This alert is in force until 31 August 2026, 06:00 UTC.
It is the 33rd strongest of the 143 detections recorded within 20 km of this point since 17 March 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Flash Flood Warning issued August 30 at 10:04PM EDT until August 31 at 2:00AM EDT by NWS Mount Holly NJ
An estimated 415,152 people live within 50 km of this point.
Nearby, since 17 March 2026
- August 31, 2026 · score 43 · 0.0 km
- June 12, 2026 · score 37 · 6.1 km
- August 27, 2026 · score 48 · 8.7 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 81 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Event Data
| Type | Severe weather |
| Severity | medium |
| Calamity Score (ours) | 43 / 100 |
| Our confidence | 81% |
| Coordinates | 40.0029, -75.9446 |
| Nearest City | West Chester (29 km) |
| Population Exposed | 415.2K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-08-31T02:04:00.000Z |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Chester, PA; Lancaster, PA |
| Headline | Flash Flood Warning issued August 30 at 10:04PM EDT until August 31 at 2:00AM EDT by NWS Mount Holly NJ |
| Expires | 2026-08-31T02:00:00-04:00 |
| SenderName | NWS Mount Holly NJ |
| HasExactCoords | true |
| MergedCount | 2 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.1b63b4eeaf3d94da3052414152270930144936d6.001.1","noaa_urn:oid:2.49.0.1.840.0.4b5e5fabcb0214c58f67616004dbab9cf3b54397.001.1"] |
Safety Information
During flooding: never walk, swim, or drive through floodwaters. Six inches of moving water can knock you down, and one foot of water can sweep away a vehicle. Move to higher ground if waters rise. After flooding, avoid contact with floodwater which may contain sewage, chemicals, or debris. Follow local emergency service guidance.
Series begins 10 February 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.
Calamity.live data shows a weather event with CalamityScore 43/100, near West Chester (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 191 scientific monitoring sources.