Alert archive / Illinois / Flash Flood Warnings in 1998

Flash Flood Warning 42, NWS St. Louis, MO

August 18, 1998Madison County, Illinois

NWS St. Louis, MO issued this flash flood warning at Aug 18, 1998, 7:32 AM CDT for Madison County, Illinois. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Aug 18, 1998, 7:32 AM CDT (12:32 UTC)
Expired
Aug 18, 1998, 10:05 AM CDT
In force
3 hr
Issued by
NWS St. Louis, MO
Area
Whole counties

County Madison County, IL

The radar

The St Louis radar (KLSX), 69 km from the middle of the area, began a volume at 12:33 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, 0.5 hours before the alert went out and 185 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 1998-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 78 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 12:00Z on 1998-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 41 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
78 J/kg
Mixed-layer CIN
-276 J/kg
Mixed-layer LCL
1033 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
41 m²/s²
0-3 km storm-relative helicity
103 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KSTL 181233
FFWSTL
ILC119-181505-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
732 AM CDT TUE AUG 18 1998

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EXTREME SOUTHWESTERN MADISON COUNTY ILLINOIS IN SOUTHWESTERN
  ILLINOIS

* UNTIL 1005 AM CDT

* AT 720 AM DOPPLER RADAR INDICATED A NARROW LINE OF THUNDERSTORMS
  WHICH WAS MOVING SOUTH THROUGH THE METRO AREA...CLIPPING THE
  SOUTHWEST CORNER OF MADISON COUNTY. GRANITE CITY AND AREAS VERY
  CLOSE TO THE MISSISSIPPI RIVER ARE IN THE PATH OF THESE STORMS

* RAINFALL AMOUNTS OF UP TO 5 INCHES OF RAIN COULD OCCUR BETWEEN NOW
  AND 830 AM WITH SERIOUS FLOODING CONSEQUENCES DUE TO THE LARGE
  AMOUNT OF PAVED SURFACES.

  THIS IS A VERY SERIOUS SITUATION. DO NOT DRIVE THROUGH OR WALK
  NEAR FLOWING WATER. LOW AREAS AND SOME AREAS THAT NORMALLY DO
  NOT FLOOD WILL HAVE EXTREME FLOODING. BE CAREFUL!

  IF FLASH FLOODING IS OBSERVED OR IMMINENT...MOVE QUICKLY TO HIGHER
  GROUND. NEVER DRIVE INTO AN AREA WHERE WATER COVERS THE ROAD...
  ESPECIALLY UNDERPASSES AND SECONDARY ROADS.

  PEDIGO

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

In the hours before

Special weather statement, Aug 18, 5:00 AM CDT, 2 hours 32 minutes before
ILZ058>060-064-065-069-070-074-079-095>102-MOZ009-010-018-019-026-
027-034>036-041-042-047>052-059>065-072>075-084-085-099-181700-

SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
500 AM CDT TUE AUG 18 1998

THIS OUTLOOK COVERS THE COUNTY WARNING AREA OF THE NATIONAL WEATHER
SERVICE FORECAST OFFICE IN ST LOUIS.  AREAS INCLUDED ARE PORTIONS OF
NORTHEAST...CENTRAL...EAST CENTRAL AND SOUTHEAST MISSOURI AS WELL AS
WEST CENTRAL AND SOUTHWEST ILLINOIS.

THUNDERSTORMS WILL CONTINUE TO DEVELOP AND MOVE SOUTHWARD THROUGH
SOUTHWESTERN ILLINOIS AND EAST CENTRAL MISSOURI THROUGH THE MORNING.
SOME STORMS WILL BE STRONG...PRODUCING VERY HEAVY RAIN...SMALL HAIL...
STRONG WIND GUSTS AND FREQUENT LIGHTNING...BUT LITTLE IF ANY SEVERE
WEATHER WILL BE NOTED WITH THESE STORMS.

STORM SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY.

GKS
Special weather statement, Aug 18, 5:00 AM CDT, 2 hours 32 minutes before
ILZ058>060-064-065-069-070-074-079-095>102-MOZ009-010-018-019-026-
027-034>036-041-042-047>052-059>065-072>075-084-085-099-181700-

SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
500 AM CDT TUE AUG 18 1998

THIS OUTLOOK COVERS THE COUNTY WARNING AREA OF THE NATIONAL WEATHER
SERVICE FORECAST OFFICE IN ST LOUIS.  AREAS INCLUDED ARE PORTIONS OF
NORTHEAST...CENTRAL...EAST CENTRAL AND SOUTHEAST MISSOURI AS WELL AS
WEST CENTRAL AND SOUTHWEST ILLINOIS.

THUNDERSTORMS WILL CONTINUE TO DEVELOP AND MOVE SOUTHWARD THROUGH
SOUTHWESTERN ILLINOIS AND EAST CENTRAL MISSOURI THROUGH THE MORNING.
SOME STORMS WILL BE STRONG...PRODUCING VERY HEAVY RAIN...SMALL HAIL...
STRONG WIND GUSTS AND FREQUENT LIGHTNING...BUT LITTLE IF ANY SEVERE
WEATHER WILL BE NOTED WITH THESE STORMS.

STORM SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY.

GKS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 18, 7:11 AM CDTFlash Flood WarningLSXSaint Clair3 hr

Nearby

Flash Flood Warnings in Illinois, 1998Every flash flood warning in 1998

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.