Tornadoes · United States · Kansas · 1964

F1 tornado, Brown County, Kansas, August 20, 1964

This F1 tornado ran 3.3 miles across Brown County on August 20, 1964, touching down at 6:20 PM GMT-5 and reaching 50 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 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
August 20, 1964
Touchdown
6:20 PM GMT-5 (23:20 UTC)
Path length
3.3 miles (5.3 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
County
Brown County
Touchdown point
39.870, -95.530
Lift-off point
39.900, -95.480
Record number
564

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.

Topeka, KS (KTOP), 12:00Z

11.3 hours before the tornado, 99 km from the path. August 20, 1964.

Skew-T log-pSkew-T log-p diagram, Topeka, KS at 12:00Z on 1964-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 249 joules per kilogram, CIN -28, lifted condensation level 684 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, Topeka, KS at 12:00Z on 1964-08-20The 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 158 square meters per square second, 0 to 6 km bulk shear 60 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
249 J/kg
Mixed-layer CIN
-28 J/kg
Surface CAPE
211 J/kg
Mixed-layer LCL
684 m above ground
0-6 km bulk shear
60 kt
0-1 km bulk shear
26 kt
0-1 km storm-relative helicity
158 m²/s²
0-3 km storm-relative helicity
344 m²/s²
Significant tornado parameter
0.3
Supercell composite
1.8
0-3 km lapse rate
5.7 K/km

Open this sounding in Storm Lab

Topeka, KS (KTOP), 00:00Z

0.7 hours after it, 99 km from the path. August 21, 1964.

Skew-T log-pSkew-T log-p diagram, Topeka, KS at 00:00Z on 1964-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 44 joules per kilogram, CIN -146, lifted condensation level 1913 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, Topeka, KS at 00:00Z on 1964-08-21The 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 167 square meters per square second, 0 to 6 km bulk shear 41 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
44 J/kg
Mixed-layer CIN
-146 J/kg
Surface CAPE
5587 J/kg
Mixed-layer LCL
1913 m above ground
0-6 km bulk shear
41 kt
0-1 km bulk shear
25 kt
0-1 km storm-relative helicity
167 m²/s²
0-3 km storm-relative helicity
243 m²/s²
Significant tornado parameter
0.0
Supercell composite
3.8
0-3 km lapse rate
6.9 K/km

Open this sounding in Storm Lab

This ground now

The live radar over the trackEvery 1964 tornado in KansasEvery tornado in Kansas since 1950Warnings in force in Kansas nowThe forecast where you are

The other tornadoes of August 20, 1964

7 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 203:15 AM GMT-5F1Little River, AR4.1100$500 to $5,000
August 204:45 PM GMT-5F0Bremer, IA1.0100$5,000 to $50,000
August 206:30 PM GMT-5F1Brown, KS0.130
August 208:30 PM GMT-5F1DeKalb, MO1.510$500 to $5,000
August 2010:00 PM GMT-5F0Decatur, IA0.550$5,000 to $50,000
August 2010:30 PM GMT-5F1Sullivan, MO0.110$500 to $5,000
August 2011:07 PM GMT-5F2Van Buren, IA0.350$50,000 to $500,000

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.