Heavy rain set to bring flash flood risk

Following a fairly quiet start to September, with many of us enjoying some warmth and sunshine, the weather is going to turn very unsettled in the coming days.

Heavy rain is going to move northwards during Friday and Saturday as an area of low pressure drifts across the UK, with warnings issued by the Met Office.

The concern is that because the rain will pivot and become slow-moving over the Midlands as well as northern parts of England and Wales, there could be some flash flooding.

Having been sitting to the north of the UK during the past week, the jet stream is not only going to move to the south of the UK, but have a branch that breaks away from the main path of the jet stream and form a closed loop – know as a cut off low pressure system.

It’s called a cut off low because it effectively becomes detached from the jet stream and therefore gets stuck in the same place until it weakens – much like a spinning top falling off a moving conveyor belt.

These situations are notoriously difficult to get right because the subtle detail of where the low pressure sits for longest determines the places that see the most rainfall.

A few days ago, it looked like eastern parts of England were at greatest risk from torrential rain and flooding, but as we get closer to the time, the detail has changed.

Whilst most of the UK will see some heavy rain during Friday, Saturday and Sunday, it’s the Midlands, southern Scotland along with northern parts of England and Wales that are likely to be the wettest.

In these areas, the weather computer models are suggesting that 30-60mm of rain is possible, which is enough to cause flash flooding – particularly in more susceptible locations.

The latest three-day flood forecast from the Environment Agency mentions these areas, highlighting the potential for significant disruption from both surface water and river flooding, especially in urban areas and smaller rivers.

Don’t forget, you can get the latest forecast for your location on the Channel 4 Weather website. I’ll also be posting updates on Twitter – @liamdutton