A swell generated by Lane could bring very large and rough surf and unsafe rip currents for south- and southeast-facing shores, the weather service said.
It said further weakening of the cyclone was expected as it continued on a track that could see it take aim at other islands beginning early on Thursday. Offshore buoys also had detected wave action associated with the storm.
The National Weather Service in Grand Junction issued a flash-flood watch from noon Tuesday to noon Wednesday.
The hurricane center has posted hurricane warnings for the Big Island and Maui, where tropical-storm-force winds may begin between Wednesday night and Thursday morning.
Hurricane Lane strengthened to a category 5 storm on Tuesday as it headed toward Hawaii, where residents prepared for "life threatening" winds and flooding when it hits the USA islands this week, the National Hurricane Center (NHC) said.
Mike Charnick, a meteorologist for the Weather Service, said a weather system from the southwest, similar to a monsoon pattern, is going to put more moisture in the air, increasing the chance for precipitation.
As Hurricane Lane continues to churn toward Hawaii packing maximum sustained winds of 155 miles per hour, scientists gathering data on the storm provided a dramatic glimpse from inside on Tuesday.
OU No. 7 in Preseason AP Top 25
The Spartans will see Penn State (No. 10) on October 13, Michigan (No. 14) on October 20 and Ohio State (No. 5) on November 10. The Owls received 38 points in the preseason coaches poll, which equates to the No. 30 overall spot.
There are only two hurricanes on record that have made landfall in Hawaii, and both were on Kauai: Category 1 Dot hit in 1959 and catastrophic Category 4 Iniki came ashore in 1992. Even close calls are somewhat rare, with Hawaii getting a named storm within 60 miles of its coastline about once every four years on average.
The state is bracing for a powerful punch: The governor has declared an emergency, and all public schools on the Big Island and Maui are closed.
Tornadoes and large waterspouts will be possible due to Lane, mainly along and to the right of the track of the hurricane, the weather service said. The sharper the turn to the north, the more likely one or more islands will endure a direct hit.
"I remember how very little rain fell".
"But I remember the wind being the strongest force of nature I've ever witnessed and probably the scariest sounds I've ever heard in my life".
Utility poles were down all over the island, and his 7th-grade classes were held in Army tents for several months.
"Now is the time to prepare your homes and families", said Mayor Bernard Carvalho Jr.