Оңтүстік желдің күрт өзгеруі: Австралиядағы суық фронт құбылысы

A southerly buster is the colloquial name of an abrupt southerly wind change in the southern regions of New South Wales and Victoria, Australia, which approaches from the southeast, mainly on a hot day, bringing in cool, usually severe weather and a dramatic temperature drop, thus ultimately replacing and relieving the prior hot conditions. Marking the boundary between hot and cool air masses, a southerly buster is sometimes represented by a roll up cloud perpendicular to the coast, which appears from the south and coexists with the wind change, though sometimes there is little visual signal of the southerly's arrival. Southerly busters occur in the backside of a low pressure trough in the Tasman Sea, followed by the speedy advance of an anticyclone south of Western Australia and South Australia (around the Great Australian Bight). They are caused by the interaction of a shallow cold front with the blocking mountain range that aligns the coast, and frictional contrasts over the mainland and the ocean that disconnect the flow. Southerly busters occur about 32 times each year on the coast of southeastern Australia, with variable strength, usually in spring and summer. Although southerly busters are often associated with NSW and Victoria, they also occur on the east coast of Tasmania, New Zealand, and in Argentina and Chile.

In New South Wales, southerly busters generally reach their maximum intensity between Nowra in the South Coast and Newcastle. Southerly busters rarely pass beyond the Mid North Coast or Port Macquarie – When they do they are usually strengthened by the presence of a tropical cyclone off the north coast of the state. Moreover, they are less pronounced in that region with narrower temperature changes. Not restricted to the immediate coast, southerly busters do generally impinge upon the inland regions of NSW as well, namely the regions in the southeastern block of the state, such as, the Greater Western Sydney area, eastern portion of the Central Tablelands region going eastwards from Bathurst, the lower Hunter Valley region, Albury in the South West Slopes in a few occasions, Cooma in the Monaro (New South Wales) to the south, Canberra in the ACT, Goulburn in the Southern Tablelands and the Snowy Mountains, with the latter regions having the most dramatic cool changes due to their southerly vicinity. Sydney receives an average of about five Southerly Busters a year, mostly in late spring and early summer, with the stronger ones generally reaching the city in the late afternoon or early evening on a hot day, though at times it would arrive after several days of hot weather. It is a crucial weather feature in the Sydney area, particularly for yachtsmen. Southerly busters most emerge in spring, as the landmass northbound of Melbourne starts to warm up. Meanwhile, though, the Southern Ocean, which provides cool breezes to Victoria from the west, does not warm up as swiftly as the mainland. As such, the temperature difference between hot air from the north and cold from the ocean would be very great, thus providing good conditions for the formation of thunderstorms. In South Australia, Mount Gambier would the most affected by southerly busters in the state due to its southeasterly location. The buster may also reach Adelaide and Whyalla in some occasions. In Western Australia, the Buster occasionally reaches Eucla due to its location near the Southern Ocean in the warm months, where it can experience dramatic temperature drops. In Wellington, New Zealand these storms are normally short and frequently have winds gusting between 120 km/h and 160 km/h though higher speeds are known. In South America, these southerly fronts frequently encroach on the southern coast of Chile and Argentina and would then advance northwards on both sides of the Andes.

The strongest recorded Southerly Buster fell around 4:30 pm on 12 March 2010 in Wellington, New Zealand, with a maximum gust recorded of
Henry Ambrose Hunt in "An Essay on Southerly Bursters" included the Dandenong Gale in his list of bursters and wrote "the wind attained, locally, to the abnormal velocity of one hundred and fifty three miles per hour (246 km/h) in a gust, the rate of one hundred and twelve miles for ten minutes and fifty seven miles per hour for nine hours." The sail steamer Dandenong foundered off Jervis Bay during the gale with the loss of forty lives. hence the name of the gale. This velocity is no longer officially recognised but the 'Kurnell Tornado' in December 2015 shows gusts in excess of are possible in the area, and the day before the tornado the possibility of a southerly buster on the following day had been proposed.

On 21 November 2016, at around 6pm, a powerful southerly change occurred in Melbourne, which resulted in the death of 10 people, who were asthmatic and succumbed to respiratory failure. Thousands of others across the city experienced allergic reactions and asthma like symptoms triggered by the storm. This was due to a stark southerly wind (60 km/hour) that distributed ryegrass pollen into the moist air, rupturing them into very fine specks, small enough particles to enter people's lungs, as they were sucked up into the warm updraft of air forming the storm cells, before they returned to earth in the storm's cool down draft, spreading across the land in the storm's efflux area. Hospitals and medical centres in the city had to arduously manage 8,500 emergency calls in the space of just five hours, and the hospitalisation of 1,400 people.