Coast-to-coast grass sparks national bushfire warnings

James Nason, 29/08/2011

The Bushfire CRC is forecasting above normal bushfire activity this spring/summer for the areas shaded red. To view larger map click on image below article.Dense stands of dry grass stretching from the Indian Ocean to the Pacific Ocean have sparked warnings of a potentially severe bushfire season across the country this spring and summer.

The Bushfire Cooperative Research Centre says large areas of drying grass that grew extensively across the continent following heavy rains last summer are fuelling above-normal prospects of bushfires in coming months as warmer weather arrives.

The release of the CRC"s bushfire outlook for Southern Australia yesterday followed the release of its forecast for northern Australia earlier this month.

Both forecasts essentially say the same thing – better than average rainfall last summer has laid the platform for higher than normal potential for bushfires this summer.

“A thick, tall band of grass extends across much of the middle of  Australia from the Indian Ocean in the west to the Pacific Ocean in southern Queensland and the Great Dividing Range in New South Wales,” yesterday’s outlook statement said.

“The grass – waist- and even shoulder-high in places – has flourished because of the heavy rains that accompanied the very strong La Niña event at the beginning of 2011.

“With much of this grass now curing because of drier recent weather, the potential exists for above-normal bushfire activity across the centre of Australia during the 2011-12 southern fire season.”

The forecasts have been formulated from input provided by country fire service representatives, land managers and meteorologists at recent bushfire assessment workshops.

Workshop attendees noted that major grass fires – once common in many areas – have been relatively few in recent years because of the long drought that ended over much of Australia in 2010.

Some jurisdictions are already warning communities about the potential for major grass fires this season.

More specific forecasts for each state include:

Below normal fire season potential is  expected in the northeast up until the end of November. Normal fire season potential  is expected for the rest of the state. Grass fuel curing may increase the fire potential in the north later in the season. Below average  moisture conditions persist in the southwest.

Grass growth across the state is prolific and widespread, representing a return to conditions more consistent with the long term average. After the prolonged dry spell, agricultural stocking rates are low, and this is expected to contribute to the incidence of fast moving grass fires.

The Mallee and Wimmera desert country is a fire-prone landscape and it is normal for bushfires to occur each year. Overall there is an above average bushfire potential. Record rainfall and partial inundation has resulted in significant and widespread native grass growth across the region. Prescribed burning has been hampered by residual soil moisture and by an increase in moisture in native grassland fuels.

The early emergence of crop and pasture species may see harvesting begin a month earlier than usual, which may see an earlier start to fires. Further rains will delay harvest and will increase fuel loads. Less irrigation in Victoria’s northern country may result in a greater than average incidence of fast moving grass fires in this area. Intensive cropping practices resulting in a lack of fallow paddocks may also contribute to this expectation.

In Victoria in August the scene for bushfire outlook, particularly for grass fires, has been only partially set. Rain events during spring will increase grass fuel loads that will contribute to an increase in fire potential. This will warrant a reassessment of the current outlook.

Western Australia
Northern WA: The Kimberley and Pilbara are fire-prone landscapes and it is normal for bushfires to occur each year. Above-normal bushfire potential is the chance of fires occurring that may be complex, protracted or could require resources beyond the local capacity.

Kimberley: Overall there is an above average bushfire potential. The area has been subject to record-breaking rainfall and this has resulted in significant and widespread grass growth across the region. This assessment is cognisant of the increased prescribed burning being undertaken across the region, but the rainfall and consequent fuel loads are significant.

Pilbara: In general rainfall across the Pilbara has been average or above average. In the areas of average rainfall and a grass type fuel the outlook is for an average season. This is in the general area from the coast to the area west of telfer and east of Newman.Rainfall across the rest of the Pilbara has been above average and it is therefore when considering the bush fire fuel type, load and structure it is expected to be an above average bushfire potential.

Southern WA: In the Mid-West, desert and Nullarbor, there are extensive areas high of fuel loads as a consequence of the very prolific rainfall, in some areas among the highest on record, which has resulted in very high, consistent and widespread grass growth. This has resulted in above average fire potential.

