(CNN) Hurricane Erick and Tropical Storm Flossie churned closer to Hawaii on Thursday as forecasters warned of high surf and flooding threats.

Erick is a Category 1 hurricane with sustained winds of 85 mph, and is expected to weaken into a tropical storm over the next 24 hours. It's expected to make its closest pass of the state late Thursday.

"Swells generated by Erick will arrive in the Hawaiian Islands tonight through Thursday night, potentially producing dangerous surf conditions, mainly along east facing shores," the Central Pacific Hurricane Center said.

A high surf warning has been issued for the eastern coast of the Big Island. Surf of 15-20 feet is expected through Thursday, CNN meteorologist Haley Brink said.

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