Welcome to the Climate and Water Outlook for October–December 2015.
With El Niño firmly established, we'd normally be looking at a hot and dry end to the year
for Australia.
However, a record warm Indian Ocean is taking the edge off El Niño impacts in some areas.
First, let’s review recent conditions.
Rainfall has been below-average for many areas of Australia in August and September.
But September is a transitional month for weather patterns—in the last two weeks we’ve
seen the first storms of the season around Brisbane, Adelaide and the Hunter region of
New South Wales.
Overall, though, poor rainfall has extended the rainfall deficiencies of the past year,
especially in South Australia and Victoria.
Long-term rainfall deficiencies over three years continue in Queensland, parts of northern
New South Wales and much of Victoria.
Lower-layer soils, between ten centimetres and a metre below the surface, have been left
dry compared to long-term averages—as shown by the red areas on this map.
In terms of temperature, Perth had its earliest 30° spring day on record on 9 September.
The heat moved across the south of the country and South Australia, Victoria and Tasmania
had a taste of summer in mid-September—a contrast to their August cold snaps.
Globally, we’ve seen the warmest June, the warmest July and the warmest August on record.
So what's driving Australia’s climate at the moment?
El Niño continues to strengthen, with the tropical Pacific Ocean reaching temperatures
not seen since 1997–98.
The two events clearly have many similarities in how they developed.
Both saw higher-than average sea surface temperatures extend from South America all the way to the
dateline.
This year, temperatures in the Indian Ocean have evolved differently: The Southern Hemisphere
Indian Ocean has been its warmest on record for June, July and August.
This has shifted weather patterns over Australia from what we typically expect to see during
El Niño.
But we are watching the cooling of waters to our northwest closely.
Historically, when these waters cool they reinforce El Niño impacts on Australia.
Most climate models we survey suggest this year’s El Niño will continue to strengthen
and persist into early 2016, before declining.
Around the globe, El Niño impacts are clearly being seen.
Global temperatures also remain at record levels, with 2015 looking highly likely to
be one of the hottest years on record.
Given the competing climate drivers, what's Australia’s outlook for the rest of the
year?
Odds favour wetter-than-average conditions for south-western and central Australia, thanks
to moisture from the warm Indian Ocean.
However, the outlook for eastern Australia is mostly neutral to drier-than-average.
Our rainfall outlook has moderate accuracy at this time of year.
Turning now to streamflows:
With below-average rainfall last month, and relatively dry soils, our September–November
forecasts show low flows are expected at 98 locations.
Near-median flows are forecast at 29 locations, with high flows more likely at only five.
Accuracy for our streamflow forecasts is high at this time of year.
For added information to help manage your water resources
you can now find 7-day streamflow forecasts for more than 100 locations on our website.
Turning our focus to temperatures: Chances are raised for warmer-than-average
days along many coastal areas of eastern and southern Australia.
Ocean cooling off Indonesia may bring cooler-than-average days to the northwest.
Accuracy for this outlook is high at this time of year.
Nights are likely to be warmer than average across most of the country.
The 2015–16 Bushfire Outlook for Southern Australia shows above-normal fire potential
over southeastern Queensland and for much of New South Wales, Victoria and Western Australia,
as shown by the red areas.
More details are available on the Bushfire and Natural Hazards Cooperative Research Centre
website.
So in summary:
El Niño continues, and the Indian Ocean also remains very warm, especially in the south.
Odds favour above-average rainfall in southwestern and central Australia—a scenario largely
dependent on conditions in the Indian Ocean.
Low streamflows are likely to continue in many areas.
The combination of dry soils and El Niño means the risks of heatwaves and bushfires
are raised in many areas.
But remember—a strong El Niño does not always mean strong impacts.
For more details, head to our website at bom.gov.au/climate/ahead
You can also follow us on Facebook and Twitter.
Our next video will be released on Thursday 29 October.
For the Bureau of Meteorology, I’m Paul Feikema.