Right now
The most recent data we hold from NOAA arrived 2 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 21 July 2026 at 02:00 UTC. It is kept here as a record.
It is the 3rd strongest of the 19 detections recorded within 20 km of this point since 15 March 2026. Another comparable one was recorded here earlier the same day. 7 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Special Marine Warning issued July 20 at 8:18PM CDT until July 20 at 9:00PM CDT by NWS Green Bay WI
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.
This is our versioned heuristic index, not source severity or a calibrated probability. Urban PEI does not count unique people.
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 | Medium |
| Calamity Score (ours) | 16 / 100 |
| Legacy data-support index | 0.60/1 |
| Coordinates | 45.6352, -86.2170 |
| Nearest City | Traverse City (108 km) |
| Urban exposure index (PEI) | 0 within 50 km |
| Impact Tier | minor |
| Date | 2026-07-21 — time not reported by the source |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.83c1f35636cf4c7959f0102bee02abc9 |
Physical priority index · v1. Heuristic priority, not calibrated probability, predictive accuracy or damage. The legacy data-support index combines assigned source support and field availability. Urban PEI is distance-weighted and does not count unique people; zero does not establish that nobody is present. Model cards.
Source and revision timeline
Source: noaa. Occurrence: 2026-07-21 — time not reported.
First archived: 2026-07-21T01:19:21.308Z. Material modification: not recorded.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
Score Breakdown
Technical Details
| Event | Special Marine Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Rock Island Passage to Sturgeon Bay WI; Lake Michigan from Rock Island Passage to Sturgeon Bay WI 5NM offshore to mid lake; Straits of Mackinac within 5 nm of Mackinac Bridge including Mackinac Island; Seul Choix Point to 5NM West of Mackinac Bridge; Norwood MI to 5NM West of Mackinac Bridge including Little Traverse Bay; Sleeping Bear Point to Grand Traverse Light MI; Lake Michigan South of a line from Seul Choix Point to the Mackinac Bridge and North of a line from Charlevoix MI to South Fox Island 5NM offshore; Lake Michigan from Charlevoix to Point Betsie MI 5NM Offshore to mid lake; Green Bay North of line from Cedar River MI to Rock Island Passage; 5NM East of a line from Fairport MI to Rock Island Passage; Lake Michigan from Seul Choix Point to Rock Island Passage 5NM offshore to Mid Lake and 3 more areas |
| Headline | Special Marine Warning issued July 20 at 8:18PM CDT until July 20 at 9:00PM CDT by NWS Green Bay WI |
| Expires | 2026-07-20T21:00:00-05:00 |
| SenderName | NWS Green Bay WI |
| HasExactCoords | true |
| MergedCount | 6 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.83c1f35636cf4c7959f0102bee02abc97518d29f.001.1","noaa_urn:oid:2.49.0.1.840.0.b6d52556f0de4a923e44b8a9bd793a81c3ebcb1e.001.1","noaa_urn:oid:2.49.0.1.840.0.0fc5b8f093c08d60ce9b52c1973e3cca6fe8b679.001.1","noaa_urn:oid:2.49.0.1.840.0.f15798776f6ea0a3ec77b1cbfc9d1d3dca537e97.001.1","noaa_urn:oid:2.49.0.1.840.0.a34d4776ed590aa07a41e228e71d9649621495bf.001.1","noaa_urn:oid:2.49.0.1.840.0.bef34dd52baf5febf24f7b525c6b1cec75413c48.001.1"] |
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.
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