Right now
The most recent data we hold from NOAA arrived 36 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 20 May 2026 at 21:45 UTC. It is kept here as a record.
No stronger detection stands among the 302 recorded within 20 km of this point since 12 March 2026 — 163 others scored the same. Another comparable one was recorded here earlier the same day. 3 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Severe Thunderstorm Warning issued May 20 at 5:30PM EDT until May 20 at 5:45PM EDT by NWS Baltimore MD/Washington DC
Urban PEI: 3,708,833 within a heuristic 50 km radius; not unique people.
Nearby, since 12 March 2026
- July 5, 2026 · score 52 · 2.7 km
- May 20, 2026 · score 52 · 4.3 km
- August 20, 2026 · score 52 · 4.8 km
How we know
8 recorded sources include NOAA; independence is not established by this count.
Our own score for this event is 52 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) | 52 / 100 |
| Legacy data-support index | 0.89/1 |
| Coordinates | 40.0396, -75.2511 |
| Nearest City | Overbrook (6 km) |
| Urban exposure index (PEI) | 3.7M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-20T21:30:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Severe Thunderstorm Warning_noaa_urn:oid:2.49.0.1.840.0.0339f6568d1aa3fd1cb6f6c31094511f |
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: 2026-05-20T21:30:00.000Z.
First archived: 2026-05-20T21:33:50.181Z. 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 | Cecil, MD; Harford, MD; New Castle, DE; Camden, NJ; Gloucester, NJ; Salem, NJ; Chester, PA; Delaware, PA; Philadelphia, PA; Hunterdon, NJ; Middlesex, NJ; Morris, NJ; Somerset, NJ; Warren, NJ; Bucks, PA; Northampton, PA and 5 more areas |
| Headline | Severe Thunderstorm Warning issued May 20 at 5:30PM EDT until May 20 at 5:45PM EDT by NWS Baltimore MD/Washington DC |
| Expires | 2026-05-20T17:45:00-04:00 |
| SenderName | NWS Baltimore MD/Washington DC |
| HasExactCoords | true |
| MergedCount | 8 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.0339f6568d1aa3fd1cb6f6c31094511f060533a0.002.1","noaa_urn:oid:2.49.0.1.840.0.17179e4b9b5dafc2f0ed37701045b41e1ef0a7b7.001.1","noaa_urn:oid:2.49.0.1.840.0.8bf3940309d865c65847f254a3c4d7b83bacf661.001.1","noaa_urn:oid:2.49.0.1.840.0.fe508ac293398ad240466709cc560c926f8ccaa3.001.1","noaa_urn:oid:2.49.0.1.840.0.769b014eafcd4f80ea87246012a3bda6c57f8b7c.001.1","noaa_urn:oid:2.49.0.1.840.0.a79fcbad9fe48cd517cd5b3c7257b85d681c3c22.001.1","noaa_urn:oid:2.49.0.1.840.0.add74f0042af4b0db11f1149a47be98019241dbc.001.1","noaa_urn:oid:2.49.0.1.840.0.443c254d0687e520d3793d6e4d3362d5ae9a66a7.001.1"] |
| Iem TypeSummary | D |
| Iem City | 3 WNW Robeson Twp |
| Iem County | Berks |
| Iem State | PA |
| Iem Wfo | PHI |
| Iem Remark | Tree down into a house. Time estimated from radar. |
| MergedSources | [{"id":"iem_D_40.540_-75.760_1779309180000","source":"iem","severity":"low","severityValue":25,"timestamp":1779309180000,"latitude":40.54,"longitude":-75.76},{"id":"iem_D_40.250_-75.650_1779310080000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310080000,"latitude":40.25,"longitude":-75.65},{"id":"iem_D_40.270_-75.820_1779309000000","source":"iem","severity":"low","severityValue":25,"timestamp":1779309000000,"latitude":40.27,"longitude":-75.82},{"id":"iem_D_40.270_-75.930_1779308100000","source":"iem","severity":"low","severityValue":25,"timestamp":1779308100000,"latitude":40.27,"longitude":-75.93},{"id":"iem_D_40.300_-75.660_1779310020000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310020000,"latitude":40.3,"longitude":-75.66},{"id":"iem_D_40.500_-75.880_1779308820000","source":"iem","severity":"low","severityValue":25,"timestamp":1779308820000,"latitude":40.5,"longitude":-75.88},{"id":"iem_D_40.260_-75.930_1779308040000","source":"iem","severity":"low","severityValue":25,"timestamp":1779308040000,"latitude":40.26,"longitude":-75.93}] |
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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