Climate and Water Outlook for summer 2019–20, issued 28 November 2019

Climate and Water Outlook for summer 2019–20, issued 28 November 2019


Welcome to the Climate and Water Outlook for
summer 2019–20. December is likely be hotter and drier than average with a
good chance the monsoon will be delayed for tropical Australia. However, the drier-than-usual pattern is likely to ease as summer progresses. But, first let’s look
at recent conditions. It’s been exceptionally dry across most of the
country with spring being one of the driest on record for Australia. At the
end of October we did see good rain in southern Queensland and northwest New
South Wales. Bourke recorded 95 mm in just 24 hours, however
this has had little impact on water storages. Spring also brought many
extremely warm days. Most States had daytime temperatures in the top 10
warmest on record. A number of locations saw their hottest November day on record, while most of the mainland topped 40 degrees at least once during November. As a result
soils are very much drier than average across most of the country. Only soils in
northern New South Wales and southern Queensland are currently wetter than
average. Bushfires and raised dust continued to affect the mainland; the
result of the dry landscape and persistent hot winds. In some places
smoke haze and dust reduced visibility for several days. The dry has meant low
river flows were recorded at 89% of locations in November. This is the
highest number of low flows recorded in at least the past decade. As a result
most mainland water storages are close to, or below, half full going into summer.
So, what will influence our climate in the coming months? The monsoon trough is
yet to reach the southern hemisphere after a record late retreat from India.
This increases a likelihood of a delayed start to the wet for tropical
Australia. A delayed monsoon also increases the risk that a positive
Indian Ocean Dipole will not break down until mid-summer, which is much later than
normal. A positive IOD typically means drier and warmer-than-average weather
for many areas and increased bushfire risk for the
southeast. Lastly, a negative Southern Annular Mode or ‘SAM’ is likely to remain
until at least late December. This increases the risk of more westerly
winds than usual, which bring hot and dry air into eastern Australia. So what does
this mean for the outlooks? December is likely to be drier than usual for most
of Australia, however the dry signal should ease over summer as the IOD and
SAM patterns break down. While parts of Western Australia are likely to see
above-average rainfall we’re unlikely to see widespread rain in the east. November
to January streamflows are expected to remain below average for most forecast
locations. While temperature outlooks suggest that days are very likely to be
warmer than average across southern and eastern Australia. This means the
risk of heatwaves and bushfires continues to be high.
So, in summary: summer is likely to see many areas remaining drier than average;
a late arrival of the northern rains; warmer-than-average days; low streamflows
at most locations; and an increased risk of heatwaves and bushfires. Thanks for
joining us, you can find out more about the outlooks on our website. We’ll see
you next time.

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