Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 163, NWS Sioux Falls, SD

September 17, 20216 counties in Iowa; Jackson County, Nobles County, Rock County, Minnesota; Lincoln County, Minnehaha County, South Dakota

NWS Sioux Falls, SD issued this severe thunderstorm warning at Sep 17, 2021, 12:36 AM CDT for 6 counties in Iowa; Jackson County, Nobles County, Rock County, Minnesota; Lincoln County, Minnehaha County, South Dakota. It was in force for 54 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: Sep 17, 2021, 12:36 AM CDT (05:36 UTC)
Expired: Sep 17, 2021, 1:30 AM CDT
In force: 54 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Damage threat: Considerable
Hail: 0.75 in
Wind: 70.0 mph

Counties Clay County, IA, Dickinson County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Sioux County, IA, Jackson County, MN, Nobles County, MN, Rock County, MN, Lincoln County, SD, Minnehaha County, SD

The radar

The Sioux Falls radar (KFSD), 77 km from the middle of the area, began a volume at 05:40 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
Sep 17, 12:37 AM CDT	TSTM WND GST 59	1 Wsw Beaver Creek, MN	MESONET STATION MN006 BEAVER CREEK I-90 MILE POST 4.
Sep 17, 1:20 AM CDT	TSTM WND GST 52	2 Ene Worthington, MN	AWOS STATION KOTG WORTHINGTON AIRPORT.
Sep 17, 1:26 AM CDT	TSTM WND GST 64	3 Nne Sheldon, IA	AWOS STATION KSHL SHELDON AIRPORT.
Sep 17, 1:28 AM CDT	TSTM WND GST 64	1 Ne Ashton, IA	REPORT FOR IOWA RWIS.
Sep 17, 1:29 AM CDT	TSTM WND DMG	2 Ene Sheldon, IA	ROOF COMPLETELY REMOVED FROM STRIP MALL AND DEPOSITED IN PIECES ON ROADWAY.
Sep 17, 1:33 AM CDT	TSTM WND DMG	1 Sw Boyden, IA	POWER LINES DOWN. TIME ESTIMATED FROM RADAR.
Sep 17, 1:33 AM CDT	TSTM WND DMG	Hull, IA	LARGE CONSTRUCTION SHED LIFTED AND COLLAPSED IN NEARBY CORN FIELD. TIME ESTIMATED FROM RADAR.
Sep 17, 1:34 AM CDT	TSTM WND DMG	Boyden, IA	LARGE TREE BRANCHES DOWN. TIME ESTIMATED FROM RADAR.
Sep 17, 1:34 AM CDT	TSTM WND DMG	Boyden, IA	SCHOOL BUS GARAGE HEAVILY DAMAGED. TIME ESTIMATED FROM RADAR.
Sep 17, 1:40 AM CDT	TSTM WND DMG	Lakefield, MN	TREES DOWN FROM DAMAGING WINDS.

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

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 5.6 hours before the alert went out and 246 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: 612 J/kg
Mixed-layer CIN: -165 J/kg
Mixed-layer LCL: 2155 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: 132 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

191 
WUUS53 KFSD 170536
SVRFSD
IAC041-059-119-141-143-167-MNC063-105-133-SDC083-099-170630-
/O.NEW.KFSD.SV.W.0163.210917T0536Z-210917T0630Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Sioux Falls SD
1236 AM CDT Fri Sep 17 2021

The National Weather Service in Sioux Falls has issued a

* Severe Thunderstorm Warning for...
  Lyon County in northwestern Iowa...
  Osceola County in northwestern Iowa...
  Western Dickinson County in northwestern Iowa...
  Northern Sioux County in northwestern Iowa...
  Northwestern Clay County in northwestern Iowa...
  Northern O'Brien County in northwestern Iowa...
  Rock County in southwestern Minnesota...
  Jackson County in southwestern Minnesota...
  Nobles County in southwestern Minnesota...
  Southeastern Minnehaha County in southeastern South Dakota...
  Eastern Lincoln County in southeastern South Dakota...

* Until 130 AM CDT.

* At 1235 AM CDT, severe thunderstorms were located along a line
  extending from near Sherman to near Larchwood to near Newton Hills
  State Park, moving east at 60 mph.

