Alert archive / Missouri / Flash Flood Warnings in 2020

Flash Flood Warning 8, NWS St. Louis, MO

May 17, 2020Saint Charles County, Saint Louis County, Missouri; Jersey County, Madison County, Illinois

NWS St. Louis, MO issued this flash flood warning at May 17, 2020, 2:02 AM CDT for Saint Charles County, Saint Louis County, Missouri; Jersey County, Madison County, Illinois. It was in force for 5 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
May 17, 2020, 2:02 AM CDT (07:02 UTC)
Expired
May 17, 2020, 7:00 AM CDT
In force
5 hr
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Flood severity
None

Counties Jersey County, IL, Madison County, IL, Saint Charles County, MO, Saint Louis County, MO

The radar

The St Louis radar (KLSX), 39 km from the middle of the area, began a volume at 07:04 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

Davenport, (KDVN), launched 00:00Z, 7.0 hours before the alert went out and 308 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, Davenport, at 00:00Z on 2020-05-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 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, Davenport, at 00:00Z on 2020-05-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 136 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1150 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
136 m²/s²
0-3 km storm-relative helicity
285 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

677 
WGUS53 KLSX 170702
FFWLSX
ILC083-119-MOC183-189-171200-
/O.NEW.KLSX.FF.W.0008.200517T0702Z-200517T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
202 AM CDT Sun May 17 2020

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Northwestern Madison County in southwestern Illinois...
  Southeastern Jersey County in southwestern Illinois...
  Northeastern St. Charles County in east central Missouri...
  Northern St. Louis County in east central Missouri...

* Until 700 AM CDT.

* At 200 AM CDT, Doppler radar indicated showers and thunderstorms 
  producing heavy rain across the warned area. Up to two inches of 
  rain have already fallen. Flash flooding is ongoing or expected to 
  begin shortly.

  HAZARD...Flash flooding caused by showers and 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...
  St. Louis, St. Charles, St. Peters, Florissant, Chesterfield,
  Granite City, Alton, Maryland Heights, Hazelwood, Edwardsville,
  Ferguson, Godfrey, Creve Coeur, Overland, Jennings, St. Ann,
  Bridgeton, Bellefontaine Neighbors, Town and Country and Wood
  River.

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

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

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 3872 9021 3877 9017 3877 9018 3874 9020
      3871 9025 3863 9062 3889 9053 3897 9045
      3896 9050 3908 9046 3916 9015 3900 9015
      3900 9010 3877 9001

FLASH FLOOD...RADAR INDICATED

$$

GKS
1 follow-up statement
222 
WGUS73 KLSX 171201
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
701 AM CDT Sun May 17 2020

ILC083-119-MOC183-189-171211-
/O.EXP.KLSX.FF.W.0008.000000T0000Z-200517T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Madison IL-Jersey IL-St. Charles MO-St. Louis MO-
701 AM CDT Sun May 17 2020

...THE FLASH FLOOD WARNING FOR NORTHWESTERN MADISON AND SOUTHEASTERN
JERSEY COUNTIES IN SOUTHWESTERN ILLINOIS...NORTHEASTERN ST. CHARLES
AND NORTHERN ST. LOUIS COUNTIES IN EAST CENTRAL MISSOURI HAS
EXPIRED...

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 3872 9021 3877 9017 3877 9018 3874 9020
      3871 9025 3863 9062 3889 9053 3897 9045
      3896 9050 3908 9046 3916 9015 3900 9015
      3900 9010 3877 9001

$$

GKS

The office that day

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

IssuedProductOfficeCountiesLasted
May 16, 7:50 PM CDTAreal Flood AdvisoryLSXJefferson, Saint Louis3 hr
May 16, 8:32 PM CDTRiver Flood WarningLSXGasconade, Montgomery3 days
May 16, 8:58 PM CDTFlash Flood WatchLSXCrawford, Franklin, Iron, Jefferson, Lincoln, Madison and 8 more21 hr
May 16, 9:14 PM CDTRiver Flood WarningLSXSaint Charles5 days
May 16, 9:14 PM CDTRiver Flood WarningLSXPerry, Sainte Genevieve32 days
May 16, 9:19 PM CDTRiver Flood WarningLSXJefferson, Saint Louis7 days
May 17, 1:36 AM CDTAreal Flood AdvisoryLSXFranklin, Lincoln, Saint Charles, Saint Louis, City of Saint Louis6 hr
May 17, 4:39 AM CDTAreal Flood AdvisoryLSXSainte Genevieve, Saint Francois6 hr
May 17, 8:45 AM CDTRiver Flood WarningLSXPike51 hr
May 17, 9:51 AM CDTRiver Flood WarningLSXGasconade, Montgomery49 hr
May 17, 10:35 AM CDTRiver Flood WarningLSXCrawford, Washington48 hr
May 17, 2:15 PM CDTRiver Flood WarningLSXReynolds29 hr
May 17, 3:32 AM CDTAreal Flood AdvisoryLSXCalhoun, Greene, Jersey, Macoupin12 hr
May 17, 11:31 AM CDTRiver Flood WarningLSXBrown33 hr
May 17, 12:26 PM CDTRiver Flood WarningLSXFayette4 days
May 17, 3:29 PM CDTAreal Flood AdvisoryLSXCalhoun, Greene, Jersey, Macoupin6 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.