Right now
The most recent data we hold from NOAA arrived 9 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 22:45 UTC. It is kept here as a record.
It is the 4th strongest of the 44 detections recorded within 20 km of this point since 15 March 2026. Another comparable one was recorded here earlier the same day. 6 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued May 17 at 4:56PM CDT until May 17 at 5:45PM CDT by NWS Sioux Falls SD
Urban PEI: 171,544 within a heuristic 50 km radius; not unique people.
Nearby, since 15 March 2026
- May 17, 2026 · score 67 · 9.4 km
- July 26, 2026 · score 43 · 14.4 km
- June 18, 2026 · score 43 · 19.4 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 43 out of 100.
This is our versioned heuristic index, not source severity or a calibrated probability. Urban PEI does not count unique people.
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) | 43 / 100 |
| Legacy data-support index | 0.79/1 |
| Coordinates | 43.4380, -96.4177 |
| Nearest City | Sioux Falls (28 km) |
| Urban exposure index (PEI) | 171.5K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-17T21:56:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.0ff46de6af47dc60c5071e5737939f7c |
Physical priority index · v1. Heuristic priority, not calibrated probability, predictive accuracy or damage. The legacy data-support index combines assigned source support and field availability. Urban PEI is distance-weighted and does not count unique people; zero does not establish that nobody is present. Model cards.
Source and revision timeline
Source: noaa. Occurrence: 2026-05-17T21:56:00.000Z.
First archived: 2026-05-17T21:58:18.410Z. Material modification: not recorded.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Lyon, IA; Nobles, MN; Rock, MN; Minnehaha, SD; Lyon, IA; Rock, MN; Lincoln, SD; Minnehaha, SD |
| Headline | Severe Thunderstorm Warning issued May 17 at 4:56PM CDT until May 17 at 5:45PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-17T17:45:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.0ff46de6af47dc60c5071e5737939f7c6edf6938.001.1","noaa_urn:oid:2.49.0.1.840.0.6ffc29873ebf2cd08e3dea5b25c669226c602ac3.002.1"] |
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.
Review the area, threshold and delivery channel in your account.
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