By: AussieStorm , 3:03 PM GMT on September 05, 2013
Welcome to my 2013/14 Australian Bushfire Season Forecast.
The 2013/14 Australian Bush Fire season is being forecast to be even more serious than last years bushfire season, we all know how that turned out. The start of 2013 saw Australia under the influence of a strong Indian Ocean Dipole (IOD). The 2012/13 Summer saw more record rains and flooding in Eastern Queensland and Northern New South Wales. These rains has meant there has been conditions for vegetation growth to exploded as seen also after the record rains in the 2011/12 summer, this allows fuel levels to continue to build. Also these record rains around Northeastern New South Wales has prevented the ability for authorities to do hazard reduction burns which also helped the undergrowth and leaf litter to continue to build. The energy levels are in the range of 2500 kW/sqm or 5-10 tonnes per hectare, this is at the very high to extreme end of energy and fuel levels.
Large areas of southern Australia, from the east coast to the west coast, face above average fire potential for the 2013-14 fire season, despite the extensive fires in some parts of the country over the last 12 months. 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 which are currently in moderate drought conditions. 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(South of Canberra to the Snowy Mountains) and Murrumbidgee corridor of the ACT(West of Canberra) and south eastern New South Wales including Sydney and surrounds. 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 of firefighting resources, are also considered. Since the breakdown of La Niña conditions in April 2012, the El Niño southern Oscillation (ENSO) has been in a neutral state. At the same time, significant sea surface temperature patterns in the Indian Ocean in 2012 and 2013 meant that this basin has exerted a strong influence on climate through the Indian Ocean Dipole (IOD). July to October 2012 saw Australia under the influence of a positive IOD, resulting in below average rainfall across southern Australia in the lead up to summer. Average daytime temperatures during this period were above average across the majority of Australia. The 2012/2013 northern Australian wet season (summer) saw vast areas from the Western Australian border, through to the Great dividing range along the east coast, record below average rainfall, with central Queensland, south east south Australia and western Victoria recording very much below average rainfall. Over this same period daytime temperatures were well above average across the majority of Australia (see map, above). Of particular note was an extensive Australia-wide heatwave lasting from late December through to mid/late January. As a result of this heatwave, Australia set new records for its hottest day,hottest January and hottest summer. since the beginning of the 2013 southern Australian wet season (May), the IOD has been negative (the opposite to its value in 2012), leading to above average rainfall from the Pilbara in WA, through to south east Australia. The exception to this is south west WA and parts of inland Queensland, which have recorded below average rainfall. During this same period daytime temperatures were above average across the Northern territory, south Australia, inland Queensland, New south Wales, Victoria and Tasmania. August saw the IOD ease, bringing with it below average rainfall south of the tropics. The exception to this was south west WA, south east south Australia, much of Victoria an Tasmania, which all received average to above average rainfall during this time. Warm to hot temperatures began early in August, with record warm temperatures in central Australia and very warm temperatures pushing into the south east of the country during the last week of August.
Indian Ocean Dipole
National rainfall outlook for September to November Spring seasonal Outlook
National temperature Seasonal outlook for September to November
Expected Climate Outlook
Neutral ENSO (neither La Niña nor El Niño) conditions have persisted since April 2012 and are expected to continue through spring and into summer 2013/2014. A negative IOD event is in progress and expected to continue until mid-spring, despite recent signs of easing. A negative IOD during winter/spring increases the chances of above normal rainfall over southern Australia. Warmer than normal sea surface temperatures currently persist around Australia, which can provide more moisture to the atmosphere. In combination with the right weather systems (e.g. interactions with cold fronts), these conditions may result in increased rainfall. The Bureau’s official spring seasonal outlook shows an increased chance of above average rainfall over most of south east Australia and the top end of the Northern territory. This outlook is influenced by the persistence of the negative IOD into mid-spring and above average sea surface temperatures around Australia. The maximum temperature outlook shows an increased chance of warmer than normal spring days over most of northern Australia, coastal WA, and tasmania, while cooler days are more likely across central and north west Victoria.
