Alert archive / Missouri / Flash Flood Warnings in 2020

Flash Flood Warning 53, NWS St. Louis, MO

August 9, 2020Saint Charles County, Missouri; Calhoun County, Illinois

NWS St. Louis, MO issued this flash flood warning at Aug 9, 2020, 12:01 AM CDT for Saint Charles County, Missouri; Calhoun County, Illinois. It was in force for 6 hr. 12 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 9, 2020, 12:01 AM CDT (05:01 UTC)
Expired
Aug 9, 2020, 6:00 AM CDT
In force
6 hr
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Flood severity
None

Counties Calhoun County, IL, Saint Charles County, MO

The radar

The St Louis radar (KLSX), 17 km from the middle of the area, began a volume at 05:00 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 9, 12:03 AM CDTFLASH FLOOD2 Nne Saint Paul, MOHIGHWAY 79 AT VOMUND ROAD IS CLOSED DUE TO ABOUT A FOOT OF WATER OVER THE HIGHWAY.
Aug 9, 12:11 AM CDTFLASH FLOOD2 N Saint Paul, MOVEHICLE IN FLOOD WATER AT HIGHWAY Y AND VOMUND RD. OCCUPANT ON TOP OF VEHICLE.
Aug 9, 12:15 AM CDTFLASH FLOODO'Fallon, MOVEHICLE IN FLOOD WATER ON MEXICO RD. BETWEEN COLLIER BLVD. AND WINTER HAVEN DR.
Aug 9, 12:20 AM CDTFLASH FLOOD1 Nw Dardenne Prairie, MOVEHICLE IN FLOOD WATER AT WINGHAVEN BLVD. AND HIGHWAY N. WATER UP TO DOORS OF VEHICLE.
Aug 9, 1:00 AM CDTFLASH FLOOD2 Ene O'Fallon, MOVIA TWITTER WITH PICTURE. BELLEAU CREEK OUT OF BANKS AND OVER BELLEAU CREEK ROAD JUST SOUTH OF INTERSECTION WITH VETERANS MEMORIAL PARKWAY. TWO CARS STUCK IN FLOOD WATERS THERE.
Aug 9, 1:00 AM CDTFLASH FLOOD3 Ene Saint Charles, MOFLOODING OF APARTMENT COMPLEX NEAR RIVERVIEW LANE AND HIGHWAY 94. WATER SEVERAL FEET DEEP STRANDED CARS AND RESULTED IN EVACUATION OF 12 UNITS. TIME ESTIMATED.
Aug 9, 1:00 AM CDTFLASH FLOOD3 Ene Saint Charles, MOROAD FLOODED NEAR RIVERVIEW LANE AND HIGHWAY 94. SEVERAL CARS STUCK IN FLOOD WATERS.
Aug 9, 1:17 AM CDTFLOOD2 Ese Dardenne Prairie, MOCORRECTS PREVIOUS FLOOD REPORT FROM 2 ESE DARDENNE PRAIRIE. THE SMALL STREAM GAUGE ON DARDENNE CREEK AT DCWM7 ROSE ABOVE FLOOD STAGE (14 FEET) AT 117 AM AND PEAKED AT 16.06 FEET AT 240 AM.
Aug 9, 1:30 AM CDTHEAVY RAIN 3.891 Sse Saint Paul, MORAINFALL SO FAR.
Aug 9, 3:00 AM CDTFLOOD2 Nw Saint Peters, MOFLOODING OF SPORTS CENTER PARK IN ST. PETERS DUE TO FLOODING OF DARDENNE CREEK. TIME ESTIMATED.
Aug 9, 4:00 AM CDTHEAVY RAIN 3.32 Ese Dardenne Prairie, MOSTORM TOTAL RAINFALL AT DCWM7 RIVER GAGE ON DARDENNE CREEK.
Aug 9, 6:00 AM CDTHEAVY RAIN 3.972 Wsw Weldon Spring, MO24 HOUR RAINFALL TOTAL, MOST OF IT FELL AFTER MIDNIGHT.

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, 5.0 hours before the alert went out and 227 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 00:00Z on 2020-08-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1146 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 00:00Z on 2020-08-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 31 square meters per square second.1939Sfc1 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
1146 J/kg
Mixed-layer CIN
-15 J/kg
Mixed-layer LCL
1029 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
31 m²/s²
0-3 km storm-relative helicity
25 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

776 
WGUS53 KLSX 090501
FFWLSX
ILC013-MOC183-091100-
/O.NEW.KLSX.FF.W.0053.200809T0501Z-200809T1100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
1201 AM CDT Sun Aug 9 2020

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Southeastern Calhoun County in southwestern Illinois...
  Western St. Charles County in east central Missouri...

* Until 600 AM CDT.

* At 1200 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to 4 inches of rain have 
  fallen so far. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar indicated.

  IMPACT...Flooding of small creeks and streams, urban areas, 
           highways, streets and underpasses as well as other 
           drainage and low lying areas.

