Weekend Argus (Saturday Edition)
La Niña poised to dominate rainy season as spring approaches
THIS rainy season will likely see the third consecutive year where our weather is dominated by a La Niña system. Three in a row is almost unheard of, according to weather experts.
The La Niña or The Girl is still largely unknown.
“We haven't really been watching these La Niña much longer than about 25 to 30 years.
“And because they come once every five or seven years, there's not that many for us to go back and correlate with the rainfall,” said Professor Peter Johnston, a climate scientist at UCT.
La Niña is supposed to bring wet weather to South Africa and it all has to do with the cooling of sea surface temperature thousands of kilometres away in the pacific ocean.
El Niño, the opposite, entails the warming of the Pacific and causes lower-than-average rainfall.
But sometimes La Niña doesn’t bring extra rainfall.
“Sixty times out of 100 it will affect the rainfall in the interior of South Africa and it will move the rainfall to the higher than normal category,” said Johnston.
This La Niña is expected not to be as strong as last year’s.
“We are expecting above-normal rainfall but might not be as extreme as it was last year. And we are expecting abovenormal temperatures, too,” said South African Weather Service (SAWS) senior forecaster Dipuo Tawana.
The La Niña is expected to take hold later in the summer. September, October and November are predicted to have lower than average rainfall.
What weather forecasters can’t predict is if there is going to be any flooding, such as what was seen in KwaZulu-Natal in April.
Johnston warned that the previous wet season had left the soil saturated and susceptible to possible flooding.
However, according to the SAWS, the predicted above-normal rainfall is not likely to benefit water reservoirs in the areas of South Africa like the Eastern Cape that are experiencing ongoing droughts.
“Why La Niña doesn’t bring extra rain to the Eastern Cape is not fully understood,” said Johnston.
But the hope is that it will do so this time and with it, break the eightyear drought.
The summer ahead could also see heat waves, said Tawana, with Limpopo and Mpumalanga experiencing temperatures in the 40s in the months ahead.
“From the beginning of September, we are probably going to see isolated showers popping up here and there,” Tawana predicted.