MANAGUA - New Orleans evacuated some residents from areas outside its levee system as Tropical Storm Nate swirled toward the US Gulf Coast on Friday after killing at least 25 people in Central America.Nate is set to become a Category 1 hurricane, the weakest on a five-category scale used by meteorologists, by the time it hits the US central Gulf Coast on Saturday night or Sunday."Nate is at our doorstep or will be soon," New Orleans mayor Mitch Landrieu said.The greatest threat from this particular storm is not rain, but strong winds and storm surge, Landrieu said. The winds could cause significant power outages, and storm surges are projected to be six to nine feet (1.8 to 2.7 meters) high, he added."We have been through this many, many times. There is no need to panic," Landrieu told a news conference.Later on Friday, the storm is expected to brush by Mexico's Yucatan peninsula, home to beach resorts such as Cancun and Playa del Carmen, before heading north into the Gulf of Mexico, according to the US National Hurricane Center in Miami.Nate was blowing maximum sustained winds of 60 miles per hour (97 kmh) and was about 80 miles (123 km) east of the Mexican resort island of Cozumel on Friday afternoon, the NHC said.In the United States, a state of emergency was declared for 29 Florida counties and states near Nate's path - Alabama, Louisiana and Mississippi - as well as the city of New Orleans, devastated by Hurricane Katrina in 2005.The NHC issued a hurricane watch from Grand Isle, Louisiana to the Alabama/Florida border."By Saturday noon you should be in your safe place," Alabama Governor Kay Ivey told a news conference. "This is a fast-moving storm and we must begin preparing now."Nearly three-quarters of US Gulf of Mexico oil production was offline ahead of the storm, and more oil companies were halting operations late Friday.On Friday afternoon, Nate was moving north-northwest at 21 miles per hour (34 kmh), a fast pace which if maintained could mean the storm does less damage when it hits land.