9 Nov 2015

Five images showing rain and gales lie ahead

After a relatively settled start to autumn, with October warmer and drier than average across the UK, we’ve turned a corner into a road of rain and gales.

During the past month, the jet stream has largely been to the north of the UK, steering low pressure systems towards Iceland and Scandinavia and allowing high pressure to build over us.

However, the jet stream is now further south, sitting over the UK, putting us in the path of rain and gales.

Powerful jet stream over Atlantic

As the temperature contrast between the North Pole and equator increases, the jet stream is now powering up significantly.

In the next few days, it’ll be zipping across the Atlantic Ocean at around 170mph, 30,000ft up in the atmosphere – shown by the purple colour in the image below (via earth.nullschool.net).


The jet stream not only spawns low pressure systems, it also acts as an atmospheric superhighway, catapulting them towards us.

Long chain of weather fronts

The Met Office chart below shows weather fronts trailing south westwards from the UK for hundreds of miles.


These weather fronts show that there is a presence of moisture. As these weather fronts ripple and interact with the jet stream, deep areas of low pressure will form.

Cloud stretching thousands of miles

The satellite image below from Eumetsat shows a daisy chain of cloud that stretches all the way from the UK to Mexico.

If you look closely, you can see that the long band of cloud ripples, with two discernible bumps along it. These are the points where areas of low pressure are beginning to form.


Rainfall building up

With a series of low pressure systems expected in quick succession this week, rainfall amounts will build up quickly over western parts of the UK, where the hills and mountains enhance the rain.

On the graphic below from Tropical Tidbits, green indicates 0-25mm of rain, blue 25-50mm and pink 50-150mm.


Such large amounts of rain in north western parts of the UK will have the potential to cause some localised river flooding.

Risk of localised flooding

The flood risk graphic below from the Environment Agency shows that parts of northern England and north Wales are at a low risk of flooding during Monday and Tuesday.

flood_risk_EA_wpThe Scottish Environment Protection Agency says that there is a low risk of localised flooding across central and western Scotland too.

Later this week, it looks like the frequency and strength of low pressure systems arriving off the Atlantic will decrease. However, the generally unsettled theme will continue into next week too.

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

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