Mr. Nguyen Van Huong - Head of Weather Forecast Department, National Center for Hydro-Meteorological Forecasting, assessed that storm No. 4 has complicated developments and a relatively unusual path.
1. "Crouching" trajectory, constantly changing direction
From the early morning of August 21, from a tropical depression passing through the Northwest area of Hainan Island, China and entering the Gulf of Tonkin. By the late afternoon of August 21, this tropical depression had strengthened into a storm and became storm No. 4. And since it strengthened into storm No. 4, the path of storm No. 4 when moving north, sometimes going west or slanting to the South" - Mr. Huong said.
Explaining the reason why the path of storm No. 4 is so complicated, according to Mr. Huong, it is because the channel determines that the path of the storm is relatively weak.
While storm No. 4 is located on a trophic convergence zone with a chain of tropical cyclones in the eastern sea of China and the storm offshore. The interaction between tropical cyclones causes storm No. 4's path to change continuously and maintain intensity for a long time in the Gulf of Tonkin area" - Mr. Huong analyzed.
2. Very slow movement speed and almost standing still state
Storm No. 4 moved at an extremely slow speed, only about 3 - 5km/h. Notably, for many consecutive hours, the storm was almost standing still (moving little) in the sea area of Quang Ninh - Hai Phong and the northern area of Bach Long Vi special zone. The slow pace of the storm caused the impact time to be prolonged.
As of this morning, August 24, the storm's center is in the northern sea area of Bach Long Vi special zone. The strongest wind near the storm's center is level 9 (75-88 km/h), gusting at level 11.
Forecast for the next 24 hours, the storm will move in a South-Southeast direction after changing direction to East-Northeast, speed 3-5 km/h over the eastern Gulf of Tonkin area. Wind intensity level 9, gusts level 11.
Forecast for the next 48 hours, the storm will move in a Northeast direction, at a speed of about 5 km/h and gradually weaken in the northeastern sea area of the Northern Gulf of Tonkin. Wind intensity is strong at level 8, gusting at level 10.
Forecast for the next 72 hours, the storm will move in a North-Northwest direction at a speed of 5-10 km/h and weaken into a tropical depression on land in the southern province of Guangxi (China).
3. Long duration of storm shelter causes prolonged heavy rain
Storm No. 4 caused a series of impacts on sea, coastal and mainland weather. In particular, due to the long duration of the storm's stay, heavy rain has lasted continuously in the Northeast and Thanh Hoa.
Forecast for August 24, rainfall in the Northeast region, southern provinces of Phu Tho, Thanh Hoa, Nghe An is commonly 20-40mm, locally over 70mm; especially Hung Yen, Ninh Binh, Thanh Hoa, Nghe An is commonly 40-100mm, locally over 200mm.
From the night of August 24 to the morning of August 25, coastal and delta areas of the Northern region, Thanh Hoa and Nghe An are commonly 20 - 50mm, locally over 100mm. From the afternoon of August 25, rain tends to gradually decrease.
The meteorological agency continues to warn that there is a high risk of flash floods on small rivers and streams and landslides on slopes in Lang Son, Bac Ninh, Cao Bang, Thai Nguyen, and Thanh Hoa provinces.
