Right now
The most recent data we hold from NOAA arrived 4 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 16 May 2026 at 02:45 UTC. It is kept here as a record.
No stronger detection stands among the 41 recorded within 20 km of this point since 15 March 2026 — 5 others scored the same. Another comparable one was recorded here earlier the same day. 4 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Tornado Warning issued May 15 at 8:53PM CDT until May 15 at 9:45PM CDT by NWS Des Moines IA
An estimated 27,366 people live within 50 km of this point.
Nearby, since 15 March 2026
- July 10, 2026 · score 58 · 13.7 km
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 58 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 | Critical |
| Calamity Score (ours) | 58 / 100 |
| Our confidence | 90% |
| Coordinates | 42.9880, -93.1480 |
| Nearest City | Mason City (19 km) |
| Population Exposed | 27.4K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-16T01:53:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.505797e8a5054e56b36e8ba6d8719fd0488ec614.001.1 |
Score Breakdown
Technical Details
| Event | Tornado Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Cerro Gordo, IA |
| Headline | Tornado Warning issued May 15 at 8:53PM CDT until May 15 at 9:45PM CDT by NWS Des Moines IA |
| Expires | 2026-05-15T21:45:00-05:00 |
| SenderName | NWS Des Moines IA |
| HasExactCoords | true |
| Iem TypeSummary | H |
| Iem Magnitude | 1 |
| Iem Unit | Inch |
| Iem City | 4 NNW Swaledale |
| Iem County | Cerro Gordo |
| Iem State | IA |
| Iem Wfo | DMX |
| Iem Remark | on I35 near mile marker 186. time estimated from radar. |
| MergedSources | [{"id":"iem_H_43.140_-93.380_1778892420000","source":"iem","severity":"low","severityValue":25,"timestamp":1778892420000,"latitude":43.14,"longitude":-93.38},{"id":"iem_H_43.030_-93.340_1778893200000","source":"iem","severity":"low","severityValue":25,"timestamp":1778893200000,"latitude":43.03,"longitude":-93.34}] |
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 Mason City?
Calamity.live data shows a weather event with CalamityScore 58/100, near Mason City (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.