State by State breakdown
The fire season in Queensland is long and traditionally commences around July in the Cape York Peninsula and Gulf Country and progresses to the central inland and coastal areas south to the NsW border during spring and into summer. in the west and south west of the state the fire season can begin as early as August and extend well into february. however, timeframes can vary significantly from year to year, as they are largely dependent on long-term climate, short-term weather conditions and available fuel loads. This season, the combination of Queensland’s climate and seasonal trends has created vast variations in vegetation growth and fuel conditions. Northern Australia wet season rainfall was well above average for the southern coastal areas. in contrast, large areas of the Lower Gulf of Carpentaria, far western and southern Queensland received well below average rainfall during the same period. Over the winter months rainfall remained near to below average for most of the state, with the majority of south western, central west and north west Queensland now under drought declaration. The grassland areas across the state have moderate to abundant fuel loads with a less continuous fuel bed than in previous years. This is due to a combination of large scale fires, rainfall deficiencies and stocking rates. As a result of milder temperatures this winter, grassland curing in the eastern areas is slightly lower than this time last year. In the north, far west and south west of the state grasslands are fully cured. Despite large scale fires in the northern and western areas of Queensland during the last fire season, there are still vast areas with moderate to abundant grassland fuels and low stock levels that could experience large scale, fast running grass fires. An above normal fire potential has been assessed for areas between Dalby and Warwick, south to the New South Wales border and west to Goondiwindi. The area to the west between Wallumbilla and Dulacca, south to St George and an area extending from the Sunshine Coast hinterland into the western areas of the Wide Bay Burnett region are also assessed as above normal fire potential.
New South Wales
Above average rainfall for much of the preceding three years is likely to continue the trend of heavy grass fuel loads throughout the grassland areas of NSW. These grassland areas include those west of the Great dividing range, the tablelands and the upper hunter. Above normal fire potential is expected to continue in these areas due to high grass fuel loads, combined with the predicted ENSO neutral (that is, neither el Niño or La Niña) summer outlook. Normal fire conditions are likely in far west NSW. Over much of the forested areas of NSW, below average rainfall since July has resulted in a drying trend in forest fuels. If this trend continues, above normal fire activity conditions are expected for the forested areas of central and southern NSW coast and ranges. A slightly higher chance for above average rainfall is likely to result in a normal fire season for both the far north coast and north coast.
Australian Capital Territory
The outlook for the grasslands reflects the current vigorous grass growth which will continue into spring and the drying trend in the Bureau of Meteorology’s seasonal outlook. As a result, above normal fire potential has been assessed for the grasslands in the ACT. The recovery of fuels since the 2003 fires continues to be monitored and managed. However should the forests dry out as we head into summer, there are concerns for the potential for above normal forest fire activity.
Over the past 12 months, much of Victoria has experienced below average rainfall. The exception is the east, where average rainfall occurred. forests are expected to be more flammable than normal due to the lingering effect of last summer’s extreme dryness and heat, with dry underlying soil profiles and more abundant dead elevated, near-surface and bark fuels in these forests. Despite some chance of above average spring rains and reasonable winter rainfall, significant underlying dryness is likely to continue to be present in many western and central forests. These areas can expect above normal fire potential. Strong drying of soils and fuels has also commenced in east Gippsland, which may result in early bushfire activity if this trend continues. The exception to this is in coastal parts of the south West, Mallee and West and south Gippsland, where above average rainfall has occurred in the past few months. As a result
of this rain, a normal fire season is expected in these areas. Current expectations are for average to above average grass growth in western Victoria and the north east of the state, based on receiving average to above average rain during spring. The timing and severity of grass fires will depend strongly on rainfall patterns throughout spring.
Normal fire potential is expected for the lead up to summer, except for small areas in the Derwent Valley and the mid-east Coast, both of which are currently drier than usual. The majority of Tasmania has either average or above average soil moisture and this will reduce fire activity while promoting growth, which may become available for large fires in the New Year. The fuel types which are less dependent upon soil moisture levels, such as moorland, heaths and scrub, have a normal fire potential. Forest fuels in the north of the state will require a considerable drying period to be available for widespread fires as these areas have had above average rainfalls over winter thanks to slow strong cold fronts.
