This alert expired on 1 September 2026 at 21:45 UTC. It is kept here as a record.
It is the 11th strongest of the 23 detections recorded within 20 km of this point since 15 March 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 1 at 4:19PM CDT until September 1 at 4:45PM CDT by NWS Sioux Falls SD
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 16 out of 100, at 70 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Event Data
| Type | Severe weather |
| Severity | medium |
| Calamity Score (ours) | 16 / 100 |
| Our confidence | 70% |
| Coordinates | 43.1708, -99.0048 |
| Nearest City | Mitchell (99 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-01T21:19:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.a29c43df7574c9dd37ffbf8ef799b0ababbc83cc.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Brule, SD; Charles Mix, SD; Gregory, SD; Charles Mix, SD; Gregory, SD; Boyd, NE; Holt, NE |
| Headline | Severe Thunderstorm Warning issued September 1 at 4:19PM CDT until September 1 at 4:45PM CDT by NWS Sioux Falls SD |
| Expires | 2026-09-01T16:45:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 3 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.a29c43df7574c9dd37ffbf8ef799b0ababbc83cc.001.1","noaa_urn:oid:2.49.0.1.840.0.f6e04764b0e917857026c959bdc7e3c90fd7e6f5.001.1","noaa_urn:oid:2.49.0.1.840.0.926490a9334e521cf329894b3cfbb804157c63ab.001.1"] |
| Spc ReportType | wind |
| Spc Speed | 63 |
| Spc Location | 10 SE Mills |
| Spc County | Keya Paha |
| Spc State | NE |
| Spc Comments | Nebraska Mesonet. (LBF) |
| Iem TypeSummary | G |
| Iem Magnitude | 63 |
| Iem Unit | MPH |
| Iem City | 10 SE Mills |
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 10 February 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 16/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.