(CNN) -- The strongest storm on the planet so far this year is rumbling across the Western Pacific near Taiwan and the Philippines, prompting authorities to issue warnings to residents in vulnerable areas.
Packing winds as strong as 260 kilometers per hour (162 mph) on Friday, Super Typhoon Usagi is forecast to plow through the Luzon Strait that lies between Taiwan and the Philippines on Saturday.
The storm is then expected to weaken to become a severe typhoon as it heads northwest toward the South China coast, where it is predicted to make landfall near the densely populated city of Hong Kong on Sunday.
Usagi's current wind strength makes it equivalent in power to a Category 5 hurricane. The overall storm system measures more than 1,000 kilometers (620 miles) across.
"It's an incredible storm system," said Pedram Javaheri, a meteorologist for CNN International. As the typhoon moves across the sea, it is estimated to be generating waves as high as about 15 meters (50 feet).
In the storm's path
Its outer bands have already brought rain to the northern Philippines, where authorities have issued storm warnings for more than 15 provinces. The local weather agency, Pagasa, said residents in mountainous and low-lying areas should beware of possible flash floods and landslides.
The lightly populated Batanes Islands -- situated right in the middle of the Luzon Strait, and the storm's path -- are the area the most at risk from potentially devastating winds, the agency said.
Usagi is expected to come closest to Taiwan on Saturday. The Central Weather Bureau issued a typhoon warning for the island, with heavy rain predicted, particularly in the east.
"If you're on the east coast of Taiwan, you've certainly got to take this storm very seriously," Javaheri said. Usagi could dump more than one meter (3 feet) of rain on the area over the coming days, he said.
Preparations in China
In China, authorities have issued a disaster relief alert ahead of the storm's expected arrival over the weekend. Usagi is expected to hit coastal areas of the populous southern province of Guangdong.
The National Disaster Reduction Commission and the Ministry of Civil Affairs have asked local authorities to prepare for potential emergencies and damage caused by the typhoon, the state-run news agency Xinhua reported Friday.
The Hong Kong Observatory warned residents that Usagi posed a threat to the territory.
"Weather will deteriorate significantly with strengthening winds and rough seas" on Sunday, it said.
East Asia is buffeted for several months a year by heavy storms that roll in from the Western Pacific. Usagi has eclipsed Super Typhoon Utor, which hit the Philippines and South China last month, as the strongest storm of the year so far.
About 50 people died as result of Utor in China, and 11 people were killed in the Philippines.
CNN's Brandon Miller contributed to this report.