New research into the catastrophic 2019 North West Queensland floods shows a need for tailored diagnostics to better represent the cold effects of summer tropical cyclones and tropical depressions on northern Australian livestock.
The research published in the journal Scientific Reports, about the catastrophic 2019 north west Queensland flood event that killed half a million cattle, says there is value in having a livestock chill forecast, instead of relying on variable forecasts that may not capture the severity and compound conditions of a weather event.
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The extreme weather event that impacted northern Queensland in February 2019 featured record-breaking rainfall, persistent high wind gusts and relatively cold day-time temperatures which caused livestock losses of around 500,000 in the northwest Queensland Gulf region.
The new study examined the livestock chill conditions associated with this week-long compound weather event and its potential for prediction from eleven world-leading sub-seasonal to seasonal forecast systems using a livestock chill index which combined daily rainfall, wind and surface temperature data.
Averaged over the event week, researchers found the potential heat loss of livestock was in the moderate to high category, with severe conditions on the day of peak rainfall (February 5).
Using calibrated forecasts from the Bureau of Meteorology the researchers found a one-week lead prediction showed a 20-30 per cent probability of extreme livestock chill conditions over the northwest Queensland Gulf region, "however the highest probabilities were located to the west of where the greatest livestock impacts were observed".
The BOM's best forecast came from ACCESS-S1, a collection of multi-week to seasonal forecast model output, using the ACCESS Prediction System.
Despite not yet being available to the general public at the time of the floods, forecasts of the livestock chill conditions from ACCESS-S1 a week prior to the start of the floods suggested the probabilities of extreme conditions at around 40pc or around times the climatological likelihood
Most of their prediction factors found a more than 20pc chance of extreme conditions, more than twice the climatological probability.
"It appears that the prediction accuracy arose from the skilful forecasts of extreme rainfall, as opposed to cold day-time temperature and strong wind forecasts," researchers said.
Despite a clear association between the observed extreme weather conditions and an active Madden-Julian Oscillation event stalling in the western Pacific, the majority of 1-week lead S2S forecasts showed little indication of a slow-down in the MJO.
However researchers cautioned that the livestock chill index was developed for southern Australian sheep, and it may not be the best metric to represent the effects of exposure on tropical cattle breeds.
Instead they draw attention to the need for tailored diagnostics that better represent the cold effects of summer tropical cyclones and tropical depressions on northern Australian livestock.
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Derek Barry
Editor of the North West Star Mount Isa since January 2016. Prior to that, an editor at several regional southern Queensland newspapers. Passionate about telling local stories. Comes with a strange accent to due an Irish accident of birth.
Editor of the North West Star Mount Isa since January 2016. Prior to that, an editor at several regional southern Queensland newspapers. Passionate about telling local stories. Comes with a strange accent to due an Irish accident of birth.
