Alert archive / Illinois / Flash Flood Warnings in 1998

Flash Flood Warning 38, NWS St. Louis, MO

August 4, 1998Montgomery County, Illinois

NWS St. Louis, MO issued this flash flood warning at Aug 4, 1998, 9:45 PM CDT for Montgomery County, Illinois. It was in force for 4 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 4, 1998, 9:45 PM CDT (02:45 UTC)
Expired
Aug 5, 1998, 1:40 AM CDT
In force
4 hr
Issued by
NWS St. Louis, MO
Area
Whole counties

County Montgomery County, IL

The radar

The Lincoln radar (KILX), 103 km from the middle of the area, began a volume at 02:44 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 00:00Z, 2.8 hours before the alert went out and 127 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 1998-08-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 421 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 00:00Z on 1998-08-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 44 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
421 J/kg
Mixed-layer CIN
-53 J/kg
Mixed-layer LCL
1463 m above ground
0-6 km bulk shear
24 kt
0-1 km storm-relative helicity
44 m²/s²
0-3 km storm-relative helicity
67 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.5

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KSTL 050246
FFWSTL
ILC135-050640-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
945 PM CDT TUE AUG 4 1998

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  MONTGOMERY COUNTY ILLINOIS IN SOUTHWESTERN ILLINOIS

* UNTIL 140 AM CDT

* AT 940 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR DETECTED
  THUNDERSTORMS CONTAINING HEAVY RAIN EXTENDING FROM NOKOMIS TO 15
  MILES SOUTHWEST OF HILLSBORO.  THUNDERSTORMS WILL CONTINUE TO MOVE
  NORTHEASTWARD FROM THE SOUTHWESTERN PORTION OF THE COUNTY INTO THE
  EAST CENTRAL PORTION OF THE COUNTY DURING THE NEXT TWO TO THREE
  HOURS.

* RADAR ESTIMATED 2 TO 4 INCHES OF RAIN HAVE FALLEN SINCE 7 PM OVER
  CENTRAL AND EAST CENTRAL MONTGOMERY COUNTY...MAINLY BETWEEN
  HILLSBORO AND NOKOMIS.  ADDITIONAL RAIN AMOUNTS OF AROUND ONE
  INCH OF CAN BE EXPECTED BETWEEN 10 PM AND MIDNIGHT.  THIS
  WILL LIKELY PRODUCE SOME FLOODING OF SMALL CREEEKS AND OTHER LOW
  LYING AND FLOOD PRONE AREAS THIS EVENING.

  BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
  DANGERS OF FLOODING. IT IS VERY DIFFICULT AT NIGHT TO TELL HOW
  DEEP THE WATER MAY BE. MOTORISTS SHOULD NEVER DRIvVE THROUGH WATER
  OF UNKNOWN DEPTH.

  GKS/AMS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 4, 9:21 PM CDTSevere Thunderstorm WarningLSXFayette, Montgomery49 min
Aug 5, 1:52 AM CDTFlash Flood WarningLSXMontgomery3 hr
Aug 5, 2:38 AM CDTFlash Flood WarningLSXMarion3 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.