Johannesburg snowfall unlikely to last longer than a day, expert predicts

Johannesburg residents should enjoy Monday's snowfall while it lasts, as an expert has predicted it is unlikely to last longer than a day.

It was winter wonderland across most of South Africa on Monday after snowfall hit various provinces from the weekend onwards.

Residents took to social media to share snaps and videos of the snow while various entities cautioned residents to be careful on the road and at home amid plummeting temperatures.

Eskom ramped up load-shedding to stage 4 amid surging demand and a “slight reduction in generation capacity”.

While the city, and other parts of Gauteng, saw a blanket of snow cover the ground by Monday afternoon, University of the Witwatersrand professor of physical geography Jennifer Fitchett predicted it was unlikely to last longer than a day.

She said snowfall was a rare occurrence in Johannesburg, with the last proper snow falling in 2012 and before that 2007.

“It's happens once every 10 years or so. We're not an area that has a lot of snowfall and that's partly because in winter we have dry conditions. We've got a strong, high pressure cell which is why we don't have any or very little rain in winter months. And so don't have much moisture in the air.”

Fitchett explained why Monday's weather created the “perfect” conditions for snowfall, revealing what her hand-held weather meter showed earlier. This was similar to conditions in place the last time Johannesburg got snow.

"[The humidity was going up to 97%. That's very high humidity and coupled with the cold temperatures. We've got cold wind coming through as well today [Monday]. That creates [perfect] conditions.”

Asked about the lengthy period between snowfalls in the city, Fitchett said there doesn't “appear to be distinct inter-annual scale drivers" and it wasn't necessarily connected to one factor or another. 

Snowfall in Johannesburg was often down to a “combination of conditions” and these “don't happen very often”.

“That [was] a very strong cold front that reached the Cape at the weekend and ... it started snowing earlier. It was very cold and wet. So that was a strong mid-latitude cyclone. The South African Weather Service [SAWS] issued a warning on July 6 regarding that strong cold front.

“These strong cold front systems carry moisture with them and if you noticed early this morning [Monday], there were bands of clouds that started coming through in Johannesburg and those are carried by this mid-latitude cyclone system. What we sometimes have is what is called a cut-off low, which is where that system breaks off, and most snowfall events in Lesotho are caused by those cut-off low events and it was also responsible for the Durban floods last year. Those are what we call unstable systems that result in precipitation events, whether that's rain or snow.

“So mid-latitude cyclones, if we have a very strong one, brings with it very cold temperatures. So we know with a mid-latitude cyclone you have a cold front and it also brings moisture and that's the recipe you need for snowfall — there has to be instability in the atmosphere to have moisture and to have those cold temperatures that drop to the point that we would have snow flakes falling.”

Fitchett said it was also “uncommon” for snow to settle in some areas around the city as “ordinarily when it snows, the snow melts as it touches the ground because the ground is still warm, but we're actually starting to see snow accumulate".

“Our snowfall events are usually short-lived, they're only a couple of hours. Usually our snowfalls in Johannesburg are not more than a day.”

The SAWS confirmed the snowfall was a result of a “cold front [that] caused a significant drop in temperatures”.

“The maximum temperatures are expected to reach 13°C in the northern areas of Gauteng, with minimum temperatures recorded to have met criteria for snowy conditions. Snow was observed over areas in the south, such as Soweto, Alberton and Roodepoort.

“Some of the areas that observed snow include the eastern areas of Gauteng, Heidelberg and parts of Vosloorus. Most of the snow observed since morning was over Heidelberg. Light snowfall and sleet are still possible over the highveld and the escarpment of Mpumalanga, where expected temperatures for areas such as Dullstroom, Belfast, Roossenekal, Mariepskop, Mount Anderson and Ermelo, will not exceed 6°C,” it said.

Hannelee Doubell from the SAWS said the last time it snowed in Gauteng was on August 7 2012 when there was very light snow.

She said there were no major disruptions caused by snowfall.

“SAWS expects Gauteng snow about every 10 years. According to research, the Mpumalanga Dullstroom area gets occasional snow towards late winter.”  

She added that the weather will be clear and become warmer over the next few days.  

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