Hurricane Nolo, a zig-zagging storm, threatens Hawaii with flooding rains

Hurricane Nolo is seen approaching Hawaii's islands, in this satellite image captured Friday. Nolo is expected to avoid making landfall as it strengthens, but forecasters warn it will bring dangerous flooding rains. NOAA/NESDIS/STAR/GOES-West hide caption

People on the Big Island of Hawaii are under a hurricane watch Friday afternoon, as Hurricane Nolo moves over the Pacific Ocean toward the Hawaiian archipelago. The alert means hurricane conditions are possible within 24 to 36 hours. By then, the storm will likely be a major hurricane, according to the National Hurricane Center (NHC).

Nolo isn't expected to make landfall this weekend, but it has two dangerous qualities: slow movement and heavy rain . Maximum rainfall amounts from the storm in some areas could top 2 feet, forecasters say, with totals of 10 to 25 inches expected more widely.

"The time to finish preparations for significant heavy rain and flooding impacts on the Big Island is now," the NHC said in its public advisory. "Life-threatening, catastrophic flooding and mudslides are possible."

As of Friday afternoon, Nolo's maximum sustained winds were at 105 mph, making it a Category 2 storm, and it was moving at only 5 mph. It's now moving north-northeast and is expected to slow to a crawl before turning toward the west and picking up forward speed on Saturday and Sunday.

But it will continue to build strength from warm ocean waters. Over the next 72 hours, Nolo's winds could top out at 140 mph, according to the forecast discussion , making it a Category 4 storm.

A forecast cone shows the expected movements of Hurricane Nolo as it approaches the Hawaiian archipelago. NOAA/National Weather Service hide caption

The heaviest rains will likely fall on the Big Island's eastern and southern areas, forecasters say. Neighboring Maui is under a tropical storm watch and could see up to 10 inches of rain.