Forest fires in the USA and Australia

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  • A MODIS image showing the location of the Queensland fires on the 15th November 2011. Source: NASA.

    Forecast Precipitation amount (in mm) for western USA for the next few days. Around 8-10mm is expected for Reno (indicated by the red flag), which will help to put out any remaining fires.

  • Forest fires in the USA and Australia
    19.11.2011 15:53

     

    A forest fire driven by strong winds has burnt nearly 2,000 acres of forest and destroyed at least 25 homes near to Reno, Nevada, prompting a state of emergency to be declared and the evacuation of thousands of people form the area. With little rainfall and high temperature, a cluster of bush fires also broke out across Queensland, Australia this week.

    Winds gusting up to 48mph (77kph) have driven a fire with flames 50 feet high across a swathe of forest just outside the city of Reno, Nevada over the past couple of days. It is thought the fire was started by a fallen power line, which set alight the tinder dry vegetation in the area. The south-west USA is highly prone to forest fires, and autumn can be one of the worst times, as the ground and vegetation is at its driest, despite cooling temperatures.

    The fire has destroyed over 2,000 acres of forest and residential land. 400 fire-fighters have been sent from all over the region and neighbouring states to put out the fire, and have been able to save an estimated 4000 homes from the flames. However the fire is expected to be contained soon, as the weather becomes more favourable. Winds are expected to die-down, with a cold front gradually moving southwards over the area tomorrow, producing rain, sleet and snow which will help to bring the flames under control.

    Northern Queensland was also affected by bushfires this week. Temperatures reached 40C in some inland areas, and with low humidity, this has allowed the bushland to become very dry, helping the spread of mainly human induced fires, but some were started by lightning strikes. The first picture indicates that dozens of fires burnt across the area last Tuesday (15th November), visible by the red outlines and the smoke fanning out from them. The fire season in the area usually ends by late October, but this year has been exceptional for both the number of fires and the length of the season as a whole.

    After arson, or accident, the weather is one of the major causes of forest fires. Periods of high temperatures and little rainfall can dry out vegetation making it highly vulnerable. Fires are often started by dry thunderstorms, which produce lightning strikes, without any rainfall that hits the ground. These are very common in south-west USA and Australia during the summer, as the air can be very dry, allowing the precipitation falling from the storms to evaporate before it reaches the ground, as was the case in Queensland last week. As seen in Reno, the weather also has an impact on the spread and longevity of a forest fire. Strong winds can fan the flames across swathes of land at high speeds, but sparks can also be blown in the wind which can set off secondary fires over a kilometre away.

    By: Chris Burton