Heat in Australia in December 2012 / January 2013 Dr

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Heat in Australia in December 2012 / January 2013 Dr. Susanne Haeseler, Christiana Lefebvre; updated: 02. February 2013

Introduction

In December 2012 and January 2013, large parts of Australia (Fig. 1) suffered from an extreme heat wave breaking several temperature records. This summery heat was accompanied by drought conditions. During the first half of January, there was widespread no or only slight rainfall of less than 10 millimetres. Bush fires, being difficult to keep under control due to partly strong winds, burned, amongst others, in the states of New South Wales, Victoria, Queensland and on Tasmania. New South Wales alone counted more than 90. Numerous buildings and livestock fell victim to the fires.

Fig. 1: Map of Australia with some stations mentioned below.

In the course of the month, the Bureau of Meteorology, the Australian national weather service, issued several Special Climate Statements about the heat wave. Meanwhile, a final report is released on the web page http://www.bom.gov.au/climate/current/statements/ titled "Extreme January heat". In the following, some results of this special report are quoted, supplemented with further information of the Bureau of Meteorology and other institutions.

Weather evolution and temperatures

Large parts of central and southern Australia suffered from a long-lived heat wave from end- December 2012 to mid-January 2013, commencing in the southwest of the state of Western Australia, as a high in the Great Australian Bight and a surface trough near the west coast of the continent directed hot air masses from eastern directions across the area (Fig. 2).

Fig. 2: Surface analysis for the area of Australia on 25 December 2012. [Source: Bureau of Meteorology]

By the eastward shift of the high, more and more parts of southern Australia were affected by the heat. On 4 January 2013, the hottest day of the heat wave in Tasmania and coastal areas of South Australia and Victoria, the high pressure system was located off the east coast of the continent across the Tasman Sea (Fig. 3 and 4). On its western flank, very hot air masses from northern directions were then directed to south-eastern Australia. These caused extremely high temperatures across the east of the state of South Australia and the northern half of New South Wales till the 8th.

Fig. 3: Surface analysis for the area of Australia on 4 January 2013. [Source: Bureau of Meteorology]

Fig. 4: Maximum temperatures in °C on 4 January 2013. [Source: Bureau of Meteorology]

Figure 5 shows the maximum temperature anomaly from the 1961-1990 average for 1 to 7 January 2013.

Fig. 5: Maximum temperature anomaly from the 1961-1990 average for 1 to 7 January 2013. Units are °C. [Source: Bureau of Meteorology]

While the high across the Tasman Sea moved eastward and lost influence, a further high, moving from southwest to the Great Australian Bight, caused an anew wave in Western Australia from 8 to 10 January with widespread more than 45 °C and new temperature records (Fig. 6).

3 Fig. 6: Maximum temperatures in °C on 8 January (left) and on 10 January 2013 (right). [Source: Bureau of Meteorology]

Then, weak low pressure influence provided for temporarily somewhat cooler conditions in southern Australia with widespread no rain (compare Fig. 12). Afterwards, the intense heat from the interior of the continent extended again and caused further heat records, particularly on 12 and 13 January. Temperatures exceeded 48 °C at numerous weather stations in the northwest of New South Wales, in the northeast of South Australia and in the west of Queensland (Fig. 7). At Moomba Airport in South Australia, e.g., 49.6 °C was recorded on 12 January and at Birdsville in Queensland 49.0 °C on 13 January. Also the night-time minimum temperatures in the mentioned areas were widespread well above average with values of more than 24 °C (Fig. 7), e.g. at Moomba Airport, where a minimum temperature of 27.0 °C was recorded on 12 January and 29.5 °C on 13 January.

Fig. 7: Maximum temperatures in °C on 13 January 2013 (top left) and their anomaly from the long-term average (top right), as well as minimum temperatures on 13 January 2013 (bottom left) and their anomaly from the long-term average (bottom right). [Source: Bureau of Meteorology]

4 North-westerly winds brought again very warm air masses to the southeast and the south of the continent, leading to temperatures of more than 40 °C up to the 18th, especially in the states of South Australia, New South Wales and Victoria.

The main part of the heat wave ended for most of the affected areas on 19 January, as southerly winds cooled the southern states and late developing monsoonal rains moderated conditions further north. It was the first day since 31 December 2012 with temperatures not reaching 45 °C somewhere in Australia.

Some new daily maximum temperature records at Australian weather stations are listed in Table 1.

Abbreviations for the Australian states are: NSW = New South Wales SA = South Australia TAS = Tasmania WA = Western Australia station state new record previous record years of record Cape Naturaliste WA 37.7 °C on 30.12.2012 37.6 °C on 26.12.2007 104 Eucla WA 48.2 °C on 03.01.2013 47.9 °C on 03.01.1979 97 Hobart TAS 41.8 °C on 04.01.2013 40.8 °C on 04.01.1976 120 Bushy Park TAS 40.3 °C on 04.01.2013 39.5 °C on 20.01.1973 53 Larapuna TAS 36.5 °C on 04.01.2013 36.1 °C on 16.01.1960 104 Adelaide Airport SA 44.1 °C on 04.01.2013 44.0 °C on 28.01.2009 58 Hay (Miller St) NSW 47.7 °C on 05.01.2013 46.0 °C on 23.01.2001 56 Meekatharra Airport WA 47.1 °C on 08.01.2013 45.7 °C on 05.01.2008 63 Wiluna WA 48.0 °C on 08.01.2013 46.9 °C on 01.01.1990 56 Leonora WA 49.0 °C on 09.01.2013 47.8 °C on 17.01.1958 57 Tibooburra Post Off. NSW 47.9 °C on 12.01.2013 47.6 °C on 03.01.1973 103 Nyngan Airport NSW 47.0 °C on 12.01.2013 46.8 °C on 15.01.1939 93 Katoomba NSW 36.4 °C on 12.01.2013 36.2 °C on 14.01.2005 51 Giles MO WA 45.7 °C on 16.01.2013 44.8 °C on 28.01.2011 57 Newcastle NSW 42.5 °C on 18.01.2013 41.4 °C on 01.01.2006 56 Williamstown NSW 44.8 °C on 18.01.2013 44.4 °C on 01.01.2006 63 Sydney Airport NSW 46.4 °C on 18.01.2013 45.2 °C on 01.01.2006 74 Richmond NSW 46.4 °C on 18.01.2013 44.9 °C on 15.01.2001 67 Tab. 1: New daily maximum temperature records. [Source: Bureau of Meteorology]

Figure 9 shows the daily maximum and minimum temperatures at six stations mentioned in Table 1 in December 2012 and January 2013. The locations of the stations are mapped in Figure 1.

5 LEONORA (Western Australia)

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