Alert archive / Iowa / Severe Thunderstorm Warnings in 2026
Severe Thunderstorm Warning 13, NWS Sioux Falls, SD
NWS Sioux Falls, SD issued this severe thunderstorm warning at Apr 13, 2026, 6:45 PM CDT for O'Brien County, Osceola County, Iowa. It was in force for 45 min. 1 report 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
- Apr 13, 2026, 6:45 PM CDT (23:45 UTC)
- Expired
- Apr 13, 2026, 7:30 PM CDT
- In force
- 45 min
- Issued by
- NWS Sioux Falls, SD
- Area
- Storm-based polygon
- Hail
- 1.25 in
- Wind
- 60.0 mph
Counties O'Brien County, IA, Osceola County, IA
The radar
The Sioux Falls radar (KFSD), 97 km from the middle of the area, began a volume at 23:44 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 |
|---|---|---|---|
| Apr 13, 6:53 PM CDT | HAIL 1 | Melvin, IA |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
Did it verify
Verified. The Iowa Environmental Mesonet's Cow matched one storm report to this severe thunderstorm warning; the first came 8 minutes after it went out.
Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.
The watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Apr 13, 4:39 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
The nearest sounding before it
Minneapolis, MN (KMPX), launched 12:00Z, 11.8 hours before the alert went out and 237 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
- 8 J/kg
- Mixed-layer CIN
- -259 J/kg
- Mixed-layer LCL
- 1506 m above ground
- 0-6 km bulk shear
- 45 kt
- 0-1 km storm-relative helicity
- 124 m²/s²
- 0-3 km storm-relative helicity
- 229 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
722
WUUS53 KFSD 132345
SVRFSD
IAC141-143-140030-
/O.NEW.KFSD.SV.W.0013.260413T2345Z-260414T0030Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Sioux Falls SD
645 PM CDT Mon Apr 13 2026
The National Weather Service in Sioux Falls has issued a
* Severe Thunderstorm Warning for...
Osceola County in northwestern Iowa...
Northwestern O'Brien County in northwestern Iowa...
* Until 730 PM CDT.
* At 644 PM CDT, a severe thunderstorm was located over Sanborn, or 8
miles east of Sheldon, moving north at 30 mph.
HAZARD...60 mph wind gusts and half dollar size hail.
SOURCE...Public. At 640 pm, half dollar sized hail was reported in
Sanborn, IA.
IMPACT...Hail damage to vehicles is expected. Expect wind damage
to roofs, siding, and trees.
* This severe thunderstorm will be near...
Sanborn and Melvin around 650 PM CDT.
Other locations in the path of this severe thunderstorm include
Sibley and Ocheyedan.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
&&
LAT...LON 4313 9557 4313 9578 4350 9574 4350 9539
TIME...MOT...LOC 2344Z 198DEG 24KT 4318 9568
HAIL THREAT...OBSERVED
MAX HAIL SIZE...1.25 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
IG2 follow-up statements
616
WWUS53 KFSD 132358
SVSFSD
Severe Weather Statement
National Weather Service Sioux Falls SD
658 PM CDT Mon Apr 13 2026
IAC141-140008-
/O.CAN.KFSD.SV.W.0013.000000T0000Z-260414T0030Z/
O'Brien IA-
658 PM CDT Mon Apr 13 2026
...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN O'BRIEN COUNTY IS
CANCELLED...
The severe thunderstorm which prompted the warning has moved out of
the warned area. Therefore, the warning has been cancelled.
A Severe Thunderstorm Watch remains in effect until 1000 PM CDT for
northwestern Iowa...and southwestern Minnesota.
&&
LAT...LON 4326 9552 4326 9569 4350 9569 4350 9539
TIME...MOT...LOC 2358Z 199DEG 35KT 4331 9560
$$
IAC143-140030-
/O.CON.KFSD.SV.W.0013.000000T0000Z-260414T0030Z/
Osceola IA-
658 PM CDT Mon Apr 13 2026
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM CDT
FOR EASTERN OSCEOLA COUNTY...
At 658 PM CDT, a severe thunderstorm was located over Melvin, or 9
miles southeast of Sibley, moving north at 40 mph.
HAZARD...60 mph wind gusts and half dollar size hail.
SOURCE...Public.
IMPACT...Hail damage to vehicles is expected. Expect wind damage to
roofs, siding, and trees.
This severe storm will be near...
Ocheyedan and Harris around 705 PM CDT.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
This storm is producing large hail. SEEK SHELTER NOW inside a sturdy
structure and stay away from windows.
To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Sioux Falls.
