Published on 13 Jul 2012

Signs of the jet stream edging north. Brighter and warmer for the Olympics?

Having delivered nothing but tales of rain and flooding for the past few months, I’ve been looking forward to this day. I can finally see a possible end in sight to the continual deluge of very wet weather that’s been with us since April.

You’ve heard me talking about the jet stream a lot during recent months and how its position influences the weather that we experience.

Normally during the summer months, the jet stream generally sits to the north of the UK which steers wind and rain bearing areas of low pressure towards Iceland and Scandinavia.

However, so far this summer, the jet stream has been sitting to the south of the UK, with a conveyor belt of low pressure systems being thrust towards our shores bringing unseasonable and record-breaking amounts of rain.

Although not a summer month, April was the wettest on record. This was followed by a cool and wet start to May, with the wettest June on record thereafter. If that wasn’t enough, the beginning of July has been very wet as well.

With the ground sodden and little or no capacity to absorb any more water, flooding has been a serious issue. Each time it rains heavily, the risk of flooding increases very quickly as full rivers struggle to cope with even more water.

Each day, as well as looking at the weather forecast for the next five days, I also take a look at the general trend for the next few weeks.

Earlier this week, there were hints that the jet stream would head further north towards the end of the month. At first, I was doubtful as it had suggested the same a few weeks ago for early July – and, as we know, that certainly didn’t come to fruition.

However, for a few days in a row now a number of different weather computer models have been suggesting a trend for the average position of jet stream to drift northwards during the next two weeks.

It’ll be a gradual process, so don’t expect to open the curtains tomorrow and be greeted with blue skies and a heat wave.

What you will notice though during the next two weeks is that unsettled weather will tend to become increasingly confined to north western parts of the UK – Scotland, Northern Ireland and north west England.

Position of jet stream (solid area of blue) on 13th July to the south of the UK.

Forecast position of jet stream (solid area of blue) on 22nd July to the north of the UK.

Elsewhere, whilst there’ll still be some showers or the odd rainy day, it’ll be drier than of late with more in the way of sunshine.

Temperatures are likely to be higher with a trend towards the range of 19-25C – especially across England and Wales.

So, the start of the Olympics may not be a washout after all. But before you get too excited, there is one caveat that you need to take away with you. This is still two weeks away and things can change, so stay up to date by bookmarking my blog or following me on Twitter – @liamdutton

Jet stream images courtesy of NOAA

Tweets by @liamdutton

9 reader comments

  1. Nigel Colborn says:

    Liam, are the computer models based purely on past trends? And if they are, how reliable is that in light of decreasing stability in world weather?

    And if they’re not, how on earth is is possible to forecast accurately, with so many variables?

    1. Liam Dutton says:

      Hi Nigel. The weather computer models have an element of average climatology in them, but they take the weather now and using complicated equations to work out how that will evolve in the future.

      Whilst detailed forecasts can only usually be made 3-5 days in advance, it is often possible to get an idea of the general trends for a few weeks ahead.

  2. Kate says:

    Hey,I am looking out my Factor15 as we speak, Liam, and the barbie’s primed!

    Hope you’re not hallucinating :)

  3. Y.S. says:

    What would have happened if the jet stream was stuck where it is in the winter? Time to leave the country?

    1. Liam Dutton says:

      It probably would have been cold with a good chance of heavy snow!

  4. ashleyhr says:

    Derek Brockway, the chief forecaster at BBC Wales, has made a similar comment to Liam’s: http://www.bbc.co.uk/blogs/walesnature/2012/07/weekend_weather_a_mixed_bag.html
    “Sunday, 15 July is St. Swithin’s Day but don’t worry Sunday will be more dry than wet so hopefully it won’t rain for the next 40 days…
    There is more rain and drizzle on the way next week but later in the month there is a hint of better weather for the fourth week of July.
    This is not definite yet but if it comes off it would be great news for the Royal Welsh Show and the start of the Olympics so keep everything crossed!”.

    I can’t believe conditions won’t improve a little, for a time, before September. There was some small improvement in the horror years of 2007 (which I remember) and 1912. And a short burst of scorching heat as the 1948 Olympics began.

    Talking of the Brockway blog, BBC Wales posted a WRONG blog dated 11 June (now removed) – they repeated his 6 June blog. When I flagged this error on the BBC message board they appeared to take umbrage: http://www.bbc.co.uk/dna/mbpointsofview/NF1951574?thread=8359869 (message 5-10) and
    http://www.bbc.co.uk/dna/mbpointsofview/NF1951574?thread=8360419
    The situation escalated and thus my relations with the BBC message board moderators are at an all-time low.

    If my preceding paragraph is judged ‘off-topic’ (as it relates to the BBC) feel free to edit this posting! (However, I seem to recall Liam once worked for the BBC so it may be of interest…)

  5. Tea Betty says:

    I can feel my spirits rising already, thanks Liam. How much of an influence could the shift in Earth’s axis cause a change of jet stream position following on from the Japanese earthquakes last year. I remember reading somewhere that the Earth’s axis shifted a few centimetres. So, is the jet stream still in its usual “position” and is it the Earth “underneath” that has moved south?

    1. Liam Dutton says:

      Hi Sue,

      If the earth’s axis shifted enough then it would affect the distribution of heat received from the sun, which would in turn probably have an influence on the jet stream. However I doubt a change of a few centimetres would make a difference.

  6. Mammamakescakes says:

    If we have been having Scandinavia’s weather,whose weather do the Scandinavians have?…

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