East Coast Low, Australia 25 June 2013
Australian east coast lows (known locally as east coast lows and sometimes as east coast cyclones) are extratropical cyclones, the most intense of these systems have many of the characteristics of subtropical cyclones. They develop between 25˚south and 40˚south and within 5˚ of the Australian coastline, typically during the winter months. Each year there are about ten "significant impact" maritime lows. Explosive cyclogenesis is seen on average just once per year, but these storms cause significant wind and flood damage when they occur. Australian east coast cyclones vary in size from mesoscale (approximately 10 km to 100 km) to synoptic scale (approximately 100 km to 1,000 km). These storms which mostly affect the south east coast should not be confused with Australian region tropical cyclones which typically affect the northern half of the continent.
Australian east coast cyclones, although variable in size and intensity, are typically characterized by widespread heavy rainfall. These storms affect large populated cities such as Sydney and Brisbane, between which over one-third of the population of Australia resides. Rain associated damages attributed to east coast cyclones are estimated in millions to tens of million dollars annually and are a major contributor to the total weather-associated insurance losses for all of Australia. 7% of all major Australian disasters since 1967 can be directly attributed to east coast cyclones. Australian east coast lows often intensify rapidly overnight making them one of the more dangerous weather systems to affect the NSW coast.
The incidence of these types of storms can be seen to fluctuate quite widely from one year to the next, with none in some years and the highest incidence being twelve in 1978/79. Another feature of east coast low development is the tendency for clustering of events when conditions remain favourable. For example, near Brisbane, almost one third of events occur within 20 days of a preceding event. Correlations of east coast cyclones with the interannual differences of the Southern Oscillation Index (SOI) indicate a strong preference for these storms to form just after a large swing from negative to positive Southern Oscillation index values and especially between swings from negative SOI the year before and positive SOI the year after. This suggests a preference for formation of east coast cyclones between extreme events of the Southern Oscillation Index.
Prior to the introduction of satellite imagery in the early 1960s, many east coast lows were classified as tropical cyclones.
Australian east coast cyclone Examples
- 2013 June
- 2009 May 21, an east coast low caused massive coastal erosion and major flooding of the Clarence River.
Pasha Bulker stranded by an east coast cyclone on Nobbys Beach, Newcastle
- 2007 June June 2007 Hunter Region and Central Coast storms the grounding of the bulk coal-carrying ship MV Pasha Bulker, ten deaths and insurance claims of around A$1.4 billion making it one of the most costly natural disasters in Australia’s history. 2007 saw five east coast cyclones develop off Australia’s east coast.
- 2005 July
- 2005 March
- 2004 October 2, mean wave heights off Sydney were 5m with around 10m maximum wave heights.
- 2001 July 27–28.
- 1998 December 7–8, a notorious case of explosive development in eastern Australia, the Sydney–Hobart yacht race cyclone resulted in the death of six race participants.
- 1998 August 7–8, parts of Sydney and Illawarra received in excess of 300 mm of rain over four days.
- 1996 August 30–31, cost at least two lives and caused almost A$20 million in damage. Heavy rain and strong to gale force winds with extreme gusts of 64 kn (119 km/h; 74 mph) at Wollongong and 53 kn (98 km/h; 61 mph) near Sydney Airport NSW.
- 1995 September, A$8 million damage.
- 1990 August, Two lows in early August cause A$12 million damage.
- 1986 August 5, 24 hour rainfall totals: over 300mm in the Sydney area.
- 1984 July 23-17, A$53m insurance costs.
- 1974 May 26, Storm saw the shipwreck of the MV Sygna.
- 1973 July 6, the cargo ship Cherry Venture ran aground on Teewah Beach in South East Queensland during the storm.
- 1967 June a series of east coast cyclones had a major impact on the northern New South Wales and southern Queensland coasts.
- 1950 June, a series of east coast cyclones develop off the New South Wales coast during which Sydney registered its highest monthly rainfall on record, 642.7 mm (25 inches).
