A low is generating flooding rain & damaging winds & surf about the NSW central & south coast. A trough is taking rain to NSW's western slopes & is causing patchy rain in QLD's eastern tropics. A high is keeping the rest of the country largely clear, chilly in the south.
Weather in Business
02 Jul 2022, 11:40PM UTC
Warragamba Dam spilling as East Coast Low inundates eastern NSW
More than half a metre of rain has drenched parts of eastern NSW during the last 48 hours, with spills from Warragamba Dam prompting major flood warnings in western Sydney. A deepening coastal trough and developing East Coast Low have driven huge amounts of rainfall onto parts of the NSW coast and adjacent ranges over the last two days. The heaviest rain between Friday and Sunday morning fell between Sydney and the Illawarra, where two-day rainfall totals reached 300 to 600mm in some places. Some of the highest observed rainfall totals during the 48 hours ending at 9am on Sunday included: 595 mm at Brogers (Kangaroo Valley) 521 mm at Wattamolla (Kangaroo Valley) 367 mm at Robertson (Nepean River) 378 mm at Foxground (Lower Shoalhaven River) 350 mm at Darkes Forest, including 297 mm in 24 hours (Georges River) 241 mm at Picton (Nepean River) 220 mm at Smallwoods Crossing (Warragamba River) This immense rain has fallen into already saturated catchments, causing river to rise rapidly and dams to spill. Image: Observed river level heights for the Nepean River at Menangle Bridge. Source: Bureau of Meteorology As of 9am on Sunday, moderate to major flood warnings were in place for the Nepean, Hawkesbury, Colo, Georges and Shoalhaven Rivers. Water NSW reported that Warragamba Dam started spilling at 2am on Sunday, which was ahead of initial projections due to the intensity of rainfall over the last two days. According to Water NSW, “at 7am the rate of spill was 240 gigalitres per day (GL/day), with inflow to the dam occurring at a rate of 380 GL/day.” For perspective, the volume of Sydney Harbour is around 500 gigalitres. These spills will combine with inflows from recent and future rainfall to cause rapid river level rises in the Nepean and Hawkesbury Rivers, where moderate to major flooding is likely from today into early next week. Unfortunately, areas of heavy rain will continue to fall over parts the state’s central coast and ranges on Sunday and Monday, including parts of the Illawarra, Sydney and Hunter regions. In addition to the riverine flood warnings in place for NSW, there are also severe weather warnings in effect for flash flooding from heavy rain, damaging winds, and damaging surf. Be sure to check the latest severe weather and flood warnings regularly for the most up-to-date information on this dangerous weather event.
02 Jul 2022, 8:20AM UTC
Rain deluges smash Illawarra
Over 100mm of rain has already been dumped over Illawarra, as the wet weather settles in for days to come. A coastal trough lingering off the east coast and a deepening low pressure system is drawing intense moisture into eastern Australia, with areas around Illawarra expecting the worst of the rain. To say that some July's rainfall averages have been surpassed is an understatement. Just two days into the month, and in the 24 hours to 9am today, Shellharbour (NSW) had reported 3.2x its average July rainfall, with a staggering 193mm falling into the rain gauge. Other nearby locations included: Albion Park: 172mm – 3.1x its monthly average Beaumont: 161mm – 1.6x average Nowra: 126mm – 1.9x average Are we getting close to the end of this event? Unfortunately, this is just the beginning. The rain will shift slightly north tomorrow, with 100-150mm expected around Sydney over the next 24 hours and 100-200mm forecast for Illawarra, which has already copped a significant drenching. 24-hr rainfall to 10pm Sunday using ACC-G model Tomorrow, we can see that the rain is still very concentrated over Sydney and the Illawarra area, with cities further north starting to see increased rainfall. The continual downpour over the same areas is leading to oversaturation, increasing water runoff and bringing the risk of major flooding. When should this all start to ease? Even after the wet weekend, the very slow-moving trough and low will see Monday receiving yet another 100-200mm over 24 hours. Tuesday, while still looking very showery will be much less intense as the trough and low pressure shift further east. A high should then build, settling the weather by the middle to end of next week.
