Cut-off low to cause widespread rainfall in parts of SA this weekend

The South African Weather Service (SAWS) expects widespread rainfall this weekend in most of the country.

This is reportedly due to a cut-off low that is expected to develop in the upper air of the atmosphere over the central interior during the latter half of the weekend.

WIDESPREAD RAINFALL EXPECTED THIS WEEKEND

The weather service said the cause of the widespread rainy weather will be the combination of three distinct circulation features in the atmosphere over southern Africa.

Firstly, a cut-off low is expected to develop in the upper air of the atmosphere over the central interior during the latter half of the weekend.

Secondly, a surface trough is expected to intensify in sympathy with the deepening upper-air cut-off low.

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“The combination of these two features is well-known to have the potential to drive episodes of widespread, often heavy, rain over southern Africa. Importantly, in this particular case, a third significant factor is expected to elevate the risk of heavy rainfall from this system.

“This factor is the anticipated introduction of a stream of tropically sourced moisture, drawn southwards over the central and eastern interior of South Africa, under the influence of the circulation associated with the surface trough and upper-air system, respectively. Tropically sourced air is well known to be associated with potentially heavy, widespread rainfall.”

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WEATHER OUTLOOK

Initially, this weekend’s weather will be relatively settled, with just a slight chance of thunderstorms over some eastern provinces on Friday, 8 December, and Saturday, 9 December. However, incidentally, neither the Western Cape nor the Eastern Cape will be directly affected by this weather system.

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“On Sunday, 10 December, weather conditions will deteriorate significantly as the cut-off low manifests itself over the northern parts of the Northern Cape, introducing marked instability into the atmosphere, driving widespread showers and thundershowers.

“As tropical air begins to stream southward over Botswana and South Africa, conditions will become progressively cloudy to overcast. During the day, rain will set in over numerous provinces, including North West, the Free State, Gauteng, Mpumalanga, Limpopo, and to a lesser extent, KwaZulu-Natal (KZN).”

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