In the southwest (including the Wheatbelt), spring and winter rainfall is approaching average in most areas. In the Wheatbelt, this has resulted in widespread areas of reasonable crops. In the southwest there is a legacy of deep soil moisture deficiency and if the rainfall does not continue to be average or above average, this region may move from normal fire potential to above-normal.

Southern Qld: Record rainfall during spring 2010 and from December 2010 to April 2011 over southern Queensland provided a wet soil moisture profile that, coupled with a warm summer, created prolific grass growth over southern Queensland extending from Wide Bay to Gold Coast west to the South Australian border.

The grassland sward is continuous with high vertical structure and current curing rates ranging from 80 per cent in coastal areas to 100 per cent over vast inland areas. Forest areas have moist soil conditions with reduced fire potential however the warm temperatures and dry southerly influenced winds are continuing to dry soil moisture rapidly.

Forecast climate conditions indicate a drier spring period with the probability of average to below average precipitation for southern Queensland through September to November 2011 with increasing higher than average daytime temperatures.

Above-normal fire potential is assessed for a large area of southern Queensland, including the Beaudesert, Boonah, Lockyer and Brisbane Valleys through to the sunshine Coast north to above Wide Bay and west to include most southern Queensland inland grassland areas to the Northern territory and South Australian border.

Normal fire potential is assessed for south east coastal parts from the Sunshine Coast to Coolangatta and for a significant area of the Central West that includes the west of Taroom to Boulia and the Carnarvon range area due to a combination of moist soil conditions, recent rainfall and reduced vegetation loading associated with the 2009 fires.

As the spring fire season progresses and conditions change, these areas may be subjected to reassessment.

Northern Qld: Influenced by a strong La Niña event, the combination of a strong monsoon wet and three tropical cyclones increased the October 2010 to April 2011 rainfall deciles to above to well-above average for the majority of coastal and inland Queensland.

Significant flooding was experienced over southern and central parts of the state causing inundation and disruptions to many areas. The wet conditions together with warm temperatures promoted productive growth over the majority of grassland across regional areas of northern, central and western Queensland.

Above-normal fire potential over a vast area of coastal and inland areas of Central and Northern Queensland has been assessed for 2011 contributed by an abundant and continuous highly cured grassland sward throughout. Widespread frosts have occurred over this vast area.
Cape York Peninsula, the Wet tropics, and tablelands to the Lower gulf areas are expecting a normal fire potential for 2011 due to a delayed curing response and continuing wet conditions leading into the dry winter period.

Tropical Cyclone Yasi caused considerable wind damage to native forests, hardwood and softwood timber plantations, increasing ground fuels.

However, with moist tropical climate and soil conditions, quick decomposition is expected to assist in reducing fire potential.

New South Wales/Australian Capital Territory
Above average rainfall over the state for much of the previous year has resulted in heavy continuous grass fuel loads through most areas west of the Great Dividing Range and the tablelands. Above normal fire potential has been assessed inland due to dry conditions in the last few months plus increased likelihood of drier than average outlooks for spring.

Northern parts of the inland are expected to begin their fire season first as these areas are already quite dry.

Southern parts of the inland (Riverina and south Western fire areas) are expected to follow. Coast and eastern ranges have received significant rainfall and given forecast average precipitation during spring the fire season is expected to be average.

Northern Territory
Extensive areas of normal fire potential conditions dominate the northern savanna and Barkly regions where early Dry Season prescribed fire management is in place and has been effectively undertaken in 2011.

These regions also have the capacity to deal with fires that will occur later in the year.
An extensive area of above-normal fire potential dominates Central Australia. The area has received two years of above-average rainfall that have increased fuel loads and fuel continuity.

The effectiveness of prescribed fire management has been limited and capacity to deal with the anticipated bushfires later in 2011 will be limited.

The extension of the above-normal conditions into the Stuart Plateau region and along the northwest coast of the Northern territory into the Darwin region reflects both a lower effectiveness of prescribed burning programs this year and the increased fuel load and fire risks associated with gamba grass in the periurban regions.

The small area of normal fire potential in the southwest Northern territory reflects slightly lower rainfall and fuel loads in that region of Central Australia.

The record-breaking run of hot weather in January 2011 also contributed to lower fuel load accumulations. However, a considerable number of fires are expected in 2011, especially in localised areas dominated by buffel grass.


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