Indian Ocean: Tropical Cyclone Seroja continues to track southwestward in the Indian Ocean as of April 8 /update 5

Event

Tropical Cyclone Seroja continues to track southwestward in the Indian Ocean, northwest of Australia, April 8. As of 11:00 AWST, the storm's center of circulation was about 640 km (398 miles) northwest of Exmouth, Western Australia. Forecast models indicate the system will continue to strengthen as it tracks southwestward and then south-southeast from April 10. Seroja is forecast to turn in a southeasterly direction the morning of April 11 before making landfall in between Coral Bay and Perth, Western Australia, as a Category-4 Cyclone late April 11 or early April 12. The storm will weaken significantly as it tracks across southwestern Western Australia through April 13. As Seroja is forecast to interact with another tropical system, significant uncertainty remains in the cyclone's track and intensity, and changes could occur in the coming days.

Government Advisories
As of 08:00 AWST April 8, the Australian Bureau of Meteorology (BOM) has not issued any weather warnings for the event. However, officials will likely issue warnings and watches for central Western Australia in the coming days.

Hazardous Conditions
Seroja will bring heavy rainfall, strong winds, and rough seas to coastal areas of central Western Australia beginning April 9. Meteorologists predict up to 10 cm (4 inches) of rain in the region and up to 4.5 cm (1.75 inches) in the Perth metropolitan area through April 13. Sustained heavy rain 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. Rain-induced landslides cannot be discounted in steeply sloped terrain. Flooding could isolate some communities for several days. Prolonged swells and storm surge generated by the system will likely result in coastal flooding, particularly as the system moves closer to land. Abnormally high tides are likely and could exacerbate storm surge in affected areas of Western Australia. Persistent onshore flow could make it difficult for surge to recede and water levels to decrease in coastal river catchments.

The cyclone will also produce damaging wind gusts up to 225 kph (139 mph) as it approaches land. Winds could down trees and electrical lines, leading to prolonged power outages and other utility disruptions.

Transport
Inclement weather associated with the storm could trigger localized business, transport, and utility disruptions through at least April 13. 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. Heavy rain and low visibility may trigger flight disruptions at regional airports. Sea conditions and high winds could also disrupt handling and other operations at ports along the Western Australian coastline, particularly Geraldton. Disruptions caused by inclement weather and resultant hazards, such as flooding, could persist well after conditions improve. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.

Advice

Review contingency plans for areas where officials forecast tropical cyclone 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

Australian Bureau of Meteorology (BOM)
Mid West Ports
Qantas
Geraldton Airport