Tornadoes · United States · Wyoming · 1978

F2 tornado, Park County, Wyoming, July 11, 1978

This F2 tornado ran 0.4 miles across Park County on July 11, 1978, touching down at 4:20 PM MDT and reaching 200 yards wide. It killed nobody, 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 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
July 11, 1978
Touchdown
4:20 PM MDT (22:20 UTC)
Path length
0.4 miles (0.6 km)
Path width
200 yards (183 m)
Deaths
0
Injuries
0
Property damage
$5,000 to $50,000
County
Park County
Touchdown point
44.670, -108.830
Record number
582

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

10.3 hours before the tornado, 206 km from the path. July 11, 1978.

Skew-T log-pSkew-T log-p diagram, Lander/Hunt Fiel, WY at 12:00Z on 1978-07-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 183 joules per kilogram, CIN -179, lifted condensation level 2751 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 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 1978-07-11The 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 74 square meters per square second, 0 to 6 km bulk shear 27 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
183 J/kg
Mixed-layer CIN
-179 J/kg
Surface CAPE
6 J/kg
Mixed-layer LCL
2751 m above ground
0-6 km bulk shear
27 kt
0-1 km bulk shear
11 kt
0-1 km storm-relative helicity
74 m²/s²
0-3 km storm-relative helicity
129 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1
0-3 km lapse rate
7.1 K/km

Open this sounding in Storm Lab

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

1.7 hours after it, 206 km from the path. July 12, 1978.

Skew-T log-pSkew-T log-p diagram, Lander/Hunt Fiel, WY at 00:00Z on 1978-07-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 141 joules per kilogram, CIN -3, lifted condensation level 3765 meters above ground. Wind barbs in knots down the right edge.LCLEL10008507005003002001001 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 1978-07-12The 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 71 square meters per square second, 0 to 6 km bulk shear 39 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
141 J/kg
Mixed-layer CIN
-3 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
3765 m above ground
0-6 km bulk shear
39 kt
0-1 km bulk shear
18 kt
0-1 km storm-relative helicity
71 m²/s²
0-3 km storm-relative helicity
31 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3
0-3 km lapse rate
10.1 K/km

Open this sounding in Storm Lab

The surface observations

Cody Municipal (Awos) (COD), 23 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
21:00 UTC8132300° 18 kt1007.8
22:00 UTC8239330° 17 kt1007.1
23:00 UTC8033270° 16 kt1007.8
00:00 UTC7438250° 14 kt1008.5

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

This ground now

The live radar over the trackEvery 1978 tornado in WyomingEvery tornado in Wyoming since 1950Warnings in force in Wyoming nowThe forecast where you are

The other tornadoes of July 11, 1978

3 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 118:10 PM MDTF0Haakon, SD0.110
July 119:30 PM MDTF0Haakon, SD0.110
July 1112:53 AM CDTF0Ward, ND0.110$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.