Australian Weather

16 Aug 2022, 5:59AM UTC

The Bureau of Meteorology has today issued a La Niña Alert, increasing the likelihood that they will officially declare a third consecutive La Niña event later this year. After two back-to-back La Niña events between September 2020 and June 2022, the Pacific Ocean has been a neutral state, albeit close to La Niña thresholds, for the last two months. However, all oceanic and atmospheric indicators used to monitor the Pacific Ocean have been trending towards La Niña levels in the past few weeks, indicating that La Niña may be re-emerging for a third consecutive year. Today’s La Niña Alert from the Bureau means that there is a 70 percent chance that they will declare a La Niña event in the coming months. The increasing likelihood of La Niña is also being closely monitored by other international climate agencies, including the U.S. climate Prediction Centre (CPC) and the Japanese Meteorological Agency (JMA). However, it is worth noting that both the CPC and JMA use different thresholds than the BoM to define La Niña. So, while the BoM declared the end of La Niña in June 2022, the JMA and CPC both classified an ongoing La Niña through the middle of this year, which is now gaining more strength. Regardless of the definition used to classify La Niña, all signs are now pointing towards a re-emerging La Niña pattern in the Pacific Ocean. This trend if likely to continue in the months ahead, with the BoM, NOAA and JMA all giving a 60 to 80 percent chance of La Niña occurring during Southern Hemisphere’s spring. Image: El Niño-Southern Oscillation (ENSO) forecast for the next 9 months, according to the U.S. CPC/IRI. The blue bars show the probability of La Niña occurring during each three-month period, with grey and red bars representing the probability of neutral and El Niño, respectively. Source: CPC/IRI Image: ENSO forecast for November 2022 from seven different international models, based on the Nino-3.4 temperature anomaly, with five of seven modles predicting La Niña. Source: Bureau of Meteorology, issued on August 16. Image: the JMA’s ENSO forecast for the rest of 2022, with a 60 percent chance of La Niña over the coming months. Source: JMA, issued on August 10. La Niña increases the likelihood of above average rain and below-average daytime temperatures over large areas of northern and eastern Australia during spring. With the landscape still holding a lot of water from the first half of 2022, flooding will be an elevated risk over eastern and southeastern Australia in the next few months.

16 Aug 2022, 2:58AM UTC

If you don't like the weather, just wait five minutes. That's the classic old saying about Melbourne weather, and it definitely looks like it will apply for the next week or so. Persistent showers are streaming across the city today in a classic chilly southwesterly winter flow in the wake of a cold front and associated trough. Between the showers, large dollops of sunshine are on offer, until you pop out to grab a sandwich for lunch – you know the drill if you live in Melbourne – and rain hammers down for those crucial few minutes before quickly clearing again. How much rain has fallen/will fall? By midday Tuesday, nowhere in the greater Melbourne metro area had received more than 5 mm, while 1.2 mm had fallen in the city – most of it in a brief burst before 11 am. That has been the pattern for most of August to date. Rain has fallen on eight of the 16 days to date this month with just 12.6 mm accumulating overall in the gauge (with a little more in the city's east, as often happens with winter weather systems). Like we said, it's classic Melbourne weather: frequent showers which often don't amount to much overall. The same pattern looks likely to continue for the next seven days, with a few millimetres of rain expected on each day except Sunday, when there's just the slight chance of a light shower. Rain is likely to be heaviest on Thursday and Friday as a cold front crosses Victoria, with up to 10 mm possible on both days. What about the Victorian floods? Image: Vic weekly rainfall from Aug 9 to 15. Source: BoM. Interestingly, Melbourne dodged the heavy weekend rain that lashed Gippsland. You can see an indication of that on the Bom weekly rain chart above. The chart also shows that a large chunk of south Gippsland received between 50 mm and 100 mm of rain. That's the large, teal-coloured section. Gippsland resident Steve Mesaric told Weatherzone there was "loads of rain" that flowed down from the Strzelecki Ranges into low-lying paddocks, inundating them. A moderate flood warning remains in place for the La Trobe River, and several minor flood warnings are also in effect for other creeks and waterways. Please check our warnings page for the latest. Eastern parts of Victoria away from the mountains can expect rainfall totals similar to Melbourne's for the rest of the week, so with luck, there'll be nothing heavy enough to exacerbate the existing flood situation. Meanwhile, Melburnians should take an umbrella to work every day this week, just in case. Image: Or you could just ride a tram all day. Rain problem sorted! Source: @wimkantona via Pixabay. But as mentioned, you can also expect frequent patches of blue. Top temps should be a degree or so either side of 15°C all week, although it will start to feel colder as the wind picks up from midweek.