Right now
The most recent data we hold from NOAA arrived 10 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
6 other detections within 20 km in the last 24 hours, the nearest 10 km from here.
This alert expired on 21 July 2026 at 23:30 UTC. It is kept here as a record.
It is the 258th strongest of the 289 detections recorded within 20 km of this point since 11 March 2026. Another comparable one was recorded here earlier the same day. 9 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Special Marine Warning issued July 21 at 5:30PM EDT until July 21 at 7:30PM EDT by NWS Mount Holly NJ
Urban PEI: 59,775 within a heuristic 50 km radius; not unique people.
Nearby, since 11 March 2026
- August 27, 2026 · score 34 · 10.1 km
- August 8, 2026 · score 34 · 10.1 km
- July 22, 2026 · score 46 · 10.1 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 32 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) | 32 / 100 |
| Legacy data-support index | 0.79/1 |
| Coordinates | 39.0569, -75.5906 |
| Nearest City | Dover (13 km) |
| Urban exposure index (PEI) | 59.8K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-07-21T21:30:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.e150d54e5c2db8fa3c94b385e54620bb |
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: 2026-07-21T21:30:00.000Z.
First archived: 2026-07-21T21:42:37.055Z. 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 | Delaware Bay waters north of East Point NJ to Slaughter Beach DE; Delaware Bay waters south of East Point NJ to Slaughter Beach DE; Chesapeake Bay north of Pooles Island MD; Chesapeake Bay from Pooles Island to Sandy Point MD; Patapsco River including Baltimore Harbor; Chesapeake Bay from Drum Point MD to Smith Point VA; Tidal Potomac from Cobb Island MD to Smith Point VA; Tangier Sound and the inland waters surrounding Bloodsworth Island and 4 more areas |
| Headline | Special Marine Warning issued July 21 at 5:30PM EDT until July 21 at 7:30PM EDT by NWS Mount Holly NJ |
| Expires | 2026-07-21T19:30:00-04:00 |
| SenderName | NWS Mount Holly NJ |
| HasExactCoords | true |
| MergedCount | 7 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.e150d54e5c2db8fa3c94b385e54620bb4689681b.001.1","noaa_urn:oid:2.49.0.1.840.0.d8773e067b0e84c1b1285318ba03a8cc80cfee04.001.1","noaa_urn:oid:2.49.0.1.840.0.d8894710b1766fc9886a8746bdf6f49a9e1fa5d4.001.1","noaa_urn:oid:2.49.0.1.840.0.407ccc4f6c93e934095615dc82360dbfe559e77d.001.1","noaa_urn:oid:2.49.0.1.840.0.82d0cb73ab5173e17ee3656c601cc817a61732a6.002.1","noaa_urn:oid:2.49.0.1.840.0.99f4d04cbb6d91577f4cf11a1406490011a3ca51.001.1","noaa_urn:oid:2.49.0.1.840.0.bf88b3ef4638a1971d6e70c58c2b02851f696073.001.1"] |
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.
Review the area, threshold and delivery channel in your account.
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