A steep upper air trough will result in scattered to widespread showers and thundershowers over the central and eastern parts of the country over the next 2 to 3 days.
Due to significant amounts of rainfall expected from this system, localised flooding is possible in places.
A steep upper air trough associated with a weak cold front will position itself over the western parts of the country by tomorrow, 22 March 2018. Cloudy and cold conditions together with an abundant influx of moisture will be brought about by a strong high pressure system, ridging behind the cold front, affecting the eastern coastline and adjacent interior of South Africa on Thursday.
Similarly, cloudy and cold conditions will spread to the north-eastern parts of the country on Friday.
In addition, the upper air trough is expected to interact with tropically-sourced air from northern Botswana, resulting in a high likelihood of heavy rainfall over parts of eastern South Africa where it will be cool. Due the prolonged duration of this system and rainfall amounts exceeding 50mm in places over a large spatial coverage, ground infiltration capacity can be surpassed, leading to overland runoff and therefore a risk of incidents of localised flooding.
We advise the public to take note of the following alerts issued by the South African Weather Service (SAWS):
- Warning: Heavy rain leading to localised flooding is expected in the eastern parts of the Free State, in places in North-West, Gauteng, Highveld areas of Mpumalanga and in places in Kwa-Zulu Natal, except in the north east of last-mentioned region. Heavy rain is expected to persist in Gauteng, the western parts of Mpumalanga, eastern parts of North-West as well as the eastern parts of the Free State on Friday, 23rd March.
- Watch: Severe thunderstorms are expected over the central and south eastern parts of the Northern Cape on Thursday, 22 March.
This weather system is expected to continue on Friday over the eastern parts of the country, where cloudy cold and wet conditions will prevail. Overall cloud cover will however begin to thin out and dissipate during Sunday the 24th of March, when it will remain predominantly cold. Gradual recovery of daytime temperatures can be expected during the course of next week.
Precautions
- We advise the public to take heed of the following precautionary measures when encountering flooding…
- If possible stay indoors and off the roads, avoid crossing rivers and swollen streams where water is above your ankles.
- If trapped in a flooding situation whilst in a vehicle, rather abandon it and climb to higher ground.
- In buildings, move valuables to a safe place above the expected flood level.
- Switch off electricity at the supply point to the building.
- In rural areas protect/relocate animals to a safe place on higher ground.
- Abandon your home immediately if evacuation is recommended by duly authorised officials, before access is cut off by flood water.
- NEVER drive on a road covered or obscured by water. You do not know how deep it is or if the road has been washed away.
- If the vehicle stalls, leave it immediately and seek higher ground.
- Be especially cautious at night when it is difficult to identify flood hazards.
- Listen to the radio or TV for warnings and obey the instructions from Disaster Management officials.
The South African Weather Service will continue to monitor any further developments relating to this weather system and will issue subsequent updates as required. Furthermore, the public are urged to regularly follow weather forecasts on television and radio.
Updated information can also be found at www.weathersa.co.za as well as via the SA Weather Service Twitter account @SAWeatherServic
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