Meteorological drivers of the eastern Victorian Black Summer (2019–2020) fires
Graham Mills![https://orcid.org/0000-0001-8440-4624](/media/client/orcid_16x16.png)
A School of Earth, Atmosphere and Environment, Monash University, Clayton, Vic., Australia.
B Natural Systems Analytics, Noojee, Vic., Australia.
C Division of Atmospheric Sciences, Desert Research Institute, Reno, NV, USA.
D Fire and Emergency Management, Country Fire Authority, East Burwood, Vic., Australia.
Journal of Southern Hemisphere Earth Systems Science 72(2) 139-163 https://doi.org/10.1071/ES22011
Submitted: 30 March 2022 Accepted: 30 July 2022 Published: 8 September 2022
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of BoM. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)
Abstract
The spring and summer of 2019–2020 (Black Summer) saw the largest and most significant bushfire outbreak recorded in eastern Australia. In Victoria, the fires ran from mid-November through early autumn. In this paper, we use a high-spatial and temporal resolution 48-year fire weather re-analysis data set (VicClim5) to describe fire weather and vertical wind and stability profiles for five significant high Forest Fire Danger Index (FFDI) fire events and compare these with detailed fire reconstructions. A feature of several of these fires was very active overnight fire spread driven by topographically enhanced low-level jets and low fine fuel moisture content. The FFDI values on these nights were either the highest or near highest on record in the 48-year data set. We describe cases of lightning ignition, prefrontal fire spread and two cases of post-frontal fire spread – one into Mallacoota on the early morning of 31 December 2019 and the other a northward overnight run down the Buffalo Valley on 4–5 January 2020. On two of the days studied there were complex wind changes associated with the inland penetration of low-level south-easterly winds under the influence of locally generated pressure gradients. An elevated hot, dry mixed layer above these shallow layers also played an important role. On one occasion there is some evidence of possible mountain-wave modulation of surface wind flows. These events demonstrate a range of features of the fire weather and climate in eastern Victoria and the utility of VicClim5 in 3-dimensional climatological analyses.
Keywords: Black Summer bushfires, climatology of extremes, cold fronts, eastern Victorian fire weather, elevated mixed layers, low level jets, overnight fire spread, wind changes.
References
Badlan RL, Lane TP, Mills GA, Caine S (2012) Mesoscale modelling of two “drying events”: governing processes and implications for fire danger. Australian Meteorological and Oceanographic Journal 62, 143–156.| Mesoscale modelling of two “drying events”: governing processes and implications for fire danger.Crossref | GoogleScholarGoogle Scholar |
Balch JK, Abatzoglou JT, Joseph MB, Koontz MJ, Mahood AL, McGlinchy J, Cattau ME, Williams AP (2022) Warming weakens the night-time barrier to global fire. Nature 602, 442–448.
| Warming weakens the night-time barrier to global fire.Crossref | GoogleScholarGoogle Scholar |
Brown T, Mills G, Harris S, Podnar D, Reinbold H, Fearon M (2016) A bias corrected WRF mesoscale fire weather dataset for Victoria, Australia 1972–2012. Journal of Southern Hemisphere Earth Systems Science 66, 281–313.
| A bias corrected WRF mesoscale fire weather dataset for Victoria, Australia 1972–2012.Crossref | GoogleScholarGoogle Scholar |
Buckley AJ (1992) Fire behaviour and fuel reduction burning: Bemm River wildfire, October 1988. Australian Forestry 55, 135–147.
| Fire behaviour and fuel reduction burning: Bemm River wildfire, October 1988.Crossref | GoogleScholarGoogle Scholar |
Bureau of Meteorology (2003) Meteorological aspects of the eastern Victorian Fires January–March 2003. Final report. Available at http://www.bom.gov.au/weather-services/fire-weather-centre/weather-patterns/past-bushfires/Eastern_Victoria_Fires_Jan_Mar_2003.pdf
Bureau of Meteorology (2019a) Special climate statement 72 – dangerous bushfire weather in spring 2019. Available at http://www.bom.gov.au/climate/current/statements/scs72.pdf
Bureau of Meteorology (2019b) Monthly weather review – November 2019. Available at http://www.bom.gov.au/climate/mwr/aus/mwr-aus-201911.pdf
Bureau of Meteorology (2019c) Monthly weather review – December 2019. Available at http://www.bom.gov.au/climate/mwr/aus/mwr-aus-201912.pdf
Bureau of Meteorology (2020) Special climate statement 73 – extreme heat and fire weather in December 2019 and January 2020. Available at http://www.bom.gov.au/climate/current/statements/scs73.pdf
Burrows N (2019) Lessons and insights from significant bushfires in Australia and overseas. Informing the 2018 Queensland Bushfires Review. Commissioned by the Office of the Inspector-General Emergency Management, Queensland. (Bushfire and Natural Hazards CRC) Available at https://www.igem.qld.gov.au/sites/default/files/2019-12/IGEM%20QBR%20BNHCRC%20-%20lessons%20and%20insights.pdf
Cheney P, Gould J, McCaw L (2001) The dead-man zone—a neglected area of fire fighter safety. Australian Forestry 64, 45–50.
