This alert expired on 28 August 2026 at 02:00 UTC. It is kept here as a record.
It is the 6th strongest of the 238 detections recorded within 20 km of this point since 11 March 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Severe Thunderstorm Watch issued August 27 at 7:47PM EDT until August 27 at 10:00PM EDT by NWS Mount Holly NJ
An estimated 1,479,586 people live within 50 km of this point.
Nearby, since 11 March 2026
- August 28, 2026 · score 58 · 0.0 km
- July 18, 2026 · score 64 · 0.0 km
- May 20, 2026 · score 52 · 0.7 km
How we know
Confirmed by 3 independent sources, including NOAA.
Our own score for this event is 66 out of 100, at 90 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Event Data
| Type | Severe weather |
| Severity | critical |
| Calamity Score (ours) | 66 / 100 |
| Our confidence | 90% |
| Coordinates | 39.0000, -76.2333 |
| Nearest City | Annapolis (22 km) |
| Population Exposed | 1.5M within 50 km |
| Impact Tier | catastrophic |
| Timestamp | 2026-08-27T23:47:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Watch_noaa_urn:oid:2.49.0.1.840.0.552b3f4ced3a98cdb23f5b00d4e851fe |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Watch |
| Urgency | Future |
| Certainty | Possible |
| AreaDesc | Kent, DE; New Castle, DE; Berks, PA; Carbon, PA; Chester, PA; Lehigh, PA; Monroe, PA; Northampton, PA; Chesapeake Bay north of Pooles Island MD; Chesapeake Bay from Pooles Island to Sandy Point MD; Chesapeake Bay from Sandy Point to North Beach MD; Chesapeake Bay from North Beach to Drum Point MD; Chesapeake Bay from Drum Point MD to Smith Point VA; Tidal Potomac from Key Bridge to Indian Head MD; Tidal Potomac from Indian Head to Cobb Island MD; Tidal Potomac from Cobb Island MD to Smith Point VA; Patapsco River including Baltimore Harbor; Patuxent River to Broomes Island MD; District of Columbia, DC; Anne Arundel, MD; Baltimore, MD; Calvert, MD; Carroll, MD; Cecil, MD; Charles, MD; Frederick, MD; Harford, MD; Howard, MD; Montgomery, MD; Prince Georges, MD; St. Marys, MD; Baltimore City, MD; Arlington, VA; Culpeper, VA; Fairfax, VA; Fauquier, VA; Greene, VA; King George, VA; Loudoun, VA; Madison, VA; Prince William, VA; Rappahannock, VA; Stafford, VA; City of Alexandria, VA; City of Fairfax, VA; City of Falls Church, VA; City of Manassas, VA; City of Manassas Park, VA |
| Headline | Severe Thunderstorm Watch issued August 27 at 7:47PM EDT until August 27 at 10:00PM EDT by NWS Mount Holly NJ |
| Expires | 2026-08-27T22:00:00-04:00 |
| SenderName | NWS Mount Holly NJ |
| HasExactCoords | false |
| MergedCount | 3 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.552b3f4ced3a98cdb23f5b00d4e851fea22accc8.003.1","noaa_urn:oid:2.49.0.1.840.0.c428a7bf456e2b1ab2b0dfd8851831f4bfdcd82c.003.1","noaa_urn:oid:2.49.0.1.840.0.c428a7bf456e2b1ab2b0dfd8851831f4bfdcd82c.002.1"] |
| Spc ReportType | wind |
| Spc Speed | UNK |
| Spc Location | 2 S Bel Air |
| Spc County | Harford |
| Spc State | MD |
| Spc Comments | Trees down on wires near the intersection of West Ring Factory Road and Dahlia Court. (LWX) |
| Ogimet StationId | 72503 |
| Ogimet WindSpeed | 84 |
| Ogimet WindUnit | knots |
| Ogimet Temperature | -56.6 |
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.
Calamity.live data shows a weather event with CalamityScore 66/100, near Annapolis (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 188 scientific monitoring sources.