(Reuters) - Hurricane Irma, one of the most powerful Atlantic storms in half a century, has triggered hurricane and storm surge warnings for south Florida and the Florida Keys, the U.S. National Hurricane Center (NHC) said on Thursday. Irma, which is about 585 miles (940 km) east-southeast of Miami, Florida, packing maximum sustained winds of 165 miles per hour (270 kph), will continue to bring life-threatening wind, storm surge, and rainfall hazards to the Turks and Caicos Islands and the Bahamas through Saturday, the NHC said. Irma should maintain a west-northwestward trajectory but slow down during the next 36 hours, it added. 