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Posts tagged ‘Jet stream’

Why is it so stormy?

Even a weather girl doesn’t escape the wrath of the weather!  Just look at my poor tree –  totally bashed and squashed by the recent storms!

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A very sorry Sycamore!

 

But why is the weather so bad right now?

It seems that for the last 3 months we have been subjected to some pretty awful weather.  Whilst we can be quick to mention the term ‘global warming’ we must remember that wild, wet, windy weather it totally normal for this time of year, and extremes of weather are also possible at any time of the year.  Added to this the fact that previous winters have been extremely dry, cold and snowy – many of us have forgotten how the wet/mild/windy scenario is actually more our ‘usual’ winter set up.

However, December 2013 had double the average amount of rainfall and was one of the windiest months since Jan ’93, but at least on a brighter note has been the 7th mildest on record in the UK.   It’s the incessant nature of the storms which is surprising many of us.  This is partly due to our old friend the jet stream (very strong winds at about 30,000ft) which, depending on it’s position, can deliver us some really devilish weather.  This winter the jet stream is in the exact sweet spot for pounding us with storm after storm.  Plus the jet is particularly strong at the moment – with winds of up to 200mph – which means our storms our not only more violent, but that one storm is rapidly followed by another…and another.  Until the jet moves further to the north away from the UK we will continue with this storm fest.  And what would you rather, wet, windy and mild, or bitter and snowy?

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Is our weather linked to the bitterly cold weather in the US?

Not really.  The jet that is affecting us does indeed wrap all the way around the world, across the northern hemisphere (therefore including the US) but our storms are generally formed in the Northern Atlantic, hence the amount of moisture (rain!) in them too.  The ice storms and snow affecting Canada and the NE States have been due to an entirely different system.  A huge area of dense cold air that forms over the poles every winter (called a polar vortex because not only is it very cold, but winds travel around it at very high speed) has travelled further south than normal – clashing with warmer/moist air – and causing huge snow falls and freezing rain.  The reason this year is exceptional is because the polar vortex has been stronger than normal, ie. stronger winds and much colder temperatures, so when the polar vortex ‘split’ and was no longer contained in one area it rapidly descended south spreading it’s icy blast. Some places have seen 60cm of snow, and wind chill has meant temperatures have often felt like -51C/-60F!  If you had any exposed skin in those conditions you could get frostbite in a matter of minutes!

So, until the weather charts show the jet stream has been shoved to the north and we start to see high pressure dominating our weather (bringing with it it’s own problems like freezing fog, ice, frost, etc) then the sog is here to stay.

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Car crushed by the St Jude’s Day storm – London, 28th October 2013

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Jet stream = Wet stream?

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Folkestone West Beach (Mermaids) 17/07/11 1.30pm

Our June/July has been so poor in relation to April/May because of the unseasonally low position of the jet stream.  Ordinarily at this time of year it should be further north, but instead it is closer to the British Isles.  This band of intensely strong winds at high level can bring us unsettled weather when it lies close to us, but deflects the bad weather when it lies to the north of us.  In fact when it’s closer to Iceland we can enjoy long periods of the Azores High – which means beautiful sunny and dry summer months.  You might recall that the last 3 summers have been, well, fairly ‘disappointing’ and that’s because we were plagued by a shifty jet stream.    The jet being in the ‘wrong’ place is one of meteorology’s little mysteries – so far we aren’t entirely sure what causes it to change position so dramatically.   There are likely to be many factors, but I think the main one is the global sea temperature.  The top ten feet of our oceans contains more heat than our entire atmosphere.  This heat, or energy, affects the position of the jet stream and therefore affects our weather – all year round.  You may have heard of El Niño and La Niña warming and cooling patterns in the Southern Pacific Ocean – and I think these have played a huge part in how our summers have been a little gooey over the last few years.  And predicting what happens next…well, that’s all part of the fun folks. 


Saturday 16 July 2011.  Birling Gap

David Burr says, “Went rushing down to Birling Gap tonight to get some cloud shots. It was blowing a gale atop the cliffs so I had to use a very high asa setting as the tripod was vibrating, however I am pleased with the grainy result processed via HDR software. Hope you like it.”

Yes we do David!  At least this wild weather creates some stunning photo opportunities.

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