On September 28, 2016 one of the most significant tornado outbreaks in Australia's history affected central and eastern parts of South Australia. Multiple supercell thunderstorms formed along a strong meridionally oriented cold front that was associated with an intense low-pressure system offshore and produced at least seven reported tornadoes, destructive wind gusts, large hail and intense rainfall. Transmission lines were brought down in four different locations, which contributed to a state-wide power outage.
Here, a case study of this event is conducted using high-resolution simulations using the ACCESS model (global, 4.0 km, 1.5 km and 400 m). Different science configurations are tested to determine model performance over the 1.5 km and 400 m South Australia domains, and simulation results are compared to radar and satellite imagery.
The results show that the location and intensity of the low and strongest surface winds are depicted well by the model, as well as the timing and location of severe thunderstorms. In the 400-m simulation a hook echo in the simulated reflectivity and a curved updraft are present, consistent with a mesocyclone, at the exact location of one of the reported tornadoes. We will report on possible reasons for this extraordinarily accurate simulation. The 2-5 km AGL updraft helicity, which measures the potential for updraft rotation in simulated storms is used to investigate the ability of the model to predict supercell timing and placement for this event.