What ’ s the go with
this weather ?
Rain , rain , rain . Floods , homes lost , livelihoods washed away , roads disappearing , mould incessantly climbing the walls , the stench and oh the potholes - some so big they ’ re chasms that have swallowed roadways .
Hawkesbury is no stranger to flooding , being situated on a floodplain along the Hawkesbury- Nepean River , it ’ s par for the course .
History shows we ’ ve endured many floods . If you add into the mix the effect of Warragamba Dam releases , the politics behind better flood mitigation , continual approvals for residential development and the way our lifestyles affect our environment – the effects of major rain events will continue to be felt .
The Bureau of Meteorology explains we ’ re in the middle of a La Niña weather pattern . So , what is it ? Australia ’ s weather is influenced by many climate drivers . El Niño and La Niña have the strongest influence on year-toyear climate variability for most of the country .
They are part of a natural cycle known as the El Niño-Southern Oscillation ( ENSO ). The ENSO cycle loosely operates over timescales from one to eight years .
In Australia ENSO is often behind our climate extremes , from devastating floods to searing droughts .
La Niña typically means :
• Increased rainfall across much of Australia
• Cooler daytime temperatures ( south of the tropics )
• Warmer overnight temperatures ( in the north )
Water , water everywhere as La Niña sweeps across the eastern seaboard of Australia . Pictures : Hawkesbury and Hornsby SES .
• Shift in temperature extremes
• Decreased frost risk
• Greater tropical cyclone numbers
• Earlier monsoon onset What causes La Niña ? La Niña occurs when equatorial trade winds become stronger , changing ocean surface currents and drawing cooler deep water up from below . This results in a cooling of the central and eastern tropical Pacific Ocean . The enhanced trade winds also help to pile up warm surface waters in the western Pacific and to the north of Australia .
The warming of ocean temperatures in the western Pacific means the area becomes more favourable for rising air , cloud development and rainfall .
As a result , heavy rainfall can occur to the north of Australia . Conversely , over the eastern and central tropical Pacific , air descends over the cooler waters , meaning the region is less favourable for cloud and rain . The air rising in the west and descending in the east enhances an atmospheric circulation – called the Walker circulation – which can result in changes to the climate felt across the globe . Increased rainfall The increased rainfall and cloudiness in the western Pacific associated with La Niña usually means above-average winter – spring rainfall for Australia , particularly across the east and north .
The six wettest winter – spring periods on record for eastern Australia occurred during La Niña years .
In the Murray – Darling Basin , winter – spring rainfall averaged over all 18 La Niña events ( including multi-year events ) since 1900 was 22 per cent higher than the long-term average , with the severe floods of 1955 , 1988 , 1998 and 2010 all associated with La Niña .
El Niño and La Niña are not turned on and off like a switch , they are part of the regular cycle of weather patterns that effect Australia – some years as we ’ ve seen are far worse than others .
Reference : Bureau of Meteorology . For more information , go online to bom . gov . au .
www . gwsmachinery . com . au
Dick Petrikas P / L Chainsaws , Mowers , Tractors Petrikas Lane , TENNYSON Ph : 4576 5555
Log Splitters
Chainsaws
Range of Tractors
Whitelock , Massey Ferguson ambassador .
5 Walker Street , South Windsor Phone 4577 4622
STOCKISTS OF LEADING BRANDS
THE HAWKESBURY INDEPENDENT theindependentmagazine . com . au ISSUE 143 // APRIL 2022 41