This alert expired on 28 June 2026 at 12:00 UTC. It is kept here as a record.
It is the 4th strongest of the 65 detections recorded within 20 km of this point since 15 March 2026. Another comparable one was recorded here earlier the same day. 2 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued June 28 at 6:17AM CDT until June 28 at 7:00AM CDT by NWS Sioux Falls SD
Nearby, since 15 March 2026
- May 18, 2026 · score 46 · 9.0 km
How we know
Confirmed by 2 independent sources, including NOAA.
Our own score for this event is 22 out of 100, at 65 % 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) | 22 / 100 |
| Our confidence | 65% |
| Coordinates | 43.5167, -94.9892 |
| Nearest City | Mankato (106 km) |
| Impact Tier | minor |
| Timestamp | 2026-06-28T11:17:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.59e7706b0ec9c22853d47b291258b061 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Clay, IA; Dickinson, IA; O'Brien, IA; Osceola, IA; Blue Earth, MN; Faribault, MN; Martin, MN; Watonwan, MN |
| Headline | Severe Thunderstorm Warning issued June 28 at 6:17AM CDT until June 28 at 7:00AM CDT by NWS Sioux Falls SD |
| Expires | 2026-06-28T07:00:00-05:00 |
| SenderName | NWS Sioux Falls SD |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.59e7706b0ec9c22853d47b291258b061b72cd34d.002.1","noaa_urn:oid:2.49.0.1.840.0.67bec69baed1ba165c9226e1d61c6298dc10bb96.001.1"] |
| Iem TypeSummary | H |
| Iem Magnitude | 1 |
| Iem Unit | Inch |
| Iem City | Sanborn |
| Iem County | O'Brien |
| Iem State | IA |
| Iem Wfo | FSD |
| MergedSources | [{"id":"iem_H_43.190_-95.660_1782644940000","source":"iem","severity":"low","severityValue":25,"timestamp":1782644940000,"latitude":43.19,"longitude":-95.66}] |
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.
Want to know when something happens in this area?
Calamity.live data shows a weather event with CalamityScore 22/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.