Indian Ocean: Category-2 Tropical Cyclone Seroja continues to track west-southwestward in the Indian Ocean as of April 7 /update 3

Event

Category-2 Tropical Cyclone Seroja continues to track west-southwest in the Indian Ocean south of Sumba, Indonesia, early April 7. The storm's center of circulation is approximately 1,075 km (668 miles) northeast of Barrow Island, Australia. Forecast models indicate that Seroja will strengthen to Category-4 Severe Tropical Cyclone strength by April 10 as it tracks west-southwestward. The system is then projected to slightly weaken to a Category-3 Severe Tropical Cyclone by April 11 and shift to a southward course before turning south-southeastward near the west coast of Western Australia. Significant uncertainty remains in the track and intensity forecast, and changes could occur over the coming days.

Government Advisories
The Australian Bureau of Meteorology (BOM) warns that the system may approach Gascoyne or Pilbara areas in Western Australia starting around April 9. Authorities will likely issue new warnings or update existing advisories 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.

Hazardous Conditions
Numerous landslides, along with significant areal flooding, have been reported in parts of southern Indonesia and Timor Leste following the passage of Cyclone Seroja. At least 117 people in Indonesia's East Nusa Tenggara Province have been killed, while dozens remain missing. Authorities in Timor Leste have reported at least 27 casualties. Official casualty figures are likely to rise in the coming days. Strong winds damaged thousands of structures, and thousands of residents of affected areas of Indonesia and Timor Leste remain displaced as of early April 7. The system caused extensive damage to roads and bridges in several communities.

Far western regions of Western Australia may experience severe weather from April 9. 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. In addition to the heavy rain, flooding, and storm surge, Seroja will likely produce damaging wind gusts. Widespread and prolonged power outages due to uprooted trees and toppled utility lines are likely.

Transport
Inclement weather associated with the storm could trigger localized business, transport, and utility disruptions in the affected areas through at least April 11. Storm impacts have damaged bridges connecting districts in Flores Island, East Nusa Tenggara Province, Indonesia. Floodwaters and debris flows may render additional 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. Disruptions caused 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 issued. 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

Indonesian Agency for Meteorology, Climatology, and Geophysics
Indonesian Agency for Meteorology, Climatology, and Geophysics Twitter
Bureau of Meteorology (BoM)