Alert archive / Illinois / Flash Flood Warnings in 2023

Flash Flood Warning 13, NWS St. Louis, MO

July 14, 2023Clinton County, Saint Clair County, Illinois

NWS St. Louis, MO issued this flash flood warning at Jul 14, 2023, 9:29 PM CDT for Clinton County, Saint Clair County, Illinois. It was in force for 4 hr. 2 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: Jul 14, 2023, 9:29 PM CDT (02:29 UTC)
Expired: Jul 15, 2023, 1:30 AM CDT
In force: 4 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Flood severity: None

Counties Clinton County, IL, Saint Clair County, IL

The radar

The St Louis radar (KLSX), 78 km from the middle of the area, began a volume at 02:30 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

Time	Report	Where	Remark
Jul 14, 9:30 PM CDT	RAIN 4.38	2 Ene Fairview Heights, IL	Fell over 90 minutes.
Jul 14, 10:30 PM CDT	FLASH FLOOD	O'Fallon, IL	Corrects previous flash flood report from O'Fallon. Roads flooded. 6+ inches of flowing water through yards.

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, 2.5 hours before the alert went out and 202 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: 1130 J/kg
Mixed-layer CIN: -23 J/kg
Mixed-layer LCL: 1704 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 57 m²/s²
0-3 km storm-relative helicity: 53 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.2

Open this sounding in Storm Lab

The text

As transmitted.

759 
WGUS53 KLSX 150229
FFWLSX
ILC027-163-150630-
/O.NEW.KLSX.FF.W.0013.230715T0229Z-230715T0630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
929 PM CDT Fri Jul 14 2023

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Northwestern Clinton County in south central Illinois...
  Northeastern Saint Clair County in southwestern Illinois...

* Until 130 AM CDT.

* At 929 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 3 inches of rain 
  have fallen. Additional rainfall amounts up to 1 inch are possible 
  in the warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Belleville, O'Fallon, East St. Louis, Fairview Heights, Swansea, 
  Shiloh, Breese, Lebanon, Caseyville, Scott AFB, Trenton, Aviston, 
  Germantown, Albers and Summerfield.

This includes Interstate 64 in Illinois between exits 12 and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 3859 9004 3866 8996 3866 8960 3869 8951
      3858 8949 3856 8949 3854 8960 3856 8971
      3856 8982 3854 8998 3855 9002 3857 9005

FLASH FLOOD...RADAR INDICATED

$$

Gosselin

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 14, 7:24 PM CDT	Severe Thunderstorm Warning	LSX	Madison	36 min
Jul 14, 8:26 PM CDT	Areal Flood Advisory	LSX	Madison	3 hr
Jul 14, 8:26 PM CDT	Severe Thunderstorm Warning	LSX	Pike	26 min
Jul 14, 8:40 PM CDT	Severe Thunderstorm Warning	LSX	Bond, Clinton, Madison, Saint Clair	36 min
Jul 14, 9:11 PM CDT	Areal Flood Advisory	LSX	Clinton, Monroe, Saint Clair	3 hr

Nearby

Flash Flood Warnings in Illinois, 2023 Every flash flood warning in 2023

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.