&&
LAT...LON 4326 9552 4326 9569 4350 9569 4350 9539
TIME...MOT...LOC 2358Z 199DEG 35KT 4331 9560
HAIL THREAT...OBSERVED
MAX HAIL SIZE...1.25 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
IG488 WWUS53 KFSD 140023 SVSFSD Severe Weather Statement National Weather Service Sioux Falls SD 723 PM CDT Mon Apr 13 2026 IAC143-140033- /O.EXP.KFSD.SV.W.0013.000000T0000Z-260414T0030Z/ Osceola IA- 723 PM CDT Mon Apr 13 2026 ...THE SEVERE THUNDERSTORM WARNING FOR EASTERN OSCEOLA COUNTY WILL EXPIRE AT 730 PM CDT... The storm which prompted the warning has weakened below severe limits, and no longer poses an immediate threat to life or property. Therefore, the warning will be allowed to expire. However, small hail and heavy rain are still possible with this thunderstorm. A Severe Thunderstorm Watch remains in effect until 1000 PM CDT for northwestern Iowa...and southwestern Minnesota. To report severe weather, contact your nearest law enforcement agency. They will relay your report to the National Weather Service Sioux Falls. && LAT...LON 4326 9552 4326 9569 4350 9569 4350 9539 TIME...MOT...LOC 0023Z 198DEG 24KT 4346 9553 $$ IG
What forecasters said that day
The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Sioux Falls, SD wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 13, 6:41 PM CDT, 4 minutes earlier. Its key messages:
- Thunderstorms return this afternoon and evening. Scattered strong to severe storms expected - greatest risk for southwestern Minnesota into adjacent areas of South Dakota and northwest Iowa. Timing of greatest concern is 4 to 9 PM.
- Main hazards are large hail greater than 2 inches in diameter and wind gusts to 70 mph. A tornado or two are also possible. Have a severe weather plan and multiple ways to receive warnings.
- Periodic chances (20-60%) for showers and thunderstorms continue this week. Details remain uncertain at this time.
Area forecast discussion, Apr 13, 6:41 PM CDT, 4 minutes before
Area Forecast Discussion National Weather Service Sioux Falls SD 641 PM CDT Mon Apr 13 2026 .KEY MESSAGES... - Thunderstorms return this afternoon and evening. Scattered strong to severe storms expected - greatest risk for southwestern Minnesota into adjacent areas of South Dakota and northwest Iowa. Timing of greatest concern is 4 to 9 PM. - Main hazards are large hail greater than 2 inches in diameter and wind gusts to 70 mph. A tornado or two are also possible. Have a severe weather plan and multiple ways to receive warnings. - Periodic chances (20-60%) for showers and thunderstorms continue this week. Details remain uncertain at this time. && .DISCUSSION... Issued at 238 PM CDT Mon Apr 13 2026 Scattered thunderstorms are set to develop over the next few hours, bringing the potential for a few severe storms with large hail, damaging winds, and perhaps a tornado or two. As of 2 pm, a surface low is located over northern Nebraska with a warm front extending northeast of it across far southeastern South Dakota into northwest Iowa. Dew points in the 60s have been gradually spreading northward, and these higher dew points are expected to reach the I-90 corridor over the next couple of hours. This boundary will be the focus of initial storm development, with these storms having access to 35-50 kts of effective bulk shear and 1500-2000 J/kg of MLCAPE. There are questions though on how much some high clouds have limited the area from reaching full heating potential, but if a storm can get going then steep mid level lapse rates of 7.5-8.5 degrees C/km and mostly straight, elongated hodographs will favor large hail to around 2 inches in diameter or larger. The secondary threat will be damaging wind gusts up to 70 mph. If a storm can get rooted to the aforementioned surface warm front, then a tornado or two will also be possible. Can't rule out a strong tornado either, primarily over southwest Minnesota. As the low pressure system drift across the area, a few additional showers and storms look to develop farther south across northwest Iowa (down to about IA Highway-3, or just north of US Highway-20) within the warm sector around sunset. These storms could also be on the strong to severe side, with an isolated instance of quarter sized hail and 60 mph as the threats. Showers and storms will exit off to our east by the mid evening hours, leaving mostly quiet conditions in its wake. A few showers may develop in central South Dakota prior to daybreak Tuesday, but dry air should win out and prevent most if not all of this from reaching the ground. Patchy fog will also be possible by early Tuesday morning across portions of northwest Iowa and southwest Minnesota as winds turn light and variable overnight and ample moisture remains in place. Temperatures tonight drop mainly in the 40s, though some 50s are possible in our easternmost areas. Low chances for showers continue into the day on Tuesday, but activity is expected to remain spotty at best as rain continues to battle a dry sub cloud layer. Highs will range from the 60s northwest to 70s southeast. Rain chances look to increase Tuesday night into Wednesday as two shortwave troughs impact our area. The best chances of rain and storms look to be over northwest Iowa and adjacent areas of Nebraska, South Dakota, and Minnesota. At this time, severe weather looks unlikely with this system as the better instability looks to be off to our south and east. Rain