Tropical Storm Nadine neared hurricane strength in the Atlantic Ocean as Tropical Storm Kristy churned the surf in the Pacific, U.S. forecasters said Thursday. Nadine, with maximum sustained winds of 70 mph, was about 800 miles east-northeast of the northern Leeward Islands, moving northwest at 16 mph, the National Hurricane Center in Miami said in its 5 a.m. EDT advisory. No coastal watches or warnings were in effect. Forecasters said Nadine could strengthen to a hurricane later Thursday. The storm was expected to shift to the north-northwest Thursday night, then turn toward the north Friday. Tropical storm-force winds extended outward from the center as far as 140 miles. In the Pacific, Tropical Storm Kristy, with 50 mph maximum sustained winds, was about 265 miles east of the Socorro Islands and about 510 miles south-southeast of the southern tip of Baja, Calif., the National Hurricane Center said. It was moving west-northwest at 10 mph. Forecasters said the coast of southwestern Mexico and the southern Baja Peninsula could expect rough surf. No coastal watches or warnings were in effect. Kristy was expected to move toward the west-northwest for the next 48 hours and could strengthen some during that time, forecasters said. The center should pass south of the southern tip of Baja, Calif., in the next 24 hours. Tropical storm-force winds extended outward from center as far as 80 miles. Swells generated by Kristy will affect portions of the coast of southwestern Mexico and southern Baja, Calif., for the next couple of days, the center said. The swells likely will cause life-threatening surf and rip currents.