Tornadoes - Severe Convective Storms and Tornadoes: Observations and Dynamics - page 311

Table 6.1. A comparison of the Fujita scale with the enhanced Fujita scale.

Fujita Scale EF Scale

1
4 -mile

Fujita Scale Fastest 3-second EF Scale 3-second

wind speeds gust speed gust speed

(mph) (mph) (mph)

F0 40-72 45-78 EF0 65-85

F1 73-112 79-117 EF1 86-109

F2 113-157 118-161 EF2 110-137

F3 158-207 162-209 EF3 138-167

F4 208-260 210-261 EF4 168-199

F5 261-318 262-317 EF5 200-234

Figure 6.6. Polarimetric radar debris signature in an EF5 tornado, as detected by the mobile
radar RaXPol, in Oklahoma, on May 24, 2011 (data processing courtesy of Jana Houser and
Jeff Snyder). (Top left) Radar reflectivity factor (Z)indBZ e ; (top right) Doppler velocity (V)in
ms 1 ; (bottom left) co-polar cross-correlation coecient ( HV ); (bottom right) spectrum width
in m s 1 . The region of HV < 0.8 is characteristic of debris, which encloses the ''debris ball'' of

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moderate reflectivity ( 30-35 dBZ e ), the cyclonic vortex shear signature (red-green couplet),

and the region of relatively high spectrum widths. Spectrum width is a measure of the variation
in wind speeds in a radar volume. The maximum wind speeds indicated are 125m s 1 .