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2012/13 Australian Bush Fire Forecast
By: AussieStorm , 3:47 PM GMT on September 13, 2012
Welcome to my 2012/13 Australian Bush Fire Forecast.
The 2012/13 Australian Bush Fire season is being forecast to be the worst in 50 years. The start of 2012 again saw Australia under the influence of La Niña. Combined, the last two years have yielded both Australia’s wettest 24 month period on record (April 2010 to March 2012), and wettest two calendar year periods (2010–2012). The record average rainfall across Australia of 1411mm in 2010–2011 beat the previous record of 1407mm from 1973–1974. THE 2010/11 La Nina brought record rains to Queensland, New South Wales, Victoria, Tasmania and South Australia. These record rains has meant there has been conditions for vegetation growth to explode after 2 years in El Nino condition. Also with La Nina, the ability for authorities to do hazard reduction burns was reduced which also helped the undergrowth and leaf litter to continue to build. The energy levels are in the range of 2500 kW/sqm, this is at the very high end of energy levels.
Large areas of southern Australia, from the east coast to the west coast, face above average fire potential for the 2012-13 fire season, despite the extensive fires in some parts of the country over the last 12 months. However, the area most at risk does not extend as far north as was seen in 2011-12. The above average forecast is due to the abundant grass growth from the high amount of rain from two strong La Niña events seen in the past two years across the eastern seaboard and South Australia. Fuel moisture content within forests is still high, but this rainfall has continued to provide widespread vegetation growth in the grasslands, which remain a threat. In Western Australia, above average average fire activity is predicted in the western part of the West Coast, North East Pastoral and North West Pastoral districts of South Australia due to abundant and continuous grass fuels. Current grass fuel levels throughout Queensland are considered abundant and continuous. As a consequence, fast running, high intensity grass fires can be expected over most of the state, with particular concerns for southern and western Queensland. In New South Wales, above normal fire potential has been assessed for grassland areas west of the Great Dividing Range, the Tablelands, the Upper Hunter and the far west. Above normal fire potential is predicted in the Monaro region and Murrumbidgee corridor of the ACT and south eastern New South Wales. Victoria is predicting an average fire season, although key grassland areas authorities are monitoring include the Mallee, Wimmera and the South West. Tasmania is expecting normal to below normal potential is expected for the fire season up until the New Year. Large fires may be possible in grasslands in the late summer.
Bushfire potential depends on many factors.
For grass fires, the stage is set by the previous wet season. The volume, location and timing of rainfall are critically important when estimating fuel volumes and growth. They also affect the timing of the curing (that is, the drying) of the fuel. The climate outlook for the next few months is also a crucial factor. Of particular interest are the future tendencies of Pacific sea surface temperature associated with the El Niño- Southern Oscillation, a major climate driver over Australia. Other less quantifiable factors, such as the distribution and readiness of firefighting resources. The breakdown of the La Niña since April has seen a return to drier weather patterns during the southern wet season. April to July rainfall in Western Australia was below average, with large areas in the south west very much below average. Southern inland New South Wales, north western Victoria and large areas of South Australia have all received below average rainfall. Much of the remainder of Australia received average rainfall; the exception being northern Queensland and southern Victoria, which received above average rainfall, with some pockets receiving very much above average rainfall.Consistent with the April to July rainfall patterns, maximum temperatures were above average across southern Western Australia,Tasmania, southeast South Australia,northwest Victoria and southwest New South Wales. August to date has been much warmer than average across most of Western Australia, while the remainder of southern Australia has been close to average. Rainfall for August is currently below average in most parts of southern Australia, and well below average in Western Australia, South Australia, south eastern Queensland and northern and coastal New South Wales.
REGIONAL FORECAST SUMMARIES
In general, above average fire potential is expected across the Mid-West, Desert, Kimberly, Pilbara, Northern Goldfields and Nullarbor regions. This as a consequence of high fuel loads from extensive rainfall, resulting in very high annual grass growth. This forecast is mindful of the increased prescribed burning planned across these regions, particularly the Nullarbor. In the South West, the bushfire potential is expected to be above average as a consequence of reduced rainfall, soil moisture deficit and high fuel loads. Prescribed burning operations have also been hampered because of the weather. In the Wheat Belt, average fuel loads are anticipated from the average rainfall and annual grass growth that has occurred across the region.
Above average fire activity is predicted in the western part of the West Coast, North East Pastoral and North West Pastoral districts due to abundant and continuous grass fuels. This is a result of the previous season’s growth remaining and the rainfall received, linked with conducive growing conditions. For the remainder of the state, including the southern settled areas, the most likely scenario is for near average levels of fire activity. Resource implications of an above average fire danger season may see the need for firefighting resources for a longer period of time being committed to incidents. The North East and North West Pastoral areas may pose resourcing issues during this fire season, as they did last season when firefighters and aircraft were committed for lengthy periods. The South Australian border with the Northern Territory in the Simpson Desert has received above average rainfall. Conducive growing conditions have seen an abundance of growth, increasing the above average fuel loads from previous growing seasons.
