Pretoria - Tshwane MMC for community safety, Grandi Theunissen, commended the emergency services department for their swift and effective response to the severe thunderstorm and to about 50 storm-related incidents on Tuesday evening.
He said the emergency services personnel were still working to clear roads, restore power and assist residents in need. He reminded residents in need of help from emergency services to call them toll-free at 107.
Meanwhile, the SA Weather Service said radar and satellite remote sensing data provided little or no indication of the possible severity of the storms.
However, a feature that proved significant was that, given the very dry conditions on the surface, the convective cloud base of the thunderstorms was at an abnormally high altitude above the ground, the ‘weatherman’ said in a statement.
“While this type of storm development can occur at any time of the year, early summer season storms are notorious in terms of frequently being associated with strong, damaging winds caused by ‘dry microbursts’. Moreover, such storms are not typically associated with delivering much rainfall at all, which explains the popular term ‘dry thunderstorms’.”
A microburst is a localised column of sinking air within a thunderstorm and is usually less than or equal to 4km in diameter. Microbursts can cause extensive damage on reaching the Earth’s surface, and in some instances, can be life-threatening.
According to the weather service, wind speeds exceeding 50 knots were observed over Harrismith between 4.15pm and 4.35pm on Tuesday, which is consistent with the typical strength of a dry microburst.
Later in the evening, towards 9pm, strong surface wind gusts of 40 to 46 knots, in association with thunderstorm activity, were reported over the central and southern parts of North West.
In the period between 9pm and 10pm, reports of extremely strong winds were reported at many localities across Gauteng.
Damage was also reported over the eastern and the north-eastern parts of Free State, eastern and the south-eastern parts of North West.