page_title: Severe storms in Australia
section_title: 2011
hierarchical_section_title: Severe storms in Australia / Victoria / 2011
caption_attribution_description: English: Camp Street during summer 2011 flooding
context_page_description: Severe storms in Australia refers to the storms, including cyclones, which have caused severe damage in Australia.
context_section_description: In the days preceding 25 December 2011, a high blocking pattern developed over south–east Australia, with a quasi-stationary high residing over New Zealand and a trough extending over Victoria from the interior of the continent. This stationary pattern allowed for a number of days of warm, moist northerly airflow across Victoria which lead to high moisture levels through a deep layer creating unstable conditions. Severe thunderstorms developed in the east and on Christmas Day an upper level trough approaching from the west lead to strong low-level shear allowing the unstable atmosphere to develop a number of supercells (very severe long lasting thunderstorm cells) around the Melbourne area, chiefly through the northern suburbs. The temperature rose to 30 °C (86 °F), with a forecast of mostly sunny with a chance of afternoon thunderstorms.
  Around 3:00pm a small storm cell formed just north of Melton and within 30 minutes the storm grew into a supercell and was headed straight for Melbourne's western suburbs. It was reported by residents that before the storm hit a loud roar could be heard, this was the sound of hail the size of tennis balls. Numerous reports of large hail were received, ranging from 8 centimetres (3.1 in) in diameter and causing significant damage to property, transport and infrastructure. Flash flooding occurred as a result of very heavy rainfall and multiple storms moving over the same location. The worst affected areas were the northern and eastern suburbs of Melbourne including Taylors Lakes, Keilor, Eltham, Greensborough/Doncaster and Keilor Downs. Tornadoes hit Fiskville, powerful enough to upend cars, and Melton. The Victorian SES handled more than 2000 calls in the first six hours; Powercor reported more than 3300 people without power; Jemena recorded more than 20,000 within its distribution area of inner Melbourne in result of the storm; Melbourne airport was closed; and the Insurance Council of Australia estimated a total damages bill of A$100 million. The storm blacked out more than 20,000 homes with major outages in Port Melbourne, Ballarat, Armadale, Essendon, South Morang, Toorak and South Melbourne. The Bureau of Meteorology predicted a morning shower and a maximum of 23 °C (73 °F) for the following day.
caption: A street in Trentham, Victoria during the summer 2011 flooding
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