Alert archive / Illinois / Flash Flood Warnings in 2018

Flash Flood Warning 42, NWS St. Louis, MO

September 7, 2018Monroe County, Randolph County, Saint Clair County, Illinois; Jefferson County, Sainte Genevieve County, Missouri

NWS St. Louis, MO issued this flash flood warning at Sep 7, 2018, 8:34 PM CDT for Monroe County, Randolph County, Saint Clair County, Illinois; Jefferson County, Sainte Genevieve County, Missouri. It was in force for 5 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
Sep 7, 2018, 8:34 PM CDT (01:34 UTC)
Expired
Sep 8, 2018, 1:40 AM CDT
In force
5 hr
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Flood severity
None

Counties Monroe County, IL, Randolph County, IL, Saint Clair County, IL, Jefferson County, MO, Sainte Genevieve County, MO

The radar

The St Louis radar (KLSX), 77 km from the middle of the area, began a volume at 01:36 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
Sep 7, 9:10 PM CDTFLASH FLOODHecker, ILWATER OVER HIGHWAY 159 AND 156.
Sep 7, 9:10 PM CDTFLASH FLOODSmithton, ILFLOODING ALONG HIGHWAY 159 THROUGH SMITHTON.

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, 1.6 hours before the alert went out and 244 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 2018-09-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 32 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 2018-09-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -26 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
32 J/kg
Mixed-layer CIN
-22 J/kg
Mixed-layer LCL
547 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
-26 m²/s²
0-3 km storm-relative helicity
-43 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

588 
WGUS53 KLSX 080134
FFWLSX
ILC133-157-163-MOC099-186-080730-
/O.NEW.KLSX.FF.W.0042.180908T0134Z-180908T0730Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
834 PM CDT FRI SEP 7 2018

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Monroe County in southwestern Illinois...
  Northern Randolph County in southwestern Illinois...
  Southern St. Clair County in southwestern Illinois...
  Eastern Jefferson County in east central Missouri...
  Northern Ste. Genevieve County in southeastern Missouri...

* Until 230 AM CDT.

* At 831 PM CDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Up to three inches of rain have 
  already fallen between Harrisonville and Prairie Du Rocher in the 
  past three hours.  Flash flooding is expected to begin shortly.

* Some locations that will experience flooding include...
  Arnold, Waterloo, Pevely, Crystal City, Ste. Genevieve, Freeburg,
  Sparta, Red Bud, Herculaneum, Barnhart, Smithton, Steeleville, New
  Athens, Marissa, Valmeyer, Tilden, Evansville, Bloomsdale, Baldwin
  and Fountain.

This includes Interstate 55 in Missouri between exits 157 and 170,
and near exit 187.
 
This also includes  Mastodon Historic Site and Gov. Dunklin's Grave
Historic Site.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3801 8966 3799 9034 3841 9040 3841 9035
      3839 9034 3841 9031 3844 8971 3822 8970
      3822 8968

$$

GKS
1 follow-up statement
055 
WGUS73 KLSX 080640
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
140 AM CDT SAT SEP 8 2018

ILC133-157-163-MOC099-186-080650-
/O.CAN.KLSX.FF.W.0042.000000T0000Z-180908T0730Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Monroe IL-Randolph IL-St. Clair IL-Jefferson MO-Ste. Genevieve MO-
140 AM CDT SAT SEP 8 2018

...THE FLASH FLOOD WARNING FOR MONROE...NORTHERN RANDOLPH...SOUTHERN
ST. CLAIR...EASTERN JEFFERSON AND NORTHERN STE. GENEVIEVE COUNTIES IS
CANCELLED...

Rain will continue to fall over the area tonight with additional 
flooding possible. Therefore, the flash flood warning has be 
replaced by an areal flood warning. Please continue to heed any 
remaining road closures and report flooding to local authorities.

LAT...LON 3801 8966 3799 9034 3841 9040 3841 9035
      3839 9034 3841 9031 3844 8971 3822 8970
      3822 8968

$$

Maples

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 7, 7:26 PM CDTFlash Flood WarningLSXSaint Clair6 hr
Sep 8, 1:31 AM CDTAreal Flood WarningLSXMonroe, Randolph, Saint Clair12 hr
Sep 8, 8:44 AM CDTAreal Flood WarningLSXMonroe, Saint Clair6 hr
Sep 8, 9:06 AM CDTAreal Flood WarningLSXBond, Clinton, Fayette, Madison, Marion, Randolph and 1 more9 hr
Sep 8, 1:28 PM CDTAreal Flood WarningLSXMonroe, Randolph, Saint Clair6 hr
Sep 8, 5:58 PM CDTAreal Flood WarningLSXClinton, Fayette, Madison, Marion, Washington12 hr
Sep 7, 7:28 PM CDTRiver Flood WarningLSXMarion17 hr
Sep 7, 8:02 PM CDTFlash Flood WarningLSXFranklin, Jefferson, Washington6 hr
Sep 7, 9:27 PM CDTAreal Flood AdvisoryLSXSaint Charles, Saint Louis, City of Saint Louis4 hr
Sep 8, 2:56 AM CDTFlash Flood WarningLSXCrawford6 hr
Sep 8, 8:59 AM CDTAreal Flood WarningLSXCrawford6 hr

Nearby

Flash Flood Warnings in Illinois, 2018Flash Flood Warnings in Missouri, 2018Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.