A tropical zone on the East Sea is likely to strengthen into a tropical depression on Wednesday, with winds of 40-60 kph, according to the National Center for Hydro-Meteorological Forecasting.

As of Tuesday morning, the center of the tropical zone lay around 60 km to the northwest of the Southwest Cay islet in Vietnam's Spratly Islands, moving west at a speed of 15-20 kph.

At 7 a.m. Wednesday, the tropical zone would be around 180 km to the east of the coast off Binh Dinh to Khanh Hoa, home to the famous resort town of Nha Trang.

Central provinces should expect heavy rains from Tuesday night until this weekend, with rainfall of between 300 and 500 mm each time. Rainfall of 180 mm a day is considered heavy.

Central regions from Ha Tinh to Quang Ngai would be hit by rainfall of up to 700 mm each time while the Central Highlands and southern provinces should expect torrential downpours of up to 350 mm.

Since Monday night, some central provinces had experienced heavy rains.

"This will be the first period of prolonged, heavy rains in the central region," said Nguyen Ngoc Huy, an independent weather and climate expert.

A second period of downpours will follow after Sunday, with complicated development.

Popular tourist destinations along the central coast like Binh Thuan, Ninh Thuan, Nha Trang, and Phu Yen, home to luxury resorts and long, sandy beaches, will receive heavy rainfall from Tuesday evening, Huy said.

Tran Quang Hoai, deputy head of the Central Steering Committee for Natural Disaster Prevention, said in a meeting Tuesday morning that with some parts of the central region battered by heavy rains of up to 1,500 mm each time, heavy flooding is inevitable.

He asked localities to prepare evacuation plans for low-lying areas and inspect river and sea embankment systems to ensure safety.

The East Sea could see 11-13 storms and tropical depressions this year, half of them affecting Vietnam, meteorologists have warned.

Its long coastline makes Vietnam particularly prone to destructive storms and flooding. Natural disasters, predominantly floods and landslides triggered by storms, killed 132 people and injured 207 others last year.

Last month, Storm Noul, the fifth tropical storm this year in the East Sea, killed six people in central Vietnam.