As of 4 a.m. Saturday, the center of Nakri, the sixth storm to hit Vietnamese waters this year, was around 160 kilometers (180 miles) northeast of the Southwest Cay islet in Vietnam's Spratly Islands, with a maximum wind speed of 115 kilometers per hour, according to the National Center for Hydro-Meteorological Forecasting.

Over the next 24 hours, the storm, projected to become the strongest East Sea storm of the year with wind speeds reaching 11 on the Beaufort scale, will move in a southwesterly direction at 10 kilometers a hour, gaining strength by Sunday morning.

By 4 a.m. Sunday, Nakri wind speeds could reach level 12 on the Beaufort scale at 135 km per hour.

Weather experts have forecast the storm to make landfall in the areas from Binh Dinh to Ninh Thuan provinces. Rainfall in the area, home to popular resort towns Nha Trang and Quy Nhon, has been forecast at 100-400 mm on Saturday night and Sunday, triggering erosion and flash floods. Rainfall of 180 mm in 24 hours is considered heavy.

It will then weaken into a tropical storm over the Central Highlands early on Monday morning, with winds of 60 kph.

The Hong Kong Observatory and the Japan Meteorological Agency have forecast the storm to make landfall in south central Vietnam on Sunday evening or night.

The U.S. Naval Research Laboratory has forecast Nakri would make landfall early on Monday morning.

"The operation of the storm is complicated. It is very rare that Vietnam faces a storm that moves from West to East and then returns to the direction of central provinces from Quang Ngai to Ninh Thuan," said Mai Van Khiem, director of the National Center for Hydro-Meteorological Forecasting.

Khiem said there were four tropical storms operating at the same time at sea, making the direction and intensity of Nakri change continuously.

In order to cope with the approaching storm, Binh Dinh, which suffered from heaviest damage from Storm Matmo late last month, will ban all ships and fishing boats from sailing and close all beaches from Saturday afternoon.

In addition, provincial authorities have ordered 1,000 families in coastal areas to evacuate to safer areas.

"Armed forces, including soldiers, members of the police force and civilian volunteers stand ready to respond to rescue operations immediately. This is a strong storm; therefore, all preparation plans should be conducted urgently and proactively"said Ho Quoc Dung, chairman of Binh Dinh Province, home to beloved beach town Quy Nhon.

Quang Ngai and Phu Yen have allowed all students to stay at home on Monday and have asked that no extracurricular activities are organized. Residents and tourists have been told not to gather at flood-prone areas.

Major General Le Manh Tien, deputy office chief of Vietnam's National Committee for Incident, Disaster Response and Search and Rescue, said at a meeting Friday that the Ministry of Defense has called for the mobilization of more than 2,300 vehicles and more than 250,000 people - soldiers, members of the police force and civilian volunteers, to stand ready to help residents in storm-hit areas.

At sea, 150 ships including that of the navy and the coast guards will be on duty.

Binh Dinh and its neighbors Phu Yen and Quang Ngai was just hit by storm Matmo on October 30. It felled hundreds of trees, damaged houses and caused widespread flooding, claiming two human casualities.

Vietnam is hit by up to 10 tropical storms during the southwest monsoon season, usually between July and October. There were nine last year.