Most of Western Australia appears set for a wetter than normal three months ahead, according to the Bureau of Meteorology’s latest seasonal climate outlook, issued this morning.

The forecast for the next three months suggests that the southern two-thirds of WA and the far south east of Australia should experience wetter than normal conditions during May, June and July, while most other areas of Australia are considered a roughly equal chance of having a wetter or drier season.

The chances of exceeding median rainfall from May to July. Click on image to view in larger format.

The Bureau rates the chances that southern and western WA will exceed median rainfall during the next three months at greater than 60pc, and at 65-70pc for the south west and Pilbara regions of the state.

Conversely, the chance of exceeding the median rainfall is less than 40pc over the Top End of the NT, and the northern tip of Queensland. In other words, the chances of below average rainfall are greater than 60% over these areas. However, it should be noted that average rainfall at this time of year is far less than is received during the summer months for most of northern Australia.

Over the rest of the country, there is no significant shift in the odds towards either a wetter or drier than normal season.

Temperature outlook

There is a 60pc chance in the latest outlook that normal daytime temperatures will be exceeded over the southwest coast of WA, southern Victoria, and Tasmania.

Conversely, over parts of the WA interior, the chances of warmer than normal daytime temperatures are less than 40pc.

Over most of Australia the chances of warmer or cooler daytime temperatures are roughly equal.

The chances that the average minimum temperature for May to July will exceed the long-term median are greater than 60pc over southern Australia, and over most of the Kimberley in WA.

The chances of receiving cooler or warmer than normal night-time temperatures for May to July is roughly equal (i.e., close to 50pc) over the remainder of the country.

El Nino pattern likely to form in winter

The El Niño-Southern Oscillation (ENSO) currently remains neutral, but is in a state of transition towards El Niño. Dynamical models surveyed by the Bureau indicate that further warming of the tropical Pacific is likely in the coming months, with models approaching or exceeding El Niño thresholds during the southern winter.

Sea surface temperatures in the eastern Indian Ocean, to the south of Australia, and in parts of the Tasman Sea are currently warmer than normal, and are generally expected to remain warm through the forecast period.

The warmer waters to the west of the continent may lead to increased evaporation and cloudiness, and hence a wetter than normal outlook for parts of the west. These warmer waters surrounding Australia are not typical of El Niño, and may be somewhat negating the effect of the developing El Niño on the eastern regions.

The Indian Ocean Dipole (IOD) is expected to remain neutral for the next three months, and is therefore unlikely to have a significant influence upon this outlook.

Source: Bureau of Meteorology.