Right now
The most recent data we hold from NOAA arrived 20 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
One other detection within 20 km in the last 24 hours, 6 km from here.
This alert expired on 17 May 2026 at 22:45 UTC. It is kept here as a record.
It is the 3rd strongest of the 55 detections recorded within 20 km of this point since 15 March 2026. Another comparable one was recorded here earlier the same day. 2 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued May 17 at 4:56PM CDT until May 17 at 5:45PM CDT by NWS Sioux Falls SD
An estimated 171,544 people live within 50 km of this point.
Nearby, since 15 March 2026
- May 17, 2026 · score 67 · 18.2 km
- June 18, 2026 · score 43 · 19.4 km
- July 26, 2026 · score 43 · 21.5 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 43 out of 100, at 79 % 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 | Medium |
| Calamity Score (ours) | 43 / 100 |
| Our confidence | 79% |
| Coordinates | 43.4450, -96.3000 |
| Nearest City | Sioux Falls (36 km) |
| Population Exposed | 171.5K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-17T21:56:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.0ff46de6af47dc60c5071e5737939f7c6edf6938.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Lyon, IA; Nobles, MN; Rock, MN; Minnehaha, SD |
| Headline | Severe Thunderstorm Warning issued May 17 at 4:56PM CDT until May 17 at 5:45PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-17T17:45:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
Safety Information
Always follow official guidance from your local emergency management agency. This platform provides scientific monitoring data and is not a substitute for official warnings. If you are in immediate danger, contact your local emergency number.
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 43/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.