Right now
The most recent data we hold from NOAA arrived 11 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 21 May 2026 at 22:30 UTC. It is kept here as a record.
It is the 6th strongest of the 57 detections recorded within 20 km of this point since 5 May 2026. The last comparable one was on 8 May 2026. One more was recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued May 21 at 3:57PM MDT until May 21 at 4:30PM MDT by NWS Denver CO
Nearby, since 5 May 2026
- June 22, 2026 · score 46 · 4.4 km
- June 23, 2026 · score 46 · 18.3 km
- May 21, 2026 · score 46 · 18.5 km
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.
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) | 22 / 100 |
| Legacy data-support index | 0.60/1 |
| Coordinates | 41.3492, -103.5165 |
| Nearest City | Cheyenne (111 km) |
| Urban exposure index (PEI) | 0 within 50 km |
| Impact Tier | minor |
| Timestamp | 2026-05-21T21:57:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.01194ad147ca485b6ab2e506f02beb62 |
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: 2026-05-21T21:57:00.000Z.
First archived: 2026-05-21T22:02:13.667Z. 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 | Logan, CO; Scotts Bluff, NE; Sioux, NE; Central Arapahoe, CO; Eastern Arapahoe, CO and 1 more areas |
| Headline | Severe Thunderstorm Warning issued May 21 at 3:57PM MDT until May 21 at 4:30PM MDT by NWS Denver CO |
| Expires | 2026-05-21T16:30:00-06:00 |
| SenderName | NWS Denver CO |
| HasExactCoords | true |
| MergedCount | 4 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.01194ad147ca485b6ab2e506f02beb6208601b9b.001.1","noaa_urn:oid:2.49.0.1.840.0.d0388528029c9734fbe20951494de3624d93531b.001.1","noaa_urn:oid:2.49.0.1.840.0.69931d102eea4bf0edcafe634c143391960adc7b.001.1","noaa_urn:oid:2.49.0.1.840.0.2e070cea09e9336413454a84c5466913432d9fc0.001.1"] |
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.
Review the area, threshold and delivery channel in your account.
Want to know when something happens in this area?