A series of complex low pressure systems, fronts and troughs will bring cold, wet and windy weather to southern Australia this week. The first low is located in the Bight today and will move east over Tasmania on Tuesday and into the Tasman Sea on Wednesday. This system, and an associated series of slow-moving cold fronts, will produce showers, thunderstorms, strong to gale force winds and alpine snow in multiple states and territories during the next three days. Squally showers will affect South Australia today and tomorrow. A severe weather warning has been issued for damaging wind gusts in a number of central and southern districts, including Adelaide, Mount Gambier and Murray Bridge. A wind gust of 106 km/h was recorded at Neptune Island earlier this morning. Showers and gusty winds will also spread over Tasmania, Victoria, NSW and the ACT between today and Wednesday. Most areas in these states will escape gales, although squally showers are likely and may produce localised damaging wind gusts. A large pool of cold air wrapping into this low will ensure that the alps see some of their best snow so far this season. Freezing temperatures, westerly winds and moisture will combine to produce 20-40cm of snow in the mountains, most of which will fall on Tuesday. The wind direction will cause the highest snow accumulations to occur on the western slopes of the ranges, although with snow lowering to about 1100m on Tuesday, all of the main resorts will see fresh falls. Snow is also likely to settle on high ground in the central and northern ranges of NSW as the cold air spreads north late on Tuesday and Wednesday. Some towns could be in for their first flakes of the season. Conditions will ease across most of the nation's southeast from Wednesday, although another, weaker front will brush Tasmania, Victoria and southeast NSW on Thursday. While Western Australia is enjoying a calmer start to the week, a cold front and deep low pressure system will bring a burst of showers and gusty winds from Tuesday. Rainfall totals of 20-40mm are possible for parts of the lower South West Land Division between Tuesday and Friday, including Perth. Part of the reason southern Australia is experiencing a burst of wintry weather this week is because the Southern Annular Mode (SAM) is negative for the first time in around a month. The SAM index measures the displacement of a westerly wind belt surrounding Antarctica. When SAM is negative, southern Australia typically experiences stronger low pressure systems and cold fronts during winter.