Climate: Wet up top, dry down low

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A graph depicting the chance of exceeding median max temperature Chance of exceeding median max temperature A graph depicting the chance of exceeding median max temperature
A graph depicting the chance of exceeding median rainfall Chance of exceeding median rainfall A graph depicting the chance of exceeding median rainfall
A graph depicting the temperatures Australia will experience from April to June Temperature guide for April to June A graph depicting the temperatures Australia will experience from April to June

April through to June is set to be warmer and dryer than average for most parts of Australia, according to the latest Climate Outlook report by the Bureau of Meteorology.

The report suggests that this period is going to be mostly dry with little rainfall for the southern two-thirds of mainland Australia.

However, the report also says that the east coast will remain largely on par in terms of rainfall and that the far north of the country will have above-average wet weather.

In addition, daytime temperatures from April to June are most likely going to be above average for the majority of Australia, with the exception being parts of eastern and northern Australia.

Night-time temperatures are set to be warmer for most parts of the country between April and June as well, with the exception of northern Western Australia and the Top End of the Northern Territory, which are expected to have cooler than average evenings.

Other areas such as southern WA, southern South Australia, eastern New South Wales and the Cape York Peninsula show a roughly 50-50-split chance of cooler or warmer nights.

Tasmania has more than an 80 per cent chance of having warmer-than-average temperatures in both day and night time.

These predictions are largely due to the warming in tropical Pacific sea surface temperatures and a cooler eastern Indian Ocean.

"The far eastern Pacific ocean has warmed substantially, with temperatures now more than three degrees above average," Bureau of Meteorology senior climatologist Andrew Watkins says.

"While this is unlikely to be affecting Australia’s climate right now, models suggest this local warming will spread across more of the tropical pacific."

The El Nino-Southern Oscillation currently remains neutral; however tropical Pacific Ocean waters have been steadily warming, increasing by 0.5 degrees since January.

The Bureau’s climate model indicates that El Nino-type weather conditions are likely to develop during winter, which is reaffirmed by most other global climate models studied by the BOM.

This means that the southern part of the country will most likely have a warmer and drier than average winter and spring, and more specifically, warmer daytime temperatures.

According to the Bureau, the historical maximum temperature accuracy for April to June is moderate to high over most of Australia. Minimum temperature accuracy is also moderate to high for most of the country, except parts of south-western WA, where accuracy is moderate to low.

All this follows a summer that stretched well into autumn, with Victoria and Tasmania having their warmest March on record.

The month of March was also a very wet one for certain parts of the country, with far-eastern and north-eastern parts of NSW having two to three times their usual amount of rainfall for March by mid-month.

The Bureau believes this has cancelled out most of the recent rainfall deficiencies caused by a very dry January and February.

As a result of all this wet weather, water storage levels are far higher than this time last year, with the South Australian Gulf storage levels at 68 per cent, up from 47 per cent in 2016, Tasmania storage levels at 52 per cent, up from 33 per cent last year and the Murray-Darling basin currently sitting at 67 per cent, up from 35 per cent this time last year.

In addition, most of northern Australia has seen a wet season well above average, predominantly in the west of the country, which is the result of a vigorous monsoon trough and a high amount of tropical lows.

However, the eastern tropics have had a less active monsoon trough over the summer period, which has resulted in clearer skies and subsequently led to further coral bleaching of the Great Barrier Reef.

At the time of writing the bureau had not updated its data regarding the effect of Tropical Cyclone Debbie on the east coast in late March and early April.

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