Wind speed characteristics in tropical cyclones

Digital wind-speed data from tropical cyclones that have impacted the United States during the last decade have been analysed. Using additional data from reconnaissance aircraft, Doppler radar, and radiosondes, relationships between surface and gradient wind speeds have been determined. In addition gust factors have been computed for offshore, coastal and inland sites. It has been found that the wind speed characteristics of tropical cyclones are essentially the same as extra-tropical cyclones. Occasionally, in spiral. rainbands feeding into a tropical cyclone, unusually high gust factors have been found, but they appear to be rare. II has also been found that, as a result of unjustified assumptions, wind conditions in tropical cyclones impacting the United States are often overestimated by the National Hurricane Center in their marine statements and public warnings. Other unjustified assumptions appear to have led to design wind-speeds in some coastal areas of the United States being overstated by approximately 25%.