Extreme drying events in the Australian high-country and their implications for bushfire risk management

Abstract

An analysis of extreme drying events in the Australian high-country and an examination of their effects in the context of fire weather and bushfire potential are presented. The analyses consider differences in low-land and high-country fire weather observations, as represented by a pair of automatic weather stations: Canberra Airport (578 m) and Mt Ginini (1760 m). An ‘extreme’ high-country drying event is formally defined and a number of extreme drying events are identified. These are used to provide information on the temporal distribution of extreme drying events and on their frequency of occurrence. In addition, instances of extreme differences between high-country and low-land values of the McArthur Forest Fire Danger Index are considered in parallel with the extreme drying events. Two extreme drying events are selected as case studies and examined using a numerical weather prediction model (meso-LAPS). In each case model diagnoses provide an indication of the atmospheric processes driving the extreme surface drying in the high-country. Some implications of the results for bushfire risk management are briefly discussed.