Right now
The most recent data we hold from NOAA arrived 78 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 1 June 2026 at 00:15 UTC. It is kept here as a record.
It is the 20th strongest of the 40 detections recorded within 20 km of this point since 15 March 2026. Another comparable one was recorded here earlier the same day. 9 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued May 31 at 6:34PM CDT until May 31 at 7:15PM CDT by NWS Sioux Falls SD
Nearby, since 15 March 2026
- May 31, 2026 · score 43 · 5.8 km
- May 31, 2026 · score 58 · 9.7 km
- July 26, 2026 · score 34 · 23.1 km
How we know
Confirmed by 2 independent sources, including NOAA.
Our own score for this event is 22 out of 100, at 63 % 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) | 22 / 100 |
| Our confidence | 63% |
| Coordinates | 43.6300, -97.3740 |
| Nearest City | Sioux Falls (53 km) |
| Impact Tier | minor |
| Timestamp | 2026-05-31T23:34:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.a1ffac3b2c576d5c3cf711b8c38c2a31704ee444.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | McCook, SD |
| Headline | Severe Thunderstorm Warning issued May 31 at 6:34PM CDT until May 31 at 7:15PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-31T19:15:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| Iem TypeSummary | C |
| Iem City | 1 N Bridgewater |
| Iem County | McCook |
| Iem State | SD |
| Iem Wfo | FSD |
| MergedSources | [{"id":"iem_C_43.570_-97.500_1780268400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780268400000,"latitude":43.57,"longitude":-97.5}] |
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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