Phenomenon explained as Bloem sandstorm moves east
Eerie sandstorms swept through parts of Gauteng, the Free State and the Northern Cape on Thursday, with the Western parts of the North West also affected.
While the South African Weather Service says this is not a common occurrence, there is a perfectly logical explanation for the phenomenon. In a nutshell, the sandstorms occurred on Thursday when a combination of two things came together: thunderstorms and intensifying upper weather systems, combined with huge amounts of extra sand on farms in the Free State where farmers have yet to plant their crops.
Puseletso Mofokent, a senior forecaster at the weather service, told the Mail & Guardian on Friday that these types of storms are more common in the Northern Cape where large swathes of the land are arid.
This week, strong winds coming off of thunderstorms in the Northern Cape moved further inland towards the Free State. There, huge amounts of sand were swept up and the storms intensified. This was because the rainy season is late this year, so many farmers in the Free State have yet to plant crops, Mofokeng said.
“It was the upper trough that intensified. As it intensified, winds became stronger on the ground, increasing the gradient. This met with great amounts of sand lying around on farms in the Free State,” he said.
From the Free State the winds swept as far inland as parts of the Western North West province. But this was not the same weather system that caused the sandstorm that engulfed parts of Gauteng on Thursday.
“Although we didn’t see rainfall in most of Gauteng, satellite images showed that there were active thunderstorms in the Western parts of Gauteng but not necessarily over the main cities, Pretoria and Johannesburg.
“The additional effects of the storm in the Free State, because of the intensifying system, caused increasing wind speeds over and above the wind from the thunderstorm weather,” he said. Mofokeng added that the storm system is moving away from Gauteng, to KwaZulu-Natal and the east coast. By Saturday, the weather service expects the winds to have exited the country off the east coast.