Jet stream at fault for soggy summer

Monday 11th Jun 2012 by theWeather Club

2012 has seen the wettest April with between two and a half to three times the amounts of rain we would actually expect. This was followed by a cold and wet first part of May and following a brief warm spell at the end of the month, the rains returned this time with fierce winds causing flooding in several parts of the country.

It turns out that our old friend the jet stream is the villain of the piece in regards to our soggy summer. The jet stream is a zone of fast moving winds, typically flowing around the globe at mid-latitudes around six miles above the earth's surface. A decent jet stream moving across the Atlantic can have wind speeds in excess of 150mph, and are powered by the huge temperature contrasts between the polar regions and the equator.

Sometimes, the jet stream will accelerate and when this happens, air is forced to move upwards through the atmosphere. This will tend to lower the atmospheric pressure at the earth's surface, and it is these areas of low pressure that bring us unsettled weather.

In a normal summer, the jet stream would typically pass to the northwest of Scotland, bringing rain to the northwest of Britain and drier weather to the southeast. This year, the jet stream has often got 'stuck' - more or less across southern England - which brings the low pressure systems straight across England and Wales. This stuck weather pattern has resulted all the rain and recently winds we have seen. And with a similar stuck jet stream pattern predicted for much of June, forecasters are predicting that we can expect these unsettled conditions to be with us for at least a couple more weeks.