This alert expired on 9 August 2026 at 10:49 UTC. It is kept here as a record.
No stronger detection stands among the 30 recorded within 20 km of this point since 15 March 2026 — 12 others scored the same. Another comparable one was recorded here earlier the same day. 8 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued August 9 at 5:39AM CDT until August 9 at 5:45AM CDT by NWS Twin Cities/Chanhassen MN
Nearby, since 15 March 2026
- June 1, 2026 · score 22 · 8.6 km
- May 26, 2026 · score 22 · 13.7 km
- May 15, 2026 · score 22 · 14.1 km
How we know
Confirmed by 2 independent sources, including NOAA.
Our own score for this event is 22 out of 100, at 67 % 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 | 67% |
| Coordinates | 43.5000, -94.5720 |
| Nearest City | Mankato (86 km) |
| Impact Tier | minor |
| Timestamp | 2026-08-09T10:39:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.cf74d1bf3ad1a94f7c5031948a89bf06 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Martin, MN; Emmet, IA |
| Headline | Severe Thunderstorm Warning issued August 9 at 5:39AM CDT until August 9 at 5:45AM CDT by NWS Twin Cities/Chanhassen MN |
| Expires | 2026-08-09T05:49:00-05:00 |
| SenderName | NWS Twin Cities/Chanhassen MN |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.cf74d1bf3ad1a94f7c5031948a89bf064fc00a26.001.1","noaa_urn:oid:2.49.0.1.840.0.a678c3745f020f17ba4090637675e835f4a3b762.001.1"] |
| Iem TypeSummary | H |
| Iem Magnitude | 1.75 |
| Iem Unit | Inch |
| Iem City | 1 S Arnolds Park |
| Iem County | Dickinson |
| Iem State | IA |
| Iem Wfo | FSD |
| Iem Remark | Photo sent in of hail around the size of golf balls. Time estimated by radar. |
| MergedSources | [{"id":"iem_H_43.350_-95.130_1786267200000","source":"iem","severity":"low","severityValue":25,"timestamp":1786267200000,"latitude":43.35,"longitude":-95.13}] |
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.