Right now
The most recent data we hold from NOAA arrived 6 hours 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 4 July 2026 at 00:30 UTC. It is kept here as a record.
It is one of only 3 we have recorded within 20 km of this point since 3 July 2026.
What the source measured
NOAA reported: Special Marine Warning issued July 3 at 7:57PM EDT until July 3 at 8:30PM EDT by NWS Detroit/Pontiac MI
Urban PEI: 76,541 within a heuristic 50 km radius; not unique people.
Nearby, since 3 July 2026
- September 3, 2026 · score 37 · 18.4 km
How we know
3 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 39 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) | 39 / 100 |
| Legacy data-support index | 0.89/1 |
| Coordinates | 42.3353, -82.1322 |
| Nearest City | Chatham (9 km) |
| Urban exposure index (PEI) | 76.5K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-07-03T23:57:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.23b16ff1e0dfa7b66239861b39681744 |
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: 2026-07-03T23:57:00.000Z.
First archived: 2026-07-04T00:10:46.796Z. 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 | St. Clair River; Port Sanilac to Port Huron MI; Lake Huron from Port Sanilac to Port Huron 5NM Off Shore to US/Canadian border; Vermilion to Avon Point OH; Avon Point to Willowick OH; Vermilion to Avon Point OH beyond 5 nm off shoreline to US-Canadian border; Avon Point to Willowick OH beyond 5 nm off shoreline to US-Canadian border |
| Headline | Special Marine Warning issued July 3 at 7:57PM EDT until July 3 at 8:30PM EDT by NWS Detroit/Pontiac MI |
| Expires | 2026-07-03T20:30:00-04:00 |
| SenderName | NWS Detroit/Pontiac MI |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.23b16ff1e0dfa7b66239861b39681744df1b9d52.002.1","noaa_urn:oid:2.49.0.1.840.0.2e4303a7dd612886a5996e6013694eded55a0b42.001.1"] |
| Iem TypeSummary | G |
| Iem Magnitude | 63 |
| Iem Unit | mph |
| Iem City | Chesterfield |
| Iem County | Macomb |
| Iem State | MI |
| Iem Wfo | DTX |
| Iem Remark | Measured on a handheld anemometer |
| MergedSources | [{"id":"iem_G_42.620_-82.830_1783120680000","source":"iem","severity":"low","severityValue":25,"timestamp":1783120680000,"latitude":42.62,"longitude":-82.83},{"id":"iem_G_42.660_-82.840_1783120380000","source":"iem","severity":"low","severityValue":25,"timestamp":1783120380000,"latitude":42.66,"longitude":-82.84}] |
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.
Review the area, threshold and delivery channel in your account.
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