Tornadoes · United States · Wyoming · 1975

F1 tornado, Natrona County, Wyoming, May 8, 1975

This F1 tornado ran 0.1 miles across Natrona County on May 8, 1975, touching down at 5:05 PM MDT and reaching 10 yards wide. It killed nobody, and did under $50 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
May 8, 1975
Touchdown
5:05 PM MDT (23:05 UTC)
Path length
0.1 miles (0.2 km)
Path width
10 yards (9 m)
Deaths
0
Injuries
0
Property damage
under $50
County
Natrona County
Touchdown point
43.450, -106.270
Record number
342

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.

Lander/Hunt Fiel, WY (KLND), 12:00Z

11.1 hours before the tornado, 209 km from the path. May 8, 1975.

Skew-T log-pSkew-T log-p diagram, Lander/Hunt Fiel, WY at 12:00Z on 1975-05-08Temperature 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 -11668, lifted condensation level 596 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 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, Lander/Hunt Fiel, WY at 12:00Z on 1975-05-08The 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 10 square meters per square second, 0 to 6 km bulk shear 6 knots.193958Sfc1 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
-11668 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
596 m above ground
0-6 km bulk shear
6 kt
0-1 km bulk shear
10 kt
0-1 km storm-relative helicity
10 m²/s²
0-3 km storm-relative helicity
16 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.4 K/km

Open this sounding in Storm Lab

Lander/Hunt Fiel, WY (KLND), 00:00Z

0.9 hours after it, 209 km from the path. May 9, 1975.

Skew-T log-pSkew-T log-p diagram, Lander/Hunt Fiel, WY at 00:00Z on 1975-05-09Temperature 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 -11476, lifted condensation level 1159 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 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, Lander/Hunt Fiel, WY at 00:00Z on 1975-05-09The 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 11 square meters per square second, 0 to 6 km bulk shear 17 knots.193958Sfc1 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
-11476 J/kg
Surface CAPE
229 J/kg
Mixed-layer LCL
1159 m above ground
0-6 km bulk shear
17 kt
0-1 km bulk shear
7 kt
0-1 km storm-relative helicity
11 m²/s²
0-3 km storm-relative helicity
52 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
7.5 K/km

Open this sounding in Storm Lab

The surface observations

Casper/Natrona International (CPR), 62 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
22:00 UTC5431.1300° 9 kt1015.2
23:00 UTC5135300° 15 kt1015.9
00:00 UTC4835300° 11 kt1016.9
01:00 UTC4536350° 6 kt1017.3

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

This ground now

The live radar over the trackEvery 1975 tornado in WyomingEvery tornado in Wyoming since 1950Warnings in force in Wyoming nowThe forecast where you are

The other tornadoes of May 8, 1975

11 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 81:05 AM CDTF2Jefferson Davis Parish, LA1.01002$50 to $500
May 81:15 AM CDTF1De Soto Parish, LA0.7331under $50
May 82:00 AM CDTF2Acadia Parish, LA0.550
May 82:30 AM CDTF1Lafayette Parish, LA0.5502$50 to $500
May 82:30 AM CDTF2East Baton Rouge Parish, LA6.250
May 83:00 AM CDTF2Saint Helena Parish, LA0.110
May 85:25 PM CDTF0Karnes, TX0.110$500 to $5,000
May 85:45 PM CDTF0Zavala, TX0.110
May 86:20 PM CDTF0Wilson, TX0.110
May 87:30 PM CDTF0Victoria, TX0.110
May 810:48 PM CDTF1Marshall, AL0.110$5,000 to $50,000

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.