Tornadoes · United States · Oklahoma · 1971

F1 tornado, Comanche County, Oklahoma, February 18, 1971

This F1 tornado ran 0.2 miles across Comanche County on February 18, 1971, touching down at 12:40 PM CST and reaching 100 yards wide. It killed nobody and injured 1, and did $5,000 to $50,000 of property damage.

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 mphthis tornado

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

  3. F2113 to 157 mph

    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
F1
Date
February 18, 1971
Touchdown
12:40 PM CST (18:40 UTC)
Path length
0.2 miles (0.3 km)
Path width
100 yards (91 m)
Deaths
0
Injuries
1
Property damage
$5,000 to $50,000
County
Comanche County
Touchdown point
34.600, -98.450
Record number
50

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.

Fort Sill, OK (KFSI), 12:00Z

6.7 hours before the tornado, 7 km from the path. February 18, 1971.

Skew-T log-pSkew-T log-p diagram, Fort Sill, OK at 12:00Z on 1971-02-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 35 joules per kilogram, CIN -393, lifted condensation level 783 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 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, Fort Sill, OK at 12:00Z on 1971-02-18The 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 280 square meters per square second, 0 to 6 km bulk shear 45 knots.193958Sfc1 km3 km6 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
35 J/kg
Mixed-layer CIN
-393 J/kg
Surface CAPE
116 J/kg
Mixed-layer LCL
783 m above ground
0-6 km bulk shear
45 kt
0-1 km bulk shear
42 kt
0-1 km storm-relative helicity
280 m²/s²
0-3 km storm-relative helicity
352 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.5 K/km

Open this sounding in Storm Lab

This ground now

The live radar over the trackEvery 1971 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are

The other tornadoes of February 18, 1971

10 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
February 1811:00 AM CSTF2Runnels, TX0.250$500 to $5,000
February 1811:00 AM CSTF2Runnels, TX0.5100$500 to $5,000
February 1812:32 PM MSTF0Las Animas, CO0.110
February 182:45 PM CSTF1Haskell, KS6.527
February 182:55 PM CSTF1Parker, TX1.0440$500 to $5,000
February 184:15 PM CSTF1Hodgeman, KS0.110
February 184:45 PM CSTF1Johnson, TX0.150$500 to $5,000
February 185:20 PM CSTF1Dallas, TX0.113$500 to $5,000
February 186:00 PM CSTF1Hunt, TX2.0440$5,000 to $50,000
February 186:30 PM CSTF2Hill, TX0.5440$500 to $5,000

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.