This alert expired on 2 September 2026 at 01:00 UTC. It is kept here as a record.
No stronger detection stands among the 49 recorded within 20 km of this point since 29 June 2026 — 32 others scored the same. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 1 at 7:46PM CDT until September 1 at 8:00PM CDT by NWS Sioux Falls SD
Nearby, since 29 June 2026
- June 29, 2026 · score 16 · 14.5 km
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 28 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 | high |
| Calamity Score (ours) | 28 / 100 |
| Our confidence | 71% |
| Coordinates | 42.6571, -98.1673 |
| Nearest City | Norfolk (93 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-02T00:46:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.a930d4213241170bc3cba40e1d51d4171bdf30eb.002.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Bon Homme, SD; Antelope, NE; Knox, NE; Holt, NE |
| Headline | Severe Thunderstorm Warning issued September 1 at 7:46PM CDT until September 1 at 8:00PM CDT by NWS Sioux Falls SD |
| Expires | 2026-09-01T20:00:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 4 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.a930d4213241170bc3cba40e1d51d4171bdf30eb.002.1","noaa_urn:oid:2.49.0.1.840.0.2cbc7ef83367f71f9bf2b44ad4d09c5f0f5c75f1.001.1","noaa_urn:oid:2.49.0.1.840.0.b0a7009363c54481ad230b36ddb2d37b4184ae13.001.1","noaa_urn:oid:2.49.0.1.840.0.b4a93174b864b0b57d4f3fdc7ff300206adf2188.001.1"] |
| Spc ReportType | hail |
| Spc Speed | 100 |
| Spc Location | 6 NNW Chambers |
| Spc County | Holt |
| Spc State | NE |
| Spc Comments | Social media report via storm chaser stream. (LBF) |
| Iem TypeSummary | G |
| Iem Magnitude | 60 |
| Iem Unit | MPH |
| Iem City | 2 S Monowi |
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 28/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.