The meteorology of Black Saturday

Abstract

The meteorological conditions are investigated over the state of Victoria, Australia on 7 February 2009, the day of the 'Black Saturday' fires. Daytime temperatures exceeding 45 • C, strong surface winds and extremely dry conditions combined to produce the worst fire weather conditions on record. A high-resolution nested simulation with the UK Met Office Unified Model and available observations are used to identify the important mesoscale features of the day. The highest resolution domain has horizontal grid spacing of 444 m and reproduces most aspects of the observed meteorological conditions. These include organized horizontal convective rolls, a strong late-afternoon cool change with many of the characteristics of an unsteady gravity current, a weaker late-evening cold front and propagating nocturnal bores. These mesoscale phenomena introduce variability in the winds, temperature and humidity at short temporal and spatial scales, which in turn lead to large spatial and temporal variability in fire danger.

Relationships between climate variability, soil moisture, and Australian heatwaves

“…So while knowing the seasonal phase of SAM may provide some information on seasonal heatwave frequency, duration, and intensity over southeast Australia, it does not provide as much information as what ENSO does for other areas of Australia, particularly with respect to HWF. This highlights the importance of other key (likely intra-seasonal and synoptic) processes in heatwave manifestation over southeast Australia, which have been researched elsewhere [e.g., Hudson et al, 2011;Engel et al, 2012;Pezza et al, 2012;White et al, 2013;Marshall et al, 2014;Parker et al, 2013Parker et al, , 2014aParker et al, , 2014b but not yet separated for specific heatwave characteristics.…”

“…Another link in the chain includes synoptic systems and associated dynamics. Depending on the region of interest, the typical persistent high sits adjacent to the area affected, to which it advects warm, dry air [Hudson et al, 2011;Engel et al, 2012;Pezza et al, 2012;Marshall et al, 2014;Miralles et al, 2014]. These sea level high-pressure systems are coupled with high-pressure anomalies aloft [e.g., Meehl and Tebaldi, 2004;Trigo et al, 2005;Dole et al, 2011] and are stationary for an extended number of days [e.g., Nairn and Fawcett, 2013].…”

A review of research on the dry season mesoscale meteorology of northern Australia

“…This experiment involved Doppler sodar measurements as well as high-temporal-resolution data from operational AWSs. The findings from GLEX II and III were reported by Reeder et al (2013).…”

“…Those reported over southern Australia appear to have been associated with cold fronts as they propagate into stable marine layers or thunderstorm outflows; e.g. the Spencer Gulf South Australia (Robin (1978), Drake (1984)); various locations over southern Australia (Clarke 1986); the Great Australian Bight (Schmidt and Goler 2010); Melbourne's Port Phillip Bay (Physick 1986); in advance of the Black Saturday cold front (Engel et al (2013)). …”

Indices for the evaluation of wildfire spread simulations using contemporaneous predictions and observations of burnt area

“…A severe wildfire that occurred on February 7, 2009, near the township of Kilmore (the 'Kilmore fire'), Victoria (36.98 S, 142.66 E) was selected for analysis. The conditions of the day were extremely hot and windy and the levels of forest fire danger were unprecedented (Engel et al, 2013). The fire was ignited by an electrical fault and was first detected at 1147 h. The fire spread at an extremely rapid rate, travelling a distance of approximately 50 km in 6 h (Cruz et al, 2012).…”