What will La Nina deliver for Gympie?

Most of the Gympie floods that have occurred have been during La Nina, BOM expert says.

Most Gympie floods that have occurred have been in a La Nina year, BOM expert Livio Ragano said.

GYMPIE may be in the firing line for floods this summer with La Nina signalling higher than usual rainfall, according to the Bureau of Meteorology.

"We're in a special type of year," BOM meteorologist and television weather presenter Livio Regano said.

La Nina, the term used for a change in sea surface temperature and wind patterns across the equatorial Pacific Ocean, happens every few years and typically causes above-average rain, cooler daytime temperatures in Australia.

 

GOOD ODDS: There is between a 65 – 70% chance of rainfall reaching the median range in the Gympie region between now and December. Picture courtesy of the Bureau of Meteorology.

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It is also when most Gympie floods have occurred, Mr Regano said.

"Most Gympie flood events happen during La Nina years - if you look at the past floods - the odds are higher."

But he warned against using the odds as a forecast and said previous La Nina years should be viewed more as a pattern than a definite indicator.

Even if there was heavy rainfall in the region, flooding was based on other factors too, he said.

Livio Regano

A long term lack of rainfall that the region is currently experiencing meant the ground may need a lot of soaking before water sits above it.

It was a different story in the disastrous Queensland floods of 2011, when there was higher than average rain leading up to the rain event, he said.

Compared to a typical October, La Nina years had average rainfalls that were higher, he said.

In spring, where rainfall is usually low in the region, an increased chance of rain still doesn't equate to much rain, he said.

 

Kaydin Vonschoeler in the first flood water to enter through the Memorial Gates, 2011. Craig Warhurst The Gympie Times

In summer though the increased odds could mean decent rain.

Between now and the end of December there is between a 65 to 70 per cent chance that Gympie will receive the median rainfall, according to data generated by the BOM.

In the Gympie region storm season usually begins in late October, when the region tends to get night time storms before the weather peaks later in summer with more clouds, storms, south easterly showers and cyclones bringing rain.

 

La Nina as seen by US NOAA agency

"All of those things will be accentuated- that includes cyclones," Mr Regano said of the coming months.

"There is a better chance of getting cyclones in the Coral Sea - even if those cyclones don't come near us it still delivers rainfall.

"It's like when you bet on the horses - the odds are much better than usual.

"There is a 2 out 3 chance of it being a wet three months."

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