Vietnam: Adverse weather forecast across much of the country through at least May 23 /update 2

Severe weather is forecast across much of Vietnam through at least May 23. As of May 15, the Vietnam National Center for Hydro-Meteorological Forecasting (NCHMF) has issued a warning for heavy rain of 4-8 cm (1.5-3 inches) and thunderstorms across the Northern regions as well as heavy rain of 2-4 cm (0.8-1.5 inches) across the North Central region May 15-16. Thunderstorms and heavy rainfall of 1.5-3 cm (0.6-1.2 inches) are forecast over the Central Highlands and Southern regions the afternoon and evening of May 15 and May 17.

Strong wind gusts, lightning, hail, and possible tornadoes may accompany storms. Heavy downpours may trigger flooding in low-lying areas and landslides on unstable slopes. The NCHMF has issued a level 1 warning of natural disaster risk due to hail, tornadoes, and lightning across the affected areas. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days. Moderate to heavy rainfall and thunderstorms are likely to persist over the Northern region May 19-20, from Thanh Hoa to Thua Thien Hue May 20-21, and across the Central Highlands and Southern region May 16-23.

Heavy rainfall late May 12 resulted in three fatalities in Ba Vi District, Hanoi, due to a collapsed wall. Reports also indicate at least 532 damaged homes across northern Vietnam.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed or a lack of stormwater drainage systems. Sites downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rain has saturated the soil. Disruptions to electricity and telecommunications services are possible where significant flooding, strong winds, or landslides impact utility networks.

Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

Severe weather could also trigger flight delays and cancellations at airports in the affected regions. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas with heavy rainfall and potential track inundation.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities and some employees' inability to reach work sites.