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The 2014-15 Southern Australia Seasonal Bushfire Outlook released today warns of an early and above normal fire season in many areas.
The outlook was determined by representatives of fire and land management authorities from each State and climatologists and meteorologists at a meeting in Hobart on August 21.
The annual Bushfire Outlook meetings are convened by the Bushfire and Natural Hazards CRC and the Australasian Fire and Emergency Service Authorities Council (AFAC). The outlook for Northern Australia was released on July 24.
The August 21 meeting discuss the weather, landscape conditions and cross-border implications leading into the 2014-15 summer and determined areas that had the potential for a fire season that was above normal, normal or below normal.
The resulting outlook will be used by fire authorities to make strategic decisions on resource planning and prescribed fire management for the upcoming fire season.
The Outlook report released today notes that leading into this year, many areas have registered below average rainfall for successive years.
The effect has been reduced soil moisture levels and increasingly dry forests and grasslands.
Rainfall since May has largely been below average across most of Queensland, northern and eastern New South Wales, northern South Australia and much of southwest Western Australia.
Most parts of Southern Australia have also experienced a particularly dry August, extending rainfall deficiencies across Victoria, southern South Australia and Tasmania.
The underlying dry conditions mean that any surface moisture is likely to decline quickly with warmer temperatures and reduced rainfall over summer.
2013 was Australia’s warmest year since comparable records began in 1910, and persistent warm conditions have continued to affect Australia during 2014.
“This combination of underlying rainfall deficits, with persistently above average temperatures and near el Niño conditions in the Pacific, means that the antecedent conditions favour an early and above normal fire season in many areas,” the report states.
From the perspective of the Seasonal Climate Outlook, the prospects of an El Niño pattern forming remain uncertain.
The Outlook says conditions approaching El Niño or weak El Niño conditions are the most likely scenarios.
“With the El Niño-Southern Oscillation still not making the shift into El Niño territory just yet and the negative IOD returning to neutral, the seasonal climate outlook for September to November does not show a strong bias toward below average or above average rainfall over most of southern Australia
“The main exception is southern NSW and central Victoria, where a dry season is most likely.”
The outlook for temperatures in spring shows that above average temperatures are most likely across southern and eastern Australia.
Long term trend towards more bad fire days
The latest Outlook also takes a longer term view and notes that Southern and Eastern Australia is experiencing a trend towards more bad fire weather days than in the past, with fire seasons that begin earlier and last longer.
“As benign fire seasons are predicted to become the exception, the concept of an
average or normal fire season becomes less meaningful as historical long-term averages are surpassed by fire seasons that are regularly above average in either duration, area burnt or in the total number of fires,” the outlook states.
“Costs to the community for firefighting and damage are already steadily rising.
“Fire severity across southern Australia has been consistently worse than the long term averages would suggest. This is partly driven by an increase in temperatures as well as an increased dryness of soils and vegetation.”
Such impacts were challenging the limited resources of fire and land management agencies and had created the situation where each fire season was proving to be demanding both in economic and human costs.
While the ACT does not have a strong signal for the severity of the coming summer, there are several reasons for expecting above normal fire potential.
• Strong grass growth into early winter.
• Forecast for above average temperatures into summer.
• A reduction in rainfall in recent months, with heavy rains falling only in adjacent central areas of NSW.
NEW SOUTH WALES
Much of NSW experienced well below average rainfall in the three months leading up to August. Temperatures have also been above average or very much above average for all of this time. This has resulted in significant drying of the heavy fuels in the forests. Reduced rainfall has also resulted in reduced growth and lower grass fuel loads through much of the west of the state.
The next three months are forecast to have average rainfall over much of the state except the southern border areas, which are forecast to have reduced rainfall.
The temperatures are forecast to remain above average for much of the state. Under these conditions the drying trend will continue and it is expected to result in above normal fire activity for the coastal table lands and central slopes of the state while the risk of significant fire in the west of the state will be normal.
In Western Australia, the Wheatbelt region has below average grass fuel loads as a result of average and below average rainfall totals across the region.
In the South West reduced rainfall, a long term deficit in the soil moisture and high fuel loads has led to above normal fire potential. Conversely, across the mid West and Desert, it is the high fuel loads as a consequence of above average rainfall totals that warrant the expectation of an above normal fire season. rainfalls in the area has led to high fuel loads. The higher rainfall across the Nullarbor, east of the Fraser range, has also led to an above normal fire potential.
In South Australia the outlook conditions indicate the most likely scenario is for near normal fire potential across southern agricultural areas of the state, with parts of the North West pastoral, West Coast, eastern Eyre Peninsula, Lower Eyre Peninsula, Flinders and mid North districts likely to be above normal fire potential.
All these areas of above normal fire potential have had above average rainfall in the period leading up to the fire season, resulting in above average fuel loads. The North West Pastoral and Flinders regions also have abundant fuel loads that have been building up from previous seasons.
The area adjacent to the Northern Territory border (north of the APY Lands) has normal fire potential, in line with the normal potential indicated by the Northern Territory.
A normal to above normal fire potential may see the need for firefighting resources over a longer period of time, together with a longer time for mop-up post fires. The districts where there is potential for above average activity may pose resourcing issues during this fire season, should above level of activity be experienced.
The overview for the state is that generally grass fire potential is reduced as a result of the drought. Forest fuels continue to dry out, making more of the fine fuels available for the upcoming fire season. Recent wet seasons have failed to deliver widespread rains resulting in significantly reduced rainfall particularly in inland areas. More than 75 percent of Queensland is now drought declared. Rainfall from tropical cyclones was patchy and as a result the pasture growth is varied across the state.
In general, grassland fuel loads are significantly less than the average and curing across much of the state is ahead of the same time last year.
Above normal fire potential has been assessed for much of south east Queensland, from Bundaberg south west to Gayndah, north west to Biloela, south to miles, across to Roma and down the Carnarvon Highway to the NSW border.
Overall, normal fire season potential is expected over most of the state and on the bass Strait Islands in the period to the end of December. There is above normal potential in the central part of the east coast between Swansea and St Helens and extending around Fingal. The south of the state is relatively moist, including the Derwent Valley and the Southern midlands. Forest fires are expected to be relatively normal up to December in the eastern half of the state. While forest fire activity in the west will be suppressed. Similarly, moorland and scrub fuels are expected to be relatively normal while grassland fire activity will be low during spring and early summer.
A preliminary investigation of factors affecting the fire season outlook for 2014-15 point to an above normal season in many areas of central, north and western Victoria. Key factors are an overall rainfall deficit coupled with the potential for an earlier start to the season. Areas with long-term rainfall deficits run from the west of Melbourne to the central Wimmera and also north through central Victoria into the Mallee. Another band exists extending from the north east of Melbourne to the northern slopes of the Great Dividing range.
Shorter term deficits are emerging in a broad band across much of the state’s north, extending south to the northern rises of the Great Dividing range.
Similar deficits are emerging in coastal and southern Victoria, though the exact pattern in these areas is not yet clear.
Climatic signals indicate a likely return to warm conditions in spring. There is no strong signal on rainfall, and agencies will be closely monitoring rainfall amounts across the state.
Widespread above average rainfall conditions are not likely, but even in the event they occur, Victoria may still expect, given the antecedent conditions, a fire season slightly more active than 2013-14.
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