This alert expired on 18 May 2026 at 02:15 UTC. It is kept here as a record.
No stronger detection stands among the 24 recorded within 20 km of this point since 16 March 2026 — 2 others scored the same. Another comparable one was recorded here earlier the same day. 11 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Tornado Warning issued May 17 at 8:48PM CDT until May 17 at 9:15PM CDT by NWS Sioux Falls SD
Nearby, since 16 March 2026
- August 13, 2026 · score 46 · 20.7 km
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 46 out of 100, at 70 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Computed under scoring rules v1. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Critical |
| Calamity Score (ours) | 46 / 100 |
| Our confidence | 70% |
| Coordinates | 42.2526, -95.3537 |
| Nearest City | Sioux City (90 km) |
| Impact Tier | minor |
| Date | 2026-05-18 — time not reported by the source |
| Source | https://api.weather.gov/alerts/merged_Tornado Warning_noaa_urn:oid:2.49.0.1.840.0.edbbf6f6d988872a8698758e5f61294e |
Score Breakdown
Technical Details
| Event | Tornado Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Clay, IA; Dickinson, IA; Harrison, IA; Clay, IA and 2 more areas |
| Headline | Tornado Warning issued May 17 at 8:48PM CDT until May 17 at 9:15PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-17T21:15:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 5 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.edbbf6f6d988872a8698758e5f61294e7a64b946.001.1","noaa_urn:oid:2.49.0.1.840.0.ab4789a85118d45ba3f24e438e7009867e2660a4.002.1","noaa_urn:oid:2.49.0.1.840.0.3c4094923dc8d43384e49d869c30e57d69dc6869.002.1","noaa_urn:oid:2.49.0.1.840.0.143039dbb5a2f87ab170dc9a8ca7cf6dfc78824c.001.1","noaa_urn:oid:2.49.0.1.840.0.86f2042d2fc7a996cfd43ada5f74ddce9e7bf4f9.001.1"] |
| Iem TypeSummary | G |
| Iem Magnitude | 74 |
| Iem Unit | MPH |
| Iem City | 4 W Correctionville |
| Iem County | Woodbury |
| Iem State | IA |
| Iem Wfo | FSD |
| Iem Remark | Via personal weather station. Exact time estimated via radar. |
| MergedSources | [{"id":"iem_G_42.190_-95.900_1779065280000","source":"iem","severity":"low","severityValue":25,"timestamp":1779065280000,"latitude":42.19,"longitude":-95.9},{"id":"iem_G_42.480_-95.860_1779065640000","source":"iem","severity":"low","severityValue":25,"timestamp":1779065640000,"latitude":42.48,"longitude":-95.86}] |
Safety Information
If a tornado warning is issued: go to a basement or an interior room on the lowest floor, away from windows. A vehicle and a mobile home are not shelter. Cover your head and neck. Wait for the official all-clear before going outside, and watch for downed power lines and gas leaks afterwards.
Series begins 8 March 2026. Comparisons refer to that period only. Collection gap: 14-26 August 2026.
This data is aggregated algorithmically from scientific sources. Not a replacement for official emergency warnings.
Want to know when something happens in this area?
Calamity.live data shows a weather event with CalamityScore 46/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.