Bushfire outlooks means you need to be prepared

What is the fire outlook this summer?

Bushfires are predicted to be worse than normal across much of Australia this summer but research shows many people, especially those in high-risk areas, remain unprepared.

By Communications Manager Nathan Maddock from the Bushfire and Natural Hazards CRC. This article was first published in Issue Four 2019 of Fire Australia.

The Bushfire and Natural Hazards CRC’s Australian Seasonal Bushfire Outlook shows the 2019–20 fire season has the potential to be an active season, following a very warm and dry start to the year.

The east coast of Queensland, New South Wales, Victoria and Tasmania, as well as parts of southern Western Australia and South Australia, face above-normal fire potential. September saw severe fires in Queensland and
New South Wales, with houses destroyed in both states.

The ingredients for a bad fire season

Above-normal bushfire potential refers to the ability of a large fire to take hold. It takes into account recent and predicted weather for a particular area, the dryness of the land and forests and recent fire history.

The year to date has been unusually warm and dry for large parts of Australia. In fact, it has been the fifth-driest start to the year on record, and the driest since 1970. Some areas, such as NSW and south-eastern Queensland, are into their third year of dry conditions.

The warming trend means that above-average temperatures now tend to occur in most years, and 2019 has followed this pattern. These high temperatures further dry the landscape and vegetation.

Queensland

While northern parts of the state saw record rainfall earlier in 2019, rainfall has been very much below average in south-eastern Queensland for the year. The lack of rain has resulted in the root zone soil moisture being below average—in the lowest one percent on record for areas around Rockhampton and south to the NSW border. The rainfall and temperature outlooks make it very likely that this current soil moisture deficit will persist for the coming months, significantly increasing the available fuel in forested areas in south-eastern Queensland. Inland Queensland has been affected by drought since 2013, and as a result there has been very little grass fuel available. However, the rainfall received this year will is likely to see a return to average fuel loads in inland parts of the state.

Above-normal fire potential is expected in forested areas along the coast south of Rockhampton down to the NSW border, for woodland and grass vegetation, inland areas in the south, and a small area west of Mackay. The Darling Downs and Granite Belt districts are facing severe water shortages as a result of the ongoing drought. This has the potential to impact the availability of water for fire suppression. The Queensland Fire and Emergency Services have been working closely with relevant local councils and their partners to manage this risk. Normal fire potential is expected for all other parts of Queensland.

New South Wales

Weather conditions have been exceptionally dry across NSW leading into the 2019–20 fire season. Much of central and northern NSW has experienced well-below-average rainfall during the last three months, with a small percentage of areas experiencing their driest conditions on record.

Long-term rainfall deficiencies, including record lows for some areas in the north of the state, have severely impacted water resources. With limited water availability, fire agencies in NSW are planning for firefighting tactics that minimise the use of water.

At the beginning of August, the NSW Department of Primary Industries mapped nearly all of NSW into one of three drought categories, with approximately 55% of the state drought affected, 23% experiencing drought, and 17% experiencing intense drought.

Widespread significant soil moisture deficit resulted in an early start to the fire danger period for many local government areas in NSW. With the short to medium-range climate outlooks favouring warmer and drier than average conditions across much of the state, there is significant concern for the potential of an above-normal fire season in forested areas on and east of the Great Dividing Range.

Reports of grassland fuel conditions west of the Divide indicate that while grassy vegetation is cured, it is below average in quantity or load. These areas have been assessed as having normal fire potential. It should be noted that while grass load is reduced and therefore the potential intensity of grass fires may be reduced, highly cured grass creates the potential for grass fire to spread rapidly.

ACT

The ACT has received less than average rainfall over the last two years, leading to a persistent and high level of drought. The lowland forests are dry, while highland forests are relatively moist. This indicates that fuel flammability in the lowland forests could remain high, creating risks early in the fire season. The dry conditions and grazing by farm stock and wildlife have led to lower levels of grass growth, resulting in reduced grass fire risk. The outlook indicates a potential for the highland forests to dry out; however, this could be delayed by the occurrence of summer rain. Heatwaves and dust storms may make bushfire detection and suppression more challenging at times during the season. The overall bushfire risk for the ACT is above-normal.

Victoria

The potential for above-normal bushfire activity continues across the coastal and foothill forests of East Gippsland, extending into West Gippsland and the Great Dividing Range. These areas are now experiencing their third consecutive year of significant rainfall deficit, with severe levels of underlying dryness persisting in soils and heavy forest fuels, along with higher abundance of dead fuel components and higher flammability of live vegetation.

Across the rest of Victoria, mostly normal bushfire activity is expected, however there is likely to be increased growth rates in pasture and croplands in the west due to winter rain.

Tasmania

For the early part of Tasmania’s fire season, most of the state has normal fire potential. The western half of the state is wet, but the east is drier than normal, especially between the Forestier Peninsula and Scamander. This eastern dry area has above-normal fire potential. Without significant rain this area will expand. As in recent years, increased fire activity is likely in this dry strip before December and will require considerable response efforts. Eastern peat soils will be susceptible to fire and will burn to depth, with traditionally wet or damp gullies already dry.

The fire season in the remainder of the state will commence more normally, in late spring or early summer, and provide good conditions for planned burning.

South Australia

Average to below-average rainfall has occurred across SA, with some areas experiencing persistent dry conditions since the start of 2018. In areas of ongoing dry conditions, grass fuel growth is either average or well below average, which creates the likelihood of normal fire potential in these areas. This level of fire potential also continues in central and southern parts of SA, where average rainfall has occurred.

The Mount Lofty Ranges have recorded almost average rainfall, which has reset the soil dryness index to zero. However, late winter rainfall may promote increased vegetation growth before summer, and could increase the available bushfire fuels during the fire season. Forecast conditions maintain the potential for bushfire across the populated areas of the Mount Lofty Ranges. Parts of the Lower Eyre Peninsula have received good rainfall, resulting in a bumper cropping season and higher than normal grass fuel growth. Due to the increased fuel load, these areas have above-normal fire potential. Kangaroo Island also has above-normal fire potential, with a combination of drier and wetter than average conditions (depending on the vegetation type) across the island. These conditions may result in above average fuel loads in parts, and drier vegetation in others, especially in areas of forested and scrub vegetation.

The prolonged dry conditions across much of SA are also likely to create increased occurrences of raised dust during the windy conditions that often accompany days with high fire risk. The dust may affect the operational capabilities of aerial firefighting assets and limit their effectiveness. Fire managers will carefully monitor this issue during the fire season, noting that without rainfall, dust suppression is impossible on the scale required.

Western Australia

Rainfall deficiencies have persisted across most of the south-west of WA, with this area experiencing its driest start to the year, followed by the seventh-driest autumn on record. In addition, conditions drier and warmer than average are forecast through to October, which will increase soil moisture deficits and stress in woody vegetation. These conditions have resulted in above-normal fire potential for parts of the Swan Coastal Plain, Avon Wheatbelt, Jarrah Forest, Warren, Esperance Plains and Mallee regions. In parts of the Nullarbor, high fuel loads will contribute to the above-normal fire potential.

Above-normal fire potential is also expected for coastal areas of the Pilbara, which experienced heavy rainfall in association with Severe Tropical Cyclone Veronica in March 2019. This rainfall promoted good growth of soft grass and spinifex, as well as delaying curing compared to the rest of the region. As conditions dry out, greater continuity and loading of grassy fuels will increase the fire potential in parts of the Pilbara affected by Veronica.

For more information on the Australian Seasonal Bushfire Outlook, see bnhcrc.com.au/hazardnotes/63