What is a Heatwave
A heatwave is a term that refers to a period of exceptionally hot, dry weather over a specific geographic area that lasts at least a few days (and sometimes longer). Although this phrase is widely used, each country’s meteorological organization will normally tailor its definition of a heatwave to suit local conditions. For a heatwave to be proclaimed, the South African Weather Service (SAWS) has established that “the highest temperature at a given station should meet or exceed the average maximum temperature for the hottest month, for three or more consecutive days” (especially for South African circumstances).
What weather systems are contributing to the current heatwave?
The country’s interior has experienced maximum levels of sunshine (insolation) during the previous few days due to a dry, cloudless stretch of weather, which has led to steadily rising temperatures. Additionally, a very sizable upper-air high-pressure system (also known as an anticyclone) that covered much of Namibia, Botswana, and the northern half of South Africa throughout the last week has dominated the weather pattern over the southern African subcontinent. Apart from the fact that this characteristic delays the commencement of our summer rains by delaying the arrival of moisture from the tropics, upper-air highs are well known for being linked to large-scale air stability and sinking air masses. Such systems prevent the formation of thunderstorms, but possibly more significant in this situation, the air that is sinking warms up considerably.
How long will the current heatwave persist?
The current time through Friday, October 7, 2022, inclusive, are predicted to have heatwave conditions throughout Gauteng, eastern parts of the North-West, the eastern Highveld of Mpumalanga, as well as the south-western bushveld of Limpopo.
Which other provinces are going to experience the heatwave?
Gauteng, the North West, the northern Free State, and portions of Limpopo and Mpumalanga are under a heatwave warning that has been extended by the South African Weather Service (SAWS) until Friday, October 7. The Highveld will continue to have exceptionally hot and dry conditions through the weekend, according to the weather service’s report on Tuesday (4 October). The service has advised South Africans to drink plenty of water, stay out of direct sunshine, or stay indoors between 11:00 and 15:00.
With no immediate sign of relief in sight, maximum temperatures are predicted to reach the high 30s.By Friday, temperatures in prominent Gauteng cities like Pretoria are predicted to reach 37 degrees, with Johannesburg three degrees behind at 34.
“A spell of dry, cloud-free weather over the past few days has allowed maximum levels of sunshine to arrive over the interior of the country, with temperatures becoming incrementally higher every day,” said the SAWS.
It added that a large upper-air high-pressure system that has dominated the weather pattern over the southern part of Africa in the past week has added to the heatwave. This so-called ‘anticyclone’ has blocked the arrival of summer rains.
Precautions to take during this heatwave
Ensure that you stay hydrated by drinking water regularly
Avoid over-exertion when exercising (sport or leisure)
Ensure that small children and infants are supplied fluids often as dehydration can set in quick
Take care of the elderly, who are also at risk of over-exertion
Be cognisant of the sunshine by wearing hats and using eye protection
Liberally apply sunblock to all exposed skin
Stay indoors or in shade and out of direct sunshine between the hours of 11h00 and 15h00.
Water shedding amid Heatwave
This comes at a time when Stage 2 water shedding has been implemented in some areas of Gauteng due to the heatwave’s increased strain on reservoirs. There are water interruptions in major metros like Tshwane, Ekurhuleni, and Johannesburg. Rand Water, a Gauteng water operator, announced that it would immediately begin enforcing limits, which would reduce flow by 30%, and would evaluate the situation every two weeks.
According to the report, water use has increased over the last two weeks to the point where overall reservoir storage has decreased from 58% to 38% capacity. According to the utility, the limitations would make it easier to guarantee that reservoir capacity is restored to 60%.
“The direct impact is extremely low levels within various reservoirs and towers. Customers are urgently requested to lower water usage to assist with sustaining already constrained systems,” Johannesburg Water said.
The Commando, Soweto, and Central systems, where the Eagle Nest, Glenvista, and Naturena reservoirs were also at critically low levels, as well as the systems in which Crosby, Brixton, and Hursthill systems were critically low to empty, were the worst affected systems.
“Pumps supplying Crown Gardens tower have been isolated due to low reservoir levels. South Hills tower is on bypass supply due to lower supply from Rand Water’s Meyer’s Hill reservoir. Customers in higher lying areas will experience low pressure/no water during this period,” the water utility said.
Customers were urged by Johannesburg Water to use less water, limiting use to necessities for people and their homes, since this would greatly speed the restoration of the damaged systems. The City of Tshwane also declared that stage 2 water restrictions had been implemented and that Rand Water had alerted the City of Joburg, and the City of Ekurhuleni.
“The water utility indicated that it had noted over the last two weeks that water consumption had increased significantly, resulting in a decline of their overall reservoir storage capacity from 52% to 38%. This necessitated Rand Water to implement, with immediate effect, stage 2 (30%) restrictions on several high consuming customer meters within each municipality, in order to reduce the current high water consumption,” the city said.
What does stage 2 water shedding mean?
Stage 2 water restrictions prohibit the filling or topping up of swimming pools or water features, irrigation or watering of gardens with a hosepipe or irrigation systems, washing of automobiles with a hosepipe, or using a hosepipe to clean driveways or patios.
The Gauteng department of health reported that the problems with the water supply were still present and continued to have a detrimental impact on the efficient delivery of healthcare services. Nevertheless, the hospitals Helen Joseph and Rahima Moosa Mother and Children’s continued to provide their services.
“The water supply challenge has put healthcare workers at the facilities under pressure as they try to mitigate against the current situation. The Gauteng department of health appeals to the community to bear with us as we navigate through this challenge and also reiterates the call for the public to use water sparingly,” the department said.
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