Article
BAMOS October 2021
23 climate drivers tend to have a minimal impact on Gascoyne and Pilbara rainfall on average , yet they can influence and interact with one another to produce compounding and significant effects . That is , on multi-week to interannual timescales , the strongest impacts on rainfall here are typically seen when two or more of the tropical modes occur in combination : the Madden-Julian Oscillation ( MJO ), El Niño-Southern Oscillation ( ENSO ) and the Indian Ocean Dipole ( IOD ). My mantra quickly became '… but every event is different !'. For example , while the average summer rainfall response to La Niña shows nearaverage rainfall for these regions , the 2010-2011 La Niña event - which occurred with a negative IOD event - produced record high rainfall for the Gascoyne ( Figure 3 ; December to February total rainfall exceeded 400 mm in some parts ) and flooding up to the rooflines at Bidgemia Station . We heard how Jodie and Hamish were stranded on their tin rooftop during the summer of 2010 – 2011 waiting for the rescue helicopter to arrive .
THE PILBARA , 25 – 31 May : Emu Creek – Wyloo – Cheela Plains – Marble Bar – Yarrie – De Grey
Our first stop upon entering the Pilbara was Emu Creek , a pastoral lease and cattle station run by new caretakers Denise and Andrew . Emu Creek has been running a Bureau weather station since 1898 ( ID 006072 ). The group here was small (~ 5 people ) but highly engaged as they asked many question during and after our presentations . They were quick to understand about climate drivers and their impacts , particularly the MJO — aided by '
Climatedog MOJO ' and Chelsea ' s ' MJO dance '. This highlighted the value of thoughtful and creative communication in delivering interesting and memorable information .
Our next visit , to Wyloo station on the 26th , was a considerably larger meeting with a group of about 10 people . Established prior to 1897 as Peake Station , Wyloo is a pastoral lease that operates as a sheep and cattle station . Our hosts Clint and Shannon , their three sons , resident employees and neighbouring station owners came together for the evening science discussion — and viewing of the total lunar eclipse . I managed to set the tone for the evening with a groanable ' dad joke ' about a total eclipse of the ( weather ) chart … just as a distant tumbleweed rolled by .
During the evening we fielded several questions about climate change , with the long-term decline in winter rainfall being at the forefront of their thinking , in addition to probing questions about forecast model accuracy . This gave me the opportunity to talk about varying timescales of predictability for the different drivers of weather and climate . For example , the longer-term modes such as ENSO and the IOD can provide useful prediction skill on the seasonal timescale , whereas short-term weather events such as blocking highs and cut-off lows are more difficult to predict beyond a week or two ahead . These varying timescales will influence a seasonal outlook and how it can change as the target season approaches . I have found this to be an important concept to convey in my climate briefings to customers over the years , for building and maintaining trust in the Bureau ' s products and services , and this point was also appreciated by the discerning crowd at Wyloo Station .
Our following station visits in the Pilbara were as educational for me as they were for the producers . This included :
Figure 2 : Itinerary for the NACP roadshow in the Gascoyne and Pilbara shires of Western Australia .
• Cheela Plains , where owners Robin and Evan had learned the importance of diversifying for getting through the bad ( low rainfall ) years . Since 2012 their business has been spread across tourism , machinery contracting , pasture growing and agistment . We also learnt here that summer rain can boil on the ground and kill seeds , making winter rain more effective for growth ( and fuelling the ongoing concern about tropical expansion ).
• Limestone Station in Marble Bar , where the Bureau has been operating a weather station since 2000 ( ID 004106 ). Here , Grant and Wendy head up an Angus cattle breeding business in one of the hottest places in the country . Recognised by the Guinness Book of Records as ' the hottest town in Australia ', the highest temperature recorded at Marble Bar was 49.3 degrees on 27 Dec 2018 , and on average more than 100 days per year are recorded at or above 40 degrees .
• Yarrie , where Annabelle and Thomas hire a young international crew of workers for their 2,500 square kilometre cattle station . Annabel and Thomas noted that expressions of empathy from the Bureau in media interviews go a long way when discussing rainfall forecasts , particularly when predicted rains do not eventuate for these regions . They would prefer to receive heavy rainfall from a tropical cyclone and then clean up afterwards than to get little to no rainfall at all .
Our final visit for the week was to De Grey Station on the 30th . It was also probably our largest and most engaged audience . The MJO again became the key focus of discussion , with the 13 producers in the room having not heard of the MJO despite its large influence on the Pilbara . Part of that influence had likely been felt in the preceding week when the
MJO was lined up to bring some rainfall to these regions .
We also spoke about the MJO ' s role on rainfall in western parts of the state only a few weeks prior with the passage of severe tropical cyclone Seroja , which formed in the Timor Sea on the 5th of April in connection with a strong MJO event . As Seroja