Tornadoes · United States · Oklahoma · 1961
F0 tornado, Nowata County, Oklahoma, April 20, 1961
This F0 tornado ran 0.1 miles across Nowata County on April 20, 1961, touching down at 11:35 PM GMT-6 and reaching 100 yards wide. It killed nobody, and did $50 to $500 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.
F040 to 72 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
F173 to 112 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
F4207 to 260 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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
- F0
- Date
- April 20, 1961
- Touchdown
- 11:35 PM GMT-6 (05:35 UTC)
- Path length
- 0.1 miles (0.2 km)
- Path width
- 100 yards (91 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $50 to $500
- County
- Nowata County
- Touchdown point
- 36.850, -95.630
- Record number
- 197
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 Smith Muni, AR (KFSM), 00:00Z
5.6 hours before the tornado, 207 km from the path. April 21, 1961.
- Mixed-layer CAPE
- 483 J/kg
- Mixed-layer CIN
- -176 J/kg
- Surface CAPE
- 276 J/kg
- Mixed-layer LCL
- 1074 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km bulk shear
- 14 kt
- 0-1 km storm-relative helicity
- 76 m²/s²
- 0-3 km storm-relative helicity
- 198 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 5.3
- 0-3 km lapse rate
- 5.3 K/km
Fort Smith Muni, AR (KFSM), 12:00Z
6.4 hours after it, 207 km from the path. April 21, 1961.
- Mixed-layer CAPE
- 194 J/kg
- Mixed-layer CIN
- -237 J/kg
- Surface CAPE
- 126 J/kg
- Mixed-layer LCL
- 764 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 204 m²/s²
- 0-3 km storm-relative helicity
- 185 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.1
- 0-3 km lapse rate
- 5.3 K/km
This ground now
The live radar over the trackEvery 1961 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are
The other tornadoes of April 20, 1961
2 more were confirmed in the United States that day.
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.