Alert archive / Missouri / Flood Watches in 2026
Flood Watch 4, NWS St. Louis, MO
NWS St. Louis, MO issued this flood watch at May 18, 2026, 1:12 AM CDT for 20 counties in Missouri; 10 counties in Illinois. It took effect at May 18, 2026, 7:00 AM CDT. It was in force for 29 hr.
The area
The counties it named.
The facts
- Issued
- May 18, 2026, 1:12 AM CDT (06:12 UTC)
- In effect from
- May 18, 2026, 7:00 AM CDT
- Expired
- May 19, 2026, 11:47 AM CDT
- In force
- 29 hr
- Issued by
- NWS St. Louis, MO
- Flood severity
- None
All 30 counties
Bond County, IL, Calhoun County, IL, Clinton County, IL, Fayette County, IL, Jersey County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Saint Clair County, IL, Washington County, IL, Audrain County, MO, Boone County, MO, Callaway County, MO, City of Saint Louis, MO, Cole County, MO, Crawford County, MO, Franklin County, MO, Gasconade County, MO, Jefferson County, MO, Lincoln County, MO, Moniteau County, MO, Monroe County, MO, Montgomery County, MO, Osage County, MO, Pike County, MO, Ralls County, MO, Saint Charles County, MO, Saint Louis County, MO, Warren County, MO, Washington County, MO
The radar
The St Louis radar (KLSX), 14 km from the middle of the area, began a volume at 06:15 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Lincoln, IL (KILX), launched 00:00Z, 6.2 hours before the alert went out and 248 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 1199 J/kg
- Mixed-layer CIN
- -142 J/kg
- Mixed-layer LCL
- 1497 m above ground
- 0-6 km bulk shear
- 9 kt
- 0-1 km storm-relative helicity
- 12 m²/s²
- 0-3 km storm-relative helicity
- 120 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
What forecasters said that day
The local office's own words before this flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS St. Louis, MO wrote its last area forecast discussion before this flood watch went out at May 17, 10:37 PM CDT, 2 hours 35 minutes earlier.
Area forecast discussion, May 17, 10:37 PM CDT, 2 hours 35 minutes before
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</html>Hazardous weather outlook, May 17, 3:55 PM CDT, 9 hours 17 minutes before
Hazardous Weather Outlook National Weather Service St Louis MO 355 PM CDT Sun May 17 2026 ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027- 034>036-041-042-047>052-059>065-072>075-084-085-099-182100- Greene IL-Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL- Marion IL-Washington IL-Randolph IL-Adams IL-Brown IL-Pike IL- Calhoun IL-Jersey IL-Madison IL-Saint Clair IL-Monroe IL-Knox MO- Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls MO-Pike MO-Boone MO- Audrain MO-Moniteau MO-Cole MO-Osage MO-Callaway MO-Montgomery MO- Lincoln MO-Gasconade MO-Warren MO-Saint Charles MO-Franklin MO- Saint Louis MO-Saint Louis City MO-Jefferson MO-Crawford MO- Washington MO-Saint Francois MO-Sainte Genevieve MO-Iron MO- Madison MO-Reynolds MO- 355 PM CDT Sun May 17 2026 This Hazardous Weather Outlook is for portions of eastern and central Missouri as well as west central and southwest Illinois. .DAYS ONE THROUGH SEVEN...This afternoon through Saturday. More detailed information can be accessed at: https://www.weather.gov/media/lsx/DssPacket.pdf The Area Forecast Discussion is available at: https://forecast.weather.gov/ product.php?issuedby=LSX&product=AFD&site=lsx .KEY MESSAGES... - Isolated showers and thunderstorms are possible early this morning for parts of northeast MO/west-central IL with the strongest storms capable of strong wind gusts. - Additional thunderstorm chances return early this week with a more widespread severe weather threat possible along a slow moving cold front Monday night into Tuesday. NOTE: Starting May 29, 2026, this outlook product will be discontinued. Please see the above products for more detailed forecast information. WFO LSX
The office that day
Everything else NWS St. Louis, MO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 18, 6:12 AM CDT | Severe Thunderstorm Warning | LSX | Audrain, Marion, Pike, Ralls | 48 min |
| May 18, 6:18 AM CDT | Severe Thunderstorm Warning | LSX | Audrain, Boone, Callaway | 42 min |
| May 18, 6:41 AM CDT | Tornado Warning | LSX | Pike, Ralls | 28 min |
| May 18, 7:21 AM CDT | Severe Thunderstorm Warning | LSX | Lincoln, Pike | 39 min |
| May 18, 10:56 AM CDT | Areal Flood Advisory | LSX | Franklin, Gasconade | 4 hr |
| May 18, 12:39 PM CDT | Areal Flood Advisory | LSX | Crawford, Franklin, Washington | 7 hr |
| May 18, 1:22 PM CDT | Areal Flood Advisory | LSX | Saint Louis, City of Saint Louis | 6 hr |
| May 18, 2:40 PM CDT | Areal Flood Advisory | LSX | Boone, Callaway, Cole, Moniteau | 4 hr |
| May 18, 3:05 PM CDT | Flash Flood Warning | LSX | Crawford, Franklin, Gasconade, Warren | 6 hr |
| May 18, 5:01 PM CDT | Flash Flood Warning | LSX | Franklin, Gasconade, Warren | 3 hr |
| May 18, 5:06 PM CDT | Flash Flood Warning | LSX | Jefferson, Saint Louis, City of Saint Louis | 4 hr |
| May 18, 5:12 PM CDT | Flash Flood Warning | LSX | Saint Charles, Saint Louis, City of Saint Louis | 3 hr |
| May 18, 7:37 AM CDT | Severe Thunderstorm Warning | LSX | Calhoun, Greene, Pike | 25 min |
| May 18, 11:25 AM CDT | Areal Flood Advisory | LSX | Fayette, Marion | 3 hr |
| May 18, 2:00 PM CDT | Areal Flood Advisory | LSX | Madison, Monroe, Saint Clair | 3 hr |
| May 18, 2:11 PM CDT | Flash Flood Warning | LSX | Clinton, Fayette, Marion | 6 hr |
| May 18, 2:13 PM CDT | Areal Flood Advisory | LSX | Bond, Clinton, Fayette, Washington | 41 min |
| May 18, 2:54 PM CDT | Flash Flood Warning | LSX | Bond, Clinton, Fayette, Madison, Marion, Saint Clair and 1 more | 6 hr |
Nearby
Flood Watches in Missouri, 2026Flood Watches in Illinois, 2026Every flood watch in 2026
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.