Hurricane Watch Posted on Hawaii’s Big Island as Nolo Approaches

A hurricane watch has been issued for Hawaii’s Big Island as Tropical Storm Nolo strengthens south of the island chain.

Nolo, with top winds of 40 miles (64 kilometers) per hour was 500 miles south of Honolulu and on a track that will take it close the Big Island early Saturday as a major hurricane, the US National Hurricane Center said in an advisory. In addition to the hurricane watch, flood watches have been posted for the Big Island, Maui, Lanai, Molokai and Kahoolawe through Saturday.

“Residents and visitors should take this threat very seriously,” the Hawaii Emergency Management Agency said in a Facebook post. Torrential rain on the Big Island and Maui are “creating the potential for life-threatening flooding and landslides.”

If Nolo follows the forecast and veers away, it will mark another near miss amid an active storm season prodded on by the strengthening El Nino in the equatorial Pacific and unusually warm ocean water around California and Mexico.

Nolo already is aggravating flood damage that’s been piling up since last winter when a series of Kona Lows began drenching Hawaii, forcing residents from their homes, closing roads and triggering widespread power outages.

Hawaii has been menaced by at least five tropical systems so far, including Hurricane Lowell that sparked warnings on Oahu and Kauai earlier this month, and Lala that came within miles of making landfall on the Big Island in August.

As much as 20 inches (51 centimeters) of rain may fall across the Big Island with some isolated spots getting as much as 35 inches, the hurricane center said. On Maui, up to 10 inches is expected, with some areas receiving as much as 20 inches and the rest of the chain may get between 1 to 3 inches.

Hurricane-strength winds of at least 74 mph are possible on the Big Island starting Friday and the southern-facing coastline could get up to a 3-foot storm surge. While Nolo is forecast to be slow to build strength in the next day, it is expected to rapidly intensify as it moves over very warm waters south of Hawaii, Eric Blake, a senior hurricane specialist at the US center wrote in a forecast.

Rapid intensification happens when a storm’s top winds rise by about 35 mph within 24 hours. These events can leave residents and officials little time to prepare.

“The time to prepare for significant heavy rain and flooding impacts on the Big Island is now, as heavy rain becomes more likely by Thursday and Friday,” Blake wrote.

While forecasters watch Nolo, powerful Hurricane Polo continues to bring heavy rain and gusty winds to Mexico’s west coast.

Polo, with top winds of 145 mph, is a Category 4 hurricane on the five-step, Saffir-Simpson wind scale, the center said in advisory.

While Polo isn’t expected to make landfall, it will be near the coast through Thursday before moving out to sea. As much as 6 inches of rain may fall across the Mexican state of Guerrero, resulting in flooding and mudslides. Parts of Michoacan, Colima and Jalisco are also expected to get heavy rain.

Top photo: Strong winds in Kapolei, Hawaii, on Sept. 7. Photographer: Michelle Bir/AFP/Getty Images. Bloomberg.