The Beast from the East is slain

Thursday 13 December 2012, 13:40

Paul Hudson Paul Hudson

The cold easterly which a large majority of computer models were predicting to develop this week has failed to materialise, with a much more unsettled weather pattern expected to return from the Atlantic during tomorrow.

Last week, 80% of the ECMWF model solutions wanted an easterly 'blocking' weather pattern, with the average of those solutions shown below.



Compare that with the atmosphere this morning (according to the GFS model), below.


Crucially the centre of gravity of the large area of high pressure, which should have been closer to Scandinavia, is further northeast than predicted.

This positional error means that Atlantic weather systems will now be able to make further progress eastwards across the UK.

It illustrates very well just how difficult it is sometimes to forecast general weather conditions a week ahead, even when there's high model confidence.

So after a temporary cold and dry spell, it now seems likely that the rest of December will be very unsettled, with showers or longer spells of rain, some of which will be heavy, with only very brief incursions of colder air.

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Comments

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  • rate this
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    Comment number 1.

    First again. Better say something clever! The beast from the east may not have made a full entry onto stage but someone or something has sucked all the warmth out of my socks.

    3/10 must try harder

  • rate this
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    Comment number 2.

    As per last topic (BftE) it is typical December weather . . . will probably stay mobile until later in Jan. Just what the ground needs just now - more rain !

    The forecast models do tend to over-state easterly PC in the winter. They also generally under-state the potential for cold air to remain stubbornly in situ once it is well established.

    I'll agree with #1 at 30% - but no reason to pull funding.

  • rate this
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    Comment number 3.

    2. chris wrote:

    "As per last topic (BftE) it is typical December weather "

    Good call chris and IIRC Boanta!

    I don't do forecasts, weather or climate. don't have the ability, just track actual observational data. Trust not too much rain and a little warmth will be appreciated.

  • rate this
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    Comment number 4.

    uh where's that big purple swirly thing heading?

  • rate this
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    Comment number 5.

    I have just come back from a walk on the Chesterfield canal at Anston. The canal was just starting to freeze over, it would have been nice for a months cold like this, so that we can ice skate on the canal like our dutch friends.

  • rate this
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    Comment number 6.

    Paul's explanation of the slain beast . . ."This positional error means that Atlantic weather systems will now be able to make further progress eastwards across the UK".

    There is a 'chicken and egg' issue here.

    The error on the models was the position of the jet. If it is firing northwards towards - say between greenland and iceland - or south east towards western med then that will ALLOW high pressure to build closer to the UK and intensify at this time of the year as cold dense air becomes established.

    However, examining GFS the forecast jet is out of north america, roughly at the same latitude as newfoundland and it is forecast to extend to the western approaches of the uk. This dynamic simply blows the high away - or further into russia etc. That configuration will NOT PERMIT the high to exist close enough to the UK. It is therefore very necessary to see what the pattern of the upper air is up wind. Our weather prevails from the west so that is normal. If the upper troughs/ridges align to divert the jet then the westerly can be 'turned off' allowing the european cold to determine our weather.

    Interestingly, the latest gfs indicates a low pressure in the southwest approaches around 21 Dec with the upper air pattern more meridional and consequently the forecast shows this low breaking away into france and the med allowing the high over russia to ridge quickly into the UK. (I mentioned this might happen in the last topic). But although the 850Mb (HPA) or approx 4500ft temperature is shown well below -5C by 22 Dec the model also suggests a new westerly jet emerging from newfoundland at that time - so in that case the forecast incursion from the east would be 2-3 days before collapsing ahead of the next westerly blow.

    Of course, the gfs to which I refer could be an outlier (8 days out is getting low confidence) and the succession of depressions may continue . . .

    It all depends on that westerly upper air pattern. All eventualities still possible but the milder atlantic type is most probable.

  • rate this
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    Comment number 7.

    Far, far, away things are getting interesting in ENSO 3.4 area.

    OLR has been increasing:

    http://www.bom.gov.au/climate/mjo/graphics/region.ts.dateline.gif

    SOI is falling:-

    http://www.bom.gov.au/climate/enso/monitoring/soi30.png

    Whilst both the above point in the direction of a potential La Nina, the trade winds, especially in the Eastern Pacific appear to be slowing and in some areas have turned, which could indicate the opposite.

    http://www.pmel.noaa.gov/cgi-tao/cover.cgi?P1=/tao/jsdisplay/plots/gif/sst_wind_anom_5day_ps32.gif&P2=900&P3=456&script=jsdisplay/scripts/biggif_startup.csh

    Either the warm pool is being recharged or it is about to come out to play? Time will tell, next few weeks will be interesting, still awaiting Dec updates of the ENSO model predictions

  • rate this
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    Comment number 8.

