Australia might be headed for a hot, dry and extended summer, but Sydneysiders hoping to exploit the conditions at their nearest beach may be disappointed.
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The Bureau of Meteorology today predicted that this week's national heatwave, which will largely miss Sydney, would be just a taste of the summer to come.
"Odds are in favour of hotter and drier conditions to the end of March," Karl Braganza, manager of climate monitoring at the Bureau of Meteorology, said.
However just as the current heatwave - which is possibly the largest in territorial extent since 1972 - is expected to miss Sydney, so too is the majority of the hot, dry weather to come.
Bureau of Meteorology manager of climate services Aaron Coutts-Smith said while 2013 would see much of NSW experiencing "above average temperatures, especially in the north", Sydney temperatures were likely to be more in line with the average over the next three months.
Less so in the city's west, with temperatures expected to be around two degrees hotter than normal in Richmond throughout summer.
Again with rain, the likelihood for dry conditions increases the further you get away from the state's coastline.
Mr Coutts-Smith said it was ‘‘even odds’’ that NSW’s east coast could expect above average rainfall over the next three months.
‘‘As you head west those odds decrease and you can expect a drier than average three months,’’ he said.
Maximum temperatures of 45 degrees or higher are expected for as long as a week in desert regions in coming days. Large areas of New South Wales, Victoria and South Australia are likely to see the mercury reach 40 degrees or more each day for the period.
BoM records released today show Australia ended 2012 with record average maximum temperatures for the final four months of the year, setting up much of south-eastern Australia for high fire risks.
Average maximum temperatures for the past four months were 1.61 degrees above the 1961-90 average, at 32.47 degrees, narrowly exceeding the previous record for the period set in 2002.
The extreme heat comes after a year in which much of Australia went from wetter and cooler conditions than normal for the first three months of the year to hotter and drier ones by the end of December.
The overall figures for 2012 show the average temperature for the year was 0.11 degrees above the 1961-90 average of 21.81 degrees. Rainfall averaged 476 millimetres, compared with a 465-millimetre average over the 1961-1990 period - well down from the 699 millimetres recorded for the 2011.
Drying out
The bureau noted in its report how much southern Australia in particular had dried out during the course of the year.
“The year also saw unusually persistent high atmospheric pressure near southern Australia,” the report said.
“This was associated with greatly suppressed westerly frontal and storm activity in south-west Australia, and indeed southern Australia as a whole, and was reflected in very poor winter–spring rainfall in many southern areas.”
Australia may be heading back towards the drier conditions seen before the two recent years of relatively wet conditions.
“That April-to-November period has been dry pretty much since the 1990s, and even in the last few years it has been reasonably dry in between the two really wet summer seasons,” Dr Braganza said.
“The fronts and changes that are coming through just don't have as much rain in them.”
Outlook unclear
It is difficult to predict the weather outlook beyond April until the bureau gets a clear fix on the prospects for an El Nino climate pattern forming.
El Nino patterns are marked by a warming of the surface of the eastern Pacific Ocean, with higher pressure systems forming over the western Pacific. Rainfall levels typically drop across much of Australia. In contrast, La Nina conditions - which prevailed for the two years to early 2011 - bring cooler and wetter weather to Australia.
“In 2013, we’re actually starting with warm conditions in the Pacific Ocean, and El-Nino-like conditions," Dr Braganza said. "All things being equal, you’d expect the year to be significantly, in climatological terms, warmer than the last two years.”
Australia's variable climate was a highlight of 2012.
Nationwide, March was the third wettest month in the century-plus records kept by the bureau. It was the second-wettest ever March for NSW, beaten only by 1956, and the third-wettest for Victoria - and not matched or exceeded in that state since 1950.
Southeastern Australia saw its biggest multi-day rainfall event between February 27 and March 4. The Murray-Darling basin saw catchment records smashed, with the Upper Murray, Murrumbidgee and Lachlan regions all nearly doubling their previous record rainfalls for a seven-day period.
While the January-March rainfall levels were 32 per cent average for Australia, they slumped to be 25 per cent below the norm for the April-December period.
“Are we going back to sort of average years after a La Nina event or are we going back to those dry conditions that really characterised the southern Murray-Darling Basin?", Dr Braganza said. “Based on the evidence we’ve seen, we are going back to drier-than-average conditions.
- with Ilya Gridneff
