Welcome to the Climate and Water Outlook for August–October 2015.
The El Niño pattern continues to strengthen and is likely to hang around into early 2016.
However, its impacts on our rainfall and temperature outlooks might not be the same as previous
strong El Niños.
But first, let’s have a closer look at recent conditions.
Winter rainfall so far has been patchy.
After good rains across inland Australia in June, there hasn’t been widespread follow-up
in July.
Above-average falls have only been seen in parts of the southeast.
The June rains made little difference to short-term drought conditions in western Victoria and
coastal South Australia … and long-term rainfall deficiencies continue
in central Queensland and northern New South Wales.
The rains did increase upper soil moisture in some of these areas, but deep soils remain
dry across much of the country.
In terms of temperatures, the most significant July event was the cold snap in the east,
which brought snow and heavy frosts as far north as Queensland.
Does this mean El Niño is backing off?
No.
Cold snaps are not unusual in El Niño years.
El Niño means warmer days overall for southern Australia, as large high-pressure systems
can block cold fronts to the south.
But when a front does punch its way through the highs and into Australia, it can draw
cold air from the far Southern Ocean.
Our July cold snap was very much a brief and local event.
Globally, it was the warmest first half of the year on record.
So what may drive Australia’s climate in the coming months?
The 2015 El Niño pattern continues to strengthen, with ocean and atmospheric indicators for
July reaching levels not seen since the strong El Niños of 1982 and 1997.
But the strength of this pattern doesn’t always tell us the strength of the impacts.
Many other factors play a part.
For example, the big dry of 1982 was associated with a strong El Niño in June, but also cool
seas around Australia and in the Indian Ocean.
Together, these reduced evaporation and changed weather patterns, driving one of Australia's
most significant droughts on record.
In June 1997, while El Niño was again strong, ocean temperatures were closer to normal around
Australia and to our west, and rainfall was greater at times than 1982.
This year, ocean temperatures are different again around Australia and the Indian Ocean.
We’ll be watching closely for any cooling of the eastern Indian Ocean and waters around
Australia that may reinforce El Niño impacts.
So, given we have El Niño but a warm Indian Ocean, what's our August–October outlook?
Well, odds favour an average to drier than average season across eastern Australia.
But there's a higher chance of wetter than usual conditions in the west, driven by the
warmer Indian Ocean.
Our three-month rainfall outlook has moderate accuracy at this time of year.
Now turning to the Seasonal Streamflow Forecast: Our service now covers all States and Territories,
with the addition of 40 new locations.
Our July to September forecast indicates low streamflows are more likely at 62 locations.
Near-median flows are forecast at 50 locations, with high flows more likely at only 12.
Accuracy for our streamflow forecasts is high at this time of year.
Turning to temperature: It's likely we'll have warmer-than-average days across eastern
and southern Australia, with clearer skies.
Accuracy for this outlook is moderate to high at this time of year.
Nights are also likely to be warmer than average in most areas, but be aware, the frost risk
period is typically longer in El Niño years.
To see the latest information for your area, you can find short-term frost potential forecasts
on our website.
So in summary:
El Niño is strengthening, and likely to persist into early 2016.
But keep in mind this doesn’t always mean stronger impacts.
August–October is likely to be wetter than average in the west of Australia, and average
to drier-than-average in the east.
Streamflow outlooks suggest low and median flows are more likely.
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 27 August.
For the Bureau of Meteorology, I’m Paul Feikema.