The Measurement of Destruction: An Analysis of Tornado Rating Systems from Fujita to Enhanced Fujita
Technically, the original Fujita scale did have an F6 category listed as "inconceivable damage." However, under the modern EF-Scale, the EF-5 rating is "open-ended." There is no cap. Whether the winds are 201 mph or 350 mph, the rating remains EF-5. The rationale is that "total destruction" is total destruction; once a well-built house is swept cleanly from its foundation and the debris granulated, the scale has done its job. There is no need for an EF-6 rating because we cannot build structures capable of surviving winds beyond an EF-5 threshold to test against. tornado ratings