Alert archive / Missouri / Flash Flood Warnings in 2021

Flash Flood Warning 40, NWS St. Louis, MO

August 30, 2021Saint Louis County, City of Saint Louis, Missouri; Madison County, Saint Clair County, Illinois

NWS St. Louis, MO issued this flash flood warning at Aug 30, 2021, 2:54 PM CDT for Saint Louis County, City of Saint Louis, Missouri; Madison County, Saint Clair County, Illinois. It was in force for 3 hr. 7 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
Aug 30, 2021, 2:54 PM CDT (19:54 UTC)
Expired
Aug 30, 2021, 6:00 PM CDT
In force
3 hr
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Flood severity
None

Counties Madison County, IL, Saint Clair County, IL, City of Saint Louis, MO, Saint Louis County, MO

The radar

The St Louis radar (KLSX), 37 km from the middle of the area, began a volume at 19:54 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

TimeReportWhereRemark
Aug 30, 3:00 PM CDTHEAVY RAIN 2.61 Sse Saint Louis, MO2.6 INCHES OF RAIN OVER THE PAST HOUR.
Aug 30, 3:15 PM CDTHEAVY RAIN 1.51Crestwood, MO1.5 INCHES OF WATER FELL IN CRESTWOOD OVER THE COURSE OF 1 HOUR.
Aug 30, 3:20 PM CDTFLASH FLOOD1 Ene Glendale, MOMOVING WATER COVERING THE ROADWAY, VIDEO SHOWS WATER APPROXIMATELY 6 INCHES DEEP.
Aug 30, 3:23 PM CDTFLASH FLOODSaint Louis, MOWATER COVERING THE ROADWAY AT THE 3900 BLOCK OF LINDELL BLVD.
Aug 30, 3:30 PM CDTFLASH FLOOD2 E Saint Louis, MOPICTURE OF AROUND TWO FEET OF WATER UP TO THE FRONT DOORS OF KIPP HIGH SCHOOL.
Aug 30, 3:46 PM CDTFLASH FLOOD1 Se Saint Louis, MOVIDEO SHOWING SEVERAL FEET OF WATER INUNDATING AN EXTENDED PORTION OF CHOUTEAU AVE.
Aug 30, 4:25 PM CDTHEAVY RAIN 1.572 Ssw Saint Louis, MO1.57 INCHES OF STORM TOTAL RAINFALL MEASURED AT MO BOTANICAL GARDENS (MBGM7) SO FAR.

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, 7.9 hours before the alert went out and 236 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-pSkew-T log-p diagram, Lincoln, IL at 12:00Z on 2021-08-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 295 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 12:00Z on 2021-08-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 47 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
-140 J/kg
Mixed-layer LCL
983 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
47 m²/s²
0-3 km storm-relative helicity
62 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.7

Open this sounding in Storm Lab

The text

As transmitted.

864 
WGUS53 KLSX 301954
FFWLSX
ILC119-163-MOC189-510-302300-
/O.NEW.KLSX.FF.W.0040.210830T1954Z-210830T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
254 PM CDT Mon Aug 30 2021

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Southwestern Madison County in southwestern Illinois...
  Northwestern Saint Clair County in southwestern Illinois...
  South Central Saint Louis County in east central Missouri...
  Saint Louis City in east central Missouri...

* Until 600 PM CDT.

* At 254 PM 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...
  St. Louis, University City, Granite City, Kirkwood, East St. 
  Louis, Collinsville, Webster Groves, Arnold, Clayton, Cahokia, 
  Crestwood, Richmond Heights, Ladue, Sunset Hills, Des Peres, 
  Brentwood, Maplewood, Valley Park, Shrewsbury and Glendale.

This includes the following State Parks...
	Scott Joplin Historic Site and Horseshoe Lake State Park.

This includes the following highways...
	Interstate 44 in Missouri between exits 276 and 277.

