22 Sep 2023 | 10:30 AM UTC
South Africa, Lesotho: Adverse weather forecast across much of both countries through at least Sept. 26
Severe weather forecast across parts of South Africa and Lesotho through at least Sept. 26. Flooding and associated disruptions possible.
Event
Severe weather is forecast across much of South Africa and Lesotho through at least Sept. 26. The South African Weather Service (SAWS) has issued a media release warning that an intense cut-off low is expected to affect much of the country Sept. 23-26. The storm system is expected to develop off the west coast of South Africa late Sept. 23, bringing light rain to southwestern coastal regions and isolated thunderstorms to western and west-central interior parts of the country. The system is expected to intensify Sept. 24 as it moves over western regions, bringing heavy rainfall and thunderstorms to parts of Eastern Cape, southern Free State, Northern Cape, and Western Cape provinces. The system is expected to move over the southern coast Sept. 25, bringing further showers and storms to southern Eastern and Western Cape provinces. Rainfall totals of 6-10 cm (2.4-3.9 inches) are expected in coastal towns and mountainous areas along the Garden Route Sept. 25. Strong winds will generate rough sea conditions along the southwestern and southern coastline. Strong winds are also expected over inland areas of central and eastern South Africa Sept. 24-25. Cold temperatures are likely over southern and western regions, with snowfall possible in elevated areas of northeastern Eastern Cape Province and Lesotho Sept. 25. Conversely, hot temperatures are likely to persist over northern and northeastern regions.
As of Sept. 22, the only warnings in place over South Africa are yellow level 1 (out of 10) severe thunderstorm warnings over parts of southern Limpopo and northern Mpumalanga provinces; however, weather advisories are in place for cold temperatures, possible flooding, and rough seas over parts of the south and west and authorities will likely issue further warnings as the system progresses over the coming days.
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly areas, especially where the soil has become saturated by heavy rainfall.
Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.
Precipitation could fall as snow in the higher elevations over the coming days. Wind gusts could cause blowing and drifting snow; decreased visibility is likely in mountainous areas.
Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.
Severe weather could also trigger flight delays and cancellations at airports across the affected area. Authorities may temporarily suspend port operations along the southwestern and southern coastlines if strong winds trigger hazardous sea conditions, impacting freight and passenger maritime traffic. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation.
Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.
Advice
Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.
