Update, 4 p.m.

A flood watch has been issued for the entire state from Thursday morning to Saturday afternoon.

The National Weather Service said a kona low is expected to bring widespread heavy rainfall to the islands from Thursday into the weekend. The heaviest rainfall will begin Thursday for the Big Island and then spread to the remaining islands Thursday night through Saturday.

Heavy rainfall rates for an extended amount of time are expected to result in flash flooding, particularly over already saturated areas. Flooding may also occur due to the overflow of streams and drainages and landslides may also occur in areas with steep terrain.

Previous coverage

The high surf advisory for the east-facing shores of most Hawaiian isles has been extended through 6 p.m. today.

The National Weather Service expected a large, very rough tradewind swell to continue through this afternoon.

Surf of 8 to 12 feet is expected along the east-facing shores of Oahu, Kauai, Molokai, Maui, Hawaii island and Kahoolawe, along with strong, breaking waves and currents, which will make swimming dangerous.

The public should heed all advice from ocean safety officials.

Additionally, The City and County of Honolulu have issued a box jellyfish advisory on Oahu’s south shore, including Ala Moana and Waikiki, as well as the west shore, including Nanakuli, Maili and Depots.

Warning signs have been posted at these beaches.

Forecasters also say by Thursday, a low-pressure system passing north of the isles will bring the threat of widespread heavy rainfall and possible flash flooding to Hawaii, which will last into the weekend.

“Soil moisture is already elevated from recent heavy rains, increasing the potential for heavy rain to lead to runoff,” say forecasters. “It is too soon to know expected rainfall amounts or where the heaviest rain will fall, but leeward areas are just as likely to see heavy rain as are windward areas.”

A small craft advisory for all Hawaiian coastal waters also remains in effect until 6 a.m. Wednesday.