The National Civil Defence Steering Committee issued an urgent directive on August 31, asking coastal authorities and relevant ministries to closely monitor the system and strong winds at sea, manage vessels and prepare rescue forces.
The tropical depression strengthened from a low-pressure area east of China's Leizhou Peninsula on Sunday morning, according to the National Centre for Hydro-Meteorological Forecasting.
At 7 am, its centre was at about 20.6 degrees north latitude and 110.3 degrees east longitude, with maximum sustained winds at level 7 and gusts reaching level 9. It was moving southwest at 10-15 kph.
The system is forecast to move east-southeast over the northwestern waters of the northern East Sea and could strengthen into a storm by 7 am on September 1, with winds reaching level 8 and gusts of level 10.
Strong winds are forecast across Vietnamese waters, with the Gulf of Tonkin and waters from southern Quang Tri to HCM City seeing winds of level 5-6 and gusts of level 7-8 on August 31.
Winds of level 6-7, with gusts of level 8-9, are forecast for the northern and central East Sea. Waters from Ca Mau to An Giang and the Gulf of Thailand could see scattered thunderstorms, with a high risk of tornadoes and strong gusts.
Concerned agencies have been told to closely monitor vessels at sea, keep track of their movements and inform shipowners and captains of the storm's development so they can avoid dangerous areas.
The danger zone over the next 24 hours is north of 18 degrees north latitude and between 109.5 and 114.5 degrees east longitude, though it may be adjusted in subsequent forecasts.
Particular attention has been ordered for tourist boats operating in bays, coastal waters and around islands. Local authorities must also have personnel and equipment ready for search and rescue operations if needed.