La Nina to bring increased rain to CQ
RAINFALL is likely to increase across Central Queensland as Christmas approaches after the Bureau of Meteorology issued an alert with a 70 per-cent chance of a La Nina eventuating.
Further cooling of the Pacific Ocean is predicted, meteorologist Rosa Hoff said, bringing with it rain and an increased chance of cyclones.
“Our ENSO (El Nino Southern Oscillation) outlook is currently at La Nina alert,” she said.
“We have about a 70 per-cent chance of a La Nina developing for the end of this year.
“In a La Nina circulation we see some cool sea surface temperatures around the equatorial ocean, and because of the cold seas surface temperatures that changes the way the air wants to flow around.
“Across the equatorial Pacific, a lot of air is rising around Northern and Eastern Australia...so we tend to see more rainfall in that kid of situation because we have got more moisture being pumped into the air.
“It means the atmosphere is a bit more primed for some dynamic weather.”
Ms Hoff said rainfall was likely to increase across Gladstone, Rockhampton and Bundaberg from the end of September.
“We do have an increased likelihood of above average rainfall across Eastern Australia during the spring months, particularly the later spring.
“There is also the chance of below average daytime temperatures, however not a direct impact on night time temperatures, or our minimums, so they might still be a bit on the warm side.”
The La Nina climate cycle also drives cyclone activity, Ms Hoff said.
“We also have an increased chance of tropical cyclones in La Nina conditions,” she said.
“However it is really important to remember that just because we have an increased chance of cyclones developing, it doesn’t mean that we will have an increased impact from cyclones.
“All it takes is one small cyclone in a bad location geographically to have a really significant impact, as opposed to multiple larger cyclones to stay off over the ocean and not impact our coast.”
The La Nina conditions, coupled with negative Indian Ocean Dipole readings which are predicted to eventuate in October, equals increased rainfall.
“Both La Niña and negative IOD typically increase the chance of above average rainfall across much of Australia during spring,” the BOM said in a statement.
“Above average summer rainfall is also typical for much of eastern Australia during La Niña. “Current climate outlooks indicate a wetter than average spring for eastern Australia.”
Another factor influencing the weather is climate change.
“Australia’s climate has warmed by around 1.4 °C since 1910, while southern Australia has seen a 10–20% reduction in cool season (April – October) rainfall in recent decades,” the BOM said.