| The dead-man zone—a neglected area of fire fighter safety.Crossref | GoogleScholarGoogle Scholar |
Cunningham P (2007) Idealized Numerical Simulations of the Interactions between Buoyant Plumes and Density Currents. Journal of the Atmospheric Sciences 64, 2105–2115.
| Idealized Numerical Simulations of the Interactions between Buoyant Plumes and Density Currents.Crossref | GoogleScholarGoogle Scholar |
Deslandes R, Reeder MJ, Mills GA (1999) A synoptic study of fronts using RASP analyses for the central Australian fronts experiment - nocturnal frontogenesis. Australian Meteorological Magazine 48, 87–110.
Doswell CA III (1987) The distinction between large-scale and mesoscale contribution to severe convection: a case study example. Weather and Forecasting 2, 3–16.
| The distinction between large-scale and mesoscale contribution to severe convection: a case study example.Crossref | GoogleScholarGoogle Scholar |
Dowdy AJ, Mills GA (2012) Atmospheric and fuel moisture characteristics associated with lightning-attributed fires. Journal of Applied Meteorology and Climatology 51, 2025–2037.
| Atmospheric and fuel moisture characteristics associated with lightning-attributed fires.Crossref | GoogleScholarGoogle Scholar |
Engel CB, Lane TP, Reeder MJ, Rezny M (2013) The meteorology of Black Saturday. Quarterly Journal of the Royal Meteorological Society 139, 585–599.
| The meteorology of Black Saturday.Crossref | GoogleScholarGoogle Scholar |
Fearon MG, Brown TJ, Curcio GM (2015) Establishing a national standard method for operational mixing height determination. Journal of Operational Meteorology 3, 172–189.
| Establishing a national standard method for operational mixing height determination.Crossref | GoogleScholarGoogle Scholar |
Garratt JR (1986) Boundary layer effects on cold fronts at a coastline. Boundary-Layer Meteorol 36, 101–105.
| Boundary layer effects on cold fronts at a coastline.Crossref | GoogleScholarGoogle Scholar |
Harris S, Lucas C (2019) Understanding the variability of Australian fire weather between 1973 and 2017. PLoS One 14, e0222328
| Understanding the variability of Australian fire weather between 1973 and 2017.Crossref | GoogleScholarGoogle Scholar |
Harris S, Nicholls N, Tapper N (2014) Corrigendum to: Forecasting fire activity in Victoria, Australia, using antecedent climate variables and ENSO indices. International Journal of Wildland Fire 23, 290–293.
| Corrigendum to: Forecasting fire activity in Victoria, Australia, using antecedent climate variables and ENSO indices.Crossref | GoogleScholarGoogle Scholar |
Harris S, Mills G, Brown T (2019) Victorian fire weather trends and variability. In ‘23rd International Congress on Modelling and Simulation’, 1–6 December 2019, Canberra, ACT, Australia. (The Modelling and Simulation Society of Australia and New Zealand Inc.) Available at https://modsim2019.exordo.com/files/papers/272/final_draft/harris.pdf
Inspector General for Emergency Management (2020) Inquiry into the 2019-20 Victorian fire season. Phase 1 Community and sector preparedness for and response to the 2019–20 fire season. Report. (Victorian Government: Melbourne, Vic., Australia) Available at https://www.parliament.vic.gov.au/file_uploads/Inquiry_into_the_2019-20_Victorian_Fire_Season_wqcRWCNG.pdf
Kepert J, Tory K, Thurston W, Ching S, Fawcett R, Yeo C (2016) Fire escalation by downslope winds. Hazard Note 24. (Bushfire and Natural Hazards Cooperative Research Centre) Available at https://www.bnhcrc.com.au/hazardnotes/24
Lim E-P, Hendon HH, Butler AH, Thompson DWJ, Lawrence ZD, Scaife AA, Shepherd TG, Polichtchouk I, Nakamura H, Kobayashi C, Comer R, Coy L, Dowdy A, Garreaud RD, Newman PA, Wang G (2021) The 2019 Southern Hemisphere Stratospheric Polar Vortex weakening and its impacts. Bulletin of the American Meteorological Society 102, E1150–E1171.
| The 2019 Southern Hemisphere Stratospheric Polar Vortex weakening and its impacts.Crossref | GoogleScholarGoogle Scholar |
Markowski P, Richardson Y (2010) ‘Mesoscale Meteorology in Mid-Latitudes.’ (Wiley)
Matthews S (2013) Dead fuel moisture research: 1991–2012. International Journal of Wildland Fire 23, 78–92.
| Dead fuel moisture research: 1991–2012.Crossref | GoogleScholarGoogle Scholar |
Mills GA (2005) On the sub-synoptic scale meteorology of two extreme fire weather days during the Eastern Australian fires of January 2003. Australian Meteorological Magazine 54, 265–290.
