Brace for a wintry weekend and possible floods as cut-off low moves over parts of the country

The weather phenomenon that resulted in the devastating KwaZulu-Natal floods in 2022 is expected to hit several parts of South Africa over the weekend, particularly in the central and eastern regions, before spreading to the southern parts of the Western Cape and Eastern Cape, the South African Weather Service (SAWS) said on Thursday, 4 April 2024.

“​​Tropical moisture has been transported from our neighbouring countries to the central and eastern interior of South Africa since yesterday (Wednesday, 3 April). This will result in scattered rainfall to continue [on Thursday] and Friday, which will spread to the southern parts of the Western Cape and parts of the Eastern Cape tonight into Friday. Cooler temperatures are forecasted for the southern and eastern parts of the country from [Friday],” the SAWS said. 

Known as a cut-off low, the weather phenomenon expected to hit the country this weekend comes after prolonged heat waves and below-average rainfall over the interior parts of the country.

According to the weather service, cooler and unsettled conditions are expected. Colder temperatures had already occurred in Johannesburg from Wednesday. 

Cut-off lows are also synonymous with widespread flooding, damaging winds, severe thunderstorms and sometimes snow, depending on the season. The phenomenon is also most common during autumn and spring, and more frequently in April. 

The country has been hit by extreme heatwaves this year, many of which have resulted in record-breaking temperatures in the northeastern interior.

Read more in Daily Maverick: ‘Heatwaves are going to get worse, like nothing we’ve ever seen before’ — SA climatologist

As the effects of the climate crisis intensify, record-shattering high temperatures are likely to persist. However, with the country experiencing the El Niño weather phenomenon, some of these heat waves are to be expected.

The climate crisis can cause weather phenomena to intensify – as seen in the 2022 KwaZulu-Natal floods that killed more than 400 people and caused billions of rands in damage to infrastructure.

Read more in Daily Maverick: A Perfect Storm: How the deadly 2022 Durban floods hold crucial lessons for the future of the city and others like it

The SAWS said the cut-off low would develop along the west coast on Saturday afternoon, move over the Northern Cape on Sunday, reach the Western Cape interior on Monday and exit from the southern coast of the Western Cape on Tuesday, with calm weather conditions expected to return thereafter. 

Temperatures are expected to range from cool to cold in parts of the Western Cape, Eastern Cape and KwaZulu-Natal from Saturday onwards, with the rest of the country following suit on Sunday and Monday.

Temperatures are expected to reach the high teens and low twenties during the day, with Eastern Cape and KwaZulu-Natal possibly having low teen temperatures over high-lying areas. 

Kevin Rae, chief forecaster at the SAWS, said the bulk of the rainfall is expected to occur on Sunday and Monday over the southern, central and eastern parts of the country, alongside a significant drop in temperatures. 

“Severe thunderstorms, accompanied by strong damaging winds and large amounts of small hail are expected over the above areas, especially over the southern half of Western Cape as well as the eastern extremities of the Northern Cape, and that would include the area of Kimberley. Given the high risk of localised flooding, pedestrians and motorists are strongly urged not to attempt to cross flooded rivers and streams as such actions are potentially life threatening,” said Rae.

The SAWS said it was uncertain about the intensity and future of this cut-off low, adding that the uncertainty could lead to changes in rainfall patterns. Regular updates would be issued over the weekend. 

The announcement comes shortly after the SAWS issued a statement saying this year’s winter season was expected to be mild, with below-normal rainfall and above-normal temperatures, including for the current autumn season.

While this may aid in curbing rolling blackouts during the winter, it could hinder agricultural performance due to limited rain. DM