This alert expired on 19 May 2026 at 02:00 UTC. It is kept here as a record.
It is the 3rd strongest of the 68 detections recorded within 20 km of this point since 15 March 2026. The last comparable one was on 18 May 2026. 6 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flash Flood Warning issued May 18 at 8:09PM CDT until May 18 at 9:00PM CDT by NWS St Louis MO
An estimated 1,306,164 people live within 50 km of this point.
Nearby, since 15 March 2026
- March 16, 2026 · score 52 · 2.2 km
- May 18, 2026 · score 52 · 3.5 km
- March 16, 2026 · score 52 · 6.6 km
How we know
Confirmed by 4 independent sources, including NOAA.
Our own score for this event is 52 out of 100, at 91 % 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) | 52 / 100 |
| Our confidence | 91% |
| Coordinates | 38.5143, -90.3353 |
| Nearest City | Mehlville (1 km) |
| Population Exposed | 1.3M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-19T01:09:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Flash Flood Warning_noaa_urn:oid:2.49.0.1.840.0.c20f07df359f7c6acf70603265bf9f1a |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Clinton, IL; Madison, IL; Monroe, IL; St. Clair, IL; Jefferson, MO; St. Louis, MO; Bond, IL; Clinton, IL; Fayette, IL; Marion, IL; Washington, IL; Crawford, MO; Franklin, MO; Gasconade, MO; Warren, MO |
| Headline | Flash Flood Warning issued May 18 at 8:09PM CDT until May 18 at 9:00PM CDT by NWS St Louis MO |
| Expires | 2026-05-18T21:00:00-05:00 |
| SenderName | NWS St Louis MO |
| HasExactCoords | true |
| MergedCount | 3 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.c20f07df359f7c6acf70603265bf9f1ad20bcbdd.002.1","noaa_urn:oid:2.49.0.1.840.0.dbabff3a536120a3ca09dab0ff473b6cc62da205.002.1","noaa_urn:oid:2.49.0.1.840.0.f51d25858704af1517e0bba1e5bf5148f039ac5f.001.1"] |
| Iem TypeSummary | R |
| Iem Magnitude | 2.03 |
| Iem Unit | Inch |
| Iem City | Ferguson |
| Iem County | St. Louis |
| Iem State | MO |
| Iem Wfo | LSX |
| MergedSources | [{"id":"iem_R_38.420_-90.780_1779131700000","source":"iem","severity":"low","severityValue":25,"timestamp":1779131700000,"latitude":38.42,"longitude":-90.78},{"id":"iem_E_38.670_-91.120_1779152280000","source":"iem","severity":"low","severityValue":25,"timestamp":1779152280000,"latitude":38.67,"longitude":-91.12},{"id":"iem_R_38.740_-90.300_1779140400000","source":"iem","severity":"low","severityValue":25,"timestamp":1779140400000,"latitude":38.74,"longitude":-90.3}] |
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.
Want to know when something happens near Mehlville?
Calamity.live data shows a weather event with CalamityScore 52/100, near Mehlville (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.