Heavy rains exceed 300mm in many areas due to Typhoon Wipha

Strong winds subside, flood risk increases

According to Mr. Mai Van Khiem, Director of the National Center for Hydro-Meteorological Forecasting, on the afternoon of July 22, after Typhoon Wipha made landfall in Vietnam, the Gulf of Tonkin (including the special administrative regions of Bach Long Vi, Co To, Van Don, Cat Hai, Hon Dau Island, and Hon Ngu Island) experienced strong winds of level 6-7, gusting to level 10 near the eye of the storm. Sea waves were 2-4m high, with very rough seas.

On the afternoon of July 22, due to the lingering effects of Typhoon Wipha, the coastal area of Hung Yen province experienced strong southeast winds, pushing water towards the shore. Coastal stations and estuarial areas saw water levels rise by nearly 1m. At the Ba Lat hydrological station (Hung Yen), water rose by 0.8m, with the highest water level reaching 297cm (surpassing the historical level of 2017 by 26cm). At the Dong Quy hydrological station (Hung Yen), water rose by 0.6m, reaching 244cm, and continued to rise.

The circulation of Typhoon Wipha is causing widespread heavy rain in the Northern and North Central regions. Total rainfall from 7 AM on July 21 to 1 PM on July 22 exceeded 300mm in many places. Particularly in Thanh Hoa, Nga Son stations recorded 412mm of rain, Sam Son 380mm, Trieu Son 336mm, Nhu Thanh 327mm, Ba Dinh 326mm, and Hac Thanh 315.8mm. In Ninh Binh, Hai Anh, Giao Linh, and Tam Diep stations, over 260mm of rain was observed. Some coastal areas like Van Don (Quang Ninh) and Cat Hai (Hai Phong) exceeded 180mm.

During Typhoon Wipha, the strongest winds recorded at sea were in the Bach Long Vi special administrative region (Hai Phong), strong at Alert Level 10, gusting to Alert Level 12. The coastal area of Tien Yen (Quang Ninh) had winds at Alert Level 10, gusting to Alert Level 14.

Due to heavy local rain, some roads and residential areas in the Ninh Binh and Thanh Hoa provinces experienced localized flooding. Prolonged heavy rain increases the risk of inundation, flash floods, and landslides. Currently, water levels in the upstream Nam Non River (Laos) and the inflow to the Ban Ve hydropower reservoir (Nghe An) are forecast to increase in the coming days. The center urges units to closely monitor developments, adjust operations in a timely manner, and proactively ensure safety downstream.

High risk of flash floods and landslides in Western mountainous areas of Thanh Hoa, Nghe An 

It is forecast that from the afternoon of July 22 to the afternoon of July 23, the typhoon will gradually weaken into a low-pressure area, causing rain along its path towards upper Laos.

After the typhoon winds pass, the biggest concern is the risk of flash floods on small rivers and streams and landslides on slopes. Areas with a high risk level include mountainous and midland regions of Northern provinces, Thanh Hoa, Nghệ An, and Ha Tinh. "Special attention should be paid to the western mountainous communes of Thanh Hoa and Nghe An provinces, as these are the rainfall centers during this typhoon," emphasized Mr. Mai Van Khiem.

It is forecast that from the afternoon of July 22 to the morning of July 23, Thanh Hoa, Nghe An, southern Phu Tho province, and Son La will experience heavy to very heavy rain and thunderstorms. Widespread rainfall is expected to be 60-120mm, with some localized areas receiving over 200mm.

Other areas in the northern region and Ha Tinh will experience rain, moderate rain, with some localized heavy rain and thunderstorms. Rainfall amounts will be 20-40mm, with some localized areas exceeding 100mm. The hydrometeorological agency warns of the risk of high-intensity rainfall exceeding 150mm within 3 hours. Heavy rain in a short period can cause flash floods, landslides in mountainous areas, and inundation in low-lying areas.

From July 22 to July 25, floods are forecast to rise on the Ma River and Ca River with a range of 3-6m. During this flood event, peak flood levels in the upstream areas of these rivers are likely to reach Alert Level 1-Alert Level 2 and above Alert Level 2. Peak flood levels in the downstream Ca River will reach Alert Level 1-Alert Level 2; downstream Ma River will remain below Alert Level 1.