Mills GA (2007) On easterly changes over elevated terrain in Australia’s southeast. Australian Meteorological Magazine 56, 177–190.
Mills GA, McCaw L (2010) Atmospheric stability environments and fire weather in Australia – extending the Haines Index. CAWCR Technical Report number 20. Available at www.cawcr.gov.au/technical-reports/CTR_020.pdf
Mills G, Harris S, Brown T, Chen A (2020) Climatology of wind changes and elevated fire danger over Victoria, Australia. Journal of Southern Hemisphere Earth Systems Science 70, 290–303.
| Climatology of wind changes and elevated fire danger over Victoria, Australia.Crossref | GoogleScholarGoogle Scholar |
Noble IR, Gill AM, Bary GAV (1980) McArthur’s Fire-Danger Meters expressed as equations. Australian Journal of Ecology 5, 201–203.
| McArthur’s Fire-Danger Meters expressed as equations.Crossref | GoogleScholarGoogle Scholar |
Peace M, Hanstrum B, Greenslade J, Rajak D, Santra A, Kepert J, Fox-Hughes P, Ye H, Jones J (2021) Coupled fire–atmosphere simulations of five Black Summer fires using the Access-Fire Model. Black Summer final report. (Bushfire and Natural Hazards Cooperative Research Centre). Available at https://www.bnhcrc.com.au/publications/black-summer-fire-modelling
Peterson DA, Fromm MD, McRae RHD, Campbell JR, Hyer EJ, Taha G, Camacho CP, Kablick GP III, Schmidt CC, DeLand MT (2021) Australia’s Black Summer pyrocumulonimbus super outbreak reveals potential for increasingly extreme stratospheric smoke events. npj Climate and Atmospheric Science 4, 38
| Australia’s Black Summer pyrocumulonimbus super outbreak reveals potential for increasingly extreme stratospheric smoke events.Crossref | GoogleScholarGoogle Scholar |
Reeder MJ (1986) The interaction of a surface cold front with a prefrontal thermodynamically well-mixed boundary layer. Australian Meteorological Magazine 34, 137–48.
Reeder MJ, Smith RK, Deslandes R, Tapper NJ, Mills GA (2000) Subtropical fronts and bores observed during the 1996 Central Australian Fronts Experiment. Australian Meteorological Magazine 49, 181–200.
Royal Commission into National Natural Disaster Arrangements (2020) Royal Commission into National Natural Disaster Arrangements – Report. (Commonwealth of Australia) Available at https://naturaldisaster.royalcommission.gov.au/system/files/2020-11/Royal%20Commission%20into%20National%20Natural%20Disaster%20Arrangements%20-%20Report%20%20%5Baccessible%5D.pdf
Salkin O (2022) Victorian Bushfire case studies. Preliminary reconstruction of the eastern Victorian Black Summer Fires. November 2019–February 2020. BNHCRC Report. Available at https://www.bnhcrc.com.au/research/understanding-and-mitigating-hazards/7935
Sharples JJ (2009) An overview of mountain meteorological effects relevant to fire behaviour and bushfire risk. International Journal of Wildland Fire 18, 737–754.
| An overview of mountain meteorological effects relevant to fire behaviour and bushfire risk.Crossref | GoogleScholarGoogle Scholar |
Sharples JJ, McRae RHD (2011) Evaluation of a very simple model for predicting the moisture content of eucalypt litter. International Journal of Wildland Fire 20, 1000–1005.
| Evaluation of a very simple model for predicting the moisture content of eucalypt litter.Crossref | GoogleScholarGoogle Scholar |
Sharples JJ, Mills GA, McRae RHD, Weber RO (2010) Foehn-like winds and elevated fire danger conditions in southeastern Australia. Journal of Applied Meteorology and Climatology 49, 1067–1095.
| Foehn-like winds and elevated fire danger conditions in southeastern Australia.Crossref | GoogleScholarGoogle Scholar |
Slijepcevic A, Anderson WR, Matthews S (2013) Testing existing models for predicting hourly variation in fine fuel moisture in eucalypt forests. Forest Ecology and Management 306, 202–215.
| Testing existing models for predicting hourly variation in fine fuel moisture in eucalypt forests.Crossref | GoogleScholarGoogle Scholar |
Wilke DJ, Kepert JD, Tory KJ (2022) The meteorology of the Tathra bushfire. Weather and Forecasting 37, 581–600.
| The meteorology of the Tathra bushfire.Crossref | GoogleScholarGoogle Scholar |