This alert expired on 20 May 2026 at 22:00 UTC. It is kept here as a record.
It is the 15th strongest of the 250 detections recorded within 20 km of this point since 11 March 2026. Another comparable one was recorded here earlier the same day. 5 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Special Marine Warning issued May 20 at 5:45PM EDT until May 20 at 6:00PM EDT by NWS Baltimore MD/Washington DC
An estimated 1,449,645 people live within 50 km of this point.
Nearby, since 11 March 2026
- August 28, 2026 · score 58 · 0.7 km
- August 27, 2026 · score 66 · 0.7 km
- July 18, 2026 · score 64 · 0.7 km
How we know
Confirmed by 13 independent sources, including NOAA.
Our own score for this event is 52 out of 100, at 89 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Event Data
| Type | Severe weather |
| Severity | medium |
| Calamity Score (ours) | 52 / 100 |
| Our confidence | 89% |
| Coordinates | 39.0023, -76.2254 |
| Nearest City | Annapolis (23 km) |
| Population Exposed | 1.4M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-20T21:45:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.5e677433cd70a1dd9a83da67932a71db |
Score Breakdown
Technical Details
| Event | Special Marine Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Tidal Potomac from Indian Head to Cobb Island MD; Chesapeake Bay from Sandy Point to North Beach MD; Eastern Bay; Chesapeake Bay north of Pooles Island MD; Chesapeake Bay from Pooles Island to Sandy Point MD; Chester River to Queenstown MD and 1 more areas |
| Headline | Special Marine Warning issued May 20 at 5:45PM EDT until May 20 at 6:00PM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-05-20T18:00:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 4 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.5e677433cd70a1dd9a83da67932a71db47e98dc2.001.1","noaa_urn:oid:2.49.0.1.840.0.5e5ed7fbe2701456c388ec76fdaf4efb213a4817.001.1","noaa_urn:oid:2.49.0.1.840.0.5ba6bbbc8322393fbb32dc825d1e0c8e124d78d7.002.1","noaa_urn:oid:2.49.0.1.840.0.1ee38cf00b3ccdcc5ba2175489f2ea0518ca4ae1.001.1"] |
| 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_39.270_-76.580_1779309360000","source":"iem","severity":"low","severityValue":25,"timestamp":1779309360000,"latitude":39.27,"longitude":-76.58},{"id":"iem_M_39.230_-76.580_1779310800000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310800000,"latitude":39.23,"longitude":-76.58},{"id":"iem_M_38.850_-77.030_1779309960000","source":"iem","severity":"low","severityValue":25,"timestamp":1779309960000,"latitude":38.85,"longitude":-77.03},{"id":"iem_G_39.270_-76.590_1779309540000","source":"iem","severity":"low","severityValue":25,"timestamp":1779309540000,"latitude":39.27,"longitude":-76.59},{"id":"iem_M_38.880_-76.480_1779312780000","source":"iem","severity":"low","severityValue":25,"timestamp":1779312780000,"latitude":38.88,"longitude":-76.48},{"id":"iem_M_38.970_-76.460_1779312300000","source":"iem","severity":"low","severityValue":25,"timestamp":1779312300000,"latitude":38.97,"longitude":-76.46},{"id":"iem_M_39.270_-76.590_1779309240000","source":"iem","severity":"low","severityValue":25,"timestamp":1779309240000,"latitude":39.27,"longitude":-76.59},{"id":"iem_M_39.340_-76.420_1779309960000","source":"iem","severity":"low","severityValue":25,"timestamp":1779309960000,"latitude":39.34,"longitude":-76.42},{"id":"iem_M_39.200_-76.520_1779310080000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310080000,"latitude":39.2,"longitude":-76.52},{"id":"iem_D_39.350_-76.690_1779308820000","source":"iem","severity":"low","severityValue":25,"timestamp":1779308820000,"latitude":39.35,"longitude":-76.69},{"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 10 February 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 near Annapolis?
Calamity.live data shows a weather event with CalamityScore 52/100, near Annapolis (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 187 scientific monitoring sources.