Tropical Cyclone Season outlooks

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2004-05 Tropical Cyclone Seasonal Outlook for Queensland

The Regional Director of the Bureau of Meteorology in Queensland, Mr Jim Davidson, said today that based on the best available and most recent information the lengthy run of relatively quiet cyclone seasons was likely to continue.

He explained that to confidently predict an active season it would require either a moderate to strong La Nina or a link established to the extreme hurricane activity in Florida and Japan in recent months. Neither is the case - so the number of tropical cyclones in the Coral Sea this season has only an outside chance of exceeding 2 or 3, and not all will cross the coast.

Mr Davidson emphasised however that it's only a matter of time before a severe cyclone does strike a coastal community, and this has occasionally happened during otherwise quiet seasons. The most important advice that people can receive at this time of year is to be well informed of the dangers posed by cyclones, to understand the warning service, and to be sensibly prepared.

Background Material

The last 15 years or so have been relatively quiet in terms of both cyclone activity in the Coral Sea and the incidence of significant cyclone impacts along the Queensland coast. The average number of cyclones in the Coral Sea during that period has been less than 3 compared to the long-term average of closer to 4. The situation for the past 3 seasons has been particularly unusual in that only 1 cyclone has crossed the east coast, and that was "Fritz" [a low Category 1] in the far north last February.

The seasonal outlook for Queensland is based largely on past cyclone behaviour and consideration of trends in both the Southern Oscillation Index [SOI] and Sea Surface Temperatures [SSTs]. In recent times, the SOI has been trending back towards zero after being negative for some months. Global climate models provide no convincing evidence of an El Nino developing and even less of a La Nina. This is supported by the SSTs across the central equatorial Pacific which are generally close to normal.

It should be noted however that the SOI has been a poor guide to Coral Sea tropical cyclone numbers in recent years. During this time, cyclone formation has been dampened by an unfavourable large-scale circulation over Eastern Australia and the Western Pacific.

At this early stage, it is impossible to predict the likely onset, path or intensity of any individual cyclones that might occur. Historically under similar environmental conditions, the first tropical cyclone of the season has often occurred in December, but this is not always the case.

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2004/2005 Northern Region Tropical Cyclone Season Outlook

"Average Expectations for Coming Cyclone Season"

This outlook is for the Northern Region, which is between 125°E and 142°E and includes the Timor Sea, Arafura Sea and the Gulf of Carpentaria.
Currently we remain in the neutral phase of the El Niño - Southern Oscillation atmospheric circulation system, but with some leaning towards an El Niño pattern. This leads to the expectation of an average cyclone season for 2004/2005.

<li>The cyclone season runs from 1 November to 30 April. An early cyclone (i.e. November or early December) is unlikely this year. The average date of the first cyclone near the Northern Territory falls during January. </li>

<li>The Gulf of Carpentaria tends to see the most cyclone activity during Neutral and El Niño years, although cyclones can still occur anywhere in the waters surrounding the Northern Territory.</LI>

<LI>It is likely that at least one tropical cyclone will form in the waters surrounding the Northern Territory, with a 60% chance of 2 to 3 cyclones. No more than 5 tropical cyclones have formed in the one season since Territory records began.</LI>

<LI>There is a 50% chance of a severe tropical cyclone (Category 3 or greater) during the season. If a severe cyclone forms, it is more likely to affect the Gulf of Carpentaria. </LI>

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Outlook for average tropical cyclone season for North West Australia

The Bureau of Meteorology's outlook for the 2004/2005 tropical cyclone season for North West Australia is :

<LI>An average season with around four cyclones expected to form off northwest Australia. </LI>

<LI>Likelihood of around two coastal impacts.</LI>
<LI>Significant risk of at least one severe tropical cyclone coastal impact during the season. </LI>
<LI>The most active period for tropical cyclones is more likely to be during January and February. There is a low to moderate risk of a cyclone forming off the northwest coast before Christmas. The Kimberley or adjacent Eighty-mile Beach is the area most likely to be affected should a cyclone form before Christmas. </LI>

This information is based on the prevailing El Niño/Southern Oscillation (ENSO) conditions. Although there are some tropical signals suggesting that an El Niño may be developing, the dominant indicators show that more neutral conditions are persisting. Additionally the majority of climate models predict near neutral conditions continuing throughout the coming cyclone season. The current 3-month mean value of the Southern Oscillation Index (SOI) is -6 compared with a value of about zero at the same time last year.