Mozambique Channel: Severe Tropical Storm Cheneso reforms in the Mozambique Channel Jan. 24 /update 4

Event

Tropical storm system Cheneso has reformed in the Mozambique Channel and has strengthened into a severe tropical storm Jan. 24. The system previously made landfall as a moderate tropical storm over Sava region in northeastern Madagascar Jan. 19 before largely dissipating as it tracked southwestward over northern and west-central Madagascar Jan. 20-23. As of 15:00 EAT, the storm's center of circulation was approximately 152 km (94 miles) west-northwest of Morondava, Menabe Region.

Forecast models indicate the system will strengthen into a tropical cyclone as it remains quasi-stationary in the Mozambique Channel Jan. 24-25. The system is expected to stay well over 100 km (62 miles) off the west and then southwest coasts of Madagascar as it tracks southwestward then south-southwestward Jan. 26-28, briefly reaching intense tropical cyclone strength Jan. 27 before weakening again into a tropical cyclone. The system is expected to take a turn to the southeast late Jan. 28, but will continue to stay offshore of Madagascar's southwest coast before starting to move away from the south coast Jan. 29. Due to the strength of the storm, impacts are expected along the west and southwest coasts of Madagascar, and possibly the southeast coast of Mozambique, as the system passes Jan. 24-29. Some uncertainty remains in the track and intensity forecast, and changes could occur in the coming days.

As of Jan. 24, the Madagascar General Directorate of Meteorology has issued green cyclone alerts (the lowest level on a three-tier scale) for Belo sur Tsiribihina, Manja, and Morondava districts in Menabe Region and Moromobe and Toliara I-II districts in Atsimo-Andrefana Region. Winds gusts of 50-80 kph (31-50 mph) are expected along the coasts of Atsimo-Andrefana and Menabe regions. Additionally, heavy rainfall of 4-8 cm (1.6-3.1 inches) in 24 hours is forecast across Atsimo-Andrefana, Atsimo-Atsinanana, Betsiboka, Boeny, Fitovinany, Melaky, and Menabe regions through Jan. 26.

Authorities have issued yellow heavy rain warnings for Atsimo-Atsinanana, Boeny, Fitovinany, and Melaky regions, as well as Analalava and Atsohihy districts in Sofia Region and Mahabo and Miandrivazo districts in Menabe Region. Yellow strong wind and strong swell warnings have been issued for much of the western, southern, and southeastern coastlines. A flood watch remains in force for the Betsiboka River basin in Betsiboka Region. Authorities will likely publish new advisories or update/rescind existing alerts throughout the system's progression in the coming days.

Disruptions due to flooding are ongoing across many parts of northern and central Madagascar following the earlier passage of the storm system across the regions Jan. 19-23. Areas where the ground is already saturated will be particularly susceptible to flooding during further heavy downpours associated with the storm system. As of Jan. 23, the National Office for Risk and Disaster Management (BNGRC) has reported three fatalities associated with the passing of Cheneso and 14 other people are missing. More than 17,000 people have been affected across nine regions and around 5,600 homes have been damaged by flooding across the affected areas, as well as dozens of schools, roads, and other infrastructure. Authorities have pre-emptively evacuated a number of residents along the Betsiboka and Mahajamba rivers in Betsiboka Region due to the risk of flooding.

Sustained heavy rainfall could trigger flooding in low-lying areas and those with easily overwhelmed drainage systems. If weather conditions prove hazardous, localized evacuations, flash flooding, and landslides are possible. The inclement weather could trigger localized business, transport, and utility disruptions and render some bridges or roadways impassable. Flight disruptions at airports in the region and temporary closures of ports are also possible. Stagnant pools of water during and after flooding increase insect- and waterborne diseases, such as dengue fever, cholera, and malaria. 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 storm 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. 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
Madagascar General Directorate of Meteorology