Right now
The most recent data we hold from NOAA arrived 8 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 21:30 UTC. It is kept here as a record.
It is the 262nd strongest of the 407 detections recorded within 20 km of this point since 12 March 2026. The last comparable one was on 9 July 2026. 7 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued July 21 at 4:43PM EDT until July 21 at 5:30PM EDT by NWS Mount Holly NJ
Urban PEI: 534,264 within a heuristic 50 km radius; not unique people.
Nearby, since 12 March 2026
- July 9, 2026 · score 52 · 7.0 km
- July 22, 2026 · score 41 · 8.9 km
- August 5, 2026 · score 37 · 9.1 km
How we know
One source: NOAA. Not yet confirmed by a second, independent source.
Our own score for this event is 41 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) | 41 / 100 |
| Legacy data-support index | 0.79/1 |
| Coordinates | 39.6501, -75.6443 |
| Nearest City | Bear (3 km) |
| Urban exposure index (PEI) | 534.3K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-07-21T20:43:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.9559ba3918892896bba700fcd29e3a3e |
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: 2026-07-21T20:43:00.000Z.
First archived: 2026-07-21T20:46:10.244Z. 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 | New Castle, DE; Gloucester, NJ; Salem, NJ; Chester, PA; Delaware, PA; Cecil, MD; Anne Arundel, MD; Calvert, MD; Charles, MD; Prince Georges, MD and 3 more areas |
| Headline | Severe Thunderstorm Warning issued July 21 at 4:43PM EDT until July 21 at 5:30PM EDT by NWS Mount Holly NJ |
| Expires | 2026-07-21T17:30:00-04:00 |
| SenderName | NWS Mount Holly NJ |
| HasExactCoords | true |
| MergedCount | 6 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.9559ba3918892896bba700fcd29e3a3e40ae9a27.001.1","noaa_urn:oid:2.49.0.1.840.0.4c5583b9f02401ee9e1e43c217fa89acca5b70c2.001.1","noaa_urn:oid:2.49.0.1.840.0.866932b8b2cb50c26d078e18f304f5be90719c17.001.1","noaa_urn:oid:2.49.0.1.840.0.6c24dc889894de7afee86951fbe3dbd3618195bd.001.1","noaa_urn:oid:2.49.0.1.840.0.a496c7d6821e4affb467f50f6ed8956ef7fa6291.001.1","noaa_urn:oid:2.49.0.1.840.0.9c8537af120e6b0682cc050197b8ef0dff4fbd7f.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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