Right now
The most recent data we hold from NOAA arrived 27 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
Nothing else has been detected within 20 km in the last 24 hours.
This alert expired on 17 May 2026 at 22:15 UTC. It is kept here as a record.
No stronger detection stands among the 67 recorded within 20 km of this point since 15 March 2026 — 9 others scored the same. Another comparable one was recorded here earlier the same day. 3 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Tornado Warning issued May 17 at 4:27PM CDT until May 17 at 5:15PM CDT by NWS Sioux Falls SD
An estimated 171,544 people live within 50 km of this point.
Nearby, since 15 March 2026
- May 25, 2026 · score 43 · 8.5 km
- May 17, 2026 · score 67 · 17.0 km
- July 26, 2026 · score 43 · 21.9 km
How we know
Confirmed by 8 independent sources, including NOAA.
Our own score for this event is 67 out of 100, at 89 % 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) | 67 / 100 |
| Our confidence | 89% |
| Coordinates | 43.4460, -96.7280 |
| Nearest City | Sioux Falls (10 km) |
| Population Exposed | 171.5K within 50 km |
| Impact Tier | severe |
| Timestamp | 2026-05-17T21:27:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.57a1f98f933e6944b8a987adb8281afeb29b4b1c.001.1 |
Score Breakdown
Technical Details
| Event | Tornado Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Lyon, IA; Lincoln, SD; Minnehaha, SD |
| Headline | Tornado Warning issued May 17 at 4:27PM CDT until May 17 at 5:15PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-17T17:15:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| Iem TypeSummary | D |
| Iem City | 8 S Freeman |
| Iem County | Hutchinson |
| Iem State | SD |
| Iem Wfo | FSD |
| Iem Remark | Damage to large road signs near intersection of Hwy 18/81. |
| MergedSources | [{"id":"iem_H_43.220_-97.510_1779050160000","source":"iem","severity":"low","severityValue":25,"timestamp":1779050160000,"latitude":43.22,"longitude":-97.51},{"id":"iem_H_43.180_-97.340_1779050640000","source":"iem","severity":"low","severityValue":25,"timestamp":1779050640000,"latitude":43.18,"longitude":-97.34},{"id":"iem_G_43.280_-97.420_1779050520000","source":"iem","severity":"low","severityValue":25,"timestamp":1779050520000,"latitude":43.28,"longitude":-97.42},{"id":"iem_G_43.210_-97.450_1779050280000","source":"iem","severity":"low","severityValue":25,"timestamp":1779050280000,"latitude":43.21,"longitude":-97.45},{"id":"iem_G_43.260_-97.270_1779050820000","source":"iem","severity":"low","severityValue":25,"timestamp":1779050820000,"latitude":43.26,"longitude":-97.27},{"id":"iem_H_43.220_-97.510_1779050640000","source":"iem","severity":"low","severityValue":25,"timestamp":1779050640000,"latitude":43.22,"longitude":-97.51},{"id":"iem_D_43.240_-97.420_1779050520000","source":"iem","severity":"low","severityValue":25,"timestamp":1779050520000,"latitude":43.24,"longitude":-97.42}] |
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 near Sioux Falls?
Calamity.live data shows a weather event with CalamityScore 67/100, near Sioux Falls (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.