Alert archive / Illinois / Flash Flood Warnings in 2021

Flash Flood Warning 31, NWS St. Louis, MO

July 16, 2021Washington County, Illinois

NWS St. Louis, MO issued this flash flood warning at Jul 16, 2021, 1:41 PM CDT for Washington County, Illinois. It was in force for 6 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 16, 2021, 1:41 PM CDT (18:41 UTC)
Expired: Jul 16, 2021, 7:30 PM CDT
In force: 6 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Flood severity: None

County Washington County, IL

The radar

The St Louis radar (KLSX), 110 km from the middle of the area, began a volume at 18:41 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 16, 4:05 PM CDT	FLASH FLOOD	Nashville, IL	FLASH FLOODING OBSERVED IN NASHVILLE MEMORIAL PARK. WATER COVERING ROADS.
Jul 16, 4:34 PM CDT	FLASH FLOOD	1 Ne Richview, IL	REPORT FROM MPING: RIVER/CREEK OVERFLOWING; CROPLAND/YARD/BASEMENT FLOODING.

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, 6.7 hours before the alert went out and 210 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: 139 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 541 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 14 m²/s²
0-3 km storm-relative helicity: 44 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

083 
WGUS53 KLSX 161841
FFWLSX
ILC189-170030-
/O.NEW.KLSX.FF.W.0031.210716T1841Z-210717T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
141 PM CDT Fri Jul 16 2021

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Washington County in south central Illinois...

* Until 730 PM CDT.

* At 141 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 4 inches of rain 
  have fallen. The expected rainfall rate is 2 to 3 inches in 1 
  hour. 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...
  Nashville, Okawville, Wamac, Lively Grove, Irvington, Ashley, 
  Posen, Beaucoup, Hoyleton, Johannisburg, Covington, Richview, 
  Addieville, Oakdale, Radom, New Minden, Du Bois, Venedy, Cordes 
  and Huegely.

This includes the following highways...
	Interstate 64 in Illinois between exits 41 and 61.

Thunderstorms with heavy rain are moving over ground which is 
already saturated. Expect immediate runoff, especially in southern 
and eastern portions of the county.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3822 8970 3842 8970 3847 8961 3848 8952
      3847 8948 3851 8935 3850 8914 3821 8915

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...2-3 INCHES IN 1 HOUR

$$

Carney

1 follow-up statement

724 
WGUS73 KLSX 162131
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
431 PM CDT Fri Jul 16 2021

ILC189-170030-
/O.CON.KLSX.FF.W.0031.000000T0000Z-210717T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washington IL-
431 PM CDT Fri Jul 16 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 730 PM CDT THIS 
EVENING FOR WASHINGTON COUNTY IN SOUTH CENTRAL ILLINOIS...

At 431 PM CDT, Local law enforcement reported flash flooding across 
much of the county. Between 3 and 5 inches of rain have fallen. The 
expected rainfall rate is 2 to 3 inches in 1 hour. Flash flooding is 
already occurring.

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...
  Nashville, Okawville, Wamac, Lively Grove, Irvington, Ashley, 
  Posen, Beaucoup, Hoyleton, Johannisburg, Covington, Richview, 
  Addieville, Oakdale, Radom, New Minden, Du Bois, Venedy, Cordes 
  and Huegely.

This includes the following highways...
	Interstate 64 in Illinois between exits 41 and 61.

Another broken line of thunderstorms will move through Washington 
County through 600 PM.  Additional heavy rain and flash flooding is 
possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3822 8970 3842 8970 3847 8961 3848 8952
      3847 8948 3851 8935 3850 8914 3821 8915

FLASH FLOOD...OBSERVED
EXPECTED RAINFALL...2-3 INCHES IN 1 HOUR

$$

Carney

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 15, 9:10 PM CDT	Areal Flood Advisory	LSX	Madison, Monroe, Saint Clair	3 hr
Jul 15, 11:04 PM CDT	Areal Flood Advisory	LSX	Randolph	3 hr
Jul 15, 11:22 PM CDT	Flash Flood Warning	LSX	Randolph	5 hr
Jul 16, 6:15 AM CDT	Areal Flood Advisory	LSX	Randolph, Saint Clair, Washington	4 hr
Jul 16, 1:19 PM CDT	Areal Flood Advisory	LSX	Washington	28 min
Jul 16, 2:57 PM CDT	Areal Flood Advisory	LSX	Marion	4 hr
Jul 16, 3:01 PM CDT	Areal Flood Advisory	LSX	Randolph	4 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.