Current grass fuel levels throughout Queensland are considered abundant and continuous. Although Queensland has experienced slightly wetter than normal early winter conditions, August to date has seen below average rainfall and cooler temperatures with extensive frosts, especially in the western and central western parts of Queensland. This contributed to a rapid increase in grassland curing, and general vegetation conditions in the south west of the state may indicate an early start to the bushfire season over a wide area. Fast running, high intensity grass fires can be expected over most of the state. There are particular concerns for large grass fires in southern and western Queensland.Woodlands with a grassy understorey may exhibit similar fire behaviour, however rates of spread may be slightly less than those of open grasslands. Forest fires with a moderate intensity are expected early in the bushfire season and fire intensity is likely to increase during the later part of the season, especially if the season is prolonged. This is due to a drying soil moisture profile, an increasing forest fine fuel layer and the influence of warmer temperatures and dry north-west to south-westerly winds. The areas assessed as being of above average fire risk are the grasslands and pastures of south western Queensland, which incorporates the areas from Stanthorpe and the Granite Belt district, north to Toowoomba, Dalby, Miles and Taroom, west to the South Australian border and south to the New South Wales border. Low stocking levels and above average fuel loads have the potential to significantly increase fire activity in these areas. All other areas are considered an average fire risk.
New South Wales
Above average rainfall over the state for much of the previous two years has resulted in heavy grass fuel loads throughout grassland areas. These grassland areas include those west of the Great Dividing Range, the Tablelands, the Upper Hunter and the far west. Above normal fire potential has been assessed in these areas due to high grass fuel loads plus an increased likelihood of warmer and drier conditions for spring. The fire potential is expected to be average for forested regions east of the Great Dividing Range due to average fuel moisture.
Australian Capital Territory and East New South Wales
Above average rainfall over the past two seasons has produced considerable grass fuel loads in areas where grazing has been low. Winter frosts and snows have increased curing rates in tableland and highland regions. These cured grasses, combined with expected low spring rainfalls associated with a weakly developing El Niño, are expected to result in above normal fire potential in the Monaro region and Murrumbidgee corridor.Forest fuels are well saturated due to good lower level soil moisture and are expected to take some time to dry, especially in rugged landscapes. As a result average fire potential in these southern ranges and slopes is expected.
Victoria is a fire prone environment,fires occur every year and are a part of the landscape. At this stage it is anticipated that Victoria will experience an average fire season, although it is important to note that fast running grass fires occur in any average Victorian season. Key grassland areas that authorities are monitoring include the Mallee, Wimmera and the South West. This may be expanded over the coming months as growth patterns become established. Over the past 12 months higher than average rainfall has occurred over the east of Victoria. Soil and forest fuel conditions are consequently saturated in the east, making it too early for an accurate forecast of fire potential in Gippsland and the North East. The expectation of warmer and drier conditions over the coming months will present ideal growing conditions for grass across Victoria. This will be the main contributor to the fire hazard, beginning in the west. Victorian fire agencies are concerned that this year’s early fire potential forecast as average may result in complacency among Victorian communities to the dangers of short-lived and destructive grass fires.
Normal to below normal potential is expected for the fire season up until the New Year. There is very little likelihood of large scale fires up to this time. Large fires may be possible in grasslands in the late summer due to retained thatch combined with expected spring growth. The Moorlands are currently wet and as such the fire potential has been assessed as normal. Forest fuel availability will be limited unless serious rainfall deficiencies occur.
NORTHERN AUSTRALIA SEASONAL BUSHFIRE FORECAST
Large areas of Northern Australia will face above-normal fire potential for the 2012-13 fire season, despite the extensive fires in some parts of the region last season. Significant areas of land were not burnt last year so the fire potential in these areas remains above-normal, largely because of the widespread vegetation growth in many areas fuelled by the wet weather that accompanied the strong La Niña events of 2010 and 2011. In Western Australia, there are a number of areas that have above-average potential in the Kimberly, Pilbara and Northern Goldfields, with fuel loads remaining significant due to high rainfall. The Top End, Gulf Region and south west of the Northern Territory can expect above-normal bushfire potential thanks to above-average rainfall and limited fire mitigation opportunities.
Conclusion: The 2012/13 fire season is more or less a powder keg just waiting for a spark. With El Niño conditions, this will mean less cloud cover on the east coast. Higher than average temperatures, Cold fronts and troughs that bring atmospheric instability, which will spark thunderstorm activity and the high chances of dry lightning which will easily spark of bushfires in inaccessible areas that can travel long distances and become dangerous.
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