Atmospheric Rivers (AR) are large scale conveyors of tropospheric moisture spanning several thousand kilometres in length. At any given time there are typically three-to-five major AR conduits in each hemisphere, which account for up to 90% of seasonal and annual mean atmospheric poleward water vapour transport. Understanding ARs is crucially important because of their significance to the Earth’s climate system and strong association with hydrometeorological extremes. This was highlighted during the 2022 - 2023 Northern Hemisphere winter when a series of ARs delivered more than 18 meters of snow to California’s Sierra Nevada mountains. In Australia, AR have been the cause of extreme rainfall resulting in flooding leading to loss of property and lives. These events are predicted to become more extreme and frequent in response to global warming.

Hamish will discuss the main characteristics of ARs, their geographic extent, classification, and predicted change over the next 50 to 80 years as climate warns. He will then discuss the impact of AR on Australia, and how they may contribute to the early demise of snow in the Australian alps. Mary Voice will then interview Hamish and extend the discussion.