Mozambique Channel: Severe Tropical Storm Chalane tracking westward toward Mozambique early Dec. 30 /update 9

Event

Severe Tropical Storm Chalane has slightly strengthened as it continues tracking westward over the Mozambique Channel early Dec. 30. As of 2000 CAT Dec. 29, the system's center of circulation was approximately 300 km (186 miles) east of Beira, Mozambique, with maximum sustained winds of 60 knots (110 kph, 70 mph). Forecast models indicate the system will weaken slightly to a Moderate Tropical Storm as it tracks westward toward central Mozambique and make landfall over Sofala Province near Beira the morning of Dec. 30. Following landfall, the system will rapidly weaken as it tracks inland and is likely to dissipate over eastern Zimbabwe by late Dec. 30. Some uncertainty remains in the track and intensity forecast, and changes could occur in the coming days.

Government Advisories
As of 0200 CAT Dec. 30, authorities maintain red-level (high risk) tropical storm warnings for Sofala and Manica provinces, orange-level (moderate risk) tropical storm warning for Zambezia Province, and yellow-level (low risk) tropical storm warning for Inhambane Province. Officials in Zimbabwe have not issued any alerts in regards to the system. Authorities will likely issue new warnings or update existing advisories throughout the system's progression in the coming days. Weather warnings could remain active even after the system's immediate threat has diminished, as some areas may still be highly susceptible to rain-induced hazards. As of early Dec. 30, evacuations are ongoing for affected communities in Sofala and Manica provinces in Mozambique and Manicaland Province in Zimbabwe. Additional localized evacuations are possible if weather conditions prove particularly hazardous.

Hazardous Conditions
Moderate Tropical Storm Chalane will likely bring heavy rainfall, strong winds, and rough seas to coastal areas of Mozambique, especially in parts of Inhambane, Zambezia, and Sofala provinces, and eastern Zimbabwe, through at least 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 or a lack of stormwater drainage systems. Sites located downstream of large reservoirs could experience flash flooding after relatively short periods of intense rainfall. Fairly arid areas may also be subject to inundation where hard, dry soil cannot absorb rainfall. Rain-induced landslides are possible in steeply sloped terrains. Flooding could isolate some communities for several days. Prolonged swells and storm surge generated by the system will likely result in coastal flooding as the system approaches land. Persistent onshore flow could make it difficult for the surge to recede and for water levels to decrease in coastal river catchments.

In addition to the heavy rain, flooding, and storm surge, Chalane will produce damaging wind gusts as it approaches Mozambique. Gusts in excess of 75 knots (140 kph, 85 mph) cannot be ruled out, especially in areas near the center of circulation. Widespread and prolonged power outages due to uprooted trees and toppled utility lines are possible.

Transport
In addition to the immediate threat to personal safety, inclement weather associated with the storm could trigger localized business, transport, and utility disruptions. 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; authorities have suspended operations at Beira port through at least Dec. 31 as a precaution. Heavy rain and low visibility may also trigger flight disruptions at regional airports, including Beira International (BEW), Chimoio (VPY), and Quelimane (UEL) airports in Mozambique. 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
Instituto Nacional de Meteorologia Mozambique (Portuguese)
Meteorological Services Department of Zimbabwe Twitter