Right now
The most recent data we hold from NOAA arrived 2 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 01:15 UTC. It is kept here as a record.
It is the 2nd strongest of the 13 detections recorded within 20 km of this point since 5 May 2026. The last comparable one was on 19 May 2026.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued June 20 at 6:12PM MDT until June 20 at 7:15PM MDT by NWS Rapid City SD
Nearby, since 5 May 2026
- June 22, 2026 · score 46 · 22.0 km
- June 26, 2026 · score 22 · 24.4 km
How we know
13 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 | 0.69/1 |
| Coordinates | 42.9649, -104.9176 |
| Nearest City | Casper (114 km) |
| Urban exposure index (PEI) | 0 within 50 km |
| Impact Tier | minor |
| Timestamp | 2026-06-21T00:12:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.1f28f53e163f1c1a1434b4c63210ac3f |
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: 2026-06-21T00:12:00.000Z.
First archived: 2026-06-21T00:14:48.849Z. 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; Campbell, WY; Crook, WY; Weston, WY; Sioux, NE; Goshen, WY; Niobrara, WY; Platte, WY and 6 more areas |
| Headline | Severe Thunderstorm Warning issued June 20 at 6:12PM MDT until June 20 at 7:15PM MDT by NWS Rapid City SD |
| Expires | 2026-06-20T19:15:00-06:00 |
| SenderName | NWS Rapid City SD |
| HasExactCoords | true |
| MergedCount | 10 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.1f28f53e163f1c1a1434b4c63210ac3f5209895f.001.1","noaa_urn:oid:2.49.0.1.840.0.7ee2e429734988965f1a32de835bd1ba41b312a2.001.1","noaa_urn:oid:2.49.0.1.840.0.07524cbafc892556271d3376ad79169b1902e987.001.1","noaa_urn:oid:2.49.0.1.840.0.2a2e66ef1ad0b729daee558755978281b2211cbc.001.1","noaa_urn:oid:2.49.0.1.840.0.aa7fe5149208cbce73a84ea580778323d3e730c0.001.1","noaa_urn:oid:2.49.0.1.840.0.18b9368c735369b22d156115e96554ffe06f39ae.001.1","noaa_urn:oid:2.49.0.1.840.0.1e2f527dea12af764defa64a76d709a2ecc71642.001.1","noaa_urn:oid:2.49.0.1.840.0.28b970a828490edf8153fba20edce00bea05b146.002.1","noaa_urn:oid:2.49.0.1.840.0.1f8e5fb1180391ac84d7a25c94380a033945a058.001.1","noaa_urn:oid:2.49.0.1.840.0.4b5bddc7ae61969a212d04d1f14a8afacc42af90.001.1"] |
| Iem TypeSummary | G |
| Iem Magnitude | 67 |
| Iem Unit | MPH |
| Iem City | 8 NNW Glendo |
| Iem County | Platte |
| Iem State | WY |
| Iem Wfo | CYS |
| Iem Remark | Mesonet station WY56 I25 Us26 Us87 - Platte Converse. |
| MergedSources | [{"id":"iem_G_43.510_-105.420_1781997240000","source":"iem","severity":"low","severityValue":25,"timestamp":1781997240000,"latitude":43.51,"longitude":-105.42},{"id":"iem_G_42.800_-105.380_1781996340000","source":"iem","severity":"low","severityValue":25,"timestamp":1781996340000,"latitude":42.8,"longitude":-105.38},{"id":"iem_G_43.000_-105.310_1781997000000","source":"iem","severity":"low","severityValue":25,"timestamp":1781997000000,"latitude":43,"longitude":-105.31},{"id":"iem_G_43.510_-105.420_1781995380000","source":"iem","severity":"low","severityValue":25,"timestamp":1781995380000,"latitude":43.51,"longitude":-105.42},{"id":"iem_G_43.460_-105.390_1781997240000","source":"iem","severity":"low","severityValue":25,"timestamp":1781997240000,"latitude":43.46,"longitude":-105.39},{"id":"iem_G_42.720_-105.490_1781995140000","source":"iem","severity":"low","severityValue":25,"timestamp":1781995140000,"latitude":42.72,"longitude":-105.49},{"id":"iem_G_42.720_-105.490_1781995680000","source":"iem","severity":"low","severityValue":25,"timestamp":1781995680000,"latitude":42.72,"longitude":-105.49},{"id":"iem_G_42.720_-105.490_1781995080000","source":"iem","severity":"low","severityValue":25,"timestamp":1781995080000,"latitude":42.72,"longitude":-105.49},{"id":"iem_G_43.460_-105.390_1781995800000","source":"iem","severity":"low","severityValue":25,"timestamp":1781995800000,"latitude":43.46,"longitude":-105.39},{"id":"iem_G_43.510_-105.420_1781998260000","source":"iem","severity":"low","severityValue":25,"timestamp":1781998260000,"latitude":43.51,"longitude":-105.42},{"id":"iem_G_42.600_-105.100_1781996760000","source":"iem","severity":"low","severityValue":25,"timestamp":1781996760000,"latitude":42.6,"longitude":-105.1},{"id":"iem_G_42.600_-105.100_1781997360000","source":"iem","severity":"low","severityValue":25,"timestamp":1781997360000,"latitude":42.6,"longitude":-105.1}] |
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.
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