Page 8 - NLN Oct18

Spring is Here, and There’s Little Drought Relief in Sight

Authors: Jonathan Pollock, Climatologist, Australian Bureau of Meteorology, Catherine Ganter,
Senior Climatologist, Australian Bureau of Meteorology, David Jones, Climate Scientist, Australian Bureau of Meteorology

So far, 2018 has been very warm and exceptionally dry over South Wales and Victoria are all on track for their warmest maximum
large parts of mainland Australia. The Bureau of Meteorology’s temperatures for the January to August period.
climate outlook for spring, released today, shows that significant The below-average rainfall combined with above-average
widespread relief is unlikely. maximum temperatures resulted in a rapid and intense drying
The chance of a spring El Niño, along with other climate drivers, of the landscape. This has led to unusually severe fire weather
is likely to mean below-average rainfall for large parts of the conditions in July and August – conditions more typically seen at
country in the coming months. the end of spring than the end of winter.
A dry Winter for most of Australia In contrast, low rainfall, cloud-free skies and dry soils mean it has
Winter rainfall has been below average over most of Australia’s been colder than usual overnight across most of the country
eastern mainland. Large parts of New South Wales are on track during winter.
to have winter rainfall in the lowest 10% of records. This has Climate conditions favour low rainfall
compounded drought conditions in the east after mixed rainfall Will spring see a break in the warmer days and below average
last year and a dry start to 2018 for much of the country. rainfall? Probably not. Both the El Niño-Southern Oscillation (ENSO)
But it’s not just the lack of rainfall that has made the impact of and the Indian Ocean Dipole (IOD), can be major influences on
drought severe. Another factor was the warmer than average Australia’s seasonal rainfall and temperature patterns.
daytime temperatures. During winter, both ENSO and the IOD were neutral, meaning that
Warmest January-August on record for some neither of them provided a large influence on winter’s weather (so
The 2017-18 summer average temperature was Australia’s second- we can’t blame them this time).
warmest in 108 years of records, while autumn was Australia’s However, most international climate models have been forecasting
fourth-warmest on record. Winter 2018 is likely to be among the a spring El Niño since June. Sea surface temperatures in the central
five warmest winters on record in terms of maximum temperatures. Pacific have been gradually warming since autumn and are rising
Many of the above-average daytime temperatures have been towards El Niño thresholds. At the beginning of June the Bureau
focused over the country’s southeast. In fact, South Australia, New went on El Niño watch, which indicates a roughly 50% chance of El