This alert expired on 31 May 2026 at 20:00 UTC. It is kept here as a record.
No stronger detection stands among the 102 recorded within 20 km of this point since 15 March 2026 — 14 others scored the same. Another comparable one was recorded here earlier the same day. 10 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued May 31 at 1:28PM MDT until May 31 at 2:00PM MDT by NWS Rapid City SD
An estimated 73,569 people live within 50 km of this point.
How we know
Confirmed by 10 independent sources, including NOAA.
Our own score for this event is 39 out of 100, at 91 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Event Data
| Type | Severe weather |
| Severity | medium |
| Calamity Score (ours) | 39 / 100 |
| Our confidence | 91% |
| Coordinates | 43.8500, -103.0500 |
| Nearest City | Rapid City (29 km) |
| Population Exposed | 73.6K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-31T19:28:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.42d0b5e48608dc75e41543c7c52b23ff2b554053.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Custer, SD; Pennington, SD |
| Headline | Severe Thunderstorm Warning issued May 31 at 1:28PM MDT until May 31 at 2:00PM MDT by NWS Rapid City SD |
| Expires | 2026-05-31T14:00:00-06:00 |
| SenderName | NWS Rapid City SD |
| HasExactCoords | true |
| Iem TypeSummary | R |
| Iem Magnitude | 1.17 |
| Iem Unit | inch |
| Iem City | 4 W Dwtn Rapid City |
| Iem County | Pennington |
| Iem State | SD |
| Iem Wfo | UNR |
| Iem Remark | 24-hour rainfall. |
| MergedSources | [{"id":"iem_R_44.150_-103.320_1780239960000","source":"iem","severity":"low","severityValue":25,"timestamp":1780239960000,"latitude":44.15,"longitude":-103.32},{"id":"iem_R_44.130_-103.410_1780236000000","source":"iem","severity":"low","severityValue":25,"timestamp":1780236000000,"latitude":44.13,"longitude":-103.41},{"id":"iem_R_43.950_-103.510_1780236000000","source":"iem","severity":"low","severityValue":25,"timestamp":1780236000000,"latitude":43.95,"longitude":-103.51},{"id":"iem_R_43.960_-103.150_1780236000000","source":"iem","severity":"low","severityValue":25,"timestamp":1780236000000,"latitude":43.96,"longitude":-103.15},{"id":"iem_R_43.860_-103.300_1780239240000","source":"iem","severity":"low","severityValue":25,"timestamp":1780239240000,"latitude":43.86,"longitude":-103.3},{"id":"iem_R_44.130_-103.430_1780237920000","source":"iem","severity":"low","severityValue":25,"timestamp":1780237920000,"latitude":44.13,"longitude":-103.43},{"id":"iem_R_43.990_-102.240_1780236000000","source":"iem","severity":"low","severityValue":25,"timestamp":1780236000000,"latitude":43.99,"longitude":-102.24},{"id":"iem_R_44.360_-103.460_1780236000000","source":"iem","severity":"low","severityValue":25,"timestamp":1780236000000,"latitude":44.36,"longitude":-103.46},{"id":"iem_R_44.090_-103.300_1780241400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780241400000,"latitude":44.09,"longitude":-103.3}] |
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 10 February 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.
Calamity.live data shows a weather event with CalamityScore 39/100, near Rapid City (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 188 scientific monitoring sources.