Durban - The South African Weather Service (Saws) has warned against yet more rainfall and widespread flooding overnight in KwaZulu-Natal and parts of the Eastern Cape.
“Following a weekend of widespread rainfall over much of the country this past weekend, the cut-off low system responsible for the inclement weather began moving eastwards over KwaZulu-Natal and the Eastern Cape overnight,” the Saws said in a statement on Tuesday afternoon.
It said that whilst impact-based warnings were issued in a timely manner by the Saws, it appeared that the exceptionally heavy rainfall overnight and this morning exceeded even the expectations of the southern African meteorological community at large.
The Saws said that at 4pm on Monday, a Level 5 warning was issued for the coast and adjacent interior of KZN and was subsequently escalated to a Level 8 warning at 8pm. However, following reports of further impacts and persistent, heavy rainfall, Saws has now upgraded the heavy rain warning to an Orange Level 9 for the remainder of Tuesday.
“Overnight rainfall reports from KwaZulu-Natal have underscored the particularly heavy and extreme nature of the rainfall, with some 24-hour falls exceeding 200mm. More noteworthy, is that a few stations even reported 300 mm or more! A selection of the highest overnight rainfall measured in KwaZulu-Natal includes King Shaka International Airport (225mm), Margate (311mm), Mount Edgecombe (307mm), Port Edward (188mm) as well as Virginia airport (Durban North) with 304mm. Such rainfall is of the order of values normally associated with tropical cyclones; however, Saws must strongly emphasise that this system is not tropical in nature, nor is it a tropical cyclone,” the Saws said.
The service said the reason for the rain was a cut-off low in the upper reaches of the troposphere moving seawards, off the eastern coast of South Africa.
The Saws explained that cut-off lows were associated with widespread instability in the atmosphere, which can promote periods of prolonged rainfall, as witnessed over many of the interior provinces of South Africa at the weekend.
“For KZN however, the effect of the cut-off low system had been markedly enhanced by the presence of sustained low-level maritime air which has been fed in from the southern Indian ocean, thus driving the system to produce more rainfall. Moreover, the original source of the maritime air was from warmer, sub-tropical parts of the ocean, with a greater capacity to transport moisture, an essential ingredient of any rain-producing system.”
The following impact-based warnings were issued by the Saws and they remain valid for the rest of Tuesday:
Orange Level 9 warning for disruptive rainfall leading to widespread flooding of settlements, schools, roads, bridges, sinkholes, mudslides, soil erosion and major disruption of traffic is expected over the extreme south-eastern parts of KZN.
Yellow Level 4 warning for disruptive rainfall leading to flooding of roads, settlements, displacement of affected communities, sinkholes, mudslides, rock falls and poor driving conditions expected over the south-eastern interior of KZN.
Orange Level 6 warning for disruptive rain leading to flooding is expected in places over Port St Johns LM, Ingquza Hill LM and Mbizana LM in the Eastern Cape.
The Saws said the weather conditions could not be attributed to global warming and climate change.
“As weather scientists we cannot attribute individual weather events occurring on short time scales to longer-term events, occurring over years or decades. However, notwithstanding the above, we can state with confidence that globally (as a direct result of global warming and associated climate change) all forms of severe and extreme weather (such as heatwaves, heavy rain, and coastal storm surge events) are becoming more frequent and more extreme that in the recent past. In other words, heavy rain events such as the current incident can rightfully be expected to recur in the future and with increasing frequency,” the Saws explained.
“The good news is that, by tomorrow (Wednesday) the current rainfall system will have weakened considerably, heralding a spell of a few days of settled dry weather. However, the public should take note that rain is expected to return to many of our provinces, ahead of and during the coming Easter weekend, when many people will be travelling to other parts of the country. The public are therefore urged to continue to monitor forecasts and warnings issued by Saws. A dedicated media release, covering the weather forecast for the Easter weekend, will be issued by Saws soon,” the Saws said.
Saws said it will continue to monitor any further developments relating to this weather system and will issue subsequent updates as required.
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