At around 1 p.m., storm Koguma was over the southern part of China's Hainan Island with a maximum wind speed of 75 kph, according to the National Center for Hydro-Meteorological Forecasting. At around 3 p.m., the storm was around 300 kilometers from the Vietnamese shore, the center added.
Within the next 12 hours, it is expected to move west-northwest at 15-20 kph and enter the Gulf of Tonkin. By 1 a.m. Sunday, the storm's eye would be above sea regions from the northern city of Hai Phong to the north central Nghe An Province with a maximum wind speed of 75 kph, it was forecast.
Within the next 24 hours, the storm would make landfall to affect northern Vietnam localities, before devolving back into a tropical depression. By 1 p.m. Sunday, the depression would be above the southern part of northern Vietnam and the Thanh Hoa which borders Nghe An, with a maximum wind speed of 50 kph.
The Japan Meteorological Agency said as Koguma approaches the Vietnamese shoreline, it would have a maximum wind speed of 72 kph.
Until June 14, northern Vietnam and localities from Thanh Hoa to Thua Thien-Hue in the central region should expect rain levels up to 150 millimeters. Certain regions in particular, including Hanoi, Thanh Hoa, Nghe An, Ha Tinh, Quang Binh, Hoa Binh, Son La and Phu Tho should expect levels of up to 350 millimeters per bout.
Tran Quang Hoai, head of Vietnam Disaster Management Authority, on Saturday said the storm might not be big but would make landfall in regions with coastal economic activities, so localities must be ready to respond.
The National Steering Committee for Disaster Prevention has instructed localities to ensure safety for all ships and vessels, calling them back to either take shelter in safe zones or stay away from dangerous areas. Depending on the storm's upcoming progression, vessels may be suspended from seafaring altogether.
By 6 a.m. Saturday, over 54,700 vessels with over 225,000 crew members had been informed of the storm's path to get out of harm's way, according to border guards.