Alert archive / Illinois / Flash Flood Warnings in 2021

Flash Flood Warning 32, NWS St. Louis, MO

July 25, 2021Saint Clair County, Washington County, Illinois

NWS St. Louis, MO issued this flash flood warning at Jul 25, 2021, 8:28 AM CDT for Saint Clair County, Washington County, Illinois. It was in force for 3 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 25, 2021, 8:28 AM CDT (13:28 UTC)
Expired: Jul 25, 2021, 11:30 AM CDT
In force: 3 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Flood severity: None

Counties Saint Clair County, IL, Washington County, IL

The radar

The St Louis radar (KLSX), 86 km from the middle of the area, began a volume at 13:29 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 25, 9:40 AM CDT	FLASH FLOOD	1 N Lenzburg, IL	FAST FLOWING WATER OVER ROUTE 13 NEAR LENZBURG.
Jul 25, 9:42 AM CDT	FLASH FLOOD	2 Nw Lenzburg, IL	FLOODING ON ROUTE 13.

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 12:00Z, 1.5 hours before the alert went out and 229 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: 295 J/kg
Mixed-layer CIN: -85 J/kg
Mixed-layer LCL: 960 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: -27 m²/s²
0-3 km storm-relative helicity: 27 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

212 
WGUS53 KLSX 251328
FFWLSX
ILC163-189-251630-
/O.NEW.KLSX.FF.W.0032.210725T1328Z-210725T1630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
828 AM CDT Sun Jul 25 2021

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Southwestern Washington County in south central Illinois...
  Southeastern Saint Clair County in southwestern Illinois...

* Until 1130 AM CDT.

* At 828 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. The expected rainfall rate is 1 to 2 inches in 1 
  hour. Additional rainfall amounts of 1 to 2 inches 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, Freeburg, New Athens, Marissa, Lively Grove, St. 
  Libory, Lenzburg, Johannisburg, Fayetteville, Venedy, Stone Church 
  and Elkton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3828 8992 3829 8992 3828 8991 3829 8990
      3831 8992 3848 8994 3843 8970 3842 8970
      3843 8969 3839 8951 3822 8954 3822 8990
      3823 8990 3825 8992

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR

$$

Glass

2 follow-up statements

026 
WGUS73 KLSX 251448
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
948 AM CDT Sun Jul 25 2021

ILC163-189-251630-
/O.CON.KLSX.FF.W.0032.000000T0000Z-210725T1630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Saint Clair IL-Washington IL-
948 AM CDT Sun Jul 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1130 AM CDT THIS 
MORNING FOR SOUTHWESTERN WASHINGTON COUNTY IN SOUTH CENTRAL ILLINOIS 
AND SOUTHEASTERN SAINT CLAIR COUNTY IN SOUTHWESTERN ILLINOIS...

At 948 AM CDT, local law enforcement reported flash flooding across 
the warned area. Several sections of Route 13 in the New Athens and 
Lenzburg area were flooded. Between 2 and 4 inches of rain have 
fallen. Additional rainfall amounts up to 1 inch are possible in the 
warned area.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Law enforcement reported.

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, Freeburg, New Athens, Marissa, Lively Grove, St. 
  Libory, Lenzburg, Johannisburg, Fayetteville, Venedy, Stone Church 
  and Elkton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3828 8992 3829 8992 3828 8991 3829 8990
      3831 8992 3848 8994 3843 8970 3842 8970
      3843 8969 3839 8951 3822 8954 3822 8990
      3823 8990 3825 8992

FLASH FLOOD...OBSERVED
EXPECTED RAINFALL...1 INCH IN 1 HOUR

$$

Glass

606 
WGUS73 KLSX 251625
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
1125 AM CDT Sun Jul 25 2021

ILC163-189-251635-
/O.EXP.KLSX.FF.W.0032.000000T0000Z-210725T1630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Saint Clair IL-Washington IL-
1125 AM CDT Sun Jul 25 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1130 AM CDT THIS MORNING FOR 
SOUTHWESTERN WASHINGTON COUNTY IN SOUTH CENTRAL ILLINOIS AND 
SOUTHEASTERN SAINT CLAIR COUNTY IN SOUTHWESTERN ILLINOIS...

Flood waters have receded. The heavy rain has ended. Flooding is no 
longer expected to pose a threat. Please continue to heed remaining 
road closures.

LAT...LON 3828 8992 3829 8992 3828 8991 3829 8990
      3831 8992 3848 8994 3843 8970 3842 8970
      3843 8969 3839 8951 3822 8954 3822 8990
      3823 8990 3825 8992

$$

Glass

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 25, 6:29 AM CDT	Areal Flood Advisory	LSX	Marion	2 hr

Nearby

Flash Flood Warnings in Illinois, 2021 Every flash flood warning in 2021

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.