Adelaide is currently in the midst of its wettest year in four decades, with 316mm of rainfall recorded as of 9am today. And the rain shows no sign of abating just yet, with more potentially heavy precipitation looming on the horizon for the city. 

For those who were directly affected by the recent deluge that resulted in road closures and prompted numerous rescue operations in the Adelaide Hills, we bring you unwelcome tidings. This Sunday 25th is anticipated to mark the culmination of a wet week. Forecasts for the city suggest rainfall ranging from 30-50mm, with some areas potentially experiencing downpours of 60-80mm, particularly during isolated thunderstorms. The heaviest falls are expected to occur in the Adelaide Hills, coastal regions of the southeast, and Kangaroo Island, once again increasing the risk of flash flooding, particularly in the Adelaide Hills. 

The preceding episode of heavy rainfall, which unfolded from Thursday and persisted into Friday morning, was characterised by prevailing northwesterly winds that enhanced precipitation through a phenomenon known as orographic uplift. In essence, this process involves the interaction between the airstream and topographical barriers, which compel the air to ascend over the mountains. As the air rises, it cools down, leading to the release of additional moisture in the form of rainfall. 

Looking ahead to tomorrow, it appears that the atmospheric moisture content will be somewhat lower compared to the previous event. Nevertheless, the potent combination of vigorous winds, orographic uplift, and storms still holds the capacity to yield substantial rainfall totals, adding to the already saturated soil and potentially resulting in fallen trees and power outages.

Image: 24-hour precipitation to Sunday 25th late evening. According to ECMWF.