Honolulu: Tropical Storm Ana weakened unexpectedly as it churned across the central Pacific, but meteorologists said the storm was still forecast to gain strength and hit Hawaii in what could be its first hurricane in more than two decades.
Ana was about 590 miles (945 km) southeast of Hawaii`s Big Island on Wednesday evening local time, packing winds of up to 60 miles per hour (97 kph). Tropical storms get classified as hurricanes when maximum sustained winds reach 74 mph (119 kph).
The last hurricane to hit Hawaii was a Category 4 storm Iniki in September 1992. It lashed the island of Kauai with winds of more than 140 miles per hour (225 kph), killing six people and causing around $2.4 billion of damage.
Ana weakened through the afternoon hours contrary to earlier forecasts that predicted a strengthening, National Weather Service meteorologists said.
Still, forecasters issued a tropical storm watch for the Big Island, with the possibility of additional watches being announced for other islands into Thursday morning.
A watch means that storm conditions are expected in the covered area within 48 hours, according to the National Weather Service.
Ana is now forecast to become a hurricane by Thursday afternoon, said meteorologist Eric Lau at the Central Pacific Hurricane Center in Honolulu.
"Earlier runs of the model were predicting a strengthening trend of tropical storm Ana. But currently, based on satellite observations, it hasn`t intensified," Lau said.
Hawaii residents were being urged to stockpile provisions and make sure they had an evacuation plan if necessary.
"There might be a perception ... that the Big Island will block this storm, but we`re telling people not to take this storm lightly. It could become a hazardous situation over the weekend," said Peter Hirai, deputy director for emergency management in Honolulu.
In August, Tropical Storm Iselle pummeled the Hawaiian Islands with high winds and heavy rain, forcing hundreds of people to seek shelter and knocking out power to more than 20,000 residents.
A second storm tracking right behind, Julio, passed hundreds of miles north of Hawaii.
The last recorded hurricane to hit Hawaii before Iniki in 1992 was the Kohala Cyclone in 1871.