Alert archive / Missouri / Flash Flood Warnings in 2018

Flash Flood Warning 29, NWS St. Louis, MO

August 10, 2018Madison County, Illinois; Saint Louis County, City of Saint Louis, Missouri

NWS St. Louis, MO issued this flash flood warning at Aug 10, 2018, 4:48 PM CDT for Madison County, Illinois; Saint Louis County, City of Saint Louis, Missouri. It was in force for 2 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: Aug 10, 2018, 4:48 PM CDT (21:48 UTC)
Expired: Aug 10, 2018, 6:56 PM CDT
In force: 2 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Flood severity: None

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

The radar

The St Louis radar (KLSX), 40 km from the middle of the area, began a volume at 21:51 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 12:00Z, 9.8 hours before the alert went out and 213 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: 31 J/kg
Mixed-layer CIN: -173 J/kg
Mixed-layer LCL: 1757 m above ground
0-6 km bulk shear: 7 kt
0-1 km storm-relative helicity: 97 m²/s²
0-3 km storm-relative helicity: 98 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

The text

As transmitted.

460 
WGUS53 KLSX 102148
FFWLSX
ILC119-MOC189-510-110045-
/O.NEW.KLSX.FF.W.0029.180810T2148Z-180811T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
448 PM CDT FRI AUG 10 2018

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Southwestern Madison County in southwestern Illinois...
  Central St. Louis City in east central Missouri...
  East central St. Louis County in east central Missouri...

* Until 745 PM CDT.

* At 447 PM CDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Up to three inches of rain have
  already fallen. Flash flooding is expected to begin shortly.

* Some locations that will experience flooding include...
  St. Louis, University City, Granite City, Maryland Heights,
  Hazelwood, Ferguson, Creve Coeur, Overland, Jennings, St. Ann,
  Bridgeton, Bellefontaine Neighbors, Berkeley, Olivette, St. John,
  Pontoon Beach, Dellwood, Normandy, Northwoods and Woodson Terrace.

This includes Interstate 70 in Missouri near exit 231.
 
This also includes  Horseshoe Lake State Park.
 
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 3874 9004 3866 9015 3866 9018 3864 9018
      3869 9052 3878 9047

$$

GKS

1 follow-up statement

056 
WGUS73 KLSX 102356
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
656 PM CDT FRI AUG 10 2018

ILC119-MOC189-510-110005-
/O.CAN.KLSX.FF.W.0029.000000T0000Z-180811T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Madison IL-St. Louis City MO-St. Louis MO-
656 PM CDT FRI AUG 10 2018

...THE FLASH FLOOD WARNING FOR SOUTHWESTERN MADISON COUNTY IN
SOUTHWESTERN ILLINOIS AND EAST CENTRAL ST. LOUIS COUNTIES IN EAST
CENTRAL MISSOURI AND CENTRAL ST. LOUIS CITY IS CANCELLED...

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

LAT...LON 3874 9004 3866 9015 3866 9018 3864 9018
      3869 9052 3878 9047

$$

GKS

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 10, 4:02 PM CDT	Severe Thunderstorm Warning	LSX	Madison, Saint Clair	43 min
Aug 10, 4:40 PM CDT	Areal Flood Advisory	LSX	Madison, Saint Clair	2 hr
Aug 10, 3:48 PM CDT	Special Weather Statement	LSX	Saint Louis, City of Saint Louis	42 min
Aug 10, 4:11 PM CDT	Severe Thunderstorm Warning	LSX	Callaway, Gasconade, Montgomery, Osage	49 min
Aug 10, 4:56 PM CDT	Areal Flood Advisory	LSX	Callaway, Montgomery, Warren	2 hr
Aug 10, 4:59 PM CDT	Severe Thunderstorm Warning	LSX	Montgomery, Warren	46 min
Aug 10, 5:12 PM CDT	Special Weather Statement	LSX	Saint Louis	48 min
Aug 10, 5:56 PM CDT	Special Weather Statement	LSX	Jefferson	49 min
Aug 10, 6:52 PM CDT	Special Weather Statement	LSX	Washington	38 min

Nearby

Flash Flood Warnings in Missouri, 2018 Flash Flood Warnings in Illinois, 2018 Every flash flood warning in 2018

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.