Alert archive / Iowa / Tornado Warnings in 2026
Tornado Warning 21, NWS Omaha, NE
NWS Omaha, NE issued this tornado warning at May 17, 2026, 8:28 PM CDT for Harrison County, Pottawattamie County, Iowa. It was in force for 25 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
- May 17, 2026, 8:28 PM CDT (01:28 UTC)
- Expired
- May 17, 2026, 8:53 PM CDT
- In force
- 25 min
- Issued by
- NWS Omaha, NE
- Area
- Storm-based polygon
- Tornado
- Radar indicated
- Hail
- 1.0 in
Counties Harrison County, IA, Pottawattamie County, IA
The radar
The Omaha radar (KOAX), 54 km from the middle of the area, began a volume at 01:27 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, 8:33 PM CDT | TSTM WND GST 65 | 1 Sse Missouri Valley, IA | Personal Weather Station. |
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, 3:16 PM CDT | Tornado Watch | SPC | 8 hr |
The nearest sounding before it
Omaha, NE (KOAX), launched 00:00Z, 1.5 hours before the alert went out and 54 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.
632
WFUS53 KOAX 180128
TOROAX
IAC085-155-180215-
/O.NEW.KOAX.TO.W.0021.260518T0128Z-260518T0215Z/
BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Omaha/Valley Nebraska
828 PM CDT Sun May 17 2026
The National Weather Service in Omaha has issued a
* Tornado Warning for...
Northwestern Pottawattamie County in southwestern Iowa...
Eastern Harrison County in southwestern Iowa...
* Until 915 PM CDT.
* At 828 PM CDT, a severe thunderstorm capable of producing a tornado
was located over Missouri Valley, or 11 miles east of Blair, moving
northeast at 45 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 dangerous storm will be near...
Missouri Valley at 830 PM
Logan around 835 PM CDT.
This includes Interstate 29 between mile markers 68 and 79.
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.
&&
LAT...LON 4141 9588 4153 9600 4155 9601 4155 9603
4186 9556 4160 9556 4160 9551
TIME...MOT...LOC 0128Z 233DEG 38KT 4153 9591
TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
$$
BLB2 follow-up statements
131
WWUS53 KOAX 180145
SVSOAX
Severe Weather Statement
National Weather Service Omaha/Valley Nebraska
845 PM CDT Sun May 17 2026
IAC155-180154-
/O.CAN.KOAX.TO.W.0021.000000T0000Z-260518T0215Z/
Pottawattamie IA-
845 PM CDT Sun May 17 2026
...THE TORNADO WARNING FOR NORTHWESTERN POTTAWATTAMIE COUNTY IS
CANCELLED...
The tornadic thunderstorm which prompted the warning has moved out
of the warned area. Therefore, the warning has been cancelled.
A Tornado Watch remains in effect until 1100 PM CDT for southwestern
Iowa.
&&
LAT...LON 4154 9568 4170 9578 4186 9556 4160 9556
4160 9551
TIME...MOT...LOC 0144Z 226DEG 45KT 4163 9565
$$
IAC085-180215-
/O.CON.KOAX.TO.W.0021.000000T0000Z-260518T0215Z/
Harrison IA-
845 PM CDT Sun May 17 2026
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 915 PM CDT FOR EASTERN
HARRISON COUNTY...
At 844 PM CDT, a severe thunderstorm capable of producing a tornado
was located 5 miles northwest of Persia, or 16 miles west of Harlan,
moving northeast at 50 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
eastern Harrison County.
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.
&&
LAT...LON 4154 9568 4170 9578 4186 9556 4160 9556
4160 9551
TIME...MOT...LOC 0144Z 226DEG 45KT 4163 9565
TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
$$
BLB967
WWUS53 KOAX 180153
SVSOAX
Severe Weather Statement
National Weather Service Omaha/Valley Nebraska
853 PM CDT Sun May 17 2026
IAC085-180203-
/O.CAN.KOAX.TO.W.0021.000000T0000Z-260518T0215Z/
Harrison IA-
853 PM CDT Sun May 17 2026
...THE TORNADO WARNING FOR EASTERN HARRISON COUNTY IS CANCELLED...
The tornado threat has diminished and the Tornado Warning has been
cancelled. However, large hail and damaging winds remain likely and a
Severe Thunderstorm Warning remains in effect for the area.
A Tornado Watch remains in effect until 1100 PM CDT for southwestern
Iowa.
&&
LAT...LON 4154 9568 4170 9578 4186 9556 4160 9556
4160 9551
TIME...MOT...LOC 0151Z 233DEG 38KT 4169 9555
$$
BLBThe office that day
Everything else NWS Omaha, NE issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 17, 7:27 PM CDT | Severe Thunderstorm Warning | OAX | Harrison, Monona | 48 min |
| May 17, 8:00 PM CDT | Severe Thunderstorm Warning | OAX | Harrison, Monona | 45 min |
| May 17, 8:04 PM CDT | Tornado Warning | OAX | Harrison, Pottawattamie | 26 min |
| May 17, 8:11 PM CDT | Severe Thunderstorm Warning | OAX | Harrison, Mills, Pottawattamie, Shelby | 64 min |
| May 17, 8:14 PM CDT | Tornado Warning | OAX | Pottawattamie | 29 min |
| May 17, 8:25 PM CDT | Severe Thunderstorm Warning | OAX | Harrison, Shelby | 65 min |
| May 17, 8:29 PM CDT | Severe Thunderstorm Warning | OAX | Fremont | 46 min |
| May 17, 8:42 PM CDT | Severe Thunderstorm Warning | OAX | Harrison, Monona | 33 min |
| May 17, 8:46 PM CDT | Tornado Warning | OAX | Mills | 29 min |
| May 17, 8:56 PM CDT | Severe Thunderstorm Warning | OAX | Harrison, Monona, Pottawattamie, Shelby | 64 min |
| May 17, 9:03 PM CDT | Severe Thunderstorm Warning | OAX | Fremont, Mills, Montgomery, Page | 72 min |
| May 17, 9:06 PM CDT | Tornado Warning | OAX | Mills, Montgomery, Pottawattamie | 39 min |
| May 17, 10:00 PM CDT | Severe Thunderstorm Warning | OAX | Fremont | 30 min |
| May 17, 10:06 PM CDT | Severe Thunderstorm Warning | OAX | Fremont, Mills, Montgomery, Page | 54 min |
| May 18, 4:02 PM CDT | Severe Thunderstorm Warning | OAX | Fremont | 43 min |
| May 18, 4:39 PM CDT | Severe Thunderstorm Warning | OAX | Fremont, Page | 66 min |
| May 18, 4:58 PM CDT | Severe Thunderstorm Warning | OAX | Monona | 21 min |
| May 18, 5:02 PM CDT | Areal Flood Advisory | OAX | Fremont, Page | 5 hr |
| May 18, 5:06 PM CDT | Tornado Warning | OAX | Fremont, Page | 54 min |
| May 18, 5:13 PM CDT | Severe Thunderstorm Warning | OAX | Page | 62 min |
| May 18, 6:18 PM CDT | Severe Thunderstorm Warning | OAX | Fremont, Mills | 31 min |
| May 18, 6:37 PM CDT | Severe Thunderstorm Warning | OAX | Mills, Montgomery, Pottawattamie | 14 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.