- 1857 August 20, The Dunbar, a sailing ship carrying 122 people from England, was wrecked off South Head while trying to seek shelter in Sydney Harbour, leaving only one survivor.
Australian east coast cyclone See also
Australian east coast cyclone References
- ^ a b c d e Leslie, Lance M.; Speer, Milton S. (1998). "Short-Range Ensemble Forecasting of Explosive Australian East Coast Cyclogenesis". Weather and Forecasting 13 (3): 822–832. doi:10.1175/1520-0434(1998)013<0822:SREFOE>2.0.CO;2.
- ^ Dowdy, Andrew J.; Graham A. Mills, Bertrand Timbal, and Yang Wang (February 2013). "Changes in the Risk of Extratropical Cyclones in Eastern Australia". Journal of Climate 26 (4): 1403–1417. doi:10.1175/JCLI-D-12-00192.1. Retrieved 7 April 2013.
- ^ a b Dowdy, Andrew J.; Graham A. Mills and Bertrand Timbal (2011). "Large-scale indicators of Australian East Coast Lows and associated extreme weather events". In Day K. A. CAWCR technical report; 37. CSIRO and the Bureau of Meteorology. ISBN 978-1-921826-36-8. Retrieved 7 April 2013.
- ^ a b c Holland, Greg J.; Lynch, Amanda H.; Leslie, Lance M. (1987). "Australian East-Coast Cyclones. Part I: Synoptic Overview and Case Study". Monthly Weather Review 115 (12): 3024–3036. doi:10.1175/1520-0493(1987)115<3024:AECCPI>2.0.CO;2.
- ^ a b Lim, Eun-Pa; Simmonds, Ian (2002). "Explosive Cyclone Development in the Southern Hemisphere and a Comparison with Northern Hemisphere Events". Monthly Weather Review 130 (9): 2188–2209. doi:10.1175/1520-0493(2002)130<2188:ECDITS>2.0.CO;2. Retrieved 21 March 2013.
- ^ a b "About East Coast Lows". Bureau of Meteorology. Retrieved 6 April 2013.
- ^ a b c d e "Australian East Coast Storm 2007: Impact of East Coast Lows". Guy Carpenter. October 2007. Retrieved 7 April 2013.
- ^ a b c d e f Hopkins, Linda C.; Holland, Greg J. (1997). "Australian Heavy-Rain Days and Associated East Coast Cyclones: 1958–92". Journal of Climate 10 (4): 621–635. doi:10.1175/1520-0442(1997)010<0621:AHRDAA>2.0.CO;2. Retrieved 7 April 2013.
- ^ a b c Harper, Bruce; Ken Granger (2000). "Chapter 5: East coast low risks". In K. Granger & M. Hayne. Natural hazards and the risks they pose to South-East Queensland. Australian Geological Survey Organisation in conjunction with Bureau of Meteorology. ISBN 0642467080. Retrieved 7 April 2013.
- ^ Guerit, Charlie (2 July 2013). "East coast low caused the flooding rains". Milton Ulladulla Times. Retrieved 7 July 2013.
- ^ "SES issues flash flooding warning for NSW coast". ABC News. 22 June 2013. Retrieved 7 July 2013.
- ^ Mills, Graham A.; Rob Webb, Noel E. Davidson, Jeffrey Kepert, Alan Seed, and Deborah Abbs (2010). "The Pasha Bulker east coast low of 8 June 2007". CAWCR Technical Report No. 023. The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology. ISBN 978-1-921605-77-2. Retrieved 8 April 2013.
- ^ "June 2007 East Coast Lows". Bureau of Meteorology. Retrieved 6 April 2013.
- ^ "Severe weather likely for south-east NSW and eastern Victoria at the weekend". Bureau of Meteorology. Retrieved 6 April 2013.
- ^ "broken link". Bureau of Meteorology. Retrieved 6 April 2013.
- ^ a b c d e "When were most recent major East Coast Lows?". Bureau of Meteorology. Retrieved 6 April 2013.