Tropical Storm Nolo forms in Pacific, Hawaii under hurricane watch

Hawaii's Big Island is under a hurricane watch as Tropical Storm Nolo threatens to dump up to 3 feet of rain later this week, the National Hurricane Center said.

Nolo formed in the Pacific Ocean on Wednesday and is expected to strengthen into a hurricane by Thursday night, and could become a major hurricane by the weekend, forecasters said.  A storm is considered a major hurricane when it reaches Category 3 or higher on the hurricane scale, meaning it has maximum sustained winds of at least 111 mph. 

Maps show Tropical Storm Nolo's path

Storm Nolo had maximum sustained winds of 50 mph as of early Thursday local time. Its core was some 460 miles south-southeast of Honolulu and 285 miles south of South Point, which is on the Big Island.

The storm was roughly stationary, but a "general north to north-northeast motion is expected through Friday, followed by a sharp westward turn by Saturday in the vicinity of the Big Island," the Miami-based hurricane center said.

Nolo is expected to approach the Big Island on Friday and Saturday.

The storm is expected to bring around 15 to 20 inches of rain to the Big Island, with up to 35 inches possible in some areas. The heavy rain could trigger "catastrophic life-threatening flooding and mudslides, especially in areas of steep terrain," the hurricane center warned.

Maui could see 5 to 10 inches of rain, with totals of up to 20 inches in some areas. Maui could also see life-threatening flooding and mudslides. The rest of the islands were forecast to get about 1 to 3 inches with 6 inches at most and could see isolated flooding.

Nolo formed as another storm, Hurricane Polo, continued to swirl in the Pacific, off Mexico's southwestern coast.

The latest storms add to an unsually active season in the Pacific. Earlier this month, Hurricane Lowell brought damaging winds and heavy rain to the western Hawaiian islands of Kauai and Niihau, bringing down trees, damaging roads and knocking out power for thousands.

Last month, Hurricane Lala washed away about 100 homes, triggered landslides and caused widespread power outages as it brushed past Hawaii.