Tropical Storm Barbara strengthens off Mexico and is expected to become a hurricane overnight

The storm is expected to become a hurricane overnight as it continues to move west-northwest for two more days, before turning toward west at a slower forward speed into the Pacific by Tuesday, forecasters said.

Barbara formed off the southwest coast of Mexico earlier Sunday.

Heavy rainfall totals of 2 to 4 inches (5 to 10 centimeters) are possible across portions of the Mexican states of Guerrero, Michoacan, Colima, and Jalisco through Monday. This rainfall may lead to flooding and mudslides.

Swells affecting portions of the southwestern Mexico coast for the next few days can produce life-threatening surf and rip current conditions, the hurricane center said.