Tropical Storm Nolo is located 285 miles south of South Point, Hawaii, with current sustained winds of 60 mph. The official forecast brings the storm to hurricane strength on Sept. 24 and major hurricane strength by Saturday morning, peaking at 120 mph. A Hurricane Watch is active for the Big Island, Kona, and Kohala, with hurricane conditions possible starting Friday night, while a Flood Watch covers the Big Island, Maui, Molokai, Lanai and seven other zones until 6:00 PM HST Saturday.

Rainfall of 15 to 20 inches, with maximums of 35 inches, may trigger catastrophic flooding and mudslides on the Big Island, whereas Maui expects 5 to 10 inches. A storm surge of 1 to 3 feet is possible in Hawaii County, and dangerous swells will reach south-facing shores by Friday. The system will pass over the state's largest island before shifting westward, compounding a series of natural disasters since March that caused hundreds of millions of dollars in damage.