Right now
The most recent data we hold from NOAA arrived 27 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 May 2026 at 01:45 UTC. It is kept here as a record.
No stronger detection stands among the 355 recorded within 20 km of this point since 12 March 2026 — 207 others scored the same. Another comparable one was recorded here earlier the same day. 5 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flash Flood Warning issued May 20 at 5:40PM EDT until May 20 at 9:45PM EDT by NWS Mount Holly NJ
Urban PEI: 3,708,833 within a heuristic 50 km radius; not unique people.
Nearby, since 12 March 2026
- May 20, 2026 · score 52 · 1.4 km
- August 20, 2026 · score 52 · 2.0 km
- July 11, 2026 · score 52 · 3.0 km
How we know
28 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 | 39.9981, -75.2275 |
| Nearest City | Overbrook (1 km) |
| Urban exposure index (PEI) | 3.7M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-20T21:40:00.000Z |
| Source | https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.40e1d94719ab16554adbf06c6b9ceba5272829ca.001.1 |
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: 2026-05-20T21:40:00.000Z.
First archived: 2026-05-21T00:33:51.687Z. 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 | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Burlington, NJ; Camden, NJ; Gloucester, NJ; Bucks, PA; Delaware, PA; Montgomery, PA; Philadelphia, PA |
| Headline | Flash Flood Warning issued May 20 at 5:40PM EDT until May 20 at 9:45PM EDT by NWS Mount Holly NJ |
| Expires | 2026-05-20T21:45:00-04:00 |
| SenderName | NWS Mount Holly NJ |
| HasExactCoords | true |
| Iem TypeSummary | D |
| Iem City | 3 SE Emmaus |
| Iem County | Lehigh |
| Iem State | PA |
| Iem Wfo | PHI |
| Iem Remark | Downed utility on BEVERLY HILLS RD / CHURCHVIEW RD both directions between LIMEPORT PK and LAMOUR ST. All lanes now open. Time estimated from radar. |
| Google News RssFeed | weather |
| Google News SourceName | NBC10 Philadelphia |
| MergedSources | [{"id":"iem_H_40.050_-75.390_1779312300000","source":"iem","severity":"low","severityValue":25,"timestamp":1779312300000,"latitude":40.05,"longitude":-75.39},{"id":"iem_D_40.280_-75.140_1779312180000","source":"iem","severity":"low","severityValue":25,"timestamp":1779312180000,"latitude":40.28,"longitude":-75.14},{"id":"iem_F_40.000_-75.350_1779314400000","source":"iem","severity":"low","severityValue":25,"timestamp":1779314400000,"latitude":40,"longitude":-75.35},{"id":"iem_D_40.230_-75.660_1779310020000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310020000,"latitude":40.23,"longitude":-75.66},{"id":"iem_D_40.200_-75.620_1779310860000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310860000,"latitude":40.2,"longitude":-75.62},{"id":"iem_D_39.980_-74.820_1779314700000","source":"iem","severity":"low","severityValue":25,"timestamp":1779314700000,"latitude":39.98,"longitude":-74.82},{"id":"iem_D_40.230_-75.530_1779310740000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310740000,"latitude":40.23,"longitude":-75.53},{"id":"iem_D_40.100_-75.540_1779311760000","source":"iem","severity":"low","severityValue":25,"timestamp":1779311760000,"latitude":40.1,"longitude":-75.54},{"id":"iem_D_39.900_-75.470_1779313140000","source":"iem","severity":"low","severityValue":25,"timestamp":1779313140000,"latitude":39.9,"longitude":-75.47},{"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_40.390_-74.750_1779314220000","source":"iem","severity":"low","severityValue":25,"timestamp":1779314220000,"latitude":40.39,"longitude":-74.75},{"id":"iem_D_40.310_-75.560_1779310980000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310980000,"latitude":40.31,"longitude":-75.56},{"id":"iem_D_40.270_-75.260_1779312300000","source":"iem","severity":"low","severityValue":25,"timestamp":1779312300000,"latitude":40.27,"longitude":-75.26},{"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_40.010_-76.100_1779309300000","source":"iem","severity":"low","severityValue":25,"timestamp":1779309300000,"latitude":40.01,"longitude":-76.1},{"id":"iem_D_39.880_-74.830_1779315000000","source":"iem","severity":"low","severityValue":25,"timestamp":1779315000000,"latitude":39.88,"longitude":-74.83},{"id":"iem_D_40.040_-76.030_1779309660000","source":"iem","severity":"low","severityValue":25,"timestamp":1779309660000,"latitude":40.04,"longitude":-76.03},{"id":"iem_D_40.300_-75.660_1779310020000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310020000,"latitude":40.3,"longitude":-75.66},{"id":"iem_M_39.650_-75.580_1779312720000","source":"iem","severity":"low","severityValue":25,"timestamp":1779312720000,"latitude":39.65,"longitude":-75.58},{"id":"iem_D_40.140_-74.710_1779314760000","source":"iem","severity":"low","severityValue":25,"timestamp":1779314760000,"latitude":40.14,"longitude":-74.71},{"id":"iem_D_40.410_-75.500_1779310200000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310200000,"latitude":40.41,"longitude":-75.5},{"id":"iem_D_40.260_-75.930_1779308040000","source":"iem","severity":"low","severityValue":25,"timestamp":1779308040000,"latitude":40.26,"longitude":-75.93},{"id":"iem_D_39.920_-75.610_1779311520000","source":"iem","severity":"low","severityValue":25,"timestamp":1779311520000,"latitude":39.92,"longitude":-75.61},{"id":"iem_D_40.510_-75.450_1779310740000","source":"iem","severity":"low","severityValue":25,"timestamp":1779310740000,"latitude":40.51,"longitude":-75.45},{"id":"gnews_weather_494251_126","source":"google_news","severity":"medium","severityValue":40,"timestamp":1779304744000,"latitude":39.95,"longitude":-75.16},{"id":"gnews_weather_494253_127","source":"google_news","severity":"medium","severityValue":40,"timestamp":1779312347000,"latitude":39.95,"longitude":-75.16}] |
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 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.
Want to know when something happens near Overbrook?