Alert archive / Iowa / Tornado Warnings in 2026
Tornado Warning 15, NWS Sioux Falls, SD
NWS Sioux Falls, SD issued this tornado warning at May 17, 2026, 8:48 PM CDT for Clay County, Dickinson County, Iowa. It was in force for 27 min. 4 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
- May 17, 2026, 8:48 PM CDT (01:48 UTC)
- Expired
- May 17, 2026, 9:15 PM CDT
- In force
- 27 min
- Issued by
- NWS Sioux Falls, SD
- Area
- Storm-based polygon
- Tornado
- Radar indicated
- Hail
- 1.0 in
Counties Clay County, IA, Dickinson County, IA
The radar
The Sioux Falls radar (KFSD), 144 km from the middle of the area, began a volume at 01:48 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 |
|---|---|---|---|
| May 17, 8:49 PM CDT | TSTM WND DMG | Greenville, IA | Damage to the Greenville grain elevator. Branches and power lines also downed. Time estimated from radar. |
| May 17, 8:49 PM CDT | TSTM WND DMG | Greenville, IA | Damage to the Greenville grain elevator. Branches and power lines also downed. Time estimated from radar. |
| May 17, 9:08 PM CDT | TORNADO | 2 Nw Terril, IA | Viewed on social media. |
| May 17, 9:08 PM CDT | TORNADO | 2 Nw Terril, IA | Viewed on social media. |
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 |
|---|---|---|---|
| May 17, 1:42 PM CDT | Tornado Watch | SPC | 8 hr |
The nearest sounding before it
Omaha, NE (KOAX), launched 00:00Z, 1.8 hours before the alert went out and 222 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.
- Mixed-layer CAPE
- 2478 J/kg
- Mixed-layer CIN
- -15 J/kg
- Mixed-layer LCL
- 1258 m above ground
- 0-6 km bulk shear
- 34 kt
- 0-1 km storm-relative helicity
- 178 m²/s²
- 0-3 km storm-relative helicity
- 298 m²/s²
- Significant tornado parameter
- 2.0
- Supercell composite
- 17.9
The text
As transmitted.
618
WFUS53 KFSD 180148
TORFSD
IAC041-059-180215-
/O.NEW.KFSD.TO.W.0015.260518T0148Z-260518T0215Z/
BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Sioux Falls SD
848 PM CDT Sun May 17 2026
The National Weather Service in Sioux Falls has issued a
* Tornado Warning for...
Southeastern Dickinson County in northwestern Iowa...
Clay County in northwestern Iowa...
* Until 915 PM CDT.
* At 847 PM CDT, severe thunderstorms capable of producing both
tornadoes and extensive straight line wind damage were located near
Greenville, or 9 miles southwest of Spencer In Clay County, moving
northeast at 70 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.
* These dangerous storms will be near...
Spencer In Clay County and Lost Island Lake around 855 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.
Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!
&&
LAT...LON 4292 9514 4298 9532 4308 9532 4341 9492
4325 9491 4301 9492
TIME...MOT...LOC 0147Z 237DEG 60KT 4303 9522
TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
$$
BP2 follow-up statements
916
WWUS53 KFSD 180159
SVSFSD
Severe Weather Statement
National Weather Service Sioux Falls SD
859 PM CDT Sun May 17 2026
IAC041-059-180215-
/O.CON.KFSD.TO.W.0015.000000T0000Z-260518T0215Z/
Dickinson IA-Clay IA-
859 PM CDT Sun May 17 2026
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 915 PM CDT FOR
SOUTHEASTERN DICKINSON AND NORTHEASTERN CLAY COUNTIES...
At 859 PM CDT, a severe squall line capable of producing both
tornadoes and extensive straight line wind damage was located near
Lost Island Lake, or 8 miles east of Spencer in Clay County, moving
northeast at 70 mph.
HAZARD...Tornado and quarter size hail.
SOURCE...Radar indicated rotation.
IMPACT...Flying debris will be dangerous to those caught without
shelter. Mobile homes will be damaged or destroyed. Damage
to roofs, windows, and vehicles will occur. Tree damage is
likely.
This tornadic thunderstorm will remain over mainly rural areas of
southeastern Dickinson and northeastern Clay Counties, including the
following locations... Dickens.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.
Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!
&&
LAT...LON 4306 9508 4320 9517 4327 9510 4340 9493
4325 9491 4305 9492
TIME...MOT...LOC 0159Z 237DEG 60KT 4314 9498
TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
$$
BP524
WWUS53 KFSD 180211 RRA
SVSFSD
Severe Weather Statement
National Weather Service Sioux Falls SD
911 PM CDT Sun May 17 2026
IAC041-059-180221-
/O.EXP.KFSD.TO.W.0015.000000T0000Z-260518T0215Z/
Dickinson IA-Clay IA-
911 PM CDT Sun May 17 2026
...THE TORNADO WARNING FOR SOUTHEASTERN DICKINSON AND NORTHEASTERN
CLAY COUNTIES WILL EXPIRE AT 915 PM CDT...
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire.
A Tornado Watch remains in effect until 1000 PM CDT for northwestern
Iowa.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Sioux Falls.
&&
LAT...LON 4306 9508 4320 9517 4327 9510 4340 9493
4325 9491 4305 9492
TIME...MOT...LOC 0211Z 237DEG 60KT 4324 9477
$$
BPThe office that day
Everything else NWS Sioux Falls, SD issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 17, 7:20 PM CDT | Severe Thunderstorm Warning | FSD | Plymouth, Sioux | 28 min |
| May 17, 7:20 PM CDT | Severe Thunderstorm Warning | FSD | O'Brien, Osceola | 26 min |
| May 17, 7:26 PM CDT | Tornado Warning | FSD | Woodbury | 49 min |
| May 17, 7:32 PM CDT | Severe Thunderstorm Warning | FSD | Cherokee, Ida, Plymouth, Woodbury | 58 min |
| May 17, 7:47 PM CDT | Tornado Warning | FSD | Cherokee, Plymouth, Woodbury | 43 min |
| May 17, 8:00 PM CDT | Severe Thunderstorm Warning | FSD | O'Brien, Osceola, Plymouth, Sioux | 45 min |
| May 17, 8:03 PM CDT | Flash Flood Warning | FSD | Plymouth, Sioux | 3 hr |
| May 17, 8:21 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista, Cherokee, Clay, Dickinson, Ida, O'Brien and 3 more | 54 min |
| May 17, 8:26 PM CDT | Tornado Warning | FSD | Buena Vista, Cherokee, Clay, O'Brien | 28 min |
| May 17, 8:54 PM CDT | Tornado Warning | FSD | Clay, Dickinson | 51 min |
| May 18, 5:11 PM CDT | Severe Thunderstorm Warning | FSD | Cherokee, Ida, Plymouth, Woodbury | 49 min |
| May 18, 5:48 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista, Cherokee, Clay, O'Brien | 42 min |
| May 18, 6:08 PM CDT | Severe Thunderstorm Warning | FSD | Plymouth, Sioux | 37 min |
Nearby
Tornado Warnings in Iowa, 2026Every tornado warning in 2026Tornadoes in 2026
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.