What is a cut-off low pressure system??

For those not familiar with cut-off low's: In short a cut-off low is a low pressure system that becomes 'cut-off', or severed, from the the main planetary circulation and spins off independently. Because it is no longer attached to the westerly pressure wave to the south, it loses all momentum and can just sit for days, or move very slowly before dissipating. Cut-off lows are associated with very strong atmospheric instability and powerful convection up drafts. They also bring a range of severe types of weather, including torrential rainfall, snow on the mountainous areas and violent winds. Cut-off lows are one of the main drivers of damaging floods in South Africa and can also trigger thunderstorms. A good example of the damage that a cut-off low can cause is the Laingsburg flood.