Indian Ocean: Intense Tropical Cyclone Chido tracking westward toward northern Madagascar Dec. 13 /update 4

Intense Tropical Cyclone Chido is tracking westward across the Indian Ocean away from Agalega in Mauritius and toward northern Madagascar early Dec. 13 following landfall over Agalega, Mauritius, late Dec. 11. As of 01:00 MUT, the system was around 1,022 km (635 miles) north-northeast of Antananarivo, Madagascar.

Forecast models indicate that the storm will make a close approach to the northern Diana Region in Madagascar the evening of Dec. 13, passing north of the country. The system is likely to weaken slightly but remain an intense tropical cyclone as it tracks west-southwestward across the Mozambique Channel Dec. 14-15, making a close approach to Mayotte the afternoon of Dec. 14, passing just north of the island. The storm will continue to weaken slightly before making landfall as an intense tropical cyclone over Cabo Delgado Province in Mozambique early Dec. 15. After landfall, Chido is forecast to weaken into a severe tropical storm as it tracks westward across Cabo Delgado Province through late Dec. 15. The system will weaken rapidly into a zone of disturbed weather as it tracks further west-southwestward inland over southern Niassa Province into southern Malawi, dissipating over Tete Province in Mozambique late Dec. 16. Some uncertainty remains in the track and intensity forecast; changes could occur in the coming hours and days.

The Mauritius Meteorological Services (MMS) is maintaining a heavy swell warning in Agalega. The sea will be very rough, with swells of around 6 meters (20 feet). Officials advise the public not to venture out to sea or along beaches.

Meteo Madagascar has issued a yellow cyclone warning (the middle level on a three-tier scale) across the Diana Region and Vohemar District in the Sava Region and green cyclone warnings for the rest of Sava and much of Sofia regions. Red strong wind warnings are in effect from Angotsy to Bobaomby and red heavy swell warnings from Bobaomby to Vohemar. Yellow strong wind and heavy swell warnings are in place for most of the rest of the northern coastal areas. Officials advise seafarers between Analalava and Cap d'Ambre, as well as between Cap d'Ambre and Ste Marie to not venture out to sea. Meteo France Mayotte has issued a cyclone pre-alert for Mayotte.

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.