Washington, Sha'ban 14, 1435, Jun 12, 2014, SPA -- Hurricane Cristina has rapidly strengthened Thursday to a major category-4 storm off the Pacific coast of Mexico, U.S. forecasters said. The storm’s maximum sustained winds increased to almost 230 kilometers per hour (kph) Thursday morning, becoming a category-4 hurricane just hours after strengthening to category-3 status, the Miami-based National Hurricane Center (NHC) said. Some additional strengthening is possible on Thursday, but Cristina is expected to start to weaken by Thursday night, the NHC said. Cristina was centered about 400 kilometers southwest of Manzanillo, Mexico, and was moving west-northwest—away from land—near 13 kph. There are no coastal watches or warnings in effect in western Mexico, but forecasters warned that waves generated by the hurricane are affecting parts of the country’s southwest coast and could cause dangerous surf and rip-current conditions. --SPA 16:47 LOCAL TIME 13:47 GMT www.spa.gov.sa/w