Alert archive / Illinois / Flash Flood Warnings in 1986

Flash Flood Warning 1, NWS Lincoln, IL

September 20, 1986DeWitt County, Logan County, Illinois

NWS Lincoln, IL issued this flash flood warning at Sep 20, 1986, 12:33 AM CDT for DeWitt County, Logan County, Illinois. It was in force for 5 hr.

The area

The counties it named.

The facts

Issued
Sep 20, 1986, 12:33 AM CDT (05:33 UTC)
Expired
Sep 20, 1986, 6:00 AM CDT
In force
5 hr
Issued by
NWS Lincoln, IL
Area
Whole counties

Counties DeWitt County, IL, Logan County, IL

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

The nearest sounding before it

Peoria Regional, IL (KPIA), launched 00:00Z, 5.6 hours before the alert went out and 70 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, Peoria Regional, IL at 00:00Z on 1986-09-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1948 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, Peoria Regional, IL at 00:00Z on 1986-09-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 316 square meters per square second.193958Sfc1 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
1948 J/kg
Mixed-layer CIN
-53 J/kg
Mixed-layer LCL
878 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
316 m²/s²
0-3 km storm-relative helicity
450 m²/s²
Significant tornado parameter
4.6
Supercell composite
34.0

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KSPI 200533
FFWSPI
ILC107-039-201100-

BULLETIN - IMMEDIATE BROADCAST REQUESTED/EBS ACTIVATION REQUESTED 
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SPRINGFIELD IL
1233 AM CDT SAT SEP 20 1986

THE NATIONAL WEATHER SERVICE HAS ISSUED A FLASH FLOOD WARNING 
EFFECTIVE UNTIL 600 AM CDT FOR PEOPLE IN THE FOLLOWING COUNTIES OF

CENTRAL ILLINOIS...LOGAN AND DE-WITT

AT 12 25 AM CDT EMERGENCY SERVICE AND DISASTER AGENCY REPORT
FLOODING IN MUCH OF DE-WITT COUNTY WHE'RE IN EXCESS OF 4 INCHES OF
RAIN HAS ALREADY FALLEN AND STILL RAINING MODERATE TO HEAVY AT
TIMES..REPORTS FROM STATE POLICE IN LOGAN COUNTY HAS FLOODING
OF STREETS..LOW LYING AREAS AND SMALL STREAMS.

 ATTN ISP DIST...6 AND 9
 HILLIARD

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, Sep 19, 10:08 PM CDT, 2 hours 25 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEORIA IL
10 PM CDT FRI SEP 19 1986

THE SEVERE THUNDERSTORM WARNING FOR MCLEAN COUNTY EXPIRED AT
10 PM.  NO FURTHER REPORTS HAVE BEEN RECEIVED OF STORMS NEAR
SEVERE INTENSITY.

THUNDERSTORMS EXTEND IN A LINE ACROSS ILLINOIS FROM BURLINGTON
IOWA THROUGH PEORIA AND BLOOMINGTON TO WEST CENTRAL INDIANA.
THE STORMS DEVELOP AND MOVE EAST ALONG THE LINE, CONTINUING
TO POUR HEAVY RAIN ON THE AREA.  THIS GIVES THE POTENTIAL
FOR HEAVY RAINFALL AMOUNTS AND POSSIBLE FLOODING ACROSS THE
AREA TONIGHT.

AN ADDITIONAL 0.75 INCH OF RAIN HAS FALLEN AT THE AIRPORT THIS
EVENING... MAKING THE TOTAL 1.66 INCHES FOR THE DAY... UP UNTIL
10 PM.

STARK
Special weather statement, Sep 19, 10:16 PM CDT, 2 hours 17 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SPRINGFIELD IL
1010 PM CDT FRI SEP 19 1986

...HEAVY THUNDERSTORMS ENTERING NORTHERN PIATT AND NORTHWESTERN
                          CHAMPAIGN COUNTIES...

AT 1010 PM CDT THE SOUTHERN EDGE OF AN AVERAGE 30 MILE WIDE AREA OF
RAINSHOWERS AND THUNDERSTORMS EXTENDED FROM THE INDIANA BORDER...JUST        [
NORTH OF DANVILLE TO THE CHAMPAIGN AREA TO 20 MILES SOUTH OF BLOOMING-
TON.

THUNDERSTORMS PRODUCING HEAVY RAIN...GUSTY WINDS...AND SMALL HAIL WERE
JUST ENTERING NORTHWEST CHAMPAIGN COUNTY AND NORTHERN PIATT COUNTY.

MOVEMENT WAS TOWARD THE EAST AND SOUTHEAST AT 20 TO 25 MPH.

PERSONS IN THE AFFECTED AREAS SHOULD BE ON THE ALERT FOR WEATHER
DEVELOPMENTS.
FS
Special weather statement, Sep 20, 12:06 AM CDT, 27 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SPRINGFIELD IL
1205 AM CDT SAT SEP 20 1986

...HEAVY THUNDERSTORMS ENTERING NORTHERN SANGAMON COUNTY...
...SOME FLOODING IN LOGAN AND DE WITT COUNTIES...

AT 1205 AM CDT THE SOUTHERN EDGE OF AN AVERAGE 30 MILE WIDE AREA OF
RAINSHOWERS AND THUNDERSTORMS EXTENDED 20 MILES NORTHWEST OF SPRINGFIELD     [
TO 10 MILES NORTH AND NORTHEAST OF SPRINGFIELD AND ON TO DECATUR AND 20
MILES SOUTH OF CHAMPAIGN.

THUNDERSTORMS PRODUCING HEAVY RAIN...GUSTY WINDS...AND SMALL HAIL WERE
REPORTED WITH THIS WEATHER SYSTEM.

MOVEMENT HAS TURNED TOWARD THE SOUTHEAST AND SOUTH AT 15 TO 20 MPH
TOWARD MACON AND SANGAMON COUNTIES.

SOME LOCAL FLOODING OF STREETS...LOW LYING AREAS AND VIADUCTS HAS
BEEN REPORTED IN LOGAN AND DE WITT COUNTIES.
PERSONS IN THE AFFECTED AREAS SHOULD BE ALERT TO DEVELOPING WEATHER
CONDITIONS.

FS

The office that day

Everything else NWS Lincoln, IL issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 19, 9:02 PM CDTSevere Thunderstorm WarningILXMcLean58 min
Sep 20, 2:46 AM CDTFlash Flood WarningILXSangamon4 hr

Nearby

Flash Flood Warnings in Illinois, 1986Every flash flood warning in 1986

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.