Nolo strengthens to Category 2 hurricane; life-threatening flash flooding possible

Updated Sept. 25, 2 p.m.

Nolo strengthened to a Category 2 hurricane on Friday morning, with maximum sustained winds of 105 mph, and was located about 155 miles south of South Point on the Big Island, according to the 2 p.m. Friday advisory from the Central Pacific Hurricane Center.

The storm continues to move at 5 mph to the north-northeast and is forecast to continue in that general motion, with a decrease in forward speed forecast through late tonight. Nolo is expected to become a major hurricane by Saturday, when it is forecast to turn toward the west-northwest and west on Saturday and Sunday.

“Life-threatening flash flooding is possible, and damaging waves (are) likely on the Big Island of Hawai‘i over the weekend from Nolo,” according to the advisory.

According to the National Weather Service, heavy rain bands remain just offshore as Nolo slowly moves northward.

Tropical storm-force winds are expected to reach the Big Island as early as this afternoon, with hurricane-force winds possible by late Friday night.

The center of Nolo is forecast to remain well south of the main Hawaiian Islands. But Hurricane-force winds now extend outward up to 45 miles from the center and tropical-storm-force winds extend outward up to 140 miles.

Along with possible catastrophic and life-threatening flash flooding, Nolo could also bring mudslides across the windward and southeast portions of the Big Island into the weekend as it passes south. Flooding can occur even in areas not usually prone to flooding.

Tropical storm conditions on the Big island are expected to begin tonight, with hurricane conditions possible by early Saturday, particularly in areas of steep terrain.

A hurricane watch, tropical storm warning, flood watch and high surf advisory all remain in effect for the island.

RAINFALL: For the eastern and southern portions of the Big Island, Nolo will produce rainfall totals of 10 to 15 inches with maximum amounts of 25 inches. This rainfall could produce catastrophic, life-threatening flooding and mudslides, especially in areas of steep terrain.

For the western portions of the Big Island, rainfall totals of 2 to 4 inches with maximum amounts of 8 inches are expected.

Bands of intense showers and thunderstorms associated with Nolo will reach the Big Island during the next couple of days.

For Maui, rainfall totals of 4 to 8 inches with maximum amounts of 15 inches are expected. Across the remainder of the Hawaiian Islands, rainfall totals of 1 to 3 inches with maximum amounts of 6 inches are expected with isolated flooding possible.

STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters that move inland from the shoreline.

The water could reach 1 to 3 feet above ground if some areas of the Big Island if the peak surge occurs at the time of high tide.

The deepest water will occur along the immediate coast and will be accompanied by large and dangerous waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances.

SURF: Today, swells generated by Nolo are expected to reach exposed east-, southeast- and south-facing shores of the Big Island , spreading westward and building through the weekend. These swells are likely to cause life-threatening surf and rip current conditions.

A high surf advisory for east-facing shores is in effect until 6 p.m. on Sunday. Large breaking waves of 8 to 12 feet are expected Friday, increasing to 10 to 14 feet on Saturday.

Additional information

• Disaster preparedness information: American Red Cross.
• Appropriate preparations: Ready.gov.

For storm information specific to your area, including possible inland watches and warnings, monitor products issued by the National Weather Service Honolulu forecast office.

Also be sure to check out the “What Big Island residents need to know about Hurricane Nolo” for information about shelters, closures and other storm-related items that will help keep you safe.