The Outlook | Unusual pattern presents confused forecast

Unusual pattern presents confused forecast


Weather
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The sea surface temperatures (SST) patterns and forecast for the tropical Pacific show El Nino conditions continuing to develop and persisting until February or early March before weakening.

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A RATHER complex and unusual weather pattern is persisting in the eastern Australian region and because it is unlikely to last, all indications are that the long term outcomes will remain a little unclear.

The sea surface temperatures (SST) patterns and forecast for the tropical Pacific show El Nino conditions continuing to develop and persisting until February or early March before weakening.

However, many of the world’s oceans including the extratropical North Atlantic and North Pacific, the western tropical Pacific and the southern Indian Ocean are expected to see above average SSTs during at least the first few months of 2019.

This has not been the case in previous El Nino events and consequently the eventual outcomes have to reflect this degree of uncertainty.

What is clear, however, is that areas of the world that experience enhanced rainfall in El Nino events will continue to receive that but other areas, such as eastern Australia, that no normally have an increased chance of drier than normal weather might instead see variable conditions persisting throughout this event instead.

Some months back I indicated that a few of the features associated with a developing El Nino event are more likely than others.

The two that have occurred have been above average temperatures and more frequent severe storms.

The above average temperatures have only been a little up on normal so far but these are now favoured to increase over summer, especially in inland NSW and Queensland and across Victoria, but are unlikely to reach the more extreme levels that occurred in the past two summers.

Severe storms, on the other hand, are likely to become less frequent.

Tropical cyclone Owen - on its wandering track over the past two weeks, brought torrential rain to many parts of Queensland, but it was a “one off” system.

Another feature mentioned by this column some months back was that rainfall in the latter part of the year would be very dependent on the “one off” type of event that effects only some areas, and this has been a feature of the weather for the past six weeks now.

In general, the wet season in the north and north-west of the country is yet to effectively develop and we could be heading into a temporary drier and hotter spell before the variable weather patterns of the past month return again later in January.

However the potential for the significant “one off” event remains and provided at least one source of optimism, at least for Queensland and eastern NSW. 

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