Above normal fire potential is predicted in the North West Pastoral and Flinders districts due to abundant and continuous grass fuels. This is as 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 agricultural areas, the most likely scenario is for near normal levels of fire activity. Both the North West Pastoral and Flinders districts have received above average rainfall. When this is combined with the abundant fuel loads from the previous growing season, the result is above normal fire potential for both districts. The area adjacent to the Northern territory border is of normal fire potential, recognizing that the Northern Territory has not indicated above normal level of activity. Resource implications of an above normal fire danger season may see the need for firefighting resources committed to incidents for a longer period of time. The North West Pastoral and Flinders districts may pose resourcing issues this fire season, as was experienced in the North West Pastoral district last season, where firefighters and aircraft were committed for lengthy periods.
Across the Mid West and desert regions, above normal fire potential is expected as a consequence of high rainfall, which has resulted in very high annual grass growth and high fuel loads. Above normal bushfire potential is also forecast in the south West, which has seen reduced rainfall, soil moisture deficit and high fuel loads though in the last few weeks has seen an increase in rainfall from strong cold fronts so the south west will become more fire active after New Year. The Wheatbelt has been assessed as having a normal fire potential, with average to below average rainfall resulting in average fuel loads. In the Nullarbor, normal fire potential is expected east of the Fraser range.
NORTHERN AUSTRALIA SEASONAL BUSHFIRE FORECAST
In the top end, a significant amount of late season rain, averaging 200 mm, has complicated mitigation efforts, with some of the rains falling after initial fuel hazard reduction burns commenced.
This resulted in later efforts being less effective. An additional broad scale aerial incendiary run has partially addressed this, but the real effectiveness is yet to be tested. In addition, ground access into much of this area is still difficult due to wet country. The Wadeye area has once again had little early season mitigation works primarily because of access and limited resources. The Douglas Daly region is starting to see the effects of gamba grass, which cures later than native species. The Darwin
peri-urban area also has gamba grass related effects, including increased fuel
loading and a considerable reduction in the number of grazing cattle, as well as a later curing period due to the late rain. Accordingly, this area is assessed as above average fire potential. The Gulf region experienced a relatively poor wet season with little rain, so the effective mitigation program by staff and landholders has led to average fire potential. the Victoria river downs region is also considered to be of average fire potential, with only isolated pockets of high fuel after mitigation efforts. The Sturt Plateau area south of Katherine is currently well grazed and fuel is being managed, resulting in average fire potential.The extensive fires in Central Australia during 2011 and into 2012 have reduced the fire potential across the majority of the southern NT, especially in the Tanami and Simpson deserts. The fuel loading's across the Barkly region have been adjusted down to four tonnes per hectare and the remaining southern regions, including Alice springs, adjusted down to three tonnes per hectare on average. With the rainfall received to date, current land use regimes, and mitigation programs and activities undertaken, the prognosis is for average fire potential for the remainder of the territory. It must be recognized that significant fire activity will still occur, and in some cases this will cause significant impacts and potential losses of property, earning capacity, and environmental values. There is one area identified as above average for fire potential in the NT. The north west top end, extending around the greater darwin peri-urban area and into the Vernon and Arafura fire Control regions, has had a continued trend of increasing density and range of gamba grass. The ineffectual management of this single species of weed has been largely responsible for an increase in average fuel loading's within this area from between 4.5 and 6 tonnes per hectare to between 9 and 11 tonnes per hectare; even exceeding this in some smaller areas.
Conclusion: The 2013/14 bushfire season is more or less, in some areas like last year, a powder keg just waiting for a spark. But with neutral ENSO and a neutral IOD conditions, above average Sea Surface Temperatures this will mean the possibility of cloud cover around the coasts also more Cyclone around and making landfall over northern Australia. Higher chances of 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 as was the case in Central NSW and also in the Monaro area south of Canberra.
A few interesting reads I found while doing my research, these are pdf files.
Predicting Bushfire Preparedness from Bushfire Expectations
Fire Impact and Risk Evaluation
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Maps are courtesy of The Australian Bureau of Meteorology
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Updated: 1:44 AM PHT on July 30, 2016