Severe thunderstorms have been wreaking havoc across eastern Australia this week, unleashing heavy rain, strong winds, flash flooding and giant hailstones.
In some regions there were wind gusts of more than 100mph (160km/h) and strong winds caused operational disruptions at Sydney airport as well as extensive damage nearby, including roofs being torn off buildings. An 80-year-old man died after a tree fell on his car in New South Wales, and several other injuries have been recorded. The storms also triggered lightning strikes, leading to widespread power outages that affected more than 200,000 homes and suspending rail services.
Hailstones associated with the storms generally reached up to 4cm in diameter across much of eastern Australia, although some areas in Southern Downs and Queensland reported hailstones as large as 10cm, larger than a tennis ball.
These thunderstorms are among the most dangerous of the Australian summer season so far. They were triggered by a combination of cold air aloft interacting with a cold front and a low-pressure trough. This consequent atmospheric instability, coupled with saturated air over southeastern Australia, created a squall line – a continuous line of thunderstorms spanning hundreds of kilometres.
Squall lines are notorious for producing intense rainfall and strong winds, amplifying the destructive power of storms.
Supercells – rare, intense individual thunderstorms with deep rotating updrafts – played a significant role in hailstorm formation. These updrafts repeatedly lifted hailstones into extremely cold air, coating them in more ice, and causing them to grow larger.
Meanwhile, India’s capital has been engulfed in dense fog, significantly affecting air quality and visibility. Since 10 January, reduced visibility has led to major transport disruption in Delhi, with hundreds of flight delays and numerous train cancellations. Fog is a common occurrence in the city at this time of year, typically caused by a combination of low temperatures, low wind speeds and high humidity.
The flat, low-lying topography of the Indo-Gangetic plain exacerbates the situation, trapping moisture and pollutants in the air and leading to prolonged periods of dense fog and poor air quality. Rainfall on Thursday finally cleared the thick fog, but it also brought a noticeable drop in temperature, with an even sharper chill expected to follow.
