Vietnam: Tropical Depression 26W tracking west-northwest after making landfall in Khanh Hoa Province early Oct. 27 /update 2

Event

Tropical Depression 26W is tracking west-northwestward over central Vietnam after making landfall in Khanh Hoa Province early Oct. 27. As of 10:00 ICT, the storm's center of circulation was approximately 294 km (183 miles) east-northeast of Ho Chi Minh City, Vietnam. Forecast models indicate the storm will continue on a west-northwesterly course while weakening and dissipating as a tropical depression over Cambodia's Preah Vihear Province by early Oct. 28. The storm's track and intensity forecast remain somewhat uncertain, and the system may change accordingly over the coming hours.

Authorities have evacuated at least 25 families to temporary shelters on the dike of Prampi Makara Dam due to flooding in Dangkor District, Phnom Penh, Cambodia.

Government Advisories
Vietnamese officials have forecast that heavy to very heavy rain will affect parts of the Central Highlands region and from Thua Thien Hue Province to Khanh Hoa Province over the coming hours. The rain is likely to abate over the South Central Coast and the Central Highlands regions from late Oct. 27. Flash flooding and landslides are possible in affected areas.

Authorities will likely issue new warnings or update existing advisories throughout the system's progression in the coming hours. Weather warnings could remain active even after the system's immediate threat has diminished, as some areas may still be highly susceptible to rain-induced hazards. The possibility of localized evacuations remains possible if weather conditions prove particularly hazardous.

Hazardous Conditions
The storm may bring heavy rainfall and strong winds to parts of central and southern Vietnam and northern Cambodia over the coming hours. Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, rivers, and urban areas with inadequate stormwater drainage systems.

Sites located downstream of large reservoirs could experience flash flooding after relatively short periods of intense rainfall. Rain-induced landslides are possible in steeply sloped terrains. Flooding could isolate some communities for several days. Prolonged swells and storm surge generated by the system will likely result in coastal flooding. Persistent onshore flow could make it difficult for the surge to recede and for water levels to decrease in coastal river catchments.

Transport
Inclement weather associated with the storm could trigger localized business, transport, and utility disruptions. Floodwaters and debris flows could render some bridges or roadways impassable, impacting overland travel in and around affected areas. Areal flooding in urban locations could also result in severe traffic congestion, while strong winds will pose a hazard to high-profile vehicles. Heavy rain and low visibility may trigger flight disruptions at regional airports. Authorities have closed 20, 120, 1KD9 (34), and 1KD11(143) roads due to flooding at the Prek Tnort River

Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after weather conditions improve. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.

Health
Stagnant pools of water during and after flooding increase the incidence of insect- and waterborne diseases, such as dengue fever, cholera, and malaria. The threat of these disease outbreaks is usually elevated in low-income or underdeveloped areas of major urban centers due to the presence of incomplete or open sewer lines. The latent threat of waterborne contaminants from inundated industrial sites cannot be discounted; exposure to raw sewage and other hazardous materials mixed with floodwaters poses a serious health threat.

Advice

Activate contingency plans in areas where officials forecast tropical weather conditions. Heed any evacuation orders that may be issued. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the potential for severe flooding and storm surge. Stockpile water, batteries, and other essentials in advance. Charge battery-powered devices when electricity is available; restrict the use of cellular phones to emergencies only. Power down mobile devices when not in use. Keep important documents and necessary medications in waterproof containers. Observe strict food and water precautions, as municipalities could issue boil-water advisories following flooding events. Take precautions against insect- and waterborne diseases in the coming weeks.

Plan accordingly for protracted commercial, transport, and logistics disruptions in areas in the path of the storm, especially if vital infrastructure is damaged. Seek updated information on road conditions before driving or routing shipments through areas where flooding has occurred. Confirm flights before checking out of hotels or driving to the airport; clearing passenger backlogs may take several days in some locations.

Resources

Joint Typhoon Warning Center
Cambodia Department of Meteorology (Khmer)
Vietnam National Centre for Hydro-Meteorological Forecasting (Vietnamese)