Alert archive / Illinois / Flash Flood Warnings in 2018

Flash Flood Warning 40, NWS St. Louis, MO

September 7, 2018Saint Clair County, Illinois

NWS St. Louis, MO issued this flash flood warning at Sep 7, 2018, 7:26 PM CDT for Saint Clair County, Illinois. It was in force for 6 hr. 5 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Sep 7, 2018, 7:26 PM CDT (00:26 UTC)
Expired
Sep 8, 2018, 1:30 AM CDT
In force
6 hr
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Flood severity
None

County Saint Clair County, IL

The radar

The St Louis radar (KLSX), 60 km from the middle of the area, began a volume at 00:27 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.

What was reported inside it

TimeReportWhereRemark
Sep 7, 7:50 PM CDTHEAVY RAIN 1.342 Se Centreville, IL
Sep 7, 9:13 PM CDTFLASH FLOODBelleville, ILSTRANDED MOTORIST IN HIS CAR STUCK IN WATER KNEE HIGH DEEP.
Sep 7, 11:15 PM CDTFLASH FLOOD2 Ssw Belleville, ILWATER RESCUE. SOUTH 11 ST FLOODED.
Sep 7, 11:58 PM CDTFLASH FLOOD2 Ese Swansea, ILNUMEROUS ROADS UNDER WATER ACROSS THE COUNTY.
Sep 8, 12:00 AM CDTHEAVY RAIN 2.053 Se Centreville, ILDAILY TOTAL.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 0.4 hours before the alert went out and 217 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-pSkew-T log-p diagram, Lincoln, IL at 00:00Z on 2018-09-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 32 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 00:00Z on 2018-09-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -26 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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

The text

As transmitted.

860 
WGUS53 KLSX 080026
FFWLSX
ILC163-080630-
/O.NEW.KLSX.FF.W.0040.180908T0026Z-180908T0630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
726 PM CDT FRI SEP 7 2018

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  St. Clair County in southwestern Illinois...

* Until 130 AM CDT Saturday.

* At 724 PM CDT, Doppler radar indicated heavy rain across the 
  warned area. Up to three inches of rain have already fallen 
  between Dupo and Fairview heights in the past threes hours. Flash 
  flooding is expected to begin shortly.

* Some locations that will experience flooding include...
  Belleville, O'Fallon, East St. Louis, Collinsville, Fairview
  Heights, Cahokia, Swansea, Shiloh, Columbia, Mascoutah,
  Centreville, Lebanon, Freeburg, Caseyville, Washington Park, Dupo,
  Millstadt, Madison, New Baden and Scott AFB.

This includes Interstate 64 in Illinois between exits 9 and 23.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 3843 8973 3841 9013 3852 9026 3857 9023
      3861 9018 3866 9017 3865 8973

$$

GKS
1 follow-up statement
727 
WGUS73 KLSX 080636
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
136 AM CDT SAT SEP 8 2018

ILC163-080643-
/O.EXP.KLSX.FF.W.0040.000000T0000Z-180908T0630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
St. Clair IL-
136 AM CDT SAT SEP 8 2018

...THE FLASH FLOOD WARNING FOR ST. CLAIR COUNTY HAS EXPIRED...

Rain will continue to fall over the area tonight with additional 
flooding possible. Therefore, the flash flood warning has be 
replaced by an areal flood warning. Please continue to heed any 
remaining road closures and report flooding to local authorities.

LAT...LON 3843 8973 3841 9013 3852 9026 3857 9023
      3861 9018 3866 9017 3865 8973

$$

Maples

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 7, 8:34 PM CDTFlash Flood WarningLSXMonroe, Randolph, Saint Clair5 hr
Sep 8, 1:31 AM CDTAreal Flood WarningLSXMonroe, Randolph, Saint Clair12 hr
Sep 8, 8:44 AM CDTAreal Flood WarningLSXMonroe, Saint Clair6 hr
Sep 8, 9:06 AM CDTAreal Flood WarningLSXBond, Clinton, Fayette, Madison, Marion, Randolph and 1 more9 hr
Sep 8, 1:28 PM CDTAreal Flood WarningLSXMonroe, Randolph, Saint Clair6 hr
Sep 8, 5:58 PM CDTAreal Flood WarningLSXClinton, Fayette, Madison, Marion, Washington12 hr

Nearby

Flash Flood Warnings in Illinois, 2018Every flash 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.