The Bureau of Meteorology’s latest three month seasonal outlook issued this morning points to the likelihood of a drier and warmer than average April to June period for northern and eastern Australia, and a wetter than average period for south western Australia.
The outlook follows the release yesterday of the another Bureau report that warns the chances of an El Niño occurring in 2014 have increased further.
The latest climate model survey by the Bureau shows that the tropical Pacific is very likely to warm in the coming months, with most models showing sea surface temperatures reaching El Niño thresholds during the southern hemisphere winter.
The Southern Oscillation Index (SOI) has dropped to -13—the lowest 30-day value since March 2010—but would need to remain firmly negative for several weeks to indicate the atmosphere and ocean are reinforcing each other.
El Niño is often, but not always, associated with below normal rainfall across large parts of southern and inland eastern Australia during the second half of the year.
The Bureau’s latest three month outlook rates the chances of exceeding media rainfall during April to June at 35 to 40pc over parts of southern Queensland, the Top End of the NT, and the western Kimberley in WA.
In other words, for every 10 April to June outlooks with similar odds to these, about four of would result in above-average rainfall over these areas, while about six would be below average.
Conversely, the chance of exceeding the median rainfall is greater than 60pc over southern and central WA, and southwest SA.
For the rest of the country, there is no significant shift in the odds towards either a wetter or drier than normal season.
The Bureau said warmer waters to the west of the continent may lead to increased evaporation and cloudiness, and thus explain the wetter than normal outlook for parts of the west.
The Indian Ocean Dipole (IOD) influence is minimal during the first part of the outlook period, with a neutral IOD likely for the second part.
In terms of temperature, warmer days are more likely over most of the northern tropics, the eastern States, southeast SA, and the south coast of WA, with greatest odds for southern Victoria and Tasmania
The chances of warmer or cooler days are roughly equal over the north of Cape York Peninsula, most of southern and central WA, the southwest of the NT, and western and central SA
Warmer nights are more likely over most of Australia, except the northeast of the NT, parts of the Pilbara in WA, and the Cape York Peninsula in Queensland. The highest odds are over southeast Australia