This alert expired on 2 September 2026 at 03:45 UTC. It is kept here as a record.
It is the 24th strongest of the 43 detections recorded within 20 km of this point since 17 May 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 1 at 10:09PM CDT until September 1 at 10:45PM CDT by NWS Omaha/Valley NE
Nearby, since 17 May 2026
- July 2, 2026 · score 22 · 9.3 km
- August 11, 2026 · score 43 · 18.4 km
- June 28, 2026 · score 43 · 20.1 km
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 16 out of 100, at 71 % 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 | 71% |
| Coordinates | 43.1046, -96.4286 |
| Nearest City | Sioux Falls (54 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-02T03:09:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.bb1cdea0986bf4334d85c0567da0639b49f825a8.002.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Cedar, NE; Lyon, IA; O'Brien, IA; Osceola, IA; Plymouth, IA; Sioux, IA; Nobles, MN; Rock, MN; Lincoln, SD; Union, SD; Bon Homme, SD; Charles Mix, SD and 2 more areas |
| Headline | Severe Thunderstorm Warning issued September 1 at 10:09PM CDT until September 1 at 10:45PM CDT by NWS Omaha/Valley NE |
| Expires | 2026-09-01T22:45:00-05:00 |
| SenderName | NWS Omaha/Valley NE |
| HasExactCoords | true |
| MergedCount | 5 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.bb1cdea0986bf4334d85c0567da0639b49f825a8.002.1","noaa_urn:oid:2.49.0.1.840.0.fcaaa35e30fbc12afb465f986c24f2765dc5bac4.001.1","noaa_urn:oid:2.49.0.1.840.0.e0e345003674f7db923fb659d95d36e011eedc0e.001.1","noaa_urn:oid:2.49.0.1.840.0.aa56ed8029017158982eef559907c8ffed370d94.002.1","noaa_urn:oid:2.49.0.1.840.0.4c5f024b0088a0a2bc5a1b7ac2c6eeb1fbfeb276.001.1"] |
| Spc ReportType | wind |
| Spc Speed | 60 |
| Spc Location | 10 SSE Alcester |
| Spc County | Union |
| Spc State | SD |
| Spc Comments | Wind measured by anemometer. (FSD) |
| Iem TypeSummary | G |
| Iem Magnitude | 60 |
| Iem Unit | MPH |
| Iem City | 10 SSE Alcester |
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.