Right now
The most recent data we hold from NOAA arrived 57 minutes 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 21 July 2026 at 22:45 UTC. It is kept here as a record.
It is the 30th strongest of the 69 detections recorded within 20 km of this point since 12 March 2026. The last comparable one was on 6 July 2026. One more was recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued July 21 at 6:24PM EDT until July 21 at 6:45PM EDT by NWS Mount Holly NJ
Urban PEI: 154,774 within a heuristic 50 km radius; not unique people.
Nearby, since 12 March 2026
- September 3, 2026 · score 37 · 4.7 km
- September 2, 2026 · score 37 · 4.7 km
- March 12, 2026 · score 43 · 6.1 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 37 out of 100.
This is our versioned heuristic index, not source severity or a calibrated probability. Urban PEI does not count unique people.
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) | 37 / 100 |
| Legacy data-support index | 0.79/1 |
| Coordinates | 39.1727, -78.0236 |
| Nearest City | Winchester (12 km) |
| Urban exposure index (PEI) | 154.8K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-07-21T22:24:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.d3fe9c5cd1e0e3c7366fb91b26beb730 |
Physical priority index · v1. Heuristic priority, not calibrated probability, predictive accuracy or damage. The legacy data-support index combines assigned source support and field availability. Urban PEI is distance-weighted and does not count unique people; zero does not establish that nobody is present. Model cards.
Source and revision timeline
Source: noaa. Occurrence: 2026-07-21T22:24:00.000Z.
First archived: 2026-07-21T22:33:54.323Z. Material modification: not recorded.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
Score Breakdown
Technical Details
| Event | Severe Thunderstorm Warning |
| Urgency | Immediate |
| Certainty | Observed |
| AreaDesc | Ocean, NJ; Kent, DE; New Castle, DE; Kent, MD; Montgomery, MD; Loudoun, VA and 5 more areas |
| Headline | Severe Thunderstorm Warning issued July 21 at 6:24PM EDT until July 21 at 6:45PM EDT by NWS Mount Holly NJ |
| Expires | 2026-07-21T18:45:00-04:00 |
| SenderName | NWS Mount Holly NJ |
| HasExactCoords | true |
| MergedCount | 8 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.d3fe9c5cd1e0e3c7366fb91b26beb730c5f9098d.002.1","noaa_urn:oid:2.49.0.1.840.0.d57dcd5a50cfda703ca01dd916cead63f8eff512.002.1","noaa_urn:oid:2.49.0.1.840.0.10c99e6cc154c7bd27acfb44fe8bf62bfd57d61a.001.1","noaa_urn:oid:2.49.0.1.840.0.cf6fdd6187f5091d97303ba50ebd2b4a05ae8507.001.1","noaa_urn:oid:2.49.0.1.840.0.f8a098ea9b7896e10bbf9d214f0d77c858493c02.001.1","noaa_urn:oid:2.49.0.1.840.0.85da92bc6010e1c1a95e4c7649fdd75bf4a4cbfd.001.1","noaa_urn:oid:2.49.0.1.840.0.eea87d77975a5b1f7d19493a0a79c269fecb4a79.001.1","noaa_urn:oid:2.49.0.1.840.0.5bfece26d0e646182bac3c6d2f0f36796c6bc8dc.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.
Review the area, threshold and delivery channel in your account.
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