Tropical Cyclone Megan has officially become the 5th named system in Australian waters this season, after the BoM upgraded the system to a category one cyclone this evening. 

According to the latest advisory issued at about 4:30pm ACST, the system is located to the east of Groote Eylandt, and is gradually moving south, with sustained winds near the centre reaching 85km/h, gusting up to 120km/h. 

As a tropical low, the system already delivered huge amounts of rainfall to parts of the eastern Top End, with Groote Eylandt Airport recording 249.4mm in the 24 hours to 9am ACST. A whopping 200.2mm of that total fell in just the five hours between 4am and 9am. At the time of writing, another 185.7mm has fallen at Groote Eylandt Airport since 9am, and at Angurugu, only 1.5km south of the airport, 234.8mm has already fallen in the gauge. 

Tropical Cyclone Megan is expected to continue intensifying as it gradually drifts south. The system is currently expected to make landfall early Monday morning over the Pellew Islands in the NT. There is a small chance, however, that it could swing east and make landfall near Mornington Island in Qld on Monday evening. The longer Megan stays over the warm waters of the Gulf of Carpentaria, the more time there is to intensify, and there is a chance that it could intensify into a severe tropical cyclone (category 3). 

Once Tropical Cyclone Megan makes landfall, it is expected to weaken rapidly; however, even as an ex-tropical cyclone, the system could continue to dump large amounts of rain over the eastern Top End throughout the week.