With El Niño waiting in the wings what's in store for Australia's winter season?

Winter is expected to be warmer than average for most of Australia, but rainfall is not forecast to be extreme. (Facebook: Violetta Kara/Weather Obsessed) Winter is forecast to be unusually warm in Australia with below-average rainfall for some areas. An El Niño looks increasingly likely to develop over the coming months. BOM says both the ocean and the atmosphere need to reach certain thresholds for the climate driver to be declared. Both appear on their way. Link copiedShareShare articleThe Bureau of Meteorology is forecasting winter to be unusually warm across the entire country as an El Niño climate pattern is increasingly likely to take hold. But despite the expected development of the major climate driver historically associated with drought in Australia, the predictions for a dry winter are not expected to be extreme. Let's take a look at what's in store around the country. Rain is often the big ticket item for winter, especially in southern Australia, which gets most of its annual rain during the cool part of the year. This winter the outlook is forecasting pockets of Australia to have below-average rainfall across the season as a whole. This includes south-west WA and parts of south-eastern Australia. Rainfall for the 3-month period from June to August is likely to be below average for most of the country. (Supplied: BOM) But a closer look at the forecast shows the dry weather mostly sets in later in the season. "The current forecast for June is no strong signal," BOM senior climatologist Caitlin Minney said. "But for July, that's where we start to see that [dry] signal emerge across parts of the south and the east … with early indications of a strengthening of that signal into August," she said. The probability of a dry winter is heavily driven by a greater chance of below‑average rainfall later in the season. (Supplied: BOM) Despite signs of an El Niño climate pattern developing over the coming months there are no strong signs that it will be "unusually" dry for any region this winter, according to Ms Minney. This includes parts of New South Wales and eastern Tasmania, which have already faced a very dry year to date. Both regions are in "severe" to record low rainfall deficiencies, meaning they are in dire need of rain. "We are keeping in mind the potential for further increases in those rainfall deficiencies for the region and carefully monitoring those regions," Ms Minney said. One part of the forecast that is looking clear is the temperature. The BOM is predicting both day and night-time temperatures are "very likely" to be warmer than average across Australia for the winter season. Daytime and overnight temperatures are likely to be above average for most of Australia except in parts of the north. (Supplied: BOM) There is also a strong chance these temperatures will be "usually" warm, meaning they fall into the top 20 per cent of all records. The combination of drier-than-average conditions and warmer-than-average temperatures is not promising for Australia's snow season. Snow levels can change rapidly based on just one strong system. (Supplied: Vail Resorts) But Ms Minney said it was far from a write-off with "just one system" able to change the outcome of a season. "Snow levels can change rapidly based on just one system, like a frontal system coming through, as long as there's enough rainfall and the temperatures are cool enough for it to be snowing," she said. The forecast shows there are still many factors that can play a part in the final outcome of Australia's weather — not just El Niño. It was Peruvian fishermen, hundreds of years ago, who first noticed and named El Niño. Little did they realise they had named one of the most consequential climate drivers on Earth. This is how it works. Every El Niño event is different. A look back at past events shows, in some cases, the driver has had no impact at all. However, they are overwhelmingly associated with lower than normal rainfall during winter and spring months across eastern Australia, and warmer temperatures through to summer. This is why the driver is often affiliated with drought and bushfire. While it has not yet developed, Ms Minney said it was likely to have an influence on the rainfall forecasts this winter, alongside warmer-than-normal ocean temperatures and long term-drying trends. El Niño is often associated with drought across Australia due to its influence on winter and spring rainfall. (ABC News: Jess Davis) But the region with the strongest chance of a dry winter, WA's south-west, is unlikely to be affected by the looming El Niño, with the driver historically not having an impact on that region. There, the stronger influence is likely to be climate change, which has caused a long-term decline in cool-season rainfall. Before the BOM declares an El Niño underway the agency needs to see both the ocean and the atmosphere reach certain thresholds. These have not been met yet but appears w

With El Niño waiting in the wings what's in store for Australia's winter season?

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