Beaufort scale the extension to 17 noted above. China also switched to this extended version without prior notice on the morning of 15 May 2006, and the extended scale was immediately put to use for Typhoon Chanchu. Hong Kong and Macau retain force 12 as the maximum. In the United States, winds of force 6 or 7 result in the issuance of a small craft advisory, with force 8 or 9 winds bringing about a gale warning, force 10 or 11 a storm warning ("a tropical storm warning" being issued instead of the latter two if the winds relate to a tropical
Hurricane force wind warning Hurricane force wind warning A hurricane force wind warning is a warning issued by the National Weather Service of the United States when sustained winds or frequent gusts of 64 knots (118 km/h, 74 mph) or greater are either being observed or are predicted to occur. The winds must not be directly associated with a tropical cyclone, or a hurricane warning will be issued. If winds are lighter than 64 knots, a storm warning or gale warning will be issued. In US maritime warning flag systems, two red square flags with a black square taking up the middle ninth of