Indian Ocean: Tropical Cyclone Batsirai tracking west-southwestwards in the Indian Ocean early Feb. 5 /update 8

Event

Intense Tropical Cyclone Batsirai is tracking west-southwestwards in the Indian Ocean early Feb. 5. As of 03:00 EAT, the storm's center of circulation was approximately 412 km (257 miles) east-southeast of Antananarivo, Madagascar. Forecast models indicate the system will weaken slightly into a tropical cyclone as it tracks west-southwestwards and makes landfall over central Madagascar's east coast evening of Feb. 5.

The storm system will weaken rapidly into a moderate tropical storm as it tracks southwestwards over central Madagascar Feb. 5-6 before emerging in the Mozambique Channel early Feb. 7. Batsirai is forecast to strengthen slightly as it tracks southwestwards then southwards in the channel through early Feb. 10. Some uncertainty remains in the track and intensity forecast, and changes could occur in the coming days.

Disruptions occurred in Mauritius and Reunion as the storm passed north of the islands Feb. 2-4. In Mauritius, 7,500 people lost power Feb. 2, most power has since been restored. Flights resumed at Sir Seewoosagur Ramgoolam International Airport (MRU) Feb. 3 after authorities suspended operations late Feb. 1. A motorcyclist died after hitting a fallen tree in Trou-aux-Biches Feb. 3.

In Reunion, reports indicate at least 12 people were injured in storm-related incidents. Power outages occurred nationwide, and as of late Feb. 4, around 72,000 people were still without power. Almost 50,000 people are also estimated to be without water supply in the western and southern municipalities due to preventative cuts at pumping stations. Schools will remain closed until Feb. 7. Flights at Roland Garros Airport (RUN) resumed Feb. 4 following the suspension of operations late Feb. 2. The RN1 Route du Littoral, RN1A, RN5 Route de Cilaos, RD41 Route de la Montagne, and RD48 Route de Salazie are closed through at least Feb. 5.

Madagascar is still recovering from the passage of Tropical Storm Ana which transited over the country Jan. 22, causing widespread flooding. Some areas remain flooded. Authorities began pre-emptive evacuations in Manakra Feb. 4. Authorities have established shelters with a capacity for 5,000 people in Toamasina. Schools are closed from Feb. 4, and all non-essential workers have been advised not to work in areas under red alert warnings.

Government Advisories
The Mauritius Meteorological Services has lifted all cyclone warnings following the passing of the storm; however, a high wave warning is in place until 10:00 MUT Feb. 5. There is also a risk of storm surge on the north and west coast during high tide 02:00-06:00 Feb. 5.

Meteo France La Reunion has moved to a backup phase cyclonic alert across the territory Feb. 4, with residents advised to avoid nonessential travel until authorities lift this phase. Orange level heavy rain and thunderstorm warnings (the middle tier on a three-tier scale) are in place for northern and western areas, and orange high waves warnings are in place along the northwestern coastline. Yellow flood risk warnings (the second-highest level on a four-tier scale) are being maintained for the Blanche, Cabris, Galets, Langevin, Marsouins, Pluies, Remparts, Roches, Saint Denis, Saint Gilles, and Saint Paul rivers.

The Madagascar General Directorate of Meteorology has warned of a high risk of a storm surge of around 2 meters (6.5 feet) in the vicinity of where the storm makes landfall. Waves of 4-12 meters (13-39 feet) are forecast. As of late Feb. 4, the following authorities issued the following warnings ahead of the storm's approach:

• Red level imminent danger alerts (the highest level on a three-tier scale): Analamanga, Atsimo Astinanana, Atsinanana, Fitovinany, Mangoro, and Vatovavy regions as well as Ambatondrazaka, Ambatolampy, Ambohimahasoa, Ambositra, Antanifotsy, Antsirabe I-II, Arivonimamo, Fandriana, Fianarantsoa I, Iakora, Isandra, Ivohibe, Lalangina, Manandriana, Vavatenina, and Vohibato districts.

• Yellow level threat alerts: Androy, Anosy, Atsimo Andrefana, Bongolava, and Menadbe regions as well as Ambatofinandrahana, Amparafaravola, Antsalova, Betafo, Faratsiho, Fenerive-Est, Ihosy, Ikalamavony, Mandoto, Miarinarivo, Soanierana Ivongo, Soavinandriana, and St. Marie districts.

• Green level warning alerts: Andilamena, Antalaha, Maevatanana, Mandritsara, Mananara Avaratra, Maroantsetra, and Tsaratanana districts.

Authorities will likely issue new warnings or update existing advisories throughout the system's progression in the coming days.

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 regional airports 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, 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
Mauritius Meteorological Services
Madagascar General Directorate of Meteorology (French)
Meteo France Reunion (French)