN	TORNADO		start of slightly over one mile long damage path. during the two-minute tornado, some damage was done to farm outbuildings and corn was flattened.
Sun Aug 18 2019 04:24:00	Lyon	Marshall	MN	HEAVY RAIN	1.37	1 hour rainfall total.
Sun Aug 18 2019 04:24:00	Dickinson	3 ESE Harris	IA	HAIL	0.88
Sun Aug 18 2019 04:25:00	Dickinson	3 SSE Lake Park	IA	TSTM WND GST	54
Sun Aug 18 2019 04:25:00	Dickinson	Lake Park	IA	TSTM WND GST	54
Sun Aug 18 2019 04:25:00	Cottonwood	4 NW Wilder	MN	TORNADO		start of 1/2 mile path. corn flattened and shredded. max path width of 20 yards.
Sun Aug 18 2019 04:30:00	Dickinson	1 WNW Wahpeton	IA	TSTM WND DMG		roof damage to a small barn. wind estimated 75 mph.
Sun Aug 18 2019 04:32:00	Dickinson	1 NNW Wahpeton	IA	TSTM WND DMG		large branches down, up to 3 inches in diameter.
Sun Aug 18 2019 04:35:00	Jackson	Jackson	MN	TSTM WND GST	56
Sun Aug 18 2019 04:35:00	Dickinson	1 SSE Okoboji	IA	TSTM WND DMG		trees uprooted. wind estimated 90 mph.
Sun Aug 18 2019 04:36:00	Murray	4 N Currie	MN	HEAVY RAIN	1.46	1 hour rainfall total.
Sun Aug 18 2019 04:40:00	Dickinson	Okoboji	IA	TSTM WND DMG		2 large tree branches down blocking lakeshore drive.
Sun Aug 18 2019 04:45:00	Cottonwood	Windom	MN	TSTM WND DMG		tree branches down blocking the road at 12th street and miller ave on the east side of town.
Sun Aug 18 2019 04:50:00	Murray	2 W Dovray	MN	TSTM WND GST	59	rwis station.
Sun Aug 18 2019 04:55:00	Lyon	Marshall	MN	HEAVY RAIN	2.23	1.5 hour rainfall total.
Sun Aug 18 2019 05:55:00	Dixon	2 S Newcastle	NE	HAIL	0.88
Sun Aug 18 2019 06:00:00	Lyon	Tracy	MN	HEAVY RAIN	3.56

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