Meteorological Aspects of the Margaret River Fires on 23 November 2011

Early in the morning of 23 November 2011, a fuel-reduction burn near Margaret River in southwest Western Australia increased dramatically in activity. The fire escaped control lines and burnt southwards along the coastal fringe, subsequently destroying some 47 homes, including the historic Wallcliffe House. Satellite imagery showed a smoke plume of vastly greater extent than other fires in the area.

Here, we present an analysis of the meteorology of the event, based mainly on very high resolution (400 m) simulations with the Bureau of Meteorology's ACCESS weather forecasting system. We find that several mesoscale features likely contributed to the fire becoming or remaining active overnight, including a region of marked near-surface drying over and around the fire ground, the development of strong down-slope winds over the fire, and the development of a pronounced low-level jet. During the day, while the fire was heading rapidly southwards under the influence of strong hot northerlies, the observed increase in activity around midday may have been due to a vortex streamer shed from hills to the north of the fire.