Tropical Storm Ana is expected to deliver heavy rain and potentially destructive winds to the southern half of Hawaii's Big Island in the next couple of days, meteorologists said Thursday.
Ana likely will become a hurricane by Friday evening but return to tropical storm strength Saturday morning, National Weather Service meteorologist Ray Tanabe said.
That's also when the storm is forecast to be closest to the island – about 85 to 90 miles offshore to the southwest.
The storm will be farther from the coast than predicted earlier, forecasters said Thursday. It also will be a hurricane for a shorter period than previously thought.
"Right now, we expect the main impacts to be on the Big Island," Tanabe said. The weather service has issued a tropical storm watch for the island.
The storm likely will bring 40 to 50 mph winds to the Big Island's Kau, Puna and South Kona districts. Tanabe warned that winds of this strength can blow down trees and knock out power.
The soil in the Kau district already is heavily saturated from recent thunderstorms, raising the risk of flooding there.
The weather service issued a flash flood watch for the entire state from Friday through Sunday, indicating flooding is possible anywhere in the archipelago, said Chris Brenchley, a weather service meteorologist.
Between 5 to 10 inches of rain may fall, though locally some areas could get 20 inches or more, he said.
Ana (AH - nah) is expected to lose some power as it moves northwest along the island chain.
"It will weaken, but it still will be packing some pretty strong winds," Tanabe said.
The current forecast calls for Ana to approach Oahu and Kauai more closely than the Big Island, but it will likely be a tropical storm and not a hurricane at that point.