Throwback: The cut-off low that flooded Laingsburg in November 2022

A cut-off low brought heavy rain and severe thunderstorms to parts of the Western Cape in November 2022, flooding streets in Laingsburg and disrupting traffic along the N1.

Provincial traffic officers went to the N1 near Dwyka Bridge to assist motorists and warn drivers about dangerous conditions.

The flooding came as the South African Weather Service (SAWS) warned of further heavy rain and thunderstorms across parts of the country.

The weather system showed how a prolonged period of unsettled conditions can turn heavy downpours into a serious danger for communities and road users.

How the cut-off low brought heavy rain

According to SAWS, a slow-moving cut-off low sat over the South Atlantic, west of South Africa, while a surface trough extended across parts of the country towards the Western Cape.

The weather service identified strong atmospheric instability, moisture and wind shear behind the storms.

Thunderstorms developed around Sutherland and moved generally southwards.

SAWS issued a Yellow Level 2 warning for severe thunderstorms on 2 and 3 November 2022.

Highlighting the danger of heavy downpours, flash flooding, gusty winds and excessive lightning.

A town familiar with flood danger

Laingsburg has a painful history with cut-off lows. On 25 January 1981, heavy rain caused the Buffels River to burst its banks, flooding Laingsburg.

The 1981 disaster killed about 90 people and flooded more than half of the town’s homes and business premises.

The November 2022 event brought back memories of that tragedy, but the rainfall and damage were far less severe.

SAWS noted that the two events demonstrated how the same type of weather system could produce flooding under very different rainfall conditions.

What makes cut-off lows dangerous?

A cut-off low develops when a pocket of cold air and low pressure separates from the main westerly circulation in the upper atmosphere.

These systems can remain over or near the same region for an extended period.

Creating conditions that support heavy rain, severe thunderstorms, strong winds and sometimes snow.

When a cut-off low combines with abundant atmospheric moisture and unstable conditions, thunderstorms can develop and produce intense downpours.