Welcome to the Climate and Water Outlook for November 2016 to January 2017.
Spring so far has been notable for its storms, winds and rain.
But the outlook suggests this pattern may be about to change.
First, let's look at recent conditions.
May to September was Australia’s wettest on record, boosting vegetation growth in many areas
Much of this rain was driven by warmth in the Indian Ocean, with moisture streaming
into southern Australia from the tropics.
October has seen a break in that pattern, with above-average rainfall only in some areas.
Despite early build-up rains, temperatures in northern Australia have stayed much warmer
than average.
For instance, Darwin reached 37.5°C in early October—its sixth-hottest day on record.
This hot weather has dried vegetation across much of northern Australia.
Lightning in the Kimberley started fires that burnt over 1.5 million hectares—an area
one quarter the size of Tasmania.
Spring brings changeable weather, as weather systems shift southwards and the oceans warm
up more slowly than the land.
This can result in periods of strong winds.
October has seen gusts over 100 km/h at low levels in all southern States, causing damage
in many areas.
Lower-layer soil moisture remains well above average across most of northern, central and
eastern Australia, due to persistent rain in recent months.
This increases the risk of floods with any further heavy or sustained rainfall.
Storages continue to rise as water flows through the landscape.
Many water storages in eastern Australia are now far higher than this time last year.
So what's driving Australia’s climate right now?
The negative Indian Ocean Dipole is gradually weakening, feeding less moisture across Australia.
Models predict it will ease back to neutral in November.
In the eastern Pacific, ocean temperatures have cooled, but not reached La Niña levels.
But in the western Pacific and around northern Australia, warmer-than-average seas may lead
to some La Niña-like impacts, such as more tropical cyclones.
For now, our ENSO Outlook remains at La Niña WATCH.
One of Australia’s biggest climate drivers this November is expected to be the
Southern Annular Mode, otherwise known as SAM.
This describes the position of the westerly winds that circle the globe between Antarctica and Australia.
Models suggest these winds will stay further north than usual.
This means air collects less moisture as it travels over the cooler-than-average waters
off WA, while also blocking the winds and moisture that would normally come in from
the warm Tasman Sea.
So what does this mean for the rainfall outlook?
The influence of SAM means rainfall during the November harvest is likely to be below
average across much of southern mainland Australia.
But for November to January as a whole, above-average rainfall is likely across much of Western
Australia, with average rainfall in most other areas.
Outlook accuracy is moderate at this time of year.
Moving to streamflow: Forecasts for October to December reflect water stored in the landscape.
Median-to-high streamflows are expected at 92 per cent of forecast locations.
Accuracy for our streamflow forecast is high at this time of year.
In terms of temperatures: Days and nights are likely to be warmer than average in the east;
and in the far west of Western Australia.
Cooler conditions are likely for other parts of WA.
Accuracy for this outlook is high at this time of year.
We usually see around 11 tropical cyclones in a season, with about four crossing our coast
This season, our tropical cyclone outlook predicts an average to above-average number
of cyclones in our region.
So in summary: Rainfall is likely to ease back towards average in the east; but with
high streamflows and wet soils, flood risk remains raised.
Temperatures are likely to be warmer than average in the east, but cooler in the west;
and tropical cyclone numbers are likely to be average to above average.
For more details, go to our website at bom.gov.au/climate/ahead.
You can also get updates via Facebook and Twitter, or download our new BOM Weather app.
Our next video will be released on Thursday 24 November.
For the Bureau of Meteorology, I’m Andrew Watkins.