Alert archive / Illinois / Severe Thunderstorm Warnings in 1988

Severe Thunderstorm Warning 21, NWS Chicago, IL

August 18, 1988McHenry County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Aug 18, 1988, 4:05 PM CDT for McHenry County, Illinois. It was in force for 40 min.

The area

The counties it named.

The facts

Issued
Aug 18, 1988, 4:05 PM CDT (21:05 UTC)
Expired
Aug 18, 1988, 4:45 PM CDT
In force
40 min
Issued by
NWS Chicago, IL
Area
Whole counties

County McHenry 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 12:00Z, 9.1 hours before the alert went out and 207 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 12:00Z on 1988-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2579 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 12:00Z on 1988-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -4 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
2579 J/kg
Mixed-layer CIN
-95 J/kg
Mixed-layer LCL
1449 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
-4 m²/s²
0-3 km storm-relative helicity
-18 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KCHI 182105
SVRCHI
ILC111-182145-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING 
NATIONAL WEATHER SERVICE CHICAGO IL
405 PM CDT THU AUG 18 1988

THE NATIONAL WEATHER SERVICE HAS ISSUED A SEVERE THUNDERSTORM 
WARNING EFFECTIVE UNTIL 445 PM CDT FOR PEOPLE IN THE FOLLOWING 
COUNTY

   IN THE NORTHEAST PART OF ILLINOIS
      MCHENRY

A SEVERE THUNDERSTORM WAS INDICATED ON RADAR IN SOUTHERN BOONE
COUNTY SOUTH OF BELVIDERE OR 15 MILES SOUTHEAST OF ROCKFORD AND WAS
MOVING EAST AT AROUND 35 MPH. IN MCHENRY COUNTY THE SEVERE
THUNDERSTORM WILL LIKELY PASS ALONG A PATH FROM NEAR UNION TO
HUNTLEY TO CRYSTAL LAKE AND ALQONQUIN. ALSO SEVERE THUNDERSTORM
DEVELOPMENT MAY DEVELOP OVER THE NORTHERN PART OF MCHENRY
AND COULD AFFECT WOODSTOCK AND HARVARD. GOLFBALL SIZE HAIL WAS
REPORTED DURING THE PAST HOUR AT ROCKFORD. WIND DAMAGE WAS
REPORTED AT WALWORTH IN SOUTHERN WALWORTH COUNTY WISCONSIN.

IF YOU ARE IN AN AREA THREATENED BY THIS STORM...GO TO A REINFORCED
SHELTER AND PREPARE FOR DAMAGING WIND...LARGE HAIL..VERY HEAVY RAIN
AND LIGHTNING.

REMEMBER...SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE A
TORNADO WITH LITTLE OR NO ADVANCE WARNING...SO BE ON THE LOOKOUT.

JJL
ATTN ISP 2 15

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 18, 4:25 PM CDTSevere Thunderstorm WarningLOTGrundy, Kendall, LaSalle50 min
Aug 18, 4:39 PM CDTSevere Thunderstorm WarningLOTCook, Lake51 min
Aug 18, 4:53 PM CDTSevere Thunderstorm WarningLOTGrundy, Kendall, LaSalle67 min
Aug 18, 5:45 PM CDTSevere Thunderstorm WarningLOTKankakee60 min

Nearby

Severe Thunderstorm Warnings in Illinois, 1988Every severe thunderstorm warning in 1988

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.