This alert expired on 2 September 2026 at 21:30 UTC. It is kept here as a record.
No stronger detection stands among the 5 recorded within 20 km of this point since 24 April 2026 — one other scored the same. The last comparable one was on 31 May 2026.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued September 2 at 2:23PM MDT until September 2 at 3:30PM MDT by NWS Great Falls MT
An estimated 32,091 people live within 50 km of this point.
How we know
Confirmed by 2 independent sources, including NOAA.
Our own score for this event is 28 out of 100, at 85 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Computed under scoring rules v4. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Medium |
| Calamity Score (ours) | 28 / 100 |
| Our confidence | 85% |
| Coordinates | 46.7287, -112.3780 |
| Nearest City | Helena (30 km) |
| Population Exposed | 32.1K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-02T20:23:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.ea497f37de2138c112a1eef308f9dc3234ed6dab.001.1 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Broadwater, MT; Jefferson, MT; Lewis and Clark, MT; Lewis and Clark, MT |
| Headline | Severe Thunderstorm Warning issued September 2 at 2:23PM MDT until September 2 at 3:30PM MDT by NWS Great Falls MT |
| Expires | 2026-09-02T15:30:00-06:00 |
| SenderName | NWS Great Falls MT |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.ea497f37de2138c112a1eef308f9dc3234ed6dab.001.1","noaa_urn:oid:2.49.0.1.840.0.d9a98a91a0a552ebc9a3613b913fe0954c32199e.001.1"] |
| Spc ReportType | wind |
| Spc Speed | 60 |
| Spc Location | 5 SSE Finn |
| Spc County | Powell |
| Spc State | MT |
| Spc Comments | Avon North MDT sensor also reported 48 mph sustained wind. (MSO) |
| MergedSources | [{"id":"spc_wind_46.15_-112.87_53","source":"spc","severity":"medium","severityValue":45,"timestamp":1788377340000,"latitude":46.15,"longitude":-112.87},{"id":"spc_wind_46.70_-112.66_55","source":"spc","severity":"medium","severityValue":45,"timestamp":1788379200000,"latitude":46.7,"longitude":-112.66}] |
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 near Helena?
Calamity.live data shows a weather event with CalamityScore 28/100, near Helena (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.