Alert archive / Illinois / Tornado Warnings in 1997

Tornado Warning 14, NWS Chicago, IL

May 18, 1997LaSalle County, Illinois

NWS Chicago, IL issued this tornado warning at May 18, 1997, 9:18 PM CDT for LaSalle County, Illinois. It was in force for 57 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: May 18, 1997, 9:18 PM CDT (02:18 UTC)
Expired: May 18, 1997, 10:15 PM CDT
In force: 57 min
Issued by: NWS Chicago, IL
Area: Whole counties

County LaSalle County, IL

The radar

The Chicago radar (KLOT), 73 km from the middle of the area, began a volume at 02:18 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.

What was reported inside it

Time	Report	Where	Remark
May 18, 9:38 PM CDT	Hail 1.75	Utica, IL	A wind gust to 70 mph and hail of 1.75 inches in diameter were reported in North Utica.

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The watch it was issued in

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

Issued	Product	Office	Lasted
May 18, 5:30 PM CDT	Tornado Watch	SPC	6 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 2.3 hours before the alert went out and 135 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1314 J/kg
Mixed-layer CIN: -31 J/kg
Mixed-layer LCL: 1926 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 104 m²/s²
0-3 km storm-relative helicity: 292 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 8.8

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KCHI 190218 RRA
TORCHI
ILC099-190315-
 
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CHICAGO IL
918 PM CDT SUN MAY 18 1997
 
THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A
TORNADO WARNING EFFECTIVE UNTIL 1015 PM CDT
FOR PEOPLE IN THE FOLLOWING LOCATION...
 
IN NORTHEAST ILLINOIS
 
   ...SOUTHERN LA SALLE COUNTY
 
AT 915 PM CDT RADAR INDICATE A POSSIBLE TORNADO 5 MILES EAST OF
PRINCETON IN BUREAU COUNTY. THIS STORM WILL MOVE INTO& LASALLE COUNTY
NEAR PERU AND LASALLE BY 930 PM CDT. THIS IS A DANGEROUS STORM!
 
ABANDON MOBILE HOMES!  GO INSIDE A NEARBY STURDY BUILDING!
AS A LAST RESORT LIE FLAT IN A DITCH AND COVER YOUR HEAD.
 
KAPLAN

The office that day

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

Issued	Product	Office	Counties	Lasted
May 18, 7:00 PM CDT	Tornado Warning	LOT	Lake, McHenry	60 min
May 18, 7:09 PM CDT	Severe Thunderstorm Warning	LOT	Kane	66 min
May 18, 7:19 PM CDT	Severe Thunderstorm Warning	LOT	LaSalle, Lee	56 min
May 18, 7:30 PM CDT	Tornado Warning	LOT	Kane	30 min
May 18, 7:42 PM CDT	Severe Thunderstorm Warning	LOT	Kendall, LaSalle	63 min
May 18, 7:47 PM CDT	Tornado Warning	LOT	DuPage, Will	58 min
May 18, 8:04 PM CDT	Tornado Warning	LOT	Grundy, Kankakee, Will	56 min
May 18, 8:04 PM CDT	Tornado Warning	LOT	Cook	56 min
May 18, 8:52 PM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois, Kankakee	2 hr
May 18, 8:52 PM CDT	Severe Thunderstorm Warning	LOT	Livingston	2 hr
May 18, 9:54 PM CDT	Severe Thunderstorm Warning	LOT	Grundy, Livingston	66 min
May 18, 10:50 PM CDT	Severe Thunderstorm Warning	LOT	Iroquois, Kankakee	55 min
May 18, 11:12 PM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois, Livingston	63 min

Nearby

Tornado Warnings in Illinois, 1997 Every tornado warning in 1997 Tornadoes in 1997

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.