Tropical Cyclone Marcus has formed off the north coast of the Northern Territory and could affect Darwin on Saturday. Marcus has become the sixth tropical cyclone to be named in Australian waters so far this season. The system was located about 95km to the north of Croker Island at 9:30am CST today, moving towards the southeast at 13km/h as winds gusted to 95km/h near its core. As Marcus moves further south during Friday, wind and rain will increase over parts of the northern Top End before the system makes landfall tonight. A cyclone warning has been issued between Maningrida and Daly River Mouth, including Darwin, where gale force winds may develop during the next 24 hours. A cyclone watch extends west to the Kimberley's Mitchell Plateau, with gales possible in this area later on Saturday and on Sunday. Cyclone Marcus is expected to make landfall over the northern Top End tonight before turning southwest and passing close to Darwin on Saturday. At this stage, Marcus may still be a category one tropical cyclone when it passes near Darwin on Saturday, before moving further west over the Timor Sea and possibly approaching the Kimberley on Sunday. If Cyclone Marcus stays over open water as it moves west from Sunday into early next week, the system has the potential to develop into a more intense, potentially severe tropical cyclone to the north of WA. Visit http://www.bom.gov.au/cyclone for the latest tropical cyclone advisories.