jet stream

Dana weather systems are formed when an area of low pressure gets "cut off" from the main flow of the jet stream.

The jet stream, which is responsible for driving low pressure systems and weather fronts towards us from the Atlantic, is currently strengthening but remaining to the north of the UK.

In September, temperatures continued to be warmer than expected as the sub-tropical jet stream's more northerly position allowed a warmer southerly flow of air over Japan.

A jet stream is a high altitude current of air that occurs when warmer air from the south meets cooler air from the north, and is responsible for much of the UK's climate.

There is some evidence that the effects of climate change on the jet stream - a band of fast-flowing winds high up in the atmosphere - may make this 'stalling' phenomenon more common.