This alert expired on 11 June 2026 at 12:45 UTC. It is kept here as a record.
No stronger detection stands among the 68 recorded within 20 km of this point since 16 March 2026 — 2 others scored the same. 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: Tornado Warning issued June 11 at 7:22AM CDT until June 11 at 7:45AM CDT by NWS Des Moines IA
An estimated 516,424 people live within 50 km of this point.
Nearby, since 16 March 2026
- June 11, 2026 · score 72 · 8.4 km
- July 21, 2026 · score 48 · 9.7 km
- June 11, 2026 · score 72 · 14.9 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 72 out of 100, at 81 % 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 | Critical |
| Calamity Score (ours) | 72 / 100 |
| Our confidence | 81% |
| Coordinates | 41.7800, -93.8460 |
| Nearest City | Johnston (17 km) |
| Population Exposed | 516.4K within 50 km |
| Impact Tier | catastrophic |
| Timestamp | 2026-06-11T12:22:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.01c467cefb9e5a677a3bfa50ef45deb73c84ea52.001.1 |
Score Breakdown
Technical Details
| Event | Tornado Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Boone, IA; Dallas, IA; Polk, IA; Story, IA |
| Headline | Tornado Warning issued June 11 at 7:22AM CDT until June 11 at 7:45AM CDT by NWS Des Moines IA |
| Expires | 2026-06-11T07:45:00-05:00 |
| SenderName | NWS Des Moines IA |
| HasExactCoords | true |
Safety Information
If a tornado warning is issued: go to a basement or an interior room on the lowest floor, away from windows. A vehicle and a mobile home are not shelter. Cover your head and neck. Wait for the official all-clear before going outside, and watch for downed power lines and gas leaks afterwards.
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 near Johnston?
Calamity.live data shows a weather event with CalamityScore 72/100, near Johnston (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.