Bushfires in Victoria, 7-8 February 2009
The presence of a slow-moving high pressure system in the Tasman Sea, combined with an active monsoon trough, provided the conditions for dry hot air of tropical origin to be directed over the southern parts of the continent. On Saturday strong northerly winds, ahead of an approaching cooler south-westerly change, brought this hot air to southern Victoria. The combination of strong and gusty winds, low humidity and record high temperatures led to extreme fire conditions ahead of the change, while the change in wind direction exacerbated the dangers in fire behaviour.
The day was mostly sunny throughout Victoria, although some mid-level cloud did affect the southwest coast. The most extreme weather conditions were observed in the afternoon shortly ahead of the wind change. Maximum temperatures were up to 23 degrees above the February average, and for many centres it was the hottest day on record. Melbourne city recorded 46.4°C, its highest maximum temperature since records began. Other places in the Port Phillip region recorded even higher temperatures including Avalon, which recorded 47.9°C. Victoria’s highest official recorded temperature on Saturday was 48.8°C at Hopetoun in the Mallee region.
Wind gusts to 115 km/h were reported at Mt William and Mt Gellibrand, while gusts over 90 km/h were recorded at a number of sites including Port Fairy, Aireys Inlet, Kilmore Gap, Dunns Hill and Mt Hotham. After the change wind speeds in excess of 50 km/h continued to be observed for some hours.
The wind change passed over the coastal regions of the Western District during the early afternoon, through Kilmore Gap and the Latrobe Valley around 6.30pm, and reached Eildon about 8pm.
Analysis chart showing the Mean Sea Level Pressure (MSLP) pattern at 00 UTC (11am EDT) on Saturday 7 February 2009
Analysis chart showing the Mean Sea Level Pressure (MSLP) pattern at 06 UTC (5 pm EDT) on Saturday 7 February 2009
Analysis chart showing the Mean Sea Level Pressure (MSLP) pattern at 12 UTC (11pm EDT) on Saturday 7 February 2009
True colour imagery from the US MODIS Aqua satellite passes around 04 UTC (3 pm EDT)
Saturday 7 February 2009 showing the smoke plumes from fires, including the dense
cloud column ascending to high altitudes from the Kilmore fire.
Image courtesy of MODIS Rapid Response Project at NASA/GSFC
Radar reflectivity image from the Melbourne radar (Laverton) at 02 UTC (1pm EDT) on 7 February. The Bureau radars are used to detect rainfall but smoke from several fires was dense enough to show up on the images.
Radar reflectivity image from the Melbourne radar (Laverton) at 09 UTC (8pm EDT) on 7 February again clearly showing the smoke plumes from several fires.