This alert expired on 20 May 2026 at 23:00 UTC. It is kept here as a record.
It is the 22nd strongest of the 142 detections recorded within 20 km of this point since 17 March 2026. The last comparable one was on 17 March 2026.
What the source measured
NOAA reported: Special Marine Warning issued May 20 at 5:59PM EDT until May 20 at 7:00PM EDT by NWS Mount Holly NJ
An estimated 141,890 people live within 50 km of this point.
Nearby, since 17 March 2026
- June 10, 2026 · score 37 · 3.3 km
- August 3, 2026 · score 37 · 3.9 km
- June 10, 2026 · score 37 · 5.6 km
How we know
Confirmed by 4 independent sources, including NOAA.
Our own score for this event is 43 out of 100, at 89 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
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) | 43 / 100 |
| Our confidence | 89% |
| Coordinates | 39.1992, -75.8955 |
| Nearest City | Middletown (32 km) |
| Population Exposed | 141.9K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-20T21:59:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.9d62057f8aa441ae88d62ea094a5574d |
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; Chesapeake Bay from Sandy Point to North Beach MD; Eastern Bay |
| Headline | Special Marine Warning issued May 20 at 5:59PM EDT until May 20 at 7:00PM EDT by NWS Mount Holly NJ |
| Expires | 2026-05-20T19:00:00-04:00 |
| SenderName | NWS Mount Holly NJ |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.9d62057f8aa441ae88d62ea094a5574d3e5be33a.001.1","noaa_urn:oid:2.49.0.1.840.0.5e5ed7fbe2701456c388ec76fdaf4efb213a4817.001.1"] |
| Iem TypeSummary | D |
| Iem City | 2 NNE Hickory |
| Iem County | Harford |
| Iem State | MD |
| Iem Wfo | LWX |
| Iem Remark | Trees blew down on MD-543 Ady Road at Smithson Drive. |
| MergedSources | [{"id":"iem_M_39.300_-76.360_1779310500000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310500000,"latitude":39.3,"longitude":-76.36},{"id":"iem_M_39.340_-76.420_1779309960000","source":"iem","severity":"low","severityValue":25,"timestamp":1779309960000,"latitude":39.34,"longitude":-76.42},{"id":"iem_D_39.610_-76.330_1779310440000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310440000,"latitude":39.61,"longitude":-76.33}] |
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 43/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.