Right now
The most recent data we hold from NOAA arrived 65 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 1 June 2026 at 03:00 UTC. It is kept here as a record.
No stronger detection stands among the 120 recorded within 20 km of this point since 15 March 2026 — 4 others scored the same. Another comparable one was recorded here earlier the same day. 4 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Tornado Warning issued May 31 at 9:28PM CDT until May 31 at 10:00PM CDT by NWS Sioux Falls SD
Nearby, since 15 March 2026
- June 1, 2026 · score 46 · 5.6 km
- September 4, 2026 · score 32 · 5.8 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 46 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 | Critical |
| Calamity Score (ours) | 46 / 100 |
| Legacy data-support index | 0.58/1 |
| Coordinates | 42.8880, -96.8080 |
| Nearest City | Sioux City (55 km) |
| Urban exposure index (PEI) | 0 within 50 km |
| Impact Tier | minor |
| Timestamp | 2026-06-01T02:28:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.6e5270ef320fb43767cdaf51383e369e06e9c06f.001.1 |
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: 2026-06-01T02:28:00.000Z.
First archived: 2026-06-01T02:45:02.664Z. 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 | Tornado Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Clay, SD; Union, SD |
| Headline | Tornado Warning issued May 31 at 9:28PM CDT until May 31 at 10:00PM CDT by NWS Sioux Falls SD |
| Expires | 2026-05-31T22:00:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
Safety Information
If a tornado warning is issued: go to a basement or an interior room on the lowest floor, away from windows. A vehicle and a mobile home are not shelter. Cover your head and neck. Wait for the official all-clear before going outside, and watch for downed power lines and gas leaks afterwards.
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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