Right now
The most recent data we hold from NOAA arrived 10 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 25 May 2026 at 04:30 UTC. It is kept here as a record.
It is the 3rd strongest of the 71 detections recorded within 20 km of this point since 15 March 2026. The last comparable one was on 17 May 2026. 8 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued May 24 at 11:02PM CDT until May 24 at 11:30PM CDT by NWS Sioux Falls SD
An estimated 171,544 people live within 50 km of this point.
Nearby, since 15 March 2026
- June 28, 2026 · score 43 · 12.0 km
- July 26, 2026 · score 43 · 13.1 km
- May 17, 2026 · score 67 · 17.8 km
How we know
Confirmed by 4 independent sources, including NOAA.
Our own score for this event is 43 out of 100, at 90 % 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 | 90% |
| Coordinates | 43.3680, -96.3600 |
| Nearest City | Sioux Falls (35 km) |
| Population Exposed | 171.5K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-25T04:02:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.b684a5667f4152af95f47a53ae449b12c13e6da6.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Lyon, IA |
| Headline | Severe Thunderstorm Warning issued May 24 at 11:02PM CDT until May 24 at 11:30PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-24T23:30:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| Iem TypeSummary | H |
| Iem Magnitude | 1.25 |
| Iem Unit | Inch |
| Iem City | 5 SSW Chandler |
| Iem County | Murray |
| Iem State | MN |
| Iem Wfo | FSD |
| MergedSources | [{"id":"iem_H_44.010_-96.100_1779663900000","source":"iem","severity":"low","severityValue":25,"timestamp":1779663900000,"latitude":44.01,"longitude":-96.1},{"id":"iem_H_44.000_-96.310_1779661200000","source":"iem","severity":"low","severityValue":25,"timestamp":1779661200000,"latitude":44,"longitude":-96.31},{"id":"iem_H_43.870_-95.990_1779668280000","source":"iem","severity":"low","severityValue":25,"timestamp":1779668280000,"latitude":43.87,"longitude":-95.99}] |
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.
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