Right now
The most recent data we hold from NOAA arrived 43 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 19 May 2026 at 01:15 UTC. It is kept here as a record.
It is the 4th strongest of the 73 detections recorded within 20 km of this point since 15 March 2026. Another comparable one was recorded here earlier the same day. 6 more were recorded here in the fortnight before it.
What the source measured
NOAA reported: Flash Flood Warning issued May 18 at 5:12PM CDT until May 18 at 8:15PM CDT by NWS St Louis MO
Urban PEI: 1,186,308 within a heuristic 50 km radius; not unique people.
Nearby, since 15 March 2026
- May 19, 2026 · score 52 · 0.0 km
- July 11, 2026 · score 52 · 4.4 km
- March 15, 2026 · score 76 · 10.6 km
How we know
3 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 | 0.90/1 |
| Coordinates | 38.5785, -90.0983 |
| Nearest City | East Saint Louis (6 km) |
| Urban exposure index (PEI) | 1.2M within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-05-18T22:12:00.000Z |
| Source | https://api.weather.gov/alerts/merged_Flash Flood Warning_noaa_urn:oid:2.49.0.1.840.0.8559e3b280a994089f93cfc728c6c064 |
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: 2026-05-18T22:12:00.000Z.
First archived: 2026-05-19T01:05:44.188Z. 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 | St. Charles, MO; St. Louis, MO; St. Louis City, MO; Clinton, IL; Madison, IL; Monroe, IL; St. Clair, IL; Jefferson, MO; St. Louis, MO; St. Louis City, MO; Bond, IL; Clinton, IL; Fayette, IL; Marion, IL; Washington, IL and 2 more areas |
| Headline | Flash Flood Warning issued May 18 at 5:12PM CDT until May 18 at 8:15PM CDT by NWS St Louis MO |
| Expires | 2026-05-18T20:15:00-05:00 |
| SenderName | NWS St Louis MO |
| HasExactCoords | true |
| MergedCount | 5 |
| MergedIds | ["noaa_urn:oid:2.49.0.1.840.0.8559e3b280a994089f93cfc728c6c06499a24d53.001.1","noaa_urn:oid:2.49.0.1.840.0.c4697f6a33e133f80b4ed71f28e56becbf43c778.001.1","noaa_urn:oid:2.49.0.1.840.0.dbabff3a536120a3ca09dab0ff473b6cc62da205.002.1","noaa_urn:oid:2.49.0.1.840.0.f51d25858704af1517e0bba1e5bf5148f039ac5f.001.1","noaa_urn:oid:2.49.0.1.840.0.981763280e670dafdad02306926ecdd4a788a568.001.1"] |
| 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_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 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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