  HAZARD...70 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect considerable tree damage. Damage is likely to 
           mobile homes, roofs, and outbuildings.

* Severe thunderstorms will be near...
  Hills, Lester and Alvord around 1240 AM CDT.
  Luverne, Rock Rapids, Hardwick and Blue Mounds State Park around 
  1245 AM CDT.
  Rock Valley, Doon, Ellsworth and Lismore around 1255 AM CDT.

Other locations in the path of these severe thunderstorms include
Sioux Center, Hull, Little Rock, Wilmont, Sibley, Boyden, Matlock,
Sheldon, Ocheyedan, Brewster, Round Lake and Archer.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4382 9502 4341 9511 4308 9541 4310 9686
      4343 9660 4379 9649
TIME...MOT...LOC 0535Z 268DEG 53KT 4376 9637 4344 9640 4317 9664 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

SG

1 follow-up statement

864 
WWUS53 KFSD 170603
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
103 AM CDT Fri Sep 17 2021

SDC099-170613-
/O.CAN.KFSD.SV.W.0163.000000T0000Z-210917T0630Z/
Minnehaha SD-
103 AM CDT Fri Sep 17 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN MINNEHAHA COUNTY
IS CANCELLED...

The storms which prompted the warning have weakened. Therefore, the 
warning has been cancelled.

LAT...LON 4382 9502 4341 9511 4308 9541 4312 9671
      4343 9641 4379 9625
TIME...MOT...LOC 0603Z 267DEG 51KT 4377 9586 4345 9589 4318 9614 

$$

IAC041-059-119-141-143-167-MNC063-105-133-SDC083-170630-
/O.CON.KFSD.SV.W.0163.000000T0000Z-210917T0630Z/
Lyon IA-Osceola IA-Dickinson IA-Sioux IA-Clay IA-O'Brien IA-Rock MN-
Jackson MN-Nobles MN-Lincoln SD-
103 AM CDT Fri Sep 17 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 130 AM CDT
FOR LYON...OSCEOLA...WESTERN DICKINSON...NORTHERN SIOUX...
NORTHWESTERN CLAY...NORTHERN O'BRIEN...EASTERN ROCK...JACKSON...
NOBLES AND SOUTHEASTERN LINCOLN COUNTIES...

At 103 AM CDT, severe thunderstorms were located along a line
extending from Wilmont to Little Rock to Hull, moving east at 60 mph.

HAZARD...70 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect considerable tree damage. Damage is likely to mobile 
         homes, roofs, and outbuildings.

Locations impacted include...
  Sibley, Wilmont, Sheldon, Ocheyedan, Brewster, Round Lake, Archer, 
  Sanborn, Primghar, Heron Lake, Melvin, Harris, Hartley, Lake Park, 
  Lakefield, Okoboji, Wahpeton, Spirit Lake, Orleans and Kilen Woods 
  State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4382 9502 4341 9511 4308 9541 4312 9671
      4343 9641 4379 9625
TIME...MOT...LOC 0603Z 267DEG 51KT 4377 9586 4345 9589 4318 9614 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

SG

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 17, 12:29 AM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Sioux	46 min
Sep 17, 1:11 AM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Clay, Ida, O'Brien, Plymouth and 2 more	49 min
Sep 17, 1:23 AM CDT	Severe Thunderstorm Warning	FSD	Clay, Dickinson, Lyon, O'Brien, Osceola, Sioux	67 min
Sep 17, 12:10 AM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Lincoln, Pipestone, Rock	35 min
Sep 17, 12:34 AM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Cottonwood, Jackson, Lincoln, Lyon, Murray, Nobles and 2 more	56 min
Sep 17, 1:21 AM CDT	Severe Thunderstorm Warning	FSD	Cottonwood, Jackson, Lyon, Murray, Nobles	39 min
Sep 16, 10:20 PM CDT	Severe Thunderstorm Warning	FSD	Charles Mix, Gregory	25 min
Sep 16, 11:31 PM CDT	Severe Thunderstorm Warning	FSD	Bon Homme, Charles Mix, Hutchinson, Yankton	29 min

Nearby

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