Australia: Tropical Cyclone Megan tracking east-northeastward in the Gulf of Carpentaria off the northeast coast of Northern Territory late March 17 /update 3

Category 3 Severe Tropical Cyclone Megan is tracking east-northeastward in the Gulf of Carpentaria off the northeast coast of the Northern Territory late March 17. As of 21:30 ACST, the storm's center of circulation was approximately 741 km (460 miles) east-southeast of Darwin.

Forecast models indicate that the system will weaken slightly as it tracks generally southwestward toward the southwest coast of the Gulf of Carperntaria through early March 18 before making landfall over the Pellew Islands during the late morning or early afternoon of March 18 and then weakening into a Category 2 tropical cyclone as it moves inland over northeastern Northern Territory late March 18. After landfall, the storm is expected to weaken into a Category 1 tropical cyclone as it generally tracks west-southwestward over northeastern Northern Territory March 19 before weakening into a tropical disturbance as it tracks west-northwestward further inland over northern Northern Territory March 20. Some uncertainty remains in the track and intensity forecast; changes could occur in the coming days.

As of late March 17, the Australian Bureau of Meteorology (BOM) has issued a cyclone warning from Alyangula, Northern Territory, to Mornington Island, Queensland, not including Mornington Island, extending inland to Borroloola, McArthur River Mine, and Robinson River, but not including Ngukurr.

Damaging winds gusting up to 110 kph (68 mph) are occurring over eastern Groote Eylandt March 17; these gales are expected to ease March 18 as the storm moves away from the island. Winds gusting up to 110 kph (68 mph) are also occurring over the Sir Edward Pellew Group and the adjacent mainland areas including Bing Bong and Port McArthur; these gales are expected to extend further over coastal mainland areas between Nathan River and the Northern Territory-Queensland border and over inland areas including Borroloola, McArthur River Mine, and Robinson River late March 17-early March 18. Winds gusting up to 125 kph (75 mph) will likely develop around the southwestern Gulf of Carpentaria coast, between Nathan River in the Northern Territory and the Northern Territory-Queensland border from early March 18 as Megan moves closer to the coast. The core of Megan, with winds of up to 200 kph (124 mph), is forecast to cross the coast between Nathan River in Northern Territory and the Northern Territory-Queensland border March 18. Gales with damaging wind gusts of up to 110 kph (68 mph) may extend further northwest to Numbulwar in Northern Territory, or east to Mornington Island in Queensland, not including Mornington Island, March 18 if Megan moves further west or east than forecast.

Intense rainfall is possible in coastal parts of Carpentaria District as Megan approaches late March 17-18. Heavy rain is ongoing over southeastern parts of the Top End, with the heaviest rainfall in coastal and island locations. The heaviest rain will extend further inland into the Carpentaria forecast district and parts of the Gulf Country coast in Queensland March 18. Coastal residents between Nathan River and the Northern Territory/Queensland border are warned of a dangerous storm tide as Megan makes landfall. Tides will likely rise significantly above the normal high tide, with damaging waves and dangerous flooding. Abnormally high tides are likely over the remaining parts of the southern Gulf of Carpentaria over the coming days and will likely rise above the normal high tide at times.

The BOM is also maintaining flood watches across the affected area and surrounding river catchments. A moderate flood warning is in place for the Daly River and a minor flood warning for the Katherine River.

Authorities have advised residents in the cyclone warning area who are not able to shelter safely to relocate if safe to do so. Those choosing to self-evacuate are being advised to register with their local police station prior to departure. Residents remaining in the area are being urged by emergency services to prepare their properties, secure loose items, ensure enough water is on hand, check on neighbors, prepare to take shelter, and listen to emergency service warnings. Heavy rainfall and strong winds have been ongoing over Groote Eylandt in recent days as the system passed to the east of the island; authorities have reported widespread flooding, downed trees, and some damage to infrastructure. Some residents are without power and water supply and several roads are impassable due to floodwaters, leaving some communities isolated. An unconfirmed number of residents in Gunbalanya in western Arnhem Land were evacuated due to rising floodwaters March 15 as heavy rainfall hit parts of the Top End.

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

The inclement weather could trigger localized business, transport, and utility disruptions, rendering some bridges or roadways impassable. Flight disruptions at regional airports and temporary closures of ports are also possible. Stagnant pools of water during and after flooding increase insect- and waterborne diseases, such as dengue fever, cholera, and malaria. Raw sewage and other hazardous materials mixed with floodwaters pose a serious health threat.