The South African Weather Services (SAWS) has unveiled its seasonal forecast outlook for the country, covering the period from September to November 2023.
According to the forecast, South Africans are advised to prepare for a warmer spring and summer season this year.
SAWS revealed that the El Niño-Southern Oscillation (ENSO) is currently in an El Niño state, and recent forecasts suggest this condition will persist throughout most of the summer months.
“ENSO’s typical impact on Southern Africa favours generally drier and warmer conditions during the warmer seasons (from October to March)” stated the weather services.
However, SAWS cautioned that global forecasts currently harbour a significant degree of uncertainty regarding the usual drier conditions associated with South Africa during an El Niño in the upcoming spring months. Nevertheless, the models offer more certainty concerning the expected conditions for the summer months.
Explaining the uncertainty, SAWS noted that typical weather conditions associated with El Niño over South Africa include warmer temperatures and reduced rainfall (or below-normal rainfall/drier conditions).
Numerical guidance models, both global and inhouse, currently diverge on rainfall predictions for the spring months in South Africa.
Some models suggest a wetter start than usual to the rainy season over central and eastern South Africa, while others predict drier conditions. This divergence may be attributed to the atmospheric adaptation to sea surface conditions in the central Pacific Ocean, which models find challenging to resolve.
The resolution of this uncertainty could take several months, leading to uncertainty about when South Africa will feel the full impact of El Niño—whether it will affect the start of the rainy season or manifest later.
Regarding the forecast for September to November 2023 across South Africa:
SAWS ensemble predictions indicate a 33-50% chance of below normal rainfall over central and eastern SA during the forecast period.
The International Research Institute (IRI) multi-model predictions indicate a 40+% chance of below normal rainfall over central SA for the forecast period.
The Global Forecast Systems, in conjunction with the North American Multi model Ensemble System, predicts wetter (or above-normal rainfall) conditions for most parts of South Africa during the forecast period.
The high uncertainty surrounding spring rainfall patterns underscores the importance of monitoring short to medium range forecasts.
“We will continue to monitor the weather and climate conditions and provide updates on any future assessments that may provide more clarity on the current expectations for the coming season,” assured SAWS. As for temperatures, SAWS anticipates greater certainty in the expected temperatures across South Africa for September to November and beyond.
Models indicate that warmer than average temperatures are likely during this period, prompting a call for South Africans to be vigilant and take precautions against the risks associated with heat and UV exposure. Heatwaves, especially during spring and summer, may become more frequent, particularly during El Niño events.
It is essential to note that while cold fronts will still impact the Cape provinces in the first half of spring, bringing bursts of cold air and possible mountain snow, temperatures are expected to rebound swiftly.
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