Right now
The most recent data we hold from NOAA arrived 66 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
15 other detections within 20 km in the last 24 hours, the nearest 4 km from here.
This alert expired on 17 May 2026 at 20:30 UTC. It is kept here as a record.
It is the 160th strongest of the 224 detections recorded within 20 km of this point since 16 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 17 at 3:12PM CDT until May 17 at 3:30PM CDT by NWS Sioux Falls SD
Nearby, since 16 March 2026
- September 8, 2026 · score 46 · 3.6 km
- May 25, 2026 · score 22 · 20.2 km
How we know
Confirmed by 4 independent sources, including NOAA.
Our own score for this event is 22 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 | Medium |
| Calamity Score (ours) | 22 / 100 |
| Our confidence | 70% |
| Coordinates | 42.9145, -98.0055 |
| Nearest City | Mitchell (88 km) |
| Impact Tier | minor |
| Timestamp | 2026-05-17T20:12:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.912e2e6ab6ff6473fa44610a9363b402 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Bon Homme, SD; Hutchinson, SD; Yankton, SD; Knox, NE |
| Headline | Severe Thunderstorm Warning issued May 17 at 3:12PM CDT until May 17 at 3:30PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-17T15:30:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.912e2e6ab6ff6473fa44610a9363b402219466a9.001.1","noaa_urn:oid:2.49.0.1.840.0.74443eb905fd5e2f30bdf6a9cf405f57f6569d15.001.1"] |
| Iem TypeSummary | H |
| Iem Magnitude | 1 |
| Iem Unit | Inch |
| Iem City | 1 SE Marty |
| Iem County | Charles Mix |
| Iem State | SD |
| Iem Wfo | FSD |
| Iem Remark | Winds estimated 40-50 mph. |
| MergedSources | [{"id":"iem_G_42.850_-98.670_1779045300000","source":"iem","severity":"low","severityValue":25,"timestamp":1779045300000,"latitude":42.85,"longitude":-98.67},{"id":"iem_G_42.840_-98.740_1779044880000","source":"iem","severity":"low","severityValue":25,"timestamp":1779044880000,"latitude":42.84,"longitude":-98.74},{"id":"iem_H_42.980_-98.410_1779046620000","source":"iem","severity":"low","severityValue":25,"timestamp":1779046620000,"latitude":42.98,"longitude":-98.41}] |
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 22/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.