22-tropicalstorTropical storm Vance gathered strength south of Mexico early on Friday and could become a hurricane and head toward the Pacific coast this weekend, the U.S. National Hurricane Center said. Vance was 475 miles (764 kilometers) south of the beach resort city of Acapulco at 1500 GMT (11 a.m. EDT), blowing maximum sustained winds of 45 mph (72 km/h) and could become a hurricane on Sunday, the Miami-based NHC said. While the storm is currently moving south-southwest at 3 mph (5 km/h), the NHC described the movement as erratic, adding that Vance could threaten the Pacific coast of Mexico by early next week. More