* Some locations that will experience flooding include...
  O'Fallon, St. Charles, St. Peters, Chesterfield, Wentzville,
  Hazelwood, Lake St. Louis, Dardenne Prairie, Weldon Spring,
  Cottleville, St. Paul, Josephville, Weldon Spring Heights,
  Harvester, Orchard Farms, Flint Hill, Brussels, Deer Plain,
  Kampville and Golden Eagle.

This also includes First Missouri State Capitol Historic Site.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 3891 9045 3883 9043 3880 9047 3876 9049
      3873 9053 3869 9054 3868 9063 3869 9066
      3862 9076 3889 9096 3887 9082 3892 9079
      3893 9073 3891 9072 3892 9071 3892 9069
      3893 9070 3893 9067 3895 9067 3897 9055

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

$$

Byrd
2 follow-up statements
048 
WGUS73 KLSX 090903
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
403 AM CDT Sun Aug 9 2020

ILC013-MOC183-091100-
/O.CON.KLSX.FF.W.0053.000000T0000Z-200809T1100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Calhoun IL-St. Charles MO-
403 AM CDT Sun Aug 9 2020

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 600 AM CDT FOR
SOUTHEASTERN CALHOUN AND WESTERN ST. CHARLES COUNTIES...

At 401 AM CDT, trained weather spotters reported flash flooding in 
numerous locations including Belleau Creek just south of Veterans 
Memorial Parkway and Interstate 70 in O'Fallon. Up to 6 inches of 
rain have fallen. Flash flooding is already occurring. Even though 
the rain has tapered off flash flooding will continue.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Trained weather spotters.

IMPACT...Flooding of small creeks and streams, urban areas, 
         highways, streets and underpasses as well as other drainage 
         and low lying areas.

Some locations that will experience flooding include...
O'Fallon, St. Charles, St. Peters, Chesterfield, Wentzville,
Hazelwood, Lake St. Louis, Dardenne Prairie, Weldon Spring,
Cottleville, St. Paul, Josephville, Weldon Spring Heights, Harvester,
Orchard Farms, Flint Hill, Brussels, Deer Plain, Kampville and Golden
Eagle.

This also includes First Missouri State Capitol Historic Site.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

&&

LAT...LON 3891 9045 3883 9043 3880 9047 3876 9049
      3873 9053 3869 9054 3868 9063 3869 9066
      3862 9076 3889 9096 3887 9082 3892 9079
      3893 9073 3891 9072 3892 9071 3892 9069
      3893 9070 3893 9067 3895 9067 3897 9055

FLASH FLOOD...OBSERVED

$$

Byrd
434 
WGUS73 KLSX 091100
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
600 AM CDT Sun Aug 9 2020

ILC013-MOC183-091110-
/O.EXP.KLSX.FF.W.0053.000000T0000Z-200809T1100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Calhoun IL-St. Charles MO-
600 AM CDT Sun Aug 9 2020

...THE FLASH FLOOD WARNING FOR SOUTHEASTERN CALHOUN AND WESTERN ST.
CHARLES COUNTIES HAS EXPIRED...

Flood waters have receded. Flooding is no longer expected to pose a
threat. Please continue to heed any remaining road closures.

LAT...LON 3891 9045 3883 9043 3880 9047 3876 9049
      3873 9053 3869 9054 3868 9063 3869 9066
      3862 9076 3889 9096 3887 9082 3892 9079
      3893 9073 3891 9072 3892 9071 3892 9069
      3893 9070 3893 9067 3895 9067 3897 9055

$$

Byrd

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 8, 10:50 PM CDTAreal Flood AdvisoryLSXLincoln, Pike6 hr
Aug 8, 11:03 PM CDTFlash Flood WarningLSXLincoln, Pike6 hr
Aug 9, 12:56 AM CDTAreal Flood AdvisoryLSXSaint Louis3 hr
Aug 9, 1:15 AM CDTRiver Flood WarningLSXSaint Charles22 hr
Aug 9, 1:25 AM CDTFlash Flood WarningLSXSaint Louis6 hr
Aug 9, 2:27 AM CDTAreal Flood AdvisoryLSXSaint Charles, Warren4 hr
Aug 9, 2:41 AM CDTFlash Flood WarningLSXJefferson, Saint Louis, City of Saint Louis6 hr
Aug 9, 3:54 AM CDTAreal Flood AdvisoryLSXFranklin, Gasconade4 hr
Aug 9, 7:29 AM CDTAreal Flood WarningLSXSaint Louis3 hr
Aug 9, 1:54 PM CDTHeat AdvisoryLSXFranklin, Iron, Jefferson, Lincoln, Madison, Reynolds and 7 more29 hr
Aug 9, 9:55 AM CDTAreal Flood AdvisoryLSXMadison, Saint Clair3 hr
Aug 9, 10:06 AM CDTFlash Flood WarningLSXMadison4 hr
Aug 9, 10:23 AM CDTFlash Flood WarningLSXSaint Clair4 hr
Aug 9, 2:07 PM CDTAreal Flood WarningLSXSaint Clair3 hr

Nearby

Flash Flood Warnings in Missouri, 2020Flash Flood Warnings in Illinois, 2020Every flash flood warning in 2020

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.