Thursday, 9 March 2017

As Australia enters Autumn 2017 eyes turn to the skies

Bureau of Meteorology (BOM), media release, 28 February 2017:

The El Niño-Southern Oscillation (ENSO) remains neutral. However, recent changes in both the tropical Pacific Ocean and atmosphere, and climate model outlooks surveyed by the Bureau, suggest the likelihood of El Niño forming in 2017 has risen. As a result, the Bureau's ENSO Outlook status has been upgraded to El Niño WATCH, meaning the likelihood of El Niño in 2017 is approximately 50%.

All atmospheric and oceanic indicators of ENSO are currently within neutral thresholds. However, sea surface temperatures have been increasing in the eastern Pacific Ocean and are now warmer than average for the first time since June 2016, while the Southern Oscillation Index (SOI) has been trending downwards.

Seven of eight international models surveyed by the Bureau indicate steady warming in the central tropical Pacific Ocean over the next six months. Six models suggest El Niño thresholds may be reached by July 2017. However, some caution must be taken at this time of year, with lower model accuracy through the autumn months compared to other times of the year.

El Niño is often associated with below average winter–spring rainfall over eastern Australia and warmer than average winter–spring maximum temperatures over the southern half of Australia.

The Indian Ocean Dipole (IOD) has little influence on Australia from December to April. Current outlooks suggest a neutral IOD may persist until the end of autumn.

Climate outlooks – monthly and seasonal Issued: 23 February 2017 – Next issue: 30 March 2017:

Climate outlook overview
Autumn (March to May) rainfall is likely to be below average over the southern two-thirds of Australia.
March is likely to be hotter and drier than average across most of Australia, except the far north and west.
Warmer autumn days and nights are likely across most of Australia, except northwest Australia where days and nights are likely to be cooler than average.
The drier than average outlooks are likely a result of forecast higher than normal pressure across western and southern Australia, meaning fewer rain-bearing systems are likely to cross the coast (see the Climate Influences section for more detail).

NSW Forecast – chance of exceeding median maximum temperature in March to May 2017:

NSW Forecast – chance of above median rainfall in March to May 2017:

The Conversation, 1 March 2017:

Crop yields around Australia have been hard hit by recent weather. Last year, for instance, the outlook for mungbeans was excellent. But the hot, dry weather has hurt growers. The extreme conditions have reduced average yields from an expected 1-1.5 tonnes per hectare to just 0.1-0.5 tonnes per hectare.

Sorghum and cotton crops fared little better, due to depleted soil water, lack of in-crop rainfall, and extreme heat. Fruit and vegetables, from strawberries to lettuce, were also hit hard.

But the story is larger than this. Globally, production of maize and wheat between 1980 and 2008 was 3.8% and 5.5% below what we would have expected without temperature increases. One model, which combines historical crop production and weather data, projects significant reductions in production of several key African crops. For maize, the predicted decline is as much as 22% by 2050.

ABC News, 17 February 2017:

The impact of several heatwaves so far this year will be felt for some time by primary producers around Australia.
From crop damage, to livestock stress, the impact of these extreme temperatures is yet to be fully understood.
Meanwhile, farmers and wholesalers say they have had to come up with innovative methods of cooling their animals and produce.
But they are not the only ones to feel the impact of the heat; consumers will feel it in their wallets and in the quality available.

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