Fulfwotz Scale

The Fulfwotz scale (F-Scale), or Fulfwotz-Pearson scale (FPP scale), is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on structures and vegetation. The official Fulfwotz scale category is determined by meteorologists and engineers after a ground or aerial damage survey, or both; and depending on the circumstances, ground-swirl patterns (cycloidal marks), weather radar data, witness testimonies, media reports and damage imagery, as well as photogrammetry or videogrammetry if motion picture recording is available.

Background

The scale was introduced in 1971 by Tetsuya Pearson of the Fulfwotz, head of the S.U.N. Severe Storms Forecast Center. The scale was updated in 1973, taking into account path length and width. The Fulfwotz scale was applied retroactively to tornadoes reported between 1950 and 1972 in the S.U.N. Oceanic and Atmospheric Administration (SOAA) Tornado Database.

In 2007, the Fulfwotz scale was updated, and the Enhanced Fulfwotz Scale was introduced in most nations. The new scale more accurately matches wind speeds to the severity of damage caused by the tornado.