“I was on my way home from the city and stopped to take pictures of the storm clouds when the tornado started to form. It was an amazing but also scary experience.”
With these words, Tanya van Rooyen describes the moment she made a video that went viral on social media. She recorded the images around 3 p.m., about 15 km outside Heilbron in the Free State, on the Vegkopweg.
She told Caxton Network News it all happened in the blink of an eye. “The storm approached very quickly and was accompanied by high winds and heavy lightning. Moments after this video, it started to rain heavily.”
South African Weather Service (SAWS) meteorologist Lehlohonolo Thobela confirmed that thunderstorms in the area intensified in the afternoon. He added that a severe thunderstorm warning had been issued. According to Thobela, gusty winds in the region, combined with wind shear, convergence and sufficient moisture, led to the formation of convective clouds, which later developed into a supercell. “Conditions were favorable for a tornado to form.”
He said no further impacts have been reported and it appears the tornado occurred over an open field and caused little or no damage.
“Based on these findings, SAWS has classified the event as an EF0 tornado – the weakest category on the Enhanced Fujita scale, with estimated wind speeds of 105–137 km/h.”
These tornadoes typically result in minor damage such as broken branches, downed trees with shallow roots, and minor damage to roofs. “While EF0 tornadoes are relatively weak, they remain dangerous weather phenomena, and the public is urged to always exercise caution during severe thunderstorms,” he added.
Tornadoes in South Africa
Yesterday’s tornado follows a tornado in Harrismithalso in the Free State, on 6 November. This raised the question of whether the province is tornado-prone. Thobela said research has shown that typical conditions conducive to tornadic and severe convective activity – namely moist, converging air, low shear and unstable environments colliding with cooler triggers – are common in parts of South Africa. He notes that historical and contemporary analyzes show that many of South Africa’s tornadoes, and even a ‘tornado belt’ of sorts, occur in the Highveld regions and eastern provinces, including Gauteng, the Free State, Mpumalanga and KZN.
He added that analyzes of historical events also show a seasonal peak for tornadoes in the midsummer months (November-March), as studied by the Water Research Commission in previous years. “Importantly, tornadoes are not strictly limited to core summer; there are documented events in spring (September-October) and late summer.”
He said this supports the sentiment that warm, moist environments with triggers from cool environments are critical indicators for tornadoes occurring this time of year.
Supercell tornadoes
Thobela said investigations of a notable tornadic supercell on December 11, 2017 (in the highveld) showed that the conditions were caused by strong low-level moisture and significant vertical wind shear in the boundary layer, exactly the ingredients observed in this case.
He said that a relevant recent study (Liesker, Dyson & Becker) found that these supercells are most common in October to November, which is early in the convective season (spring to early summer). “The average lifespan of their preferred tracks is about an hour and 12 minutes, with a horizontal speed of 41 km/h and a distance of about 49 km, mostly from the south-west and further south as the season progresses.”
There also appears to be some influence of topography, especially in the eastern Mpumalanga and highveld regions, on where supercells form. “This is consistent with the idea that the interaction of terrain, moisture and shear helps define preferred corridors for severe cell development, which could explain the spatial clustering of the severe thunderstorm reports.”
Watch the video:
Van Rooyen explained Paris Gazette that she could see some corrugated iron being picked up and blown around by the tornado.
“It was the first time we experienced something like this here,” she told the newspaper.
An inquiry was sent to the Free State Department of Co-operative Governance and Traditional Affairs and Human Settlements to find out if any damage had been reported in the area. At the time of publication this was still being verified.
Not uncommon in South Africa
Every time a tornado hits South Africa, social media fills with ‘what’s happening with the weather?’ to inform. But according to SAWS, tornadoes are not new here.
We’re simply seeing more of it because smartphones and social media are now capturing what once went undocumented.
SAWS says tornadoes can happen anywhere Thunderstorms are forming, most historically reported in Gauteng, the Free State, KZN (between Pietermaritzburg and Ladysmith) and the northern former Transkei, often in mountainous areas. About 65% are weak (F0-F1) and more than 90% fall under the strength of F3, although South Africa has experienced stronger events such as the 1998 Harrismith (F2) and 1999 Mount Ayliff (F4) tornadoes.
SAWS adds that even internationally, tornado forecasting remains limited, with radar typically only providing about 20 minutes of warning.
Tornadoes may be unusual, but they have long been part of South Africa’s weather and are not a new phenomenon.
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Ruan de Ridder
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