Categories: Report

Cut-off low-pressure KZN weather with NO warning!

Synoptic chart cut-off low pressure system 31 May 2021

Cut-off low-pressure KZN weather with NO warning!

This currently performing cut-off low-pressure smashing KZN with wet weather, thunder and lightning – arrived with NO warning! Again! These things are lethal in that they are fast and unpredictable.

And, they really pack a punch.

Cut-off low systems

In 1990 we had a cut-off low fire up in the middle of an epic Sunday afternoon’s fishing session on the salmon reefs off Port Shepstone. A plume of spray came down the Umzimkulu Valley being charged on by a phenomenal offshore wind that blew umbrellas and deck chairs right off the beach and out to sea. It came in a literal flash and we were caught out there in a melee of zero visibility, crashing electric storm and gale force offshore wind.

The thing lasted about 30 minutes before it took off for Cape Town sinking FOUR ships along the way!

That was a mean one.

A cut-off low is when a little low-pressure anti-cyclone, is hemmed in at each side, by the continent of Africa, and two or more high pressure systems being forced in at us by a cyclonic gathering up north.

Or by Google…

A Cut–Off Low (COL) is a low pressure system that develops south of South Africa, stemming from the main westerly trough systems of cold air. As the COL develops, it deepens into a defined closed system that extends to the surface and which also becomes displaced equator-ward of the main westerly flow .

There are many more in-depth descriptions on the web that you can dive into.

Today

Today’s cut-off low-pressure system also arrived with zero warning. Although the system had been spotted lurking 300kms out a day or so ago. It moved in with lightning speed and this is what it does.

The two weather radar maps going ballistic at left and middle, are of the electric storm activity loitering just offshore. Right up and down the KZN coastline. The shot at right is the prediction as it moves into the continent and makes landfall.

Danger

This is very dangerous weather. Many casualties and deaths are recorded each year, because of these tempests. These are the conditions that cause the dreaded flash floods that KZN has long been infamous for. Rivers swell. Drainage can’t cope.

It keeps raining hard.

And eventually the naturally occurring and human built flood systems cannot cope anymore.

And the water takes over.