    "Whilst both the above point in the direction of a potential La Nina,"

    Is a load of cobblers, cut and paste from wrong post, one points El Nino and one points La Nina.

  • rate this
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    Comment number 9.

    could you please give that quality of computer model to my local bookie?

  • rate this
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    Comment number 10.

    Could have told you that last Sunday it was the Beast from The West that was blowing a gale shown in the Video here >>http://telly.com/768XC

  • rate this
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    Comment number 11.

    Lead story from the Second Order Draft: strong evidence for solar forcing beyond TSI now acknowledged by IPCC
    http://wattsupwiththat.com/2012/12/13/ipcc-ar5-draft-leaked-contains-game-changing-admission-of-enhanced-solar-forcing/

    For your entertainment.

  • rate this
    0

    Comment number 12.

    @ukpahonta

    Well this is going to be interesting................ I've brought popcorn................

    Still downloading it all, it's painfully slow, I wonder how many others are doing the same?

  • rate this
    0

    Comment number 13.

    oopsies...... we seem to have killed the server..............

  • rate this
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    Comment number 14.

    Well the evil secret team (UN plot to take over the world) allows anybody to sign up to be a reviewer. You then get to see the drafts.

    Leaking it sort of ruins the reviewing process really. Then again if they had restricted the reviewing process they would of been accused of a cover up, etc.

    Another side show hailed as THE game breaker? (how many of those now? losing count!).

  • rate this
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    Comment number 15.

    Finally, got them all, time to sit and digest now that I'm awake again.

    BTW There are now multiple download sources available at WUWT now.

  • rate this
    0

    Comment number 16.

    #15. - blunderbunny wrote:
    "Finally, got them all, time to sit and digest now that I'm awake again.

    BTW There are now multiple download sources available at WUWT now."

    I tried the alternative links but I get the option to download "setup.exe".

    Is that safe?

  • rate this
    0

    Comment number 17.

    "It illustrates very well just how difficult it is sometimes to forecast general weather conditions a week ahead, even when there's high model confidence."

    So despite "high model confidence", the models were wrong.
    Despite 80% of the models "wanting an easterly blocking weather pattern", the other 20% were correct.

    If models cannot reliably forecast one week ahead, how can they forecast 100 years ahead?

    In practice the MO cannot reliably forecast 24 hours ahead. In my location, they forecasted a cloudy sky overnight December 12/13 and it was clear, while they forecasted clear sky last night and it was mostly cloudy.

    But we don't know how accurate MO 5 day forecasts are, because they don't monitor them and publish accuracy statistics.

  • rate this
    0

    Comment number 18.

    @QV

    Not sure mate, I left my downloads chugging away (very slowly) on the original site with automatic restarts and continues and I went to sleep, face down in a soggy bowl of popcorn ;-)

    Personally, I wouldn't ever download a .exe unless I trusted the source. So, I'd say probably no. Unfortunately, I can't try and download them here in work to check it out for you, as they get a tad funny about that sort of thing here, but I can put my copies somewhere publically accessable when I get home from work.

  • rate this
    0

    Comment number 19.

    #18. - blunderbunny wrote:
    "Personally, I wouldn't ever download a .exe unless I trusted the source."

    Thanks.

    Same here, it may be safe, but I am suspicious of .exe files.
    It has the "TRUSTe" logo, but I am not familiar with that.
    I just don't know why it should be necessary to use "Optimum Installer", to download the data.
    I think I'll play safe.

  • rate this
    0

    Comment number 20.

    @QV

    No worries mate, I'll see what I can do to help when I get home.......

 

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Hello, I’m Paul Hudson, weather presenter and climate correspondent for BBC Look North in Yorkshire and Lincolnshire. 

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I worked as a forecaster with the Met Office for nearly 15 years locally and at the international unit, after graduating with first class honours in Geophysics and Planetary physics at the University of Newcastle upon Tyne in 1992. I then joined the BBC in October 2007, where I divide my time between forecasting and reporting on stories about climate change and its implications for people's everyday lives.

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