Severe Weather near Greater Upper Marlboro
This alert expired on 9 July 2026 at 21:38 UTC. It is kept here as a record.
It is the 617th strongest of the 744 detections recorded within 20 km of this point since 10 March 2026. Another comparable one was recorded here earlier the same day. 53 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Special Marine Warning issued July 9 at 5:28PM EDT until July 9 at 5:30PM EDT by NWS Baltimore MD/Washington DC
An estimated 4,281,877 people live within 50 km of this point.
Nearby, since 10 March 2026
- June 22, 2026 · score 66 · 7.0 km
- March 17, 2026 · score 52 · 7.8 km
- March 17, 2026 · score 52 · 8.5 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 52 out of 100, at 80 % 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 | 80% |
| Coordinates | 38.8488, -76.7876 |
| Nearest City | Greater Upper Marlboro (4 km) |
| Population Exposed | 4.3M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-07-09T21:28:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Special Marine Warning_noaa_urn:oid:2.49.0.1.840.0.36e36588e5bf1f28893c1a3f25c7f2ab |
Score Breakdown
Technical Details
| Event | Special Marine Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Tidal Potomac from Key Bridge to Indian Head MD; Tidal Potomac from Indian Head to Cobb Island MD; Chesapeake Bay from Pooles Island to Sandy Point MD; Patapsco River including Baltimore Harbor; Chester River to Queenstown MD; Chesapeake Bay north of Pooles Island MD; Chesapeake Bay from Pooles Island to Sandy Point MD; Patapsco River including Baltimore Harbor; Chester River to Queenstown MD and 1 more areas |
| Headline | Special Marine Warning issued July 9 at 5:28PM EDT until July 9 at 5:30PM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-07-09T17:38:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 4 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.36e36588e5bf1f28893c1a3f25c7f2ab0c6d41a8.001.1","noaa_urn:oid:2.49.0.1.840.0.a1c3612082c5b6ad2979c1791cbd35e5356acc42.001.1","noaa_urn:oid:2.49.0.1.840.0.b57ff1461551459a70de4b63496a2bce51eea1ba.001.1","noaa_urn:oid:2.49.0.1.840.0.47326905a24819af8682d8d69aa20f277aa8a7ad.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 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 Greater Upper Marlboro?
Calamity.live data shows a weather event with CalamityScore 52/100, near Greater Upper Marlboro (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.