Hurricane Nolo watch issued for Hawaii's Big Island

Hurricane Nolo strengthened Thursday, with heavy rainfall threatening "catastrophic" flooding on Hawaii's Big Island, the US National Hurricane Center (NHC) said.

A hurricane watch was in place for Hawaii County, which covers the Big Island, and a tropical storm warning was in place for Maui County.

Nolo is expected to bring 15 to 30 inches (38 to 76 cm) of rain to the eastern and southern areas of the Big Island, with totals possibly reaching 35 inches.

Heavy rainfall "could produce catastrophic life-threatening flooding and mudslides, especially in areas of steep terrain," the NHC said.

Nolo is expected to approach the Big Island, but its center is forecast to stay "well south of the main Hawaiian Islands," the NHC said.

It is expected to become a major hurricane on Saturday.

The state was last hit by a "major" hurricane -- meaning Category 3, 4, or 5 on the Saffir-Simpson scale -- in 1992, when Hurricane Iniki caused at least six deaths and billions of dollars in damage.