Vietnam: Adverse weather forecast across much of the country through at least May 15 /update 1

Severe weather is forecast across much of Vietnam through at least May 15. As of May 9, the Vietnam National Center for Hydro-Meteorological Forecasting (NCHMF) has issued a warning for heavy rain and thunderstorms across northern, north-central, south-central, and southern regions. Strong wind gusts, lightning, hail, and possible tornadoes may accompany storms. Thunderstorms accompanied by locally heavy rainfall are expected in northern regions late May 9-early May 10, with rainfall amounts of 2-4 cm (0.8-1.6 inches) and localized higher totals over 6 cm (2.4 inches) likely in the region. Scattered showers and storms with localized heavy downpours are expected in north-central, south-central, and southern regions late May 9, with rainfall amounts of 1.5-3 cm (0.6-1.2 inches) and localized higher totals of over 5 cm (2 inches) likely in these areas. 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. Further showers and thunderstorms with localized heavy downpours are expected across northern regions through May 15, with scattered showers and storms expected in most other regions of the country. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

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.