La Nina to bring severe weather to Queensland
Weather pattern linked to more flooding rain and intense cyclones.
Queensland is at risk of experiencing more severe weather events over the coming months after the Bureau of Meteorology (BoM) declared a La Nina system had developed in the Pacific Ocean.
The upgrade to “active” from the BoM’s previous La Nina “alert” status followed forecasts that recent changes in ocean temperatures and weather patterns over the Pacific were now likely to remain until at least the end of the year.
The Bom said La Nina typically resulted in above-average spring rainfall for Australia, particularly across eastern, central and northern regions.
It can also mean cooler days, more tropical cyclones, and an earlier onset of the wet season across the north.
This La Nina event is not expected to be as intense as the last event in 2010–2012 which resulted in one of Australia’s wettest two-year periods on record. Widespread flooding occurred in many parts of Australia associated with the record rainfalls.
Tropical cyclone activity in the 2010-2011 season was near normal, however five cyclones during that period were in the severe category and included Cyclone Yasi which caused widespread damage across north Queensland.
The BoM expected this new La Nina to be of “moderate strength”.
La Nina is associated with cooler than average sea surface temperatures in the central and eastern tropical Pacific Ocean.
Recent BoM observations and model forecasts show the central tropical Pacific Ocean is now 0.8°C cooler than normal, and that has resulted in changes to Trade Winds and pressure patterns.
Climate models suggest these patterns will continue until at least the end of the year.
La Nina events often form in autumn or winter, then decay in late summer. The greatest impact normally occurs during spring and early summer.
They normally last for about a year however they can be shorter or much longer.