Right now
The most recent data we hold from NOAA arrived this minute, 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 12 September 2026 at 03:15 UTC. It is kept here as a record.
It is the 34th strongest of the 42 detections recorded within 20 km of this point since 30 June 2026. The last comparable one was on 2 September 2026. 26 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 11 at 9:24PM CDT until September 11 at 10:15PM CDT by NWS Sioux Falls SD
An estimated 24,366 people live within 50 km of this point.
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 28 out of 100, at 81 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Computed under scoring rules v4. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Medium |
| Calamity Score (ours) | 28 / 100 |
| Our confidence | 81% |
| Coordinates | 42.3808, -97.2748 |
| Nearest City | Norfolk (41 km) |
| Population Exposed | 24.4K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-12T02:24:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.a3d2d4fbcede5d0eebd9a9687425cbf442c91667.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Plymouth, IA; Sioux, IA; Dixon, NE; Clay, SD; Union, SD; Antelope, NE |
| Headline | Severe Thunderstorm Warning issued September 11 at 9:24PM CDT until September 11 at 10:15PM CDT by NWS Sioux Falls SD |
| Expires | 2026-09-11T22:15:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.a3d2d4fbcede5d0eebd9a9687425cbf442c91667.001.1","noaa_urn:oid:2.49.0.1.840.0.d71b6b398dc58da195540a59b600da593bdd145f.001.1"] |
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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