Parts of KwaZulu-Natal experienced an outbreak of severe storms and at least two tornadoes on Monday afternoon, affecting parts of Newcastle, Utrecht, Ballito, and Tongaat.
The sudden onset of these extreme weather events, part of a broader spell of severe weather being experienced around South Africa this week, underscores the importance of understanding how tornadoes form and the potential impact of climate change on their frequency and intensity.
Kevin Rae, Chief Forecaster for Disaster Risk Reduction at the South African Weather Service, said in a statement that “the severe weather was predicted due to an upper air cut-off low system. This system triggered severe storms, heavy rainfall, flooding, and heavy snowfall in various regions, including the Eastern Cape and KwaZulu-Natal.”
According to the US National Center for Atmospheric Research, a tornado is a rapidly rotating column of air that extends from a thunderstorm to the ground. The formation of a tornado requires specific atmospheric conditions.
Tornadoes form in areas where there is warm, moist air near the ground. This air serves as the fuel for thunderstorms. Above the warm, moist air, there must be cooler, dry air. This creates an unstable atmosphere conducive to severe weather.
Wind shear is a significant factor in tornado formation. It involves a change in wind speed and direction with height. When winds at different altitudes blow at different speeds or in different directions, it can create a rotating column of air.
A lifting mechanism, such as a cold front or a low-pressure system, is needed to push the warm air upwards. As the warm air rises, it cools and condenses to form thunderstorms.
Tornadoes most commonly form from supercell thunderstorms, which are characterised by a rotating updraft called a mesocyclone. Under the right conditions, the mesocyclone can tighten and intensify, forming a tornado.
As the National Severe Storms Laboratory at the National Oceanic and Atmospheric Administration (Noaa) notes, tornadoes can happen any time of the year and due to climate change, the intensity and frequency of tornadoes are expected to get worse.
As global temperatures rise, the atmosphere can hold more moisture, leading to more severe thunderstorms. Increased heat and humidity provide more energy for storms, potentially leading to more frequent and intense tornadoes.
In South Africa, warm, humid regions like KwaZulu-Natal could see more severe storms due to climate change, making tornadoes a more common threat. Rae’s statement, highlighting the recent severe weather, including heavy rain and flooding in the Eastern Cape, which resulted in at least seven fatalities.
The South African Weather Service has issued warnings for isolated communities in high-altitude areas of the Eastern Cape, advising the public to stay sheltered and avoid driving on dangerous roads and mountain passes.
IOL