A MAJOR change in the synoptic weather patterns around the Australian region has occurred in the past week or two.
The tropical parts of the continent, especially the north west, have become much more active with tropical lows bringing significant rain in the north west of Western Australia around Broome and another low doing the same in the into the Pilbara.
These events brought widespread cloud as well over almost half the continent so their main effect on the weather in the eastern and south east states will come in the next week or so.
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This extensive cloud in the north west half of the continent reduced temperatures in the north west 'heat engine' area of the country where there had been a lack of cloud in the past two months.
This resulted in conditions becoming very hot there.
All that has been needed is a synoptic pattern to result in a day of north/north west air and some of the hot air has been introduced to the south east with record temperatures in places towards the end of November.
With the onset of the wet season now, the air in the north west will not be as hot so there is a reasonable chance (but not certain) that some parts of south east Australia have already had their highest temperatures of the summer season.
True to form, the La Nina event in the Pacific Ocean has increased moisture infeed into eastern Australia and this has already resulted in extensive rain in south east Queensland and north west NSW.
Such an event is likely to be repeated a couple of times during summer and will contribute to the scenario of above average summer rainfall in the east.
The increase in tropical activity has coincided as expected with the pulse of the Madden-Julian Oscillation moving into the Australia region.
Its presence will lead to an increased change of tropical cyclone development to the north west of Australia and possibly to the north east (more likely further east around the Solomon Islands or Vanuatu initially) in the coming week or so but exactly where such cyclones will form is challenging to predict.
To our south the Southern Annular Mode has returned to the positive after the period of cool westerly winds that occurred around early December and this is now unlikely to be repeated in the coming months of summer.
To the west, the Indian Ocean is likely to remain neutral during this time.
However, the Indian Ocean Dipole is unlikely to influence the weather much in the coming months.
The IOD will assume greater importance once again in autumn.
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