  Offshore wind energy development is underway in the U.S., with proposed sites
located in hurricane-prone regions. Turbine design criteria outlined by the
International Electrotechnical Commission do not encompass the extreme wind
speeds and directional shifts of hurricanes stronger than a Category 2. We
examine the most turbulent portion of a hurricane (the eyewall) using
large-eddy simulations with Cloud Model 1 (CM1). Gusts and mean wind speeds
near the eyewall exceed the current design threshold of 50 m s-1 mean wind and
70 m s-1 gusts for Class I turbines. Gust factors are greatest at the
eye-eyewall interface. Further, shifts in wind direction at wind turbine hub
height suggest turbines must rotate into the wind faster than current practice.
Although current design standards omit mention of wind direction change across
the rotor layer, large values (15-50 deg) suggest that veer should be
considered in design standards.
