This alert expired on 4 September 2026 at 15:45 UTC. It is kept here as a record.
It is the 13th strongest of the 15 detections recorded within 20 km of this point since 11 June 2026. The last comparable one was on 27 July 2026.
What the source measured
NOAA reported: Special Marine Warning issued September 4 at 9:41AM EDT until September 4 at 11:45AM EDT by NWS Grand Rapids MI
Nearby, since 11 June 2026
- June 12, 2026 · score 41 · 16.9 km
- June 11, 2026 · score 41 · 19.5 km
- June 16, 2026 · score 48 · 21.0 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 16 out of 100, at 62 % 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) | 16 / 100 |
| Our confidence | 62% |
| Coordinates | 42.9641, -87.1306 |
| Nearest City | Racine (59 km) |
| Impact Tier | minor |
| Timestamp | 2026-09-04T13:41:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.d38a32fb38183870d3888b73bb9a748f95966a97.001.1 |
Score Breakdown
Technical Details
| Event | Special Marine Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | South Haven to Holland MI; Holland to Grand Haven MI; Grand Haven to Whitehall MI; Whitehall to Pentwater MI; Lake Michigan from Whitehall to Pentwater MI 5NM offshore to Mid Lake; Lake Michigan from Grand Haven to Whitehall MI 5NM offshore to Mid Lake; Lake Michigan from Holland to Grand Haven MI 5NM offshore to Mid Lake; Lake Michigan from South Haven to Holland MI 5NM offshore to Mid lake; Port Washington to North Point Light WI; North Point Light to Wind Point WI; Lake Michigan from Port Washington to North Point Light WI 5NM offshore to Mid Lake; Lake Michigan from North Point Light to Wind Point WI 5NM offshore to Mid Lake |
| Headline | Special Marine Warning issued September 4 at 9:41AM EDT until September 4 at 11:45AM EDT by NWS Grand Rapids MI |
| Expires | 2026-09-04T11:45:00-04:00 |
| SenderName | NWS Grand Rapids MI |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.d38a32fb38183870d3888b73bb9a748f95966a97.001.1","noaa_urn:oid:2.49.0.1.840.0.12251acf0a834d615f71f0861c5a8071ec301218.001.1"] |
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 16/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.