Alert archive / Illinois / Flash Flood Warnings in 2021

Flash Flood Warning 2, NWS St. Louis, MO

April 29, 2021Monroe County, Illinois; Jefferson County, Missouri

NWS St. Louis, MO issued this flash flood warning at Apr 29, 2021, 2:27 AM CDT for Monroe County, Illinois; Jefferson County, Missouri. It was in force for 4 hr. 3 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: Apr 29, 2021, 2:27 AM CDT (07:27 UTC)
Expired: Apr 29, 2021, 6:08 AM CDT
In force: 4 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Flood severity: None

Counties Monroe County, IL, Jefferson County, MO

The radar

The St Louis radar (KLSX), 58 km from the middle of the area, began a volume at 07:28 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
Apr 29, 3:00 AM CDT	FLOOD	1 Nw Hillsboro, MO	DEBRIS ON HIGHWAY BB NEAR DYES DRIVE DUE TO FLOODING.
Apr 29, 3:00 AM CDT	FLASH FLOOD	1 Nw Festus, MO	DELAYED REPORTS FROM SOCIAL MEDIA. CRITES MEMORIAL PARK FLOODED DUE TO FLOODING FROM JOACHIM CREEK.
Apr 29, 4:17 AM CDT	HEAVY RAIN 2.09	2 Nne Mapaville, MO	APRSWXNET/CWOP.

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, 7.5 hours before the alert went out and 271 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: 145 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 1042 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 98 m²/s²
0-3 km storm-relative helicity: 176 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

As transmitted.

329 
WGUS53 KLSX 290727
FFWLSX
ILC133-MOC099-291130-
/O.NEW.KLSX.FF.W.0002.210429T0727Z-210429T1130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
227 AM CDT Thu Apr 29 2021

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Southwestern Monroe County in southwestern Illinois...
  Central Jefferson County in east central Missouri...

* Until 630 AM CDT.

* At 227 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 3 inches of rain 
  have fallen. 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...
  Festus, Waterloo, Pevely, Crystal City, Herculaneum, Hillsboro, 
  Valmeyer, Olympian Village, Horine, Maeystown, Fults, 
  Harrisonville, Chalfin Bridge, Monroe City, Madonnaville, 
  Hematite, Mapaville, Foster Pond, Wartburg and Burksville.

This includes the following State Parks...
	Gov. Dunklin's Grave Historic Site.

This includes the following highways...
	Interstate 55 in Missouri between exits 170 and 180.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3810 9045 3821 9051 3822 9072 3822 9078
      3824 9068 3824 9069 3836 9020 3818 9011
      3814 9026

FLASH FLOOD...RADAR INDICATED

$$

Glass

2 follow-up statements

273 
WGUS73 KLSX 290832
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
332 AM CDT Thu Apr 29 2021

ILC133-MOC099-291130-
/O.CON.KLSX.FF.W.0002.000000T0000Z-210429T1130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Monroe IL-Jefferson MO-
332 AM CDT Thu Apr 29 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 AM CDT THIS 
MORNING FOR SOUTHWESTERN MONROE COUNTY IN SOUTHWESTERN ILLINOIS AND 
CENTRAL JEFFERSON COUNTY IN EAST CENTRAL MISSOURI...

At 332 AM CDT, Doppler radar indicated showers continued across the 
warned area. Thunderstorms which moved across the area earlier this 
morning have produced between 2 and 3 inches of rain. 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...
  Festus, Waterloo, Pevely, Crystal City, Herculaneum, Hillsboro, 
  Valmeyer, Olympian Village, Horine, Maeystown, Fults, 
  Harrisonville, Chalfin Bridge, Monroe City, Madonnaville, 
  Hematite, Mapaville, Foster Pond, Wartburg and Burksville.

This includes the following State Parks...
	Gov. Dunklin's Grave Historic Site.

This includes the following highways...
	Interstate 55 in Missouri between exits 170 and 180.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3810 9045 3821 9051 3822 9072 3822 9078
      3824 9068 3824 9069 3836 9020 3818 9011
      3814 9026

FLASH FLOOD...RADAR INDICATED

$$

Glass

542 
WGUS73 KLSX 291108
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
608 AM CDT Thu Apr 29 2021

ILC133-MOC099-291118-
/O.CAN.KLSX.FF.W.0002.000000T0000Z-210429T1130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Monroe IL-Jefferson MO-
608 AM CDT Thu Apr 29 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHWESTERN MONROE COUNTY 
IN SOUTHWESTERN ILLINOIS AND CENTRAL JEFFERSON COUNTY IN EAST 
CENTRAL MISSOURI...

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 3810 9045 3821 9051 3822 9072 3822 9078
      3824 9068 3824 9069 3836 9020 3818 9011
      3814 9026

$$

Glass

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 29, 1:49 AM CDT	Flash Flood Warning	LSX	Crawford, Jefferson, Washington	4 hr
Apr 29, 2:53 AM CDT	River Flood Warning	LSX	Crawford, Washington	42 hr
Apr 29, 9:35 AM CDT	River Flood Warning	LSX	Lincoln	12 hr
Apr 29, 9:44 AM CDT	River Flood Warning	LSX	Jefferson	30 hr

Nearby

Flash Flood Warnings in Illinois, 2021 Flash Flood Warnings in Missouri, 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.