4 Jun 2015

Thunderstorms to bring flood risk on Friday

Whilst there’s not going to be a heatwave in the UK, as I mentioned in my blog a few days ago, the close proximity of hot and humid air will spark off some thunderstorms on Friday.

Temperatures on the near continent will widely reach 28-32C on Friday, and it’s the edge of this body of hot air that will inject enough energy into the atmosphere to form some thunderstorms.

At the moment, the area at greatest risk from catching thunderstorms will be eastern parts of England.


What’s causing the thunderstorms?

As the periphery of the body of hot air over the near continent grazes across eastern parts of England tomorrow, temperatures will reach 23-26C.

Heat is a source of energy for the weather – the fuel for the weather’s fire if you like. So this will provide a reservoir of potential energy in the atmosphere on Friday.

road_flooding_g_wpNext, a trigger is needed to release this energy, to make the air rise, cool and condense to form cumulonimbus clouds.

This will come in the form of convective heating, whereby the sun heats the ground, which in turn heats the air above it, causing it to rise upwards.

Also, there is a cold front moving in from the west, which will give the air an extra bit of a kick upwards, helping the potential energy to be released.

Warning of intense rain and surface water flooding

rain_warning_MO_wpThe result of the processes mentioned above will be scattered thunderstorms breaking out across eastern parts of England.

As is often the case with thunderstorms, some places will see a lot of rain, whilst others will see little, if anything at all.

However, the places that do see thunderstorms could see enough rain in a short space of time to cause localised surface water flooding on roads, which could potentially disrupt travel.

At the moment, the Met Office has a yellow “be aware” warning for thunderstorms across eastern parts of England tomorrow, with the Environment Agency highlighting the same area in its three-day flood risk forecast.

The chance of seeing thunderstorms in this part of the UK will be greatest in the morning and afternoon, with the risk diminishing into the early evening.

What about the rest of the UK?

The rest of the UK will have quite a mixed day on Friday, thanks to an area of low pressure moving just to the west of Scotland.

Scotland and Northern Ireland will see morning rain followed by sunshine and showers in the afternoon.

The rest of England (away from the east) and Wales have cloudier skies and a little rain for a time, before sunshine returns through the afternoon.

Looking further ahead, high pressure is going to dominate our weather through next week, so sunshine, little rain and pleasant warmth will be more prevalent.

Don’t forget, you can get the latest forecast on the Channel 4 Weather website. I also post regular updates on Twitter – @liamdutton

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