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 3841 9032 3843 9035 3844 9035 3845 9034
      3846 9036 3845 9038 3848 9042 3848 9041
      3849 9041 3850 9041 3850 9046 3852 9048
      3861 9043 3879 9010 3864 9005 3849 9023
      3852 9026 3844 9029

FLASH FLOOD...RADAR INDICATED

$$

KD
2 follow-up statements
733 
WGUS73 KLSX 302022
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
322 PM CDT Mon Aug 30 2021

ILC119-163-MOC189-510-302300-
/O.CON.KLSX.FF.W.0040.000000T0000Z-210830T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Madison IL-Saint Clair IL-Saint Louis MO-Saint Louis City MO-
322 PM CDT Mon Aug 30 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 6 PM CDT THIS EVENING 
FOR SOUTHWESTERN MADISON AND NORTHWESTERN SAINT CLAIR COUNTIES IN 
SOUTHWESTERN ILLINOIS, SOUTH CENTRAL SAINT LOUIS COUNTY IN EAST 
CENTRAL MISSOURI AND THE SAINT LOUIS CITY IN EAST CENTRAL MISSOURI...

At 322 PM CDT, The public reported 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...Public reported flash flooding in downtown St. Louis and
         in Webster Groves.

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...
  St. Louis, University City, Granite City, Kirkwood, East St. 
  Louis, Collinsville, Webster Groves, Arnold, Clayton, Cahokia, 
  Crestwood, Richmond Heights, Ladue, Sunset Hills, Des Peres, 
  Brentwood, Maplewood, Valley Park, Shrewsbury and Glendale.

This includes the following State Parks...
	Scott Joplin Historic Site and Horseshoe Lake State Park.

This includes the following highways...
	Interstate 44 in Missouri between exits 276 and 277.

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 3841 9032 3843 9035 3844 9035 3845 9034
      3846 9036 3845 9038 3848 9042 3848 9041
      3849 9041 3850 9041 3850 9046 3852 9048
      3861 9043 3879 9010 3864 9005 3849 9023
      3852 9026 3844 9029

FLASH FLOOD...OBSERVED

$$

KD
234 
WGUS73 KLSX 302251
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
551 PM CDT Mon Aug 30 2021

ILC119-163-MOC189-510-302301-
/O.EXP.KLSX.FF.W.0040.000000T0000Z-210830T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Madison IL-Saint Clair IL-Saint Louis MO-Saint Louis City MO-
551 PM CDT Mon Aug 30 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 6 PM CDT THIS EVENING FOR 
SOUTHWESTERN MADISON AND NORTHWESTERN SAINT CLAIR COUNTIES IN 
SOUTHWESTERN ILLINOIS, SOUTH CENTRAL SAINT LOUIS COUNTY IN EAST 
CENTRAL MISSOURI AND THE SAINT LOUIS CITY IN EAST CENTRAL MISSOURI...

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

LAT...LON 3841 9032 3843 9035 3844 9035 3845 9034
      3846 9036 3845 9038 3848 9042 3848 9041
      3849 9041 3850 9041 3850 9046 3852 9048
      3861 9043 3879 9010 3864 9005 3849 9023
      3852 9026 3844 9029

$$

19

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 30, 2:38 PM CDTAreal Flood AdvisoryLSXJefferson, Saint Louis, City of Saint Louis3 hr
Aug 30, 4:04 PM CDTAreal Flood AdvisoryLSXSaint Charles, Saint Louis3 hr
Aug 30, 1:53 PM CDTAreal Flood AdvisoryLSXFayette, Marion3 hr
Aug 30, 4:10 PM CDTAreal Flood AdvisoryLSXMontgomery3 hr
Aug 30, 5:40 PM CDTAreal Flood AdvisoryLSXRandolph3 hr
Aug 30, 6:22 PM CDTAreal Flood AdvisoryLSXClinton, Marion3 hr

Nearby

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