Tornadoes · United States · Illinois · 1997

F2 tornado, Lindenhurst to Gurnee, Illinois, May 18, 1997

From Lindenhurst to Gurnee, this F2 tornado ran 6.0 miles across Lake County on May 18, 1997, touching down at 7:18 PM CDT and reaching 73 yards wide. It killed nobody.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. F040 to 72 mph

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. F173 to 112 mph

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. F2113 to 157 mphthis tornado

    Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

  4. F3158 to 206 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. F4207 to 260 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. F5261 to 318 mph

    Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

  7. Unrated

    The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

The record

Rating
F2
Date
May 18, 1997
Touchdown
7:18 PM CDT (00:18 UTC)
Path length
6.0 miles (9.7 km)
Path width
73 yards (67 m)
Deaths
0
Injuries
0
County
Lake County
Touchdown point
42.420, -88.050
Lift-off point
42.370, -87.900
Record number
232

What the Weather Service recorded

A tornado touched down on the southeast side of Lindenhurst and damaged trees and the roofs of several homes. The tornado reached F2 intensity near Sand Lake Road and Route 45 where 2 barns were destroyed, two foot diameter oak trees were broken off or uprooted and the roof was taken off a nursery. Signs were blown down along Sand Lake Road and Stearns School Road. A subdivision on the north side of Gurnee had damage to trees, a chimney blown off a house, windows broken, walls damaged, a garage door blown in and a fence blown down. Three quater inch hail also occurred in Lindenhurst.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

The warnings

18 minutes of warning. NWS LOT issued a tornado warning for this county at 00:00 UTC, 18 minutes before the tornado touched down, in force until 01:00 UTC.

Issued (UTC)ExpiredProductOffice
23:56 UTC01:00 UTCSevere Thunderstorm WarningLOT
00:00 UTC01:00 UTCTornado WarningLOT

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The forecast that day

The Storm Prediction Center had this point in a Moderate Risk. The outlook in force was issued at 06:19 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The air that afternoon

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Davenport, (KDVN), 00:00Z

0.3 hours before the tornado, 226 km from the path. May 19, 1997.

Skew-T log-pSkew-T log-p diagram, Davenport, at 00:00Z on 1997-05-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 2339 joules per kilogram, CIN -25, lifted condensation level 1544 meters above ground. Wind barbs in knots down the right edge.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. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Davenport, at 00:00Z on 1997-05-19The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 145 square meters per square second, 0 to 6 km bulk shear 49 knots.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. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
2339 J/kg
Mixed-layer CIN
-25 J/kg
Surface CAPE
1899 J/kg
Mixed-layer LCL
1544 m above ground
0-6 km bulk shear
49 kt
0-1 km bulk shear
24 kt
0-1 km storm-relative helicity
145 m²/s²
0-3 km storm-relative helicity
165 m²/s²
Significant tornado parameter
1.0
Supercell composite
9.0
0-3 km lapse rate
7.5 K/km

Open this sounding in Storm Lab

Davenport, (KDVN), 12:00Z

11.7 hours after it, 226 km from the path. May 19, 1997.

Skew-T log-pSkew-T log-p diagram, Davenport, at 12:00Z on 1997-05-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -57482, lifted condensation level 801 meters above ground. Wind barbs in knots down the right edge.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. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Davenport, at 12:00Z on 1997-05-19The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity -76 square meters per square second, 0 to 6 km bulk shear 53 knots.1939587897Sfc1 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. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-57482 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
801 m above ground
0-6 km bulk shear
53 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
-76 m²/s²
0-3 km storm-relative helicity
69 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.4 K/km

Open this sounding in Storm Lab

The surface observations

Waukegan (UGN), 10 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
22:48 UTC73.466.2220° 10 kt1000.7
23:58 UTC57.257.230° 8 kt999.3TSRA BR
00:50 UTC66.266.2300° 12 kt998.3-TSRA

From the Iowa Environmental Mesonet's archive of airport observations.

The radar

The Milwaukee radar (KMKX), 79 km away, was scanning. The volume nearest the touchdown began at 00:17 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

This ground now

The live radar over the trackEvery 1997 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

The other tornadoes of May 18, 1997

13 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 184:40 PM CDTF1Cedar, IA3.250
May 185:47 PM CDTF0Reno, KS0.550
May 186:07 PM CDTF0Reno, KS0.550
May 184:37 PM PDTF1San Bernardino, CA3.5100
May 186:43 PM CDTF0Reno, KS0.250
May 184:50 PM PDTF1San Bernardino, CA9.040
May 188:00 PM CDTF0Scott, IA0.110
May 188:30 PM CDTF0Warren, IL0.110
May 188:55 PM CDTF0Bureau, IL0.110
May 189:19 PM CDTF0Knox, IL0.150
May 189:30 PM ESTF0LaGrange, IN1.01001$1.5 million
May 189:38 PM ESTF0LaGrange, IN1.02001$1.5 million
May 1810:00 PM ESTF0Steuben, IN1.0200$10 million

What this means

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

Sources

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.