La Nina ENSO event predicted - high likelihood of a wet summer
The Bureau of Meteorology has issued an update indicating that we are currently at a La Nina watch alert.
What is La Nina?
Australia's climate is driven by cycles in ocean temperatures, currents and trade winds. From Australia’s west, the Indian Ocean Dipole strongly influences monsoonal rains and in the east coast, the Pacific Ocean is subject to the El Nino Southern Oscillation (ENSO). ENSO are massive ocean and air currents that rotate across the entire Pacific Ocean.
During an El Nino event they rotate in an anti-clockwise direction, driving warm water and hot dry air across to the east coast, causing hot and dry summers, and warm dry winters (i.e. drought and fire).
During a La Nina event, they rotate in a clockwise direction, bringing cool water and cold, wet air to the east coast. This drives wetter weather, high snowfall in winter, and flooding in summer.
The Bureau's prediction indicates that there is a 50% chance that we will experience a La Nina year. This means that we are twice as likely than normal to experience La Nina. This signals a high likelihood of a wet summer, with heavy rainfall and flooding.
How do we prepare?
Ensure there are plans in place for heavy rain and wet weather on any existing or proposed construction/development or maintenance projects and advise staff, contractors and development industry contacts accordingly.
Pre-prepare site-based wet weather response plans that allow a scalable response to rain events.
Ensure there are appropriate erosion and sediment control plans including stormwater management in place. IECA guidelines should be strictly followed to ensure a best practice approach to minimise site erosion. Sites should have good drainage (including clean and dirty water diversion/treatment) and ground cover treatments implemented on exposed soils or stockpiles. On sites greater than 2500m2 High Efficiency Sediment Basins must be implemented as stipulated in legislation.