Indian Ocean: TD Chalane to make landfall over northern Madagascar late Dec. 26 /update 2

Event

Tropical Depression Chalane continues tracking westward in the southern Indian Ocean, Dec. 26. As of 1200 EAT, the center of circulation was approximately 606 km (377 miles) east-northeast of Antananarivo, Madagascar, with the system carrying maximum sustained winds of 35 knots (65 kph, 40 mph). The latest forecast guidance indicates the storm will maintain its strength over the coming hours, and will weaken as it makes landfall over northern Madagascar late Dec. 26. Chalane is projected to slowly track southwestward across Madagascar through Dec. 28, weakening to a post-tropical low. Afterward, the system is expected to turn back to the west in the Mozambique Channel and may increase in strength to a moderate tropical storm. A subsequent landfall could occur in central Mozambique, possibly north of Beira, Dec. 30. The system will then track inland over Zimbabwe, where it will likely dissipate. Significant uncertainty remains in the track and intensity forecast, and significant changes could occur in the coming days.

Government Advisories
In advance of Chalane, Meteo Madagascar has issued yellow-level warnings for Sambava, Andapa, Antalaha, Toamasina I-II, Befandriana Avaratra, Mandritsara, Andilamena, Amparafaravola, and Ambatondrazaka districts. Green-level warnings have been issued for Vohemar, Bealalana, Antsohihy, Mampikony, Boriziny, Tsaratanana, Brickaville, Moramanga, Antanambao Manampotsy, and Anosibe an’Ala districts. Authorities in Madagascar could expand or rescind those warnings depending on the track of Chalane. Additionally, authorities in Mozambique, Malawi, Zimbabwe, and possibly South Africa, may issue weather warnings over the coming days.

Hazardous Conditions
Depending on the track of the storm, there is likely to be strong winds and heavy rainfall in northern and central Madagascar beginning Dec. 26, Mozambique beginning Dec. 29, and potentially Zimbabwe, southern Malawi, and far northern South Africa beginning Dec. 30. Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, and rivers, as well as in urban areas with easily overwhelmed stormwater drainage systems. Sites located downstream of large reservoirs could experience flash flooding after relatively short periods of intense rainfall.

Transport
In addition to the immediate threat to personal safety, inclement weather associated with the storm could trigger localized business, transport, and utility disruptions beginning Dec. 26 in Madagascar. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Areal flooding in urban locations could also result in severe traffic congestion, while strong winds will pose a hazard to high-profile vehicles. High winds and rough seas could prompt temporary port closures. Heavy rain and low visibility may trigger flight disruptions at regional airports. Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after conditions have improved. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.

Advice

Activate contingency plans in areas where officials forecast tropical storm conditions. Heed all evacuation orders. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the high 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 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. Keep any necessary medications in a waterproof container.

Plan accordingly for 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