Alert archive / Illinois / Tornado Warnings in 1998

Tornado Warning 1, NWS Chicago, IL

April 15, 1998LaSalle County, Lee County, Illinois

NWS Chicago, IL issued this tornado warning at Apr 15, 1998, 5:19 PM CDT for LaSalle County, Lee County, Illinois. It was in force for 31 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
Apr 15, 1998, 5:19 PM CDT (22:19 UTC)
Expired
Apr 15, 1998, 5:50 PM CDT
In force
31 min
Issued by
NWS Chicago, IL
Area
Whole counties

Counties LaSalle County, IL, Lee County, IL

The radar

The Chicago radar (KLOT), 84 km from the middle of the area, began a volume at 22:18 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
Apr 15, 3:15 PM CDTTornado WatchSPC6 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 10.3 hours before the alert went out and 117 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, Davenport, at 12:00Z on 1998-04-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Davenport, at 12:00Z on 1998-04-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 344 square meters per square second.1939587897117Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
667 m above ground
0-6 km bulk shear
68 kt
0-1 km storm-relative helicity
344 m²/s²
0-3 km storm-relative helicity
446 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.

522 
WFUS1 KCHI 152221 RRA
TORCHI
ILC099-103-152250-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CHICAGO IL
519 PM CDT WED APR 15 1998

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* TORNADO WARNING FOR...
  SOUTHEASTERN LEE COUNTY IN NORTH CENTRAL ILLINOIS
  NORTHWESTERN LASALLE COUNTY IN NORTH CENTRAL ILLINOIS

* UNTIL 550 PM CDT

* TORNADO WILL BE NEAR-
  MENDOTA AT 509 PM CDT
  COMPTON AT 510 PM CDT
  PAW PAW AT 530 PM CDT
  EARLVILLE AT 530 PM CDT

* AT 517 PM CDT... TORNADO INDICATED 19 MILES SOUTHEAST OF DIXON OR 5
  MILES WEST OF MENDOTA... BY SPOTTERS... MOVING EAST 20 MPH.

A TORNADO IS ON THE GROUND GO TO THE BASEMENT IF A BASEMENT IS NOT
AVAILABLE...GO TO A SMALL INTERIOR ROOM ON THE LOWEST FLOOR

KURASH

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 15, 4:36 PM CDTSevere Thunderstorm WarningLOTLee49 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.