Australian Weather

10 Jul 2023, 12:11PM UTC

It was a wild and windy one out there over much of southeastern Australia on the weekend. But just how windy was it? The table below shows the maximum wind gust in each state for the period including Saturday July 8 and Sunday July 9. As you can see, the action was mostly down south with four states – Tas, Vic, SA, and NSW – all recording gusts in excess of 100 km/h. Indeed no fewer than 19 Australian weather stations recorded gusts of 100 km/h or stronger over the weekend – eight in Tasmania, six in Victoria, three in New South Wales, and two in South Australia. It's extremely likely that winds over 100 km/h would also have been recorded at Australia's highest weather station (Thredbo Top Station in NSW at an elevation of 1957 metres) as well as Victoria's highest weather station (Mt Hotham at 1849 metres). But the anemometers (wind measuring devices) at both stations stopped working for all or part of the weekend. This happens quite a lot in winter, often because they have frozen over. Why so blowy and will it continue? The winds were caused by a strong cold front which brought rain to most parts of Victoria and Tasmania, as well as southern parts of SA and NSW. The system also brought heavy snowfalls to the mountains before things warmed up a little on Sunday and drizzle set in with a windflow that was more westerly than southerly. Mainland areas that were super windy over the weekend are now set for a reprieve for a few days, as high pressure dominates and winds drop off significantly until the approach of the next frontal system later in the working week. Elevated and exposed parts of Tasmania won’t be quite as lucky. Being just that little bit further south keeps Tassie in the target zone for that band of Southern Ocean cold fronts you can see in the Monday synoptic chart above.

09 Jul 2023, 12:56PM UTC

The Burragorang Valley lies to the west of Sydney and forms part of the Warragamba dam, Sydney’s main water supply. The valley once had a river flowing through it and a small town until the Warragamba dam was built and it was flooded to become a lake. Image: The Burragorang Valley with cumulus clouds and a thunderstorm. Source: Billy Rout This past Wednesday morning, the Burragorang Valley was filled with a river of thick cloud. Image: Valley fog in the Burragorang Valley on Wednesday 5 July. Source: Author’s photo. This cloud is called Valley fog and it’s a special type of radiation fog. There was rainfall over the region on Tuesday evening which increased the surface moisture. Then skies cleared overnight with high pressure, allowing the air near the surface to cool quickly. As the air cooled it became denser and sank down to the bottom of the valley. The pooling of cold air over a valley floor allows fog to form easier and remain longer through the day than over flat land. This valley fog was visible from space as seen in the following satellite image. You can see the cloud winding along the valley in the middle of the image. Image: Himawari-9 visible satellite imagery with numbers indicating visibility in metres at 8:55am AEST Wednesday 5 July.