Right now
The most recent data we hold from NOAA arrived 6 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 18 May 2026 at 03:45 UTC. It is kept here as a record.
No stronger detection stands among the 47 recorded within 20 km of this point since 15 March 2026 — 4 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: Tornado Warning issued May 17 at 10:19PM CDT until May 17 at 10:45PM CDT by NWS Twin Cities/Chanhassen MN
An estimated 27,366 people live within 50 km of this point.
Nearby, since 15 March 2026
- July 9, 2026 · score 34 · 13.7 km
- July 10, 2026 · score 58 · 14.2 km
- May 16, 2026 · score 58 · 17.4 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 | 43.0735, -93.3271 |
| Nearest City | Mason City (13 km) |
| Population Exposed | 27.4K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-18T03:19:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Tornado Warning_noaa_urn:oid:2.49.0.1.840.0.74e62b5f2df2a833a291311f74a96c23 |
Score Breakdown
Technical Details
| Event | Tornado Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Faribault, MN; Freeborn, MN; Cerro Gordo, IA; Mitchell, IA; Mower, MN and 3 more areas |
| Headline | Tornado Warning issued May 17 at 10:19PM CDT until May 17 at 10:45PM CDT by NWS Twin Cities/Chanhassen MN |
| Expires | 2026-05-17T22:45:00-05:00 |
| SenderName | NWS Twin Cities/Chanhassen MN |
| HasExactCoords | true |
| MergedCount | 6 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.74e62b5f2df2a833a291311f74a96c235c3fecbb.001.1","noaa_urn:oid:2.49.0.1.840.0.a5f6ee690c3b513eee9b98c5d9f5740a90a7663c.001.1","noaa_urn:oid:2.49.0.1.840.0.f753b08be1c87db023429149ffdccfc08dbfd3ca.001.1","noaa_urn:oid:2.49.0.1.840.0.039ba2b2cb5ddde635997e740604ed4c6edb5681.002.1","noaa_urn:oid:2.49.0.1.840.0.de2128ee654c46cf613f3790bcdbf501294d9585.002.1","noaa_urn:oid:2.49.0.1.840.0.72dd54d36cfedf664cc22309d12c3fdd450094fb.001.1"] |
| Iem TypeSummary | T |
| Iem City | 4 N Crystal Lake |
| Iem County | Winnebago |
| Iem State | IA |
| Iem Wfo | DMX |
| Iem Remark | Reports of power line sparking/flashing. |
| MergedSources | [{"id":"iem_T_43.070_-93.990_1779071880000","source":"iem","severity":"low","severityValue":25,"timestamp":1779071880000,"latitude":43.07,"longitude":-93.99},{"id":"iem_T_43.280_-93.790_1779073140000","source":"iem","severity":"low","severityValue":25,"timestamp":1779073140000,"latitude":43.28,"longitude":-93.79}] |
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.