Right now
The most recent data we hold from NOAA arrived 32 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 31 May 2026 at 19:30 UTC. It is kept here as a record.
No stronger detection stands among the 141 recorded within 20 km of this point since 15 March 2026 — 25 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 12:58PM MDT until May 31 at 1:30PM MDT by NWS Rapid City SD
An estimated 73,569 people live within 50 km of this point.
Nearby, since 15 March 2026
- August 10, 2026 · score 39 · 11.0 km
- May 31, 2026 · score 39 · 14.0 km
How we know
Confirmed by 30 independent sources, including NOAA.
Our own score for this event is 39 out of 100, at 90 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
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) | 39 / 100 |
| Our confidence | 90% |
| Coordinates | 43.8700, -103.2220 |
| Nearest City | Rapid City (23 km) |
| Population Exposed | 73.6K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-31T18:58:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.2585e2dbc7714838afad0f22010ffa1679903de9.001.1 |
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 12:58PM MDT until May 31 at 1:30PM MDT by NWS Rapid City SD |
| Expires | 2026-05-31T13:30:00-06:00 |
| SenderName | NWS Rapid City SD |
| HasExactCoords | true |
| Iem TypeSummary | R |
| Iem Magnitude | 1.5 |
| Iem Unit | inch |
| Iem City | 3 E Wasta |
| Iem County | Pennington |
| Iem State | SD |
| Iem Wfo | UNR |
| Iem Remark | 24-hour rainfall. |
| MergedSources | [{"id":"iem_R_43.770_-103.600_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":43.77,"longitude":-103.6},{"id":"iem_R_44.230_-103.030_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.23,"longitude":-103.03},{"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_43.800_-103.520_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":43.8,"longitude":-103.52},{"id":"iem_R_44.240_-103.250_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.24,"longitude":-103.25},{"id":"iem_R_44.470_-103.550_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.47,"longitude":-103.55},{"id":"iem_R_44.020_-103.240_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.02,"longitude":-103.24},{"id":"iem_R_44.050_-103.210_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.05,"longitude":-103.21},{"id":"iem_R_44.350_-103.750_1780239600000","source":"iem","severity":"low","severityValue":25,"timestamp":1780239600000,"latitude":44.35,"longitude":-103.75},{"id":"iem_R_44.290_-103.150_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.29,"longitude":-103.15},{"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_43.780_-102.620_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":43.78,"longitude":-102.62},{"id":"iem_R_44.280_-103.810_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.28,"longitude":-103.81},{"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_43.770_-103.570_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":43.77,"longitude":-103.57},{"id":"iem_R_43.440_-103.560_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":43.44,"longitude":-103.56},{"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_44.100_-103.290_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.1,"longitude":-103.29},{"id":"iem_R_44.390_-103.800_1780235220000","source":"iem","severity":"low","severityValue":25,"timestamp":1780235220000,"latitude":44.39,"longitude":-103.8},{"id":"iem_R_44.060_-103.410_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.06,"longitude":-103.41},{"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_44.100_-102.950_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.1,"longitude":-102.95},{"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_44.300_-103.430_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.3,"longitude":-103.43},{"id":"iem_R_44.230_-103.390_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.23,"longitude":-103.39},{"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_44.050_-103.320_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.05,"longitude":-103.32},{"id":"iem_R_44.090_-103.300_1780241400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780241400000,"latitude":44.09,"longitude":-103.3},{"id":"iem_R_44.070_-102.390_1780232400000","source":"iem","severity":"low","severityValue":25,"timestamp":1780232400000,"latitude":44.07,"longitude":-102.39}] |
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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