Indian Ocean: Tropical Cyclone 4 tracking west-northwestward towards Agalega, Mauritius, early Dec. 10

Tropical Cyclone 4 is tracking west-northwestward across the Indian Ocean, towards Agalega, Mauritius, early Dec. 10. As of 01:00 EAT, the system was around 1,148 km (713 miles) north-northeast of Port Louis, Mauritius.

Forecast models indicate that the storm will strengthen into a severe tropical storm as it gradually turns to track west-southwestward and makes a close approach to Agalega, Mauritius, late Dec. 11, passing just south of the islands, before weakening into a moderate tropical storm and making landfall over northern Diana Region in Madagascar late Dec. 13. The system is likely to weaken into a tropical depression across the Mozambique Channel before making a close approach to Mayotte late Dec. 14. Some uncertainty remains in the track and intensity forecast; changes could occur in the coming hours and days.

The Mauritius Meteorological Services (MMS) has issued a special weather bulletin warning that the weather over Agalega will deteriorate Dec. 10. Moderate to heavy showers with thunderstorms and strong winds are forecast. Rough to very rough seas with swells are forecast, deteriorating further Dec. 11. Over St Brandon, passing showers are likely from Dec. 10, while the sea will gradually become rough with swells.

Sustained heavy rainfall could trigger flooding in low-lying areas and those with easily overwhelmed drainage systems. Localized evacuations, flash flooding, and landslides are possible. The inclement weather could trigger localized business, transport, and utility disruptions, rendering 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. Raw sewage and other hazardous materials mixed with floodwaters pose a serious health threat.