Rick was centered at 6:15 a.m. EDT (1015 GMT) Saturday about 255 miles (410 kilometers) southwest of Acapulco, Mexico, and was moving west-northwest near 12 mph (19 kph) as of 6:15 a.m. EDT (1015 GMT) Saturday, the Miami-based center said.
"It's a bad storm. It's a strong Category 4 hurricane at this time," meteorologist Jessica Schauer told The Associated Press, adding it could become a Category 5 hurricane later in the day.
She said the storm was now "extremely dangerous" after warm waters fueled its rapid jump from a Category 1 hurricane to a strong Category 4 hurricane in only about 36 hours.
Schauer said Rick was moving parallel to southwestern Mexico's coast and more strengthening was expected in the next 36 hours. "Right now it's over very warm water and the current forecast track keeps it over warm water for quite a while," she said.
Acapulco's Civil Protection Department had earlier issued a warning that expected rains from outer bands of the storm could trigger landslides and flooding in the resort city.
Schauer said residents of Mexico's Baja California peninsula should be closely monitoring the storm because it could make its way to the region as early as Thursday. She added that forecast models show the storm will likely lose strength later in the week as it reached cooler waters.
