Durban - The South African Weather Services has issued a warning of disruptive rainfall over the central part of the country, including Gauteng and the North West.
SAWS has further issued a Yellow Level 4 warning of heavy rains and localised flooding over Gauteng, the North West and northern Free State.
"There is a greatly elevated risk of significant impacts in relation to localised flooding. The warning level for the last-mentioned area is therefore classified as Level 6 Orange," the forecaster said.
SAWS said further rainfall will therefore very quickly lead to overland run-off and localised flooding. Stream and river systems can also be expected to begin flowing strongly.
“The public are strongly encouraged to exercise extreme caution, whether in a vehicle or on foot, when crossing low-water bridges, to avoid being swept away by strong water flow," SAWS said in a statement.
It explained that a cut-off low, located in the mid to upper reaches of the atmosphere, lay over the western parts of southern Africa.
This system was likely to significantly influence the circulation over the southern African subcontinent, especially during the next 48 hours.
The forecaster added that widespread rainfall and thunderstorms are occurring in a broad band of tropically sourced air, migrating southwards through Zambia and Botswana.
This is expected to bring rain to parts of the country, more especially over the eastern half of the country. In particular, there is a moderate to high risk of localised flooding of a disruptive nature, especially over North-West, Gauteng, the Free State, as well as adjacent parts of Limpopo, Mpumalanga and the north-eastern sector of the Northern Cape.
SAWS has also warned of a cut-off upper air low pressure system that continues to dominate the circulation pattern over southern Africa, resulting in a broad band of rain, thunderstorms and associated cloud cover across most of the central and eastern parts of southern Africa.
"Much of the rainfall expected over North-West, Free State and Gauteng during today (Monday) and extending into tomorrow (Tuesday) is expected to be fairly significant, with at least 30-60 mm per day indicated for the aforementioned provinces.
"The rainfall output from the Unified Model (UM) numeric weather prediction (NWP) scheme suggests quite widespread, significant rainfall persisting over numerous South African provinces today and tomorrow," SAWS added.
SAWS warned that there had already been a substantial amount of rainfall in the North West and Free State in recent weeks, so the ground was quite saturated, lessening the infiltration capacity of the soil.
IOL