The unprecedented flash flooding along the Great Ocean Road was a result of a powerful weather system that unleashed record-breaking rain on the popular holiday towns. Here's a breakdown of what happened and why.
The Weather System:
A series of thunderstorms developed across Victoria, most notably in the north and east of the state. This was fueled by ex-Cyclone Koji, which had already caused flooding in parts of outback Queensland. The key factor was the extremely high moisture content in the atmosphere, which Angus Hines, a senior forecaster at the Bureau of Meteorology, attributed to the cyclone's arrival.
Intense Rainfall and Flooding:
The humid conditions, combined with an upper-level trough, created the perfect storm for heavy rainfall. When this moist air reached the hills above the Great Ocean Road, it had to rise, leading to intense condensation and cloud formation. This resulted in swift and severe flash flooding in areas like Lorne, Separation Creek, Cumberland River, Wye River, and Kennett River.
Impact:
The flooding displaced between 200 and 400 people, many of them holidaymakers in caravan parks. Dozens of vehicles were affected, and the damage assessments revealed cars, caravans, and tents were washed away or inundated. The rapid onset of flooding caught some people off guard, leading to the loss of possessions.
Records Broken:
The storms broke daily rainfall records for the area. Mount Cowley recorded an astonishing 180mm of rain in just 6 hours, surpassing the previous 24-hour record of 123mm. This level of rainfall is considered incredibly heavy for that region.
Warnings and Safety:
VicEmergency issued timely warnings, starting with a Watch and Act, urging people in the Otways and inland from Lorne to take shelter. The warning was later upgraded to an Emergency, with authorities broadcasting the Standard Emergency Warning Signal. Despite the severity, there were no reported injuries or lives lost.
Ongoing Risks:
Even after the flooding, the area remains hazardous. Authorities warn of potential dangers like floodwater, mud, debris, damaged roads, and fallen trees. The weather bureau predicts further rain, with up to 15mm expected on Friday, increasing the risk of landslips and more debris on roads.
Looking Ahead:
The same weather system is now affecting Gippsland in eastern Victoria, bringing frequent showers and potential heavy rain. Residents are urged to stay vigilant and heed weather warnings.
