This alert expired on 20 May 2026 at 20:45 UTC. It is kept here as a record.
It is the 2nd strongest of the 38 detections recorded within 20 km of this point since 17 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: Severe Thunderstorm Warning issued May 20 at 4:23PM EDT until May 20 at 4:45PM EDT by NWS Baltimore MD/Washington DC
An estimated 601,110 people live within 50 km of this point.
Nearby, since 17 March 2026
- July 5, 2026 · score 48 · 7.3 km
- July 9, 2026 · score 43 · 10.7 km
- August 10, 2026 · score 43 · 15.1 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 48 out of 100, at 79 % 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) | 48 / 100 |
| Our confidence | 79% |
| Coordinates | 39.8136, -76.5434 |
| Nearest City | York (23 km) |
| Population Exposed | 601.1K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-20T20:23:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.51f9274d2e052b1aaa3e081af95b1bac |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Fauquier, VA; Loudoun, VA; Prince William, VA; Lancaster, PA; Fauquier, VA; Loudoun, VA and 4 more areas |
| Headline | Severe Thunderstorm Warning issued May 20 at 4:23PM EDT until May 20 at 4:45PM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-05-20T16:45:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 8 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.51f9274d2e052b1aaa3e081af95b1bac4256833e.001.1","noaa_urn:oid:2.49.0.1.840.0.a8bdf41eb46defff1c2c8b77ddb6618195a4c8a7.001.1","noaa_urn:oid:2.49.0.1.840.0.2469b311e4f66eb731f22833246ed389f1412280.002.1","noaa_urn:oid:2.49.0.1.840.0.1c8e99e1bbee2af388c0600d82a297b2998ee31a.001.1","noaa_urn:oid:2.49.0.1.840.0.a0ab8246b7b09ef29b85c3ecf668bffad604ded6.001.1","noaa_urn:oid:2.49.0.1.840.0.e978b8286df11fe1dce62556b9491b2eded1f433.001.1","noaa_urn:oid:2.49.0.1.840.0.467ed2667cb19e1e8a04b08c7618f3c53e6b4665.001.1","noaa_urn:oid:2.49.0.1.840.0.53946a10d5ab41fce2586b92cdf04eaf2e0d692b.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 York?
Calamity.live data shows a weather event with CalamityScore 48/100, near York (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 187 scientific monitoring sources.