What do new measurements and simulations tell us about Hurricane Andrew?
Mark D. Powell, NOAA/AOML/HRD, Miami, FL; and J. D. Kepert, A. Boissonnade, and P. J. Vickery The Best Track committtee of the Tropical Prediction Center recently reclassifed Hurricane Andrew as a Category Five storm at landfall in South Florida, based on an interpretation (that peak surface winds are ~ 90% of the flight-level winds at the 700 mb level) of open ocean GPS sonde measurements made since 1997. The accuracy of applying a single flight-level wind reduction factor is assessed by describing the distribution of reduction factors. Reducing eyewall aircraft measurements to the surface with the 90% method overestimates key eyewall surface observations at Fowey Rocks and Perrine. One possible reason is that open ocean marine roughness is much smoother than that on the coast. Very few sondes are available over shallow waters but coastal tower observations suggest that coastal marine roughness differs greatly from open ocean conditions. In addition, recent measurements from the GPS s
