Australia: Tropical Cyclone Ilsa tracking west-southwestward across the Indian Ocean as of early April 12 /update 3

Event

Tropical Cyclone Ilsa is tracking west-southwestward across the Indian Ocean early April 12. As of 11:00 AWST, the storm's center of circulation was approximately 346 km (215 miles) northwest of Broome, Western Australia, Australia. Forecast models indicate that the storm will track southwestwards along the northwestern coast of Western Australia while strengthening into a Category 4 Severe Tropical Cyclone through late April 12. The system is forecast to intensify further into a Category 5 Severe Tropical Cyclone as it turns slowly to track southeast through late April 13 and make landfall over the coast of northwestern Western Australia, between Port Hedland and Broome, early April 14. The storm will then track east-southeastward across central Western Australia before dissipating in southwestern Northern Territory early April 15. Some uncertainty remains in the track and intensity forecast; changes could occur in the coming days.

As of early April 12, the Australian Bureau of Meteorology (BOM) has issued a cyclone watch from Beagle Bay to Whim Creek, including Port Hedland and Broome, as well as inland areas to Nullagine and Parnngurr, including Telfer and Marble Bar. The core of Ilsa, with extreme gusts of up to 270 kph (168 mph), is forecast to impact the coast between Bidyadanga and De Grey late April 13 and inland to Telfer early April 14. Destructive winds with gusts up to 155 kph (96 mph) are likely between Bidyadanga and De Grey and inland to Marble Bar the afternoon of April 13 and as far inland as Telfer April 14, while damaging winds with gusts of up to 90 kph (56 mph) are possible between Bidyadanga and Whim Creek, including Port Hedland, the early afternoon of April 13 if the system moves further to the west. The damaging winds may extend further to Beagle Bay, including Broome, and inland to Marble Bar the afternoon of April 13 and to Telfer early April 14. Heavy rainfall and squally thunderstorms are likely over the western Kimberley and may extend to the eastern Pilbara April 13 and Northern Interior April 14. Abnormally high tides are possible about the coast between Broome and Port Hedland April 12-13. A flood watch is also in place for the west Kimberley and De Grey rivers as well as Sandy Desert and Western Desert districts catchments from April 12.

Authorities have shipped in food and fuel to last Bidyadanga, Western Australia's largest remote Aboriginal community, seven days. Several residents requiring medical treatment have been evacuated to Broome. A large number of people in Broome remain homeless following the catastrophic flooding in January; a lack of shelter is likely to exacerbate Ilsa's impact. Children and some adults in Punmu are being evacuated in advance of the storm. Authorities have evacuated holidaymakers and people traveling in caravans between Port Hedland and Broome.

Sustained heavy rainfall could trigger flooding in low-lying areas and those with easily overwhelmed drainage systems. If weather conditions prove hazardous, localized evacuations, flash flooding, and landslides are possible.

The inclement weather could trigger localized business, transport, and utility disruptions and render some bridges or roadways impassable. Flight disruptions at regional airports and temporary closures of ports are also possible. Exposure to raw sewage and other hazardous materials mixed with floodwaters poses a severe health threat.

Advice

Activate contingency plans in areas where officials forecast tropical cyclone conditions. Heed any evacuation orders that may be issued. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the 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 and necessary medications 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.

Plan accordingly for protracted 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
Australian Bureau of Meteorology