Tropical Storm Guillermo’s threat to Hawaii is expected to diminish further Thursday as wind shear continues to tear apart the storm while it tracks north of the islands.

With maximum sustained winds of 40 mph, the storm was centered 145 miles northeast of Kahului and 225 miles east of Honolulu at 11 p.m. Wednesday. It was churning west near 12 mph.

The west, rather than west-northwest path of Guillermo brings it closer to Oahu and Kauai. But the storm continues to weaken quickly and should become a tropical depression later Thursday.

Tropical storm force winds extend 150 miles from the center, but mostly in the storm’s northeast quadrant, away from the islands.

But as Guillermo weakened, a new storm formed in the Eastern Pacific. Tropical Storm Hilda formed Thursday morning and was on a path to come close to Hawaii.

The storm, formerly Tropical Depression 10-E, was about 1,630 miles east-southeast of Hilo with maximum sustained winds of 40 mph at 5 a.m. Thursday. The storm was expected to cross into the Central Pacific on a northwest path and grow into a hurricane before weakening. It was moving west at 13 mph.

On Wednesday, the National Weather Service dropped a tropical storm watch for Hawaii and Maui counties and a flash flood watch for the state, but a tropical storm watch for waters north of Kauai, Oahu and Maui County remained in effect.

“Guillermo is weakening and is moving far enough north of the main Hawaiian islands to keep land areas beyond tropical storm force conditions,” the Central Pacific Hurricane Center said. The storm is expected to become a tropical depression by Thursday night or Friday as it passes north of Oahu and Kauai.

On its current track, Guillermo is expected to pass 160 miles north-northeast of Hawaii island late Wednesday night and 90 miles north-northeast of Maui Thursday morning, forecaster said. 

“Showers over the main Hawaiian islands have become heavier and more numerous as clouds on the southwest fringe of Guillermo have spread across the area. The weather over the islands will be dependent on the track Guillermo follows, but moisture from Guillermo is likely to remain over the islands through Friday,” forecasters said.

By late Friday and Saturday, a normal tradewind-weather pattern should return to the state.

 Potentially dangerous surf generated by the storm is still a concern.

East shores of Hawaii, Maui, Molokai, Oahu and Kauai are under a high surf warning with waves of 10 to 15 feet expected through 6 p.m. Thursday.

Honolulu lifeguards urged people to stay off shoreline ledges, where waves could wash people into the ocean and said only experts should be in the water.

The state Department of Land and Natural Resources’ Division of State Parks closed Waianapanapa State Park on Maui Wednesday morning due to dangerous high surf from Guillermo. People are urged to stay clear of the blow hole and black sand beach and coastline areas, officials said.

On Kauai, the Kalalau Trail to Hanakapiai Stream in the Na Pali Coast State Wilderness Park on the island’s north shore was closed due to a flash flood watch and the potential for heavy rain, state officials said Wednesday. 

During recent storms, dozens of people have had to be rescued after being stranded on the wrong side of the stream during flash floods. The Division of State Parks advises the public to stay off the trail until the storm has passed. 

Forecasters are still watching the storm closely with hurricane hunter planes flying through its center to determine whether more watches or warnings are issued.

“We’re going to see quite a bit of weakening over the next 48 hours,” Chevy Chevalier, a meteorologist with the hurricane center, said Wednesday. “We may not have to issue a watch for Oahu because the tropical storm force winds may not affect Oahu.”

The forecast for Wednesday calls for frequent showers in windward and mountain areas across the state with scattered leeward showers. Locally heavy showers are possible starting Wednesday night. Winds are expected to be from the northeast at 15 mph, with higher gusts.

Mostly cloudy skies are expected Thursday with more windward and mauka showers and scattered showers in leeward areas.