Vietnam: Adverse weather forecast across much of the country through at least Dec. 5 /update 1

Event

Heavy rainfall accompanied by thunderstorms is forecast to affect much of Vietnam through at least Dec. 5. As of Nov. 29, the Vietnam National Center for Hydro-Meteorological Forecasting (NCHMF) has warned of heavy rainfall in northern and central mountain areas Nov. 29-Dec. 1. Rainfall amounts of 4-8 cm (1.6-3.1 inches), with isolated amounts of over 12 cm (4.7 inches), are forecast over mountainous areas of northeastern and northern Vietnam Nov. 29-30. Rainfall amounts of 7-15 cm (2.8-5.9 inches), with isolated amounts of over 15 cm (5.9 inches), are expected over central regions between the provinces of Ha Tinh and Quang Ngai Nov. 30-Dec. 1. The warning also states that further heavy rainfall is forecast over central and southern regions Dec. 1-3. Rainfall totals of 10-35 cm (3.9-13.8 inches) are possible over parts of the affected area. The heavy rainfall is likely to persist in central regions through Dec. 5.

The heavy downpours could trigger flooding in low-lying areas and landslides on stable slopes. Thunderstorms could be accompanied by strong winds, lightning, hail, and possible tornadoes. The NCHMF has issued a level 1 warning of natural disaster risk due to heavy rain, tornadoes, hail, and lightning.

Hazardous Conditions
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 located 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 the soil has become saturated by heavy rainfall. Disruptions to electricity and telecommunications services are possible where significant flooding, strong winds, or landslides impact utility networks.

Transport
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. Authorities may temporarily suspend port operations or close beach fronts along the South China Sea if strong winds trigger hazardous sea conditions. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see 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.

Advice

Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

Vietnam National Centre for Hydro-Meteorological Forecasting