After the worst fire weather South Australia has seen in nearly three years, conditions have become more benign, aiding fire fighters.
The combination of temperature, humidity and wind hasn't been as extreme since the summer of 2009/2010 for some of the state's south. This includes parts of the Lower Eyre Peninsula, southern Yorke Peninsula, Adelaide, the Mount Lofty Ranges and the South East, where fire danger ratings were extreme, in some cases catastrophic.
For example in the Port Lincoln area, 35-degree heat combined with 60-65km/h winds and humidity lower than 10 percent, leading to extreme fire danger.
In the bushfire zone just northwest of Port Lincoln one of the most difficult periods for fire fighters was when a gusty westerly wind change arrived. The wind change from northerly to westerly did bring significant cooling and also raised the humidity but it caused the fires to turn sharp left. The area of threat changed in an instant in the afternoon.
Last night the wind eased as it turned more southerly and the temperature dropped below 15 degrees and the humidity rose to 80 percent. Easing cooler winds reduced the overall threat from the fire but the change in direction moved the area of threat further north.
For the rest of Wednesday humid southerly winds will pick up, reaching 25-35km/h, giving the fire a bit of life again, a concern for fire fighters.
Over the next few days, cool winds will ease further and turn more easterly. The easing winds should allow the fire to be kept under control, possibly even extinguished.
Hotter weather will develop again on the weekend as wind turns more northeasterly but the wind will be lighter and humidity higher than yesterday. On Saturday Port Lincoln is forecast to reach 30 degrees and Adelaide 37. It will be a generally dry weekend with only the odd light shower about. Thunderstorms and lightning are only a low risk.
Yesterday, lightning strikes sparked fresh grass and scrub fires in the Adelaide area and in the state's South East.
There were about 500 lightning strikes in the Adelaide area, 10,000 in the South East and 30,000 state-wide.
© Weatherzone 2012
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