and storms exit off to our east by Wednesday night, leading to a dry Thursday. Winds look to increase on Thursday especially west of I-29 closer to a deepening surface low, and winds may take on a southwesterly component especially in south central South Dakota. This could lead to another day with higher fire danger as temperatures will be warm and relative humidity values drop to 25% or below mainly along and west of the James River. Still some uncertainty into how breezy the winds will be, so keep up to date with the latest forecast. Not too much time to look into the extended forecast given the near term severe weather threat, but guidance is in fairly good agreement that the western trough will begin to move into our area by the end of the work week/early weekend. This could bring more rain and storms to our area on Friday and then colder weather into Saturday as guidance indicates a stronger push of cold air advection behind this system. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 641 PM CDT Mon Apr 13 2026 VFR conditions are expected for the majority of the period. Thunderstorms, some severe producing 2+ inch hail, are ongoing east of I-29 in northwest Iowa and southwest Minnesota. These storms will continue to track northeast through about 14.03Z. Some patchy dense fog is possible near daybreak east of I-29. This should burn off by mid morning. A few light rain showers are possible again Wednesday afternoon but confidence is too low to include in the TAFs at this time. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && DISCUSSION...Samet AVIATION...AJP
Hazardous weather outlook, Apr 13, 3:56 PM CDT, 2 hours 49 minutes before
Hazardous Weather Outlook National Weather Service Sioux Falls SD 356 PM CDT Mon Apr 13 2026 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-142100- Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson- Pipestone-Rock-Dixon-Dakota-Beadle-Kingsbury-Brookings-Gregory- Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook- Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton- Union- 356 PM CDT Mon Apr 13 2026 This Hazardous Weather Outlook is for northwest Iowa, west central Iowa, southwest Minnesota, northeast Nebraska, central South Dakota, east central South Dakota, south central South Dakota and southeast South Dakota. .DAY ONE...This afternoon and tonight. Scattered strong to severe thunderstorms expected Monday afternoon and evening. Some storms may produce large hail 2 inches in diameter and damaging wind gusts up to 70 mph. A tornado or two cannot be ruled out. Greatest risk of storms is north of I-90 between 4 and 10 PM. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. More widespread chances for showers and thunderstorms exists for Tuesday afternoon into Wednesday. This more active pattern continues into the weekend. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
In the hours before
Local storm report, Apr 13, 6:26 PM CDT, 19 minutes before
Preliminary Local Storm Report
National Weather Service Sioux Falls SD
626 PM CDT Mon Apr 13 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0608 PM Hail 4 SE Granville 42.94N 95.82W
04/13/2026 M1.75 Inch O'Brien IA Trained Spotter
&&
JCLocal storm report, Apr 13, 6:32 PM CDT, 13 minutes before
Preliminary Local Storm Report
National Weather Service Sioux Falls SD
632 PM CDT Mon Apr 13 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0622 PM Hail 3 NE Tea 43.48N 96.79W
04/13/2026 E1.00 Inch Lincoln SD Trained Spotter
&&
TRMLocal storm report, Apr 13, 6:35 PM CDT, 10 minutes before
Preliminary Local Storm Report
National Weather Service Sioux Falls SD
635 PM CDT Mon Apr 13 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0621 PM Hail 4 N Windom 43.93N 95.12W
04/13/2026 M2.00 Inch Cottonwood MN Public
&&
JCLocal storm report, Apr 13, 6:36 PM CDT, 9 minutes before
Preliminary Local Storm Report
National Weather Service Sioux Falls SD
636 PM CDT Mon Apr 13 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0618 PM Hail 4 WSW Sioux Falls 43.52N 96.80W
04/13/2026 M1.50 Inch Minnehaha SD NWS Employee
&&
JCLocal storm report, Apr 13, 6:39 PM CDT, 6 minutes before
Preliminary Local Storm Report
National Weather Service Sioux Falls SD
639 PM CDT Mon Apr 13 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0615 PM Hail 5 NW Windom 43.93N 95.18W
04/13/2026 E2.00 Inch Cottonwood MN Public
&&
JCLocal storm report, Apr 13, 6:43 PM CDT, 2 minutes before
Preliminary Local Storm Report
National Weather Service Sioux Falls SD
643 PM CDT Mon Apr 13 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0559 PM Hail 2 NW Dundee 43.87N 95.50W
04/13/2026 M1.00 Inch Murray MN Trained Spotter
&&
JCThe office that day
Everything else NWS Sioux Falls, SD issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 13, 5:26 PM CDT | Severe Thunderstorm Warning | FSD | Plymouth, Sioux, Woodbury | 49 min |
| Apr 13, 5:56 PM CDT | Severe Thunderstorm Warning | FSD | Cherokee, Plymouth | 29 min |
| Apr 13, 6:05 PM CDT | Severe Thunderstorm Warning | FSD | Cherokee, O'Brien, Plymouth, Sioux | 40 min |
| Apr 13, 6:30 PM CDT | Severe Thunderstorm Warning | FSD | Dickinson, Osceola | 45 min |
| Apr 13, 6:53 PM CDT | Severe Thunderstorm Warning | FSD | Cherokee, Clay, O'Brien | 52 min |
Nearby
Severe Thunderstorm Warnings in Iowa, 2026Every severe thunderstorm warning 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.