Right now
The most recent data we hold from NOAA arrived 6 minutes ago, 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 17 May 2026 at 19:00 UTC. It is kept here as a record.
No stronger detection stands among the 46 recorded within 20 km of this point since 15 March 2026 — 10 others scored the same. Another comparable one was recorded here earlier the same day. 2 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued May 17 at 1:29PM CDT until May 17 at 2:00PM CDT by NWS Sioux Falls SD
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 22 out of 100, at 60 % 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 | 60% |
| Coordinates | 42.9616, -99.3909 |
| Nearest City | Mitchell (138 km) |
| Impact Tier | minor |
| Timestamp | 2026-05-17T18:29:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.d74bec13ab9bf732205511df46811da2 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Gregory, SD; Boyd, NE; Brown, NE; Holt, NE; Keya Paha, NE; Rock, NE; Boyd, NE; Keya Paha, NE |
| Headline | Severe Thunderstorm Warning issued May 17 at 1:29PM CDT until May 17 at 2:00PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-17T14:00:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 3 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.d74bec13ab9bf732205511df46811da241dba7c8.001.1","noaa_urn:oid:2.49.0.1.840.0.2cbd1da0b76219014a07d04682e3e5aceb8bbb5d.001.1","noaa_urn:oid:2.49.0.1.840.0.27b209d67deeb64ec1128b83a3318e99c2cd54a0.001.1"] |
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.
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.