Indian Ocean: Intense Tropical Cyclone Chido tracking westward toward Agalega, Mauritius, early Dec. 12 /update 3

Intense Tropical Cyclone Chido is tracking westward across the Indian Ocean toward Agalega, Mauritius, early Dec. 12. As of 01:00 MUT, the system was around 1,080 km (671 miles) north of Port Louis, Mauritius.

Forecast models indicate that the storm will make landfall over Agalega, Mauritius, over the coming hours. Chido will likely weaken slightly but remain an intense tropical cyclone as it tracks west-southwestward away from Agalega Dec. 12. The storm is forecast to make a close approach to the northern Diana Region in Madagascar late Dec. 13, passing north of the country. The system is likely to weaken into a tropical cyclone as it tracks southwestward across the Mozambique Channel Dec. 14-15, making a subsequent landfall over Mayotte late Dec. 14. The storm will continue to weaken into a severe tropical storm before making another landfall over Nampula Province in Mozambique late Dec. 15. After landfall, Chido will probably weaken rapidly into a zone of disturbed weather and dissipate as it tracks southwestward inland over southern Nampula through 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) has issued a special weather bulletin warning that a heavy rain warning, a strong wind warning, and a heavy swell warning are in force in Agalega. Heavy continuous showers with thunderstorms are forecast and may result in water accumulation in certain places. Wind will strengthen from the southern sector to 100 kph (62 mph) with gusts of 180-200 kph (112-124 mph). After the passage of the eye, the wind of 100 kph (62 mph) with gusts of 180-200 kph (112-124 mph) will blow from the northern sector. The sea will become increasingly rough with swells of around 8 meters (26 feet). As Chido approaches Agalega, storm surges will inundate the coastal areas of the island. Officials advise the public at Agalega to not venture out to sea, to stay indoors, and maintain all precautions.

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. Yellow strong wind and heavy swell warnings are in place for northern coastal areas. Widespread flooding and landslides are likely for vulnerable areas in Diana and Sava regions. Storm surges and swells from the system may result in inundation along the coasts of Vohemar and Antsiranana I-II. 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 from the afternoon of Dec. 12. 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.