Alert archive / Missouri / Flash Flood Warnings in 2020

Flash Flood Warning 9, NWS St. Louis, MO

May 24, 2020Jefferson County, Missouri

NWS St. Louis, MO issued this flash flood warning at May 24, 2020, 5:13 PM CDT for Jefferson County, Missouri. It was in force for 4 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
May 24, 2020, 5:13 PM CDT (22:13 UTC)
Expired
May 24, 2020, 9:15 PM CDT
In force
4 hr
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Flood severity
None

County Jefferson County, MO

The radar

The St Louis radar (KLSX), 62 km from the middle of the area, began a volume at 22:17 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
May 24, 6:06 PM CDTFLASH FLOOD1 Ne Victoria, MOCREEK OUT OF ITS BANKS AND OVER A ROADWAY NEAR ARGONNE ROAD AND HIGHWAY P.
May 24, 6:25 PM CDTFLASH FLOODVictoria, MOJOACHIM CREEK OUT OF ITS BANKS AND OVER HIGHWAY P.

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, 10.2 hours before the alert went out and 281 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 2020-05-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 489 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 2020-05-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -57 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
489 J/kg
Mixed-layer CIN
-186 J/kg
Mixed-layer LCL
1250 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
-57 m²/s²
0-3 km storm-relative helicity
-36 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

205 
WGUS53 KLSX 242213
FFWLSX
MOC099-250215-
/O.NEW.KLSX.FF.W.0009.200524T2213Z-200525T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
513 PM CDT Sun May 24 2020

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Southern Jefferson County in east central Missouri...

* Until 915 PM CDT.

* At 513 PM CDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. 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...
  Festus, De Soto, Pevely, Crystal City, Herculaneum, Hillsboro,
  Olympian Village, Horine, Hematite, Victoria, Fletcher and
  Mapaville.

Additional rainfall amounts of 1-2 inches are possible in the warned 
area.

This also includes Gov. Dunklin's Grave Historic Site.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report flooding to your local law enforcement agency when you
can do so safely.

&&

LAT...LON 3809 9065 3810 9066 3809 9067 3809 9068
      3810 9068 3820 9078 3821 9078 3832 9038
      3824 9036 3822 9035 3813 9033 3808 9066

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

$$

Gosselin
1 follow-up statement
634 
WGUS73 KLSX 242310
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
610 PM CDT Sun May 24 2020

MOC099-250215-
/O.CON.KLSX.FF.W.0009.000000T0000Z-200525T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Jefferson MO-
610 PM CDT Sun May 24 2020

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 PM CDT FOR
SOUTHERN JEFFERSON COUNTY...

At 609 PM CDT, the public reported thunderstorms producing 
flash flooding on Joachim Creek near Argonne Road and Highway P.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Public.

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...
Festus, De Soto, Pevely, Crystal City, Herculaneum, Hillsboro,
Olympian Village, Horine, Hematite, Victoria, Fletcher and Mapaville.

This also includes Gov. Dunklin's Grave Historic Site.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report flooding to your local law enforcement agency when you
can do so safely.

&&

LAT...LON 3809 9065 3810 9066 3809 9067 3809 9068
      3810 9068 3820 9078 3821 9078 3832 9038
      3824 9036 3822 9035 3813 9033 3808 9066

FLASH FLOOD...OBSERVED

$$

Gosselin

The office that day

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

IssuedProductOfficeCountiesLasted
May 24, 3:54 PM CDTSevere Thunderstorm WarningLSXKnox51 min
May 24, 4:08 PM CDTSevere Thunderstorm WarningLSXKnox, Lewis52 min
May 24, 4:31 PM CDTSevere Thunderstorm WarningLSXFranklin, Saint Charles, Warren30 min
May 24, 5:18 PM CDTSevere Thunderstorm WarningLSXLewis42 min
May 24, 5:25 PM CDTAreal Flood AdvisoryLSXKnox, Lewis3 hr
May 24, 5:44 PM CDTSevere Thunderstorm WarningLSXLewis46 min
May 24, 6:22 PM CDTFlash Flood WarningLSXPike, Ralls5 hr
May 24, 6:55 PM CDTSevere Thunderstorm WarningLSXPike, Ralls22 min

Nearby

Flash Flood Warnings in Missouri, 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.