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 20:19 UTC. It is kept here as a record.
It is the 14th strongest of the 82 detections recorded within 20 km of this point since 16 March 2026. Another comparable one was recorded here earlier the same day. 7 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued May 20 at 4:09PM EDT until May 20 at 4:15PM EDT by NWS Baltimore MD/Washington DC
An estimated 387,474 people live within 50 km of this point.
Nearby, since 16 March 2026
- July 9, 2026 · score 43 · 5.4 km
- August 7, 2026 · score 37 · 7.1 km
- March 17, 2026 · score 43 · 7.8 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 43 out of 100, at 79 % 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) | 43 / 100 |
| Our confidence | 79% |
| Coordinates | 39.8792, -76.6923 |
| Nearest City | York (10 km) |
| Population Exposed | 387.5K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-20T20:09:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.33b6de68d1d2bb196475e5ee60cdb3c4 |
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Carroll, MD; Frederick, MD; Clarke, VA; Fauquier, VA; Loudoun, VA; Lebanon, PA; Schuylkill, PA and 5 more areas |
| Headline | Severe Thunderstorm Warning issued May 20 at 4:09PM EDT until May 20 at 4:15PM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-05-20T16:19:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 8 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.33b6de68d1d2bb196475e5ee60cdb3c4e3f761fc.001.1","noaa_urn:oid:2.49.0.1.840.0.88606b03fe8c197f21b60de4423ff6d6d647fc6e.001.1","noaa_urn:oid:2.49.0.1.840.0.62312563014b3be988cb1e28e75c3df0e450c6b6.002.1","noaa_urn:oid:2.49.0.1.840.0.e63a9d380995c32362ad5ecf9c6b3e54d22d59d3.001.1","noaa_urn:oid:2.49.0.1.840.0.467ed2667cb19e1e8a04b08c7618f3c53e6b4665.001.1","noaa_urn:oid:2.49.0.1.840.0.d49ee16cc91daba4dfb9b456f5dfc80d38a1bc2a.001.1","noaa_urn:oid:2.49.0.1.840.0.5ed1aff7c835f2ae9a3254701b57db7e124869e0.001.1","noaa_urn:oid:2.49.0.1.840.0.b6dd6edc202b43936fad86731e9dae1a2ed34101.001.1"] |
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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