Alert archive / Missouri / Flash Flood Warnings in 2021

Flash Flood Warning 26, NWS St. Louis, MO

July 12, 2021Saint Charles County, Missouri

NWS St. Louis, MO issued this flash flood warning at Jul 12, 2021, 5:09 AM CDT for Saint Charles County, Missouri. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 12, 2021, 5:09 AM CDT (10:09 UTC)
Expired: Jul 12, 2021, 9:15 AM CDT
In force: 4 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Flood severity: None

County Saint Charles County, MO

The radar

The St Louis radar (KLSX), 13 km from the middle of the area, began a volume at 10:12 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.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 10.2 hours before the alert went out and 253 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: 460 J/kg
Mixed-layer CIN: -16 J/kg
Mixed-layer LCL: 553 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 78 m²/s²
0-3 km storm-relative helicity: 89 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

349 
WGUS53 KLSX 121009
FFWLSX
MOC183-121415-
/O.NEW.KLSX.FF.W.0026.210712T1009Z-210712T1415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
509 AM CDT Mon Jul 12 2021

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Southwestern Saint Charles County in east central Missouri...

* Until 915 AM CDT.

* At 509 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 3 inches of rain 
  have fallen. The expected rainfall rate is 2 to 3 inches in 1 
  hour. Additional rainfall amounts of 1 to 2 inches are possible in 
  the warned area. 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...
  Wildwood, New Melle, Defiance and Matson.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 3874 9096 3875 9078 3866 9069 3866 9070
      3865 9071 3864 9074 3860 9076 3859 9078
      3859 9079 3859 9091 3857 9096

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

$$

Gosselin

1 follow-up statement

029 
WGUS73 KLSX 121115 RRA
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
615 AM CDT Mon Jul 12 2021

MOC183-121415-
/O.CON.KLSX.FF.W.0026.000000T0000Z-210712T1415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Saint Charles MO-
615 AM CDT Mon Jul 12 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 AM CDT THIS 
MORNING FOR SOUTHWESTERN SAINT CHARLES COUNTY...

At 615 AM CDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 2 and 4 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...
  Wildwood, New Melle, Defiance and Matson.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 3874 9096 3875 9078 3866 9069 3866 9070
      3865 9071 3864 9074 3860 9076 3859 9078
      3859 9079 3859 9091 3857 9096

FLASH FLOOD...RADAR INDICATED

$$

Gosselin

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 11, 8:05 PM CDT	River Flood Warning	LSX	Lewis	58 hr
Jul 12, 1:42 AM CDT	Areal Flood Advisory	LSX	Franklin	5 hr
Jul 12, 3:46 AM CDT	Areal Flood Advisory	LSX	Warren	40 min
Jul 12, 4:26 AM CDT	Flash Flood Warning	LSX	Warren	4 hr
Jul 12, 5:56 AM CDT	Areal Flood Advisory	LSX	Callaway, Gasconade, Osage	5 hr
Jul 12, 1:12 PM CDT	Areal Flood Advisory	LSX	Lincoln	3 hr
Jul 12, 2:14 PM CDT	Flash Flood Warning	LSX	Lincoln, Montgomery	4 hr
Jul 12, 6:27 PM CDT	Areal Flood Advisory	LSX	Pike	3 hr

Nearby

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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.