A trough and front moving over western & southern WA are bringing gusty winds, heavy rainfall & some storms. Troughs are generating alpine snow, showers & storms in VIC, inland NSW & southern QLD. High pressure is keeping elsewhere settled, directing gusty winds to the Top End
Weather in Business
Today, 5:59AM UTC
La Nina Alert issued
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.
Today, 2:58AM UTC
A very, very Melbourne week of weather
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.
Today, 1:58AM UTC
Rain and floods beckon as La Nina looms and IOD deepens
New data reveals that a negative IOD is gaining strength in the Indian Ocean and La Niña is re-emerging in the Pacific Ocean, boosting the likelihood of heavy rain and flooding across Australia during the months ahead. The weather in Australia, and many other parts of the world, is strongly influenced by sea surface temperatures in the tropical Pacific and Indian Oceans. When the Pacific Ocean is in a La Niña pattern, cooler-than-normal water sits near the central and eastern equatorial Pacific Ocean and wetter-than-average water sits in the western tropical Pacific. This pattern of sea surface temperature anomalies drives moisture-laden winds towards Australia, which typically increases rainfall over large areas the country’s north and east. Image: Typical changes in sea surface temperatures and rainfall patterns during La Niña. A similar mechanism also occurs in the Indian Ocean, called the Indian Ocean Dipole (IOD). When the IOD is in a negative phase, abnormally cool water sits near eastern Africa and unusually warm water lies around Indonesia. This pattern of sea surface temperature anomalies sends more rain-bearing winds towards Australia from the northwest. A negative IOD typically enhances the frequency and strength of northwest cloudbands over Australia, which increases rainfall over parts of the country’s south and southeast. Image: Typical changes in sea surface temperatures and rainfall patterns during a negative IOD. New data out this week The Indian Ocean is currently in a negative IOD phase, which was officially declared earlier this month. However, new data came out at the start of this week showing that the IOD index had dipped to its lowest value since 2016. This means that the negative IOD is becoming entrenched to the northwest of Australia and is likely to enhance rainfall and flooding over our continent in the coming months. Image: Indian Ocean Dipole (IOD) weekly index values from the past 4.5 years. Likewise, the latest observations from the Pacific Ocean show that La Niña is now re-emerging after briefly weakening over the last couple of months. The graph below shows an index that monitors sea surface temperature anomalies in the central equatorial Pacific. Sustained negative values of this index represent periods of La Niña and as you can see, it has become more negative over the last five consecutive weeks. Image: NINO-3.4 weekly sea surface temperature anomaly values from the past 4.5 years. This latest data shows that both the Indian and Pacific Oceans are trending more towards a state that promotes rainfall and flooding over Australia. With most forecast models suggesting that this trend will continue over the coming months, large areas of Australia are expected to have a wetter-than-average spring, particularly over the eastern half of the country. Image: Seasonal rainfall outlook for spring from the Bureau of Meteorology.
Weather in Business
11 Jul 2022, 3:11AM UTC
Record month for wind power in Australia's National Electricity Market
New data shows June was one of the best ever months for renewable energy in Australia’s National Electricity Market and a record-breaking month for wind power. June 2022 was a relatively dry and cool month for much of eastern and southeastern Australia, with frequent periods of strong winds and clear skies. NSW registered its driest June since 1986, while Sydney and Brisbane had their sunniest June since 2004. This abundance of sunshine and wind created an ideal month for renewable energy generation in the National Electricity Market (NEM). The combined generation of solar (rooftop and utility), wind and hydropower across the NEM in June 2022 was 5,969 Gigawatt hours (GWh). This is the third highest monthly volume of renewable energy generation in the NEM in records dating back to 1998. Wind power Wind power had a record-breaking month in the NEM, with 2,527 GWh of generation in June 2022 beating the previous monthly record of 2472 GWh from July 2021. Victoria also set a new record for wind power in June this year, with 1,073 GWh easily surpassing the state’s previous record of 922 GWh from July 2021. Solar Power Solar power also had a strong month, with rooftop generation in June outperforming May 2022, despite May usually being the sunnier month. This was the first year on record where June rooftop solar generated more power than May. Utility solar also continued to see strong growth, producing 589 GWh in the NEM during June 2022, which was a big step up from 445 GWh in June 2021. Hydropower While June was a very dry month for large areas of eastern and southeastern Australia, an abundance of rain earlier in the year ensured that there was plenty of water available for hydropower. The NEM received 1,885 GWh of electricity from hydropower in June 2022, which was the 8th highest monthly value in 283 months of records dating back to 1998. The combination of favourable weather and continued growth in the sector caused June 2022 to be an exceptional, and in some cases record-breaking month for renewable energy in the NEM.
21 Jun 2022, 3:53AM UTC
La Nina floods make NSW ports too fresh for ships
La Niña has had a surprising impact on shipping operations in NSW this year, with increased freshwater outflows from flooded rivers affecting the behavior of ships entering some ports. Ships entering tidal ports in NSW are affected by local weather conditions, tides and waves, which can all affect a vessel’s ability to enter and operate safely within a port. One of the important things to consider when allowing larger vessels to enter NSW ports is the tide, which needs to be high enough to allow deep drafted vessels to enter, navigate and exit a port safely. This year, the window of time where water levels are high enough for ships to enter some NSW ports has been reduced by enhanced freshwater inflows from heavy rain and flooding. Image: Rainfall between January and May 2022 was in the top 10 percent of historical records for most of eastern NSW, with some areas receiving their highest rainfall on record for this period. Source: Bureau of Meteorology Freshwater is less dense than salt water, which allows ships to sit lower in the water. The prolific flooding seen in parts of eastern NSW earlier this year caused huge injections of freshwater into the coastal zone, which decreased salinity and affected shipping operations. According to Philip Perkins, Meteorologist and Sales Executive of Ports, Offshore and Safety at Weatherzone, "port users and operators at river-based terminals have been impacted by summer and autumn rainfall. “During high river flows water salinity is reduced. This means vessels can behave differently, resulting in elevated risk to vessels even at berth. Even when secured properly, berthed vessels can be impacted by passing traffic in the terminal.’’ In addition to the safety of ships, decreased salinity at river-based terminals can also reduce the window of time where larger vessels can enter these ports. In some cases, this may force ships to wait for the next high tide before entering or departing the port. Fortunately, river levels and discharge rates have now returned to more normal levels in eastern NSW. However, the ongoing influence of La Niña and a developing negative Indian Ocean Dipole increases the risk of more flooding in the months ahead. With the ground still holding a lot of water, any periods of heavy rain this winter and spring are likely to cause flooding, which may have immediate impacts on shipping operations.