Tropical Storm Moke has formed in the vast Pacific Ocean, a system that could again threaten Hawaii with over a foot of rain just days after the state's unwelcome visit from Hurricane Lala.

"It appears the core of the storm will pass farther south of Hawaii than Lala did, perhaps 150-200 miles south of the Big Island," AccuWeather hurricane expert Alex DaSilva said in an online forecast. "Lala passed about 30 miles south of the southern tip of the Big Island last weekend."

According to the National Hurricane Center, Moke (pronounced MOH-keh) is located some 660 miles southeast of Hilo, Hawaii, and is moving to the west-northwest at 9 mph. It has maximum sustained winds of 45 mph.

On Aug. 20, the hurricane center warned some locations could face over a foot of rain from the system.

Environmental conditions appear favorable for gradual strengthening during the next few days as the system approaches the Hawaiian Islands, the hurricane center said in an online forecast.

Rain appears to be the main concern with Moke. "This rainfall may produce life-threatening flooding and mudslides for the windward and southeast Big Island, especially in steep terrain and over areas that were affected recently by Lala," the hurricane center said.