Alert archive / Illinois / Tornado Warnings in 1998

Tornado Warning 3, NWS Chicago, IL

May 15, 1998Ogle County, Winnebago County, Illinois

NWS Chicago, IL issued this tornado warning at May 15, 1998, 9:20 PM CDT for Ogle County, Winnebago County, Illinois. It was in force for 50 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
May 15, 1998, 9:20 PM CDT (02:20 UTC)
Expired
May 15, 1998, 10:10 PM CDT
In force
50 min
Issued by
NWS Chicago, IL
Area
Whole counties

Counties Ogle County, IL, Winnebago County, IL

The radar

The Milwaukee radar (KMKX), 103 km from the middle of the area, began a volume at 02:20 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
May 15, 5:00 PM CDTTornado WatchSPC6 hr
May 15, 8:45 PM CDTTornado WatchSPC4 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 2.3 hours before the alert went out and 233 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 1998-05-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3559 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 1998-05-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 183 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
3559 J/kg
Mixed-layer CIN
-11 J/kg
Mixed-layer LCL
821 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
183 m²/s²
0-3 km storm-relative helicity
254 m²/s²
Significant tornado parameter
3.7
Supercell composite
20.9

Open this sounding in Storm Lab

The text

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

666 
WFUS1 KCHI 160221 RRA
TORCHI
ILC141-201-160305-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CHICAGO IL
920 PM CDT FRI MAY 15 1998

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* TORNADO WARNING FOR...
  SOUTHEASTERN WINNEBAGO COUNTY IN NORTH CENTRAL ILLINOIS
  NORTHEASTERN OGLE COUNTY IN NORTH CENTRAL ILLINOIS

* UNTIL 1010 PM CDT

* AT 920 PM CDT RADAR INDICATED A POSSIBLE TORNADO ABOUT 5 MILES
NORTHEAST OF OREGON.  THE STORM IS MOVING TO THE NORTHEAST AT 45
MPH.

 * THE TORNADO WILL BE NEAR...
   STILLMAN VALLEY AT 925 PM...
   CHERRY VALLEY AT 935 PM CDT.

GO TO THE BASEMENT OR A SMALL INTERIOR ROOM ON THE LOWEST FLOOR

MERZLOCK

The office that day

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

IssuedProductOfficeCountiesLasted
May 15, 8:25 PM CDTSevere Thunderstorm WarningLOTLee, Ogle45 min
May 15, 8:25 PM CDTSevere Thunderstorm WarningLOTLee, Ogle55 min
May 15, 9:10 PM CDTSevere Thunderstorm WarningLOTOgle50 min

Nearby

Tornado Warnings in Illinois, 1998Every tornado warning in 1998Tornadoes 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.