A tropical depression west of the state is expected to intensify into a tropical storm but is not likely to affect the main Hawaiian Islands, the Central Pacific Hurricane Center in Honolulu said.

At 5 p.m. Saturday, Tropical Depression Five-C was about 370 miles west-northwest of Johnston Atoll, moving north-northeast at 8 mph with maximum sustained winds of 35 mph.

The storm is expected to gain strength as it continues on the same path until Monday, when forecasters expect it will gradually turn to the north.

If the depression intensifies into a tropical storm, it will be named Malia.

The National Weather Service issued a tropical storm warning for portions of the Papahanaumokuakea National Marine Monument from the French Frigate Shoals to Maro Reef to Lisianski Island. A warning means that tropical storm conditions are expected within 36 hours.

Lisianski Island to Pearl and Hermes Atoll are under a tropical storm watch. A watch means that tropical storm conditions are possible within 36 hours.

The weather service predicted that swells from the south and southwest will build across central portions of the Papahanaumo- kuakea Marine National Monument between Saturday and Sunday. Surf and seas were expected to become large and increasingly rough and dangerous on Sunday and early Monday.