Right now
The most recent data we hold from NOAA arrived 56 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 June 2026 at 01:18 UTC. It is kept here as a record.
No stronger detection stands among the 15 recorded within 20 km of this point since 21 June 2026 — 7 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: Severe Thunderstorm Warning issued June 20 at 7:08PM MDT until June 20 at 7:15PM MDT by NWS Rapid City SD
Nearby, since 21 June 2026
- July 21, 2026 · score 16 · 13.0 km
How we know
2 recorded sources include NOAA; independence is not established by this count.
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 | 0.64/1 |
| Coordinates | 42.2514, -103.9844 |
| Nearest City | Cheyenne (142 km) |
| Urban exposure index (PEI) | 0 within 50 km |
| Impact Tier | minor |
| Timestamp | 2026-06-21T01:08:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.63044c5c7d41310beb0c7100cffd98aa |
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: 2026-06-21T01:08:00.000Z.
First archived: 2026-06-21T01:11:14.068Z. 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 | Custer, SD; Fall River, SD; Weston, WY; Box Butte, NE; Dawes, NE; Morrill, NE; Scotts Bluff, NE; Sioux, NE; Goshen, WY; Laramie, WY and 1 more areas |
| Headline | Severe Thunderstorm Warning issued June 20 at 7:08PM MDT until June 20 at 7:15PM MDT by NWS Rapid City SD |
| Expires | 2026-06-20T19:18:00-06:00 |
| SenderName | NWS Rapid City SD |
| HasExactCoords | true |
| MergedCount | 6 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.63044c5c7d41310beb0c7100cffd98aa84272550.001.1","noaa_urn:oid:2.49.0.1.840.0.317442fc9c2a18c3d5d24131330a462425b29aaf.001.1","noaa_urn:oid:2.49.0.1.840.0.8b2d368fcc449e3cfa21ff486571a0e8210f6e89.001.1","noaa_urn:oid:2.49.0.1.840.0.aaab344b3df2ce3de64b7635eec68acd3c4e9abb.001.1","noaa_urn:oid:2.49.0.1.840.0.a231dec2fb65edd5621248a72f28158fc8f6b579.001.1","noaa_urn:oid:2.49.0.1.840.0.eec7d54b2c7e217d75a3f2eef4d7e0021cf85b8c.001.1"] |
| Iem TypeSummary | H |
| Iem Magnitude | 0.75 |
| Iem Unit | Inch |
| Iem City | 7 W La Grange |
| Iem County | Goshen |
| Iem State | WY |
| Iem Wfo | CYS |
| Iem Remark | Penny sized hail measured. |
| MergedSources | [{"id":"iem_H_41.650_-104.290_1781990640000","source":"iem","severity":"low","severityValue":25,"timestamp":1781990640000,"latitude":41.65,"longitude":-104.29}] |
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.
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