MEXICO CITY — Tropical Storm Enrique gained strength off southern Mexico and forecasters predicted it would become the first hurricane of the eastern Pacific season Saturday.

The U.S. National Hurricane Center said Enrique’s maximum sustained winds had risen to 65 mph (100 kph) by late Friday and were expected to grow to hurricane force soon. The storm’s core was predicted to stay at sea while moving parallel to Mexico’s coast over the next several days.

Enrique was centered about 185 miles (300 kilometers) south of the port of Manzanillo late Friday and was headed to the west-northwest at 9 mph (15 kph).

While the storm was expected to remain offshore, forecasters warned that it could cause heavy rains and dangerous flash floods and mudslides over parts of southwestern Mexico.

Mexico’s Defense Department said it was sending troops to aid civilians in advance of the storm.