Alert archive / Illinois / Flash Flood Warnings in 2021

Flash Flood Warning 35, NWS St. Louis, MO

July 31, 20217 counties in Illinois

NWS St. Louis, MO issued this flash flood warning at Jul 31, 2021, 8:34 AM CDT for 7 counties in 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 31, 2021, 8:34 AM CDT (13:34 UTC)
Expired: Jul 31, 2021, 12:45 PM CDT
In force: 4 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Flood severity: None

Counties Bond County, IL, Calhoun County, IL, Greene County, IL, Jersey County, IL, Macoupin County, IL, Montgomery County, IL, Pike County, IL

The radar

The St Louis radar (KLSX), 81 km from the middle of the area, began a volume at 13:36 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 31, 9:41 AM CDT	FLASH FLOOD	Carrollton, IL	WATER OVER THE ROADWAY, CLOSING HIGHWAY 108 NEAR CARROLLTON.
Jul 31, 9:43 AM CDT	FLASH FLOOD	3 Ssw Wrights, IL	WATER OVER THE ROADWAY, CLOSING DAUM-STATION ROAD.

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, 1.6 hours before the alert went out and 166 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1802 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: -14 m²/s²
0-3 km storm-relative helicity: 55 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

117 
WGUS53 KLSX 311334
FFWLSX
ILC005-013-061-083-117-135-149-311745-
/O.NEW.KLSX.FF.W.0035.210731T1334Z-210731T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
834 AM CDT Sat Jul 31 2021

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  North Central Bond County in south central Illinois...
  Southern Montgomery County in south central Illinois...
  North Central Calhoun County in southwestern Illinois...
  Greene County in southwestern Illinois...
  Northeastern Jersey County in southwestern Illinois...
  Macoupin County in southwestern Illinois...
  Southeastern Pike County in west central Illinois...

* Until 1245 PM CDT.

* At 834 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 3 inches of rain 
  have fallen. Additional rainfall amounts of 1 to 3 inches are 
  possible in the warned area as a line of storms approaches. 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...
  Litchfield, Hillsboro, Carlinville, Staunton, Pittsfield, 
  Gillespie, White Hall, Carrollton, Mount Olive, Roodhouse, Benld, 
  Greenfield, Pleasant Hill, Palmyra, Taylor Springs, Coffeen, 
  Shipman, Wilsonville, Schram City and Athensville.

This includes the following State Parks...
	Beaver Dam State Park and Lake Lou Yaeger.

This includes the following highways...
	Interstate 55 in Illinois between exits 41 and 60.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3941 9095 3961 9088 3954 9057 3952 9058
      3949 9011 3928 8959 3910 8925 3904 8927
      3900 8970 3928 9071

FLASH FLOOD...RADAR INDICATED

$$

KD

2 follow-up statements

950 
WGUS73 KLSX 311446
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
946 AM CDT Sat Jul 31 2021

ILC005-013-061-083-117-135-149-311745-
/O.CON.KLSX.FF.W.0035.000000T0000Z-210731T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Bond IL-Calhoun IL-Greene IL-Jersey IL-Macoupin IL-Montgomery IL-
Pike IL-
946 AM CDT Sat Jul 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1245 PM CDT THIS 
AFTERNOON FOR NORTH CENTRAL BOND AND SOUTHERN MONTGOMERY COUNTIES IN 
SOUTH CENTRAL ILLINOIS, NORTH CENTRAL CALHOUN, GREENE, NORTHEASTERN 
JERSEY AND MACOUPIN COUNTIES IN SOUTHWESTERN ILLINOIS AND 
SOUTHEASTERN PIKE COUNTY IN WEST CENTRAL ILLINOIS...

At 946 AM CDT, local law enforcement reported several roadways under 
water near Carrollton and Greenfield. Between 2 and 3 inches of rain 
have fallen. Flash flooding is ongoing.

HAZARD...Flash flooding caused by thunderstorms.

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...
  Litchfield, Hillsboro, Carlinville, Staunton, Pittsfield, 
  Gillespie, White Hall, Carrollton, Mount Olive, Roodhouse, Benld, 
  Greenfield, Pleasant Hill, Palmyra, Taylor Springs, Coffeen, 
  Shipman, Wilsonville, Schram City and Athensville.

This includes the following State Parks...
	Beaver Dam State Park and Lake Lou Yaeger.

This includes the following highways...
	Interstate 55 in Illinois between exits 41 and 60.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3941 9095 3961 9088 3954 9057 3952 9058
      3949 9011 3928 8959 3910 8925 3904 8927
      3900 8970 3928 9071

FLASH FLOOD...OBSERVED

$$

KD

889 
WGUS73 KLSX 311741
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
1241 PM CDT Sat Jul 31 2021

ILC005-013-061-083-117-135-149-311751-
/O.EXP.KLSX.FF.W.0035.000000T0000Z-210731T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Bond IL-Calhoun IL-Greene IL-Jersey IL-Macoupin IL-Montgomery IL-
Pike IL-
1241 PM CDT Sat Jul 31 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1245 PM CDT THIS AFTERNOON FOR 
NORTH CENTRAL BOND AND SOUTHERN MONTGOMERY COUNTIES IN SOUTH CENTRAL 
ILLINOIS, NORTH CENTRAL CALHOUN, GREENE, NORTHEASTERN JERSEY AND 
MACOUPIN COUNTIES IN SOUTHWESTERN ILLINOIS AND SOUTHEASTERN PIKE 
COUNTY IN WEST CENTRAL 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 3941 9095 3961 9088 3954 9057 3952 9058
      3949 9011 3928 8959 3910 8925 3904 8927
      3900 8970 3928 9071

$$

KD

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 31, 9:53 AM CDT	Areal Flood Advisory	LSX	Bond, Fayette, Madison, Marion, Montgomery	3 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.