Alert archive / Missouri / Areal Flood Warnings in 2018

Areal Flood Warning 10, NWS St. Louis, MO

September 8, 20184 counties in Missouri; Monroe County, Randolph County, Saint Clair County, Illinois

NWS St. Louis, MO issued this areal flood warning at Sep 8, 2018, 1:31 AM CDT for 4 counties in Missouri; Monroe County, Randolph County, Saint Clair County, Illinois. It was in force for 12 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Sep 8, 2018, 1:31 AM CDT (06:31 UTC)
Expired: Sep 8, 2018, 1:30 PM CDT
In force: 12 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Flood severity: None

Counties Monroe County, IL, Randolph County, IL, Saint Clair County, IL, Franklin County, MO, Jefferson County, MO, Sainte Genevieve County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 63 km from the middle of the area, began a volume at 06:33 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, 6.5 hours before the alert went out and 266 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 32 J/kg
Mixed-layer CIN: -22 J/kg
Mixed-layer LCL: 547 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: -26 m²/s²
0-3 km storm-relative helicity: -43 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this areal flood warning 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 areal flood warning went out at Sep 7, 11:17 PM CDT, 2 hours 14 minutes earlier.

Area forecast discussion, Sep 7, 11:17 PM CDT, 2 hours 14 minutes before

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Hazardous weather outlook, Sep 7, 3:53 PM CDT, 9 hours 38 minutes before

Hazardous Weather Outlook
National Weather Service Saint Louis MO
353 PM CDT Fri Sep 7 2018

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-081115-
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-
353 PM CDT Fri Sep 7 2018

...FLASH FLOOD WATCH UNTIL 7 AM CDT SUNDAY...

This hazardous weather outlook is for portions of eastern and
central Missouri as well as west central and southwest Illinois.

.DAY ONE...Tonight

There is a chance of thunderstorms, and heavy rain is likely
this evening and overnight. A Flash Flood Watch is in effect for
the entire area.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

There is a chance for thunderstorms, and heavy rain is likely
through Sunday over parts of the area. A Flash Flood Watch is in
effect for the entire area through early Sunday morning due to
this expected heavy rainfall. The highest rainfall amounts will be
just north of I-70 and also in southwest IL. Flash flooding is
most likely in these areas.

.SPOTTER INFORMATION STATEMENT...

Spotters are asked to call in any flooding reports or rainfall
reports greater than one inch.

BSH

In the hours before

Local storm report, Sep 8, 12:01 AM CDT, 1 hour 30 minutes before

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Local storm report, Sep 8, 12:02 AM CDT, 1 hour 29 minutes before

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Local storm report, Sep 8, 12:04 AM CDT, 1 hour 27 minutes before

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Local storm report, Sep 8, 12:10 AM CDT, 1 hour 21 minutes before

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Local storm report, Sep 8, 12:27 AM CDT, 1 hour 4 minutes before

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Local storm report, Sep 8, 1:12 AM CDT, 19 minutes before

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The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 7, 7:28 PM CDT	River Flood Warning	LSX	Marion	17 hr
Sep 7, 8:02 PM CDT	Flash Flood Warning	LSX	Franklin, Jefferson, Washington	6 hr
Sep 7, 8:34 PM CDT	Flash Flood Warning	LSX	Jefferson, Sainte Genevieve	5 hr
Sep 7, 9:27 PM CDT	Areal Flood Advisory	LSX	Saint Charles, Saint Louis, City of Saint Louis	4 hr
Sep 8, 2:56 AM CDT	Flash Flood Warning	LSX	Crawford	6 hr
Sep 8, 8:44 AM CDT	Areal Flood Warning	LSX	Jefferson, Saint Louis, City of Saint Louis	6 hr
Sep 8, 8:59 AM CDT	Areal Flood Warning	LSX	Crawford	6 hr
Sep 8, 1:28 PM CDT	Areal Flood Warning	LSX	Jefferson, Sainte Genevieve	6 hr
Sep 7, 7:26 PM CDT	Flash Flood Warning	LSX	Saint Clair	6 hr
Sep 8, 9:06 AM CDT	Areal Flood Warning	LSX	Bond, Clinton, Fayette, Madison, Marion, Randolph and 1 more	9 hr
Sep 8, 5:58 PM CDT	Areal Flood Warning	LSX	Clinton, Fayette, Madison, Marion, Washington	12 hr

Nearby

Areal Flood Warnings in Missouri, 2018 Areal Flood Warnings in Illinois, 2018 Every areal flood warning in 2018

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.