Tropical Storm Lane drenched parts of Hawaii with about four feet of rain as it crept past the state on Saturday, causing flash floods and prompting evacuations even as it dissipated over the islands’ rugged slopes.

The storm had weakened over several days from a Category 5 storm, with maximum winds now reaching up to 60 miles per hour, according to the National Weather Service. But its plodding pace — just 3 m.p.h. — prolonged the rains. Some 46 inches fell on the eastern side of the Island of Hawaii, where landslides shut down roads and search-and-rescue efforts were underway. Flash flood warnings were still in effect on Saturday.

Kelly Wooten, a spokeswoman for the Hawaii County Civil Defense, which has been coordinating the emergency response in hard-hit areas on Hawaii Island, said the agency had not yet been able to assess the damage from the storm. She said police, fire and other departments were working to keep people off the roads, as some areas were still under water.

Ms. Wooten said no injuries or deaths had been reported so far. The county would be clearing debris and opening closed roads over the next few days, she added, as it recovered from a series of landslides.