F1 tornado, Terreton, Idaho, May 31, 1997

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.

Rating

F1

Date

May 31, 1997

Touchdown

5:05 PM MDT (23:05 UTC)

Path length

4.0 miles (6.4 km)

Path width

200 yards (183 m)

Deaths

0

Injuries

0

County

Jefferson County

Touchdown point

43.830, -112.500

Lift-off point

43.870, -112.430

Record number

256

A F1 Tornado touch down about one mile west of Mud Lake demolishing a shed, damaging a quanset hut, lifting a roof off another shed, and rolling over an irrigation circle line. The tornado moved east toward Mud Lake knocking down trees, large branches and two power poles. In Mud Lake metal siding was stripped off a few buildings and a large portion of a restaurant roof was blown off. An approximate 100 x 50 foot roof was lifted off a building at the Feed Company Shed on the NW corner of town and deposited on two trucks. The tornado continued to move northeast causing damage to sheds, roofs, trees and other structures 1 to 2 miles north of Terreton. Two miles north of Terreton a large roof was lifted off a shed and thrown over 150 feet landing on top of a home. The large funnel associated with the tornado was visible from the NWS in Pocatello at 5:05 pm MDT...a distance of about 65 miles.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

3 minutes of warning. NWS PIH issued a tornado warning for this county at 23:02 UTC, 3 minutes before the tornado touched down, in force until 23:30 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a Slight Risk. The outlook in force was issued at 05:57 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

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.

The Pocatello radar (KSFX), 85 km away, was scanning. The volume nearest the touchdown began at 23:03 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

The live radar over the trackEvery 1997 tornado in IdahoEvery tornado in Idaho since 1950Warnings in force in Idaho nowThe forecast where you are

10 more were confirmed in the United States that day.

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.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.