Right now
The most recent data we hold from NOAA arrived 2 hours ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
Nothing else has been detected within 20 km in the last 24 hours.
This alert expired on 20 May 2026 at 19:30 UTC. It is kept here as a record.
It is the 19th strongest of the 129 detections recorded within 20 km of this point since 12 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 2:46PM EDT until May 20 at 3:30PM EDT by NWS Baltimore MD/Washington DC
An estimated 60,054 people live within 50 km of this point.
Nearby, since 12 March 2026
- September 4, 2026 · score 45 · 3.0 km
- August 10, 2026 · score 39 · 9.8 km
- August 28, 2026 · score 34 · 13.6 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 39 out of 100, at 80 % 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) | 39 / 100 |
| Our confidence | 80% |
| Coordinates | 39.0913, -78.2720 |
| Nearest City | Winchester (15 km) |
| Population Exposed | 60.1K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-20T18:46:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.e51387fc3ef1d89d83eb58d8f114e099 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Frederick, MD; Washington, MD; Loudoun, VA; Jefferson, WV; Page, VA; Shenandoah, VA; Frederick, VA; Hampshire, WV |
| Headline | Severe Thunderstorm Warning issued May 20 at 2:46PM EDT until May 20 at 3:30PM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-05-20T15:30:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 3 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.e51387fc3ef1d89d83eb58d8f114e09998b03ce7.001.1","noaa_urn:oid:2.49.0.1.840.0.07a69e0c1e04f067a6ab96e20f0fdea9c52bc3b6.001.1","noaa_urn:oid:2.49.0.1.840.0.18ba045e82f37a43a39ef5ce8a30e7a04b179169.001.1"] |
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 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.
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