According to the National Center for Hydro-Meteorological Forecasting, the eye of the storm lay 580 kilometers (360 miles) to the southeast of the south central province of Khanh Hoa at 3 p.m., with its strongest wind speed measured at 150-185 kph.
In the next hours, the storm will move in the west-northwest direction at the speed of 20-25 kph and by 10 a.m. Sunday, be 180 kilometers to the east of the coastline from Binh Dinh to Khanh Hoa. Its strongest wind speed by then would be 135-165 kph.
Under impacts of a cold spell, the storm, however, will change its direction to north-northeast on Monday before weakening into a tropical depression in the East Sea, known as the South China Sea globally.
Affected by the storm and the cold spell, provinces from Thua Thien Hue to Khanh Hoa, home to popular tourist destinations Hue, Da Nang, Hoi An, Quy Nhon and Nha Trang, will receive rains of 100-250 millimeters and up to more than 300 millimeters from late Saturday night to the end of Sunday, the center stated. Rainfall of 180 millimeters a day is considered heavy.
Those localities should also expect strong winds of more than 100 kph along their coastal areas and waves of 4-8 meters high.
Mountainous areas have been warned of flash floods and landslides while flooding should be expected for low-land areas.
The Japan meteorological station said the wind speed at the eye of the storm stood at 160 kph on Saturday morning and would continue as it approaches the central coast. According to the Hong Kong radio channel, the storm was as strong as 175 kph Saturday morning and when about 200 kilometers from the central coast, would drop to 155 kph.
Both stations said the storm will change its direction, traveling parallel along the central coast.
By Saturday, it was confirmed at least 21 people had been killed after Typhoon Rai swept through the Philippines, AFP reported.
Rai had intensified to a Category 5 storm, the highest classification with maximum sustained winds of at least 156 mph, before making landfall in the southern Philippines on Thursday.
On Friday afternoon, the storm became the ninth to enter the East Sea this year.