01 Jul 2022, 6:21AM UTC
Extreme chill in outback Qld, parts of NT
If you live in the southern half of Australia and you think it's a typically chilly winter day this Friday, spare a thought for residents of outback Queensland and even parts of the Northern Territory who are enduring an exceptionally cold day by their standards. Some of the readings in small towns and outback localities situated north of the Tropic of Capricorn are quite Canberra-like as we write this story in the middle of Friday afternoon. Well, perhaps not quite that cold – Canberra was just 7.1°C at 3:30 pm on a day of steady rain in the national capital – but pretty close. For example: The town of Camooweal (population approx. 200), northwest of Mt Isa near the NT border, was just 10.2°C at 3:30 pm, having reached a not-so-high 11.7°C earlier in the day. Its record low max for July is 11°C but its average July max is 25.9°C! Tennant Creek, in the NT's Barkly forecast district, was just 12.5°C at 3 pm local time (3:30 pm AEST), having reached 12.7°C a little earlier. Its record low max for July is 12.8°C but its average July max is 24.8°C! Whether today’s max is a record or not depends on the weather in the next few hours. These are just two examples. We could also pick some other well-known towns like Daly Waters (NT), Mt Isa (Qld) and several other spots whose names are familiar to most Australians – all of which are having exceptionally cold days, with unseasonable rain accompanying the chill in most cases. READ MORE: HOW LOW CAN NORTHERN TERRITORY TEMPS GO? Why so cold? The current satellite image tells you most of what you need to know. That broad cloudband stretching from Bali to the Tasman Sea has kept temperatures down, with thick cloud and cooling showers allowing almost no warming today. So anywhere that started the day with even a modest morning chill would have been hard-pressed to warm up. Again, Camooweal is a good example of that. Its minimum last night was 10.4°C at 7:52 am. It's not often a northern Queensland town would be warmer in the afternoon than the early morning, but then again, we don’t often see cloudbands covering that area during the Dry Season. It's also worth mentioning that the Southern Annular Mode (SAM) has recently turned positive, which indicates the likelihood of increased rainfall in the east. So while some of the rain might be unseasonable, it does have some support from SAM. READ MORE: WHAT IS THE SOUTHER ANNULAR MODE (SAM)? Cool temps are expected to persist in most of the areas mentioned for the next 48 hours or so, before a gradual warming begins.
Weather in Business
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.
17 Jun 2022, 1:24AM UTC
Does winter or summer cause more energy demand?
Australia’s National Electricity Market (NEM) is in the throes of an energy crisis that has partially being driven by an abnormally cold start to winter. But how does energy demand change throughout the year and would this crisis have been worse if it happened in summer? Summer and winter are both challenging seasons for everyone involved in the electrical market. Heatwaves and cool spells both place a significant strain on the electricity system in Australia as they increase the amount of heating or cooling occurring in homes and businesses. Extremely hot or cool temperatures can also impair key electrical infrastructure, which can also play a part in causing electricity outages in both summer and winter. Furthermore, extreme weather events such as bushfires, flooding, lightning, tornadoes and severe storms can all affect electricity networks. Each season has their own unique mix of challenges for Australia’s electricity markets. Summer Heatwaves and extreme high temperatures cause high energy demand through increased air conditioner use during summer. Heatwaves have the greatest impact on the network when they impact multiple states at the same time. Some other common summer impacts include: High temperatures impair the operation of key electrical infrastructure. This can be compounded by high energy demand that often occurs at the same time. Generators, power lines, transformers and other electrical equipment can underperform or fail when temperatures get too hot. Renewable energy infrastructure is also impacted by the heat with solar panels and wind turbines underperforming. During summer, raging bushfires often threaten the electricity network and transmission lines. The Black Summer bushfires during 2019 and 2020 damaged power lines and caused widespread power outages that impacted tens of thousands of households in Australia’s southeast. Dust storms in summer can cause sparking between lines, sometimes initiating more fires and line failures. Winter Cool temperatures also increase energy demand with increased heater use in homes and businesses. Some of the typical winter impacts on the electricity market include: Strong winter winds in southern Australia can damage transmission lines causing black outs or outages. Key electrical infrastructure also underperforms when temperatures get too cold. Is energy demand higher in summer or winter? According to the Australian Energy Market Operator (AEMO), maximum operational demand occurs in summer, driven by cooling loads across most of Australia’s states and territories. However, Tasmania’s peak demand occurs in winter, driven by heavy heater use amid bitterly cold outdoor temperatures. The chart below shows that demand in Victoria has been higher in January (summer) than July (winter) during each of the past ten years. Chart: Highest energy demand (MW) in Victoria during the past 10 years in January and July. Source: AEMO’s Aggregated Price and Demand Data - Historical In AEMO’s 2019 summer readiness report, they stated that weather forecasts are “now the most important input into forecasting of demand and supply of generation for the National Energy Market (NEM)”. Given the intrinsic relationship between temperature and electricity demand, Australia’s warming climate is likely to have an impact on demand and infrastructure in the future.