Australia is expected to prepare for flooding this storm season, with the Bureau of Meteorology (Bom) predicting that there is twice as much chance of a La Niña formation forming.
La Niña events increase the chances of above average precipitation for northern and eastern Australia in spring and summer. Bom’s climatologist Tamika Tihema said the office predicted La Niña was twice as likely to form after updates to its current modeling.
“This does not guarantee that a La Niña will occur, but that there is about a 50% chance that La Niña will form. This means that about half of the climate models used by the office suggest that a La Niña event is likely to develop, ”she says.
Tihema says the possibility of La Niña influencing severe weather events, with above-average rainfall forecast for the eastern two-thirds of the country for the rest of the year, has increased the risk of flooding.
“For many areas, including parts of eastern New South Wales, eastern Victoria, northern Tasmania and southwestern Western Australia and northern Australia ‘Australia the soil moisture is wetter than average,’ she said. “As this will mean more rain on wet soils, there is an increased risk of flooding in these areas.”
Tihema said the increased risk from La Niña was in part attributed to sea surface temperatures in the central tropical Pacific Ocean which have cooled over the past two months.
“We are seeing changes in the observations and outlook of the climate model that indicate an increased likelihood of La Niña in the coming months,” she said.
“The chances of exceeding median precipitation are over 70% for much of the eastern two-thirds of the country for the remainder of 2021.
“The chances of above-median precipitation for the period November to January are about 60% or more for the eastern two-thirds of Australia.”
NSW SES Commissioner Carlene York said this year’s storm season – which traditionally runs from October to March – would likely bring similar conditions to last year, including widespread heavy rains and the risk of river and flash floods.
“In the previous storm season, we experienced major flooding across the state,” York said.
“Not too long ago, our volunteers responded to the major flooding that overwhelmed the communities of Hawkesbury-Nepean, Hunter and the Mid-North Coast. This event alone enabled us to respond to more than 14,000 requests for assistance, including more than 1,000 rescues in the event of a flood.
“It is extremely important that communities make sure they are ready. Storms can strike at any time. The more you can do now to prepare, the less emergency help you will need from our volunteers when these weather events occur.
York said safe Covid practices have been implemented to respond to lockdowns and ongoing health measures.
The Bom says that while El Niño-Southern Oscillation (ENSO) is a “natural” part of the climate system, climate change continues to impact changing weather patterns. Australia has warmed by 1.44 ° C since the records began in 1910.
South Australia has seen a 10-20% reduction in rainfall during its cool season over the past few decades, while rainfall in northern Australia during its wet season has increased since the 1990s, with more downpours. short and more abundant becoming more frequent.
“Research suggests that El Niño could bring heavier precipitation over the central and eastern tropical Pacific Ocean under global warming, and La Niña precipitation could be more abundant in the western and southern Pacific … but what it is not clear what changes mean for Australia, ”Tihema mentioned.
“Research also suggests that there may be an increase in the frequency of major El Niño and La Niña events. What the future holds for El Niño, La Niña and their impacts are the subject of ongoing research.