Welcome to the Climate and Water Outlook for May–July 2018.
Warmer than average conditions in April look set to continue in May, while drier than average
conditions are possible in parts of southwest Western Australia and western Victoria.
But first, let's look at recent conditions.
In the tropics, the wet season is ending—having delivered average to above-average rainfall
since October.
This included nine tropical cyclones in the Australian region—close to average for a season.
Tropical lows also brought flooding to Broome in January and to western Queensland in March,
easing drought conditions.
Water is now flowing inland through Queensland's Channel Country, past Birdsville, and is headed
towards Lake Eyre.
In contrast, large areas of southern Australia have had little rain since January.
Autumn in the south felt more like summer: Temperatures in the first two months of the
season were unusually high.
Bushfire activity continued in Victoria, New South Wales and South Australia, and dry topsoil
was lifted into dust storms.
The prolonged heatwave in early April was exceptional.
New April temperature records were set in many parts of the country, over several days.
Australia as a whole had its hottest April day on record on the 9th, with a national
average close to 35°C. With little rain and high temperatures leading
to high evaporation, soils have remained very dry in the south.
Water storages in the southeastern mainland are lower than at this time last year.
In Tasmania and the southwest of Western Australia, storages are higher than last April.
In areas with dry soils, any rain will first soak into the ground before it begins to flow through catchments.
This means that once the rains do arrive, the winter water storage filling season is
likely to start late in the south.
So what's driving our climate right now?
Both the Pacific and Indian oceans are showing neutral climate patterns, and are likely to
stay that way into winter.
However, warm sea surface temperatures around New Zealand and low air pressures over the
Tasman Sea are forecast to continue.
This may weaken the westerly winds that bring moisture into southern Australia.
So what's our rainfall outlook for May–July?
The rainfall outlook shows little shift towards a wetter or drier than average season for
much of the country.
But below-average rainfall is likely for parts of southwest Western Australia and western Victoria.
The north is also likely to be wetter than average, but it's the start of the dry season,
so it won't be as wet as recent months.
The streamflow forecast for April–June is for mostly low and near-median flows, particularly in the south.
High flows are more likely in Queensland, following that heavy rainfall we saw in March.
In terms of temperatures: In May, warmer-than-average autumn temperatures are likely to continue.
But as we move into winter, there's less chance of warmer than average temperatures in all
but some southern parts of the country.
So in summary: there is little shift towards a wetter or drier season for much of the country,
but it's likely to be drier than average in parts of southwest Western Australia and western Victoria;
temperatures are likely to be warmer than average in May; but closer to average for winter for most parts;
and low or near-median streamflows are likely at most locations,
with high streamflows in Queensland.
For more details, visit our website at bom.gov.au/climate/ahead.
You can also get updates via Facebook and Twitter.
Our first look at likely conditions for winter will be available on Thursday 17 May.
For the Bureau of Meteorology, I’m Felicity Gamble.