Enhanced F Scale for Tornado Damage An update to the the original F-scale by a team of meteorologists and wind engineers, implemented in the U.S. on 1 February 2007.

FUJITA SCALE DERIVED EF SCALE OPERATIONAL EF SCALE F Number Fastest 1/4-mile (mph) 3 Second Gust (mph) EF Number 3 Second Gust (mph) EF Number 3 Second Gust (mph) 0 40-72 45-78 0 65-85 0 65-85 1 73-112 79-117 1 86-109 1 86-110 2 113-157 118-161 2 110-137 2 111-135 3 158-207 162-209 3 138-167 3 136-165 4 208-260 210-261 4 168-199 4 166-200 5 261-318 262-317 5 200-234 5 Over 200

*** IMPORTANT NOTE ABOUT ENHANCED F-SCALE WINDS: The Enhanced F-scale still is a set of wind estimates (not measurements) based on damage. Its uses three-second gusts estimated at the point of damage based on a judgment of 8 levels of damage to the 28 indicators listed below. These estimates vary with height and exposure. Important: The 3-second gust is not the same wind as in standard surface observations. Standard measurements are taken by weather stations in open exposures, using a directly measured, "one-minute mile" speed.