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Model Output Discussion - 10th Jan Onwards


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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

    The current situation is fascinating as we run into the second half of January. I am uncertain, however, whether this block hanging around is a good thing or not. There is a trend at 100hPa and 70hPa for the core of the vortex at that level to move away towards Siberia prior to the start of the major wave 1 warming currently set to peak around Jan 28. If the atlantic wins the battle in the next week then the trough can pass to the east and to my mind there is then a strong signal for heights to rise towards Greenland and winds to swing around to the NE.

     

    If the block holds and we dont get sufficient undercut then we might possibly run into initally a period of horrible stalling fronts bringing cold rain and then insufficient low pressure to our south to make anything interesting happen once the vortex starts to move away. On the other hand if it hangs around long enough then we might get proper retrogression as the vortex starts to shift. So much up for grabs.

     

    All much more interesting watching than anything from the last 4 weeks!

     

    Charts for today have me increasingly optimistic as we run towards February. With zonal winds decreasing, and the vortex showing these tentative signs of heading to the east I think the chances of an easterly developing somewhere at the outer edge of the models is growing...

     

    ... but I think we need the atlantic to win the current stand off if we are to cash in properly at the second attempt. I'm not convinced that full retrogression is likely. I hope I'm wrong.

    Edited by Catacol_Highlander
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    Posted
  • Location: Back in Edmonton Alberta(via Chelmsford, Exeter & Calgary)
  • Location: Back in Edmonton Alberta(via Chelmsford, Exeter & Calgary)

    Have noticed a big pattern change being shown for the western half of North America and the eastern Pacific...we see that limpet like ridge migrating north into Alaska and the arctic..this may in turn aid pressure to rise across Greenland and force the jet south..its a long way out still but is a similar pattern developing here that is akin to Dec 2010.

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    Posted
  • Location: South Essex
  • Location: South Essex

    Some good ensembles knocking around this morning. The better ones as you would expect raise heights over Greenland and I'm always very wary of GEFS when as in low res it can really overcook this (when not overdoing zonality).  

     

    Nonetheless a few colder options on the table again as the models seem to have reduced the atlantic push. Its probably still the odds on favourite, but no longer the dead cert it looked yesterday.

    Edited by Jason M
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    Posted
  • Location: Weardale 300m asl
  • Weather Preferences: Snow
  • Location: Weardale 300m asl

    Or, "we don't know"?

     

    Ish…  what is called Shannon Information theory has proved one of the most useful tools in modelling according to my techie husband - from Wiki…

     

    Information theory is a branch of applied mathematics, electrical engineering, and computer science involving the quantification of information. Information theory was developed by Claude E. Shannon to find fundamental limits on signal processing operations such as compressing data and on reliably storing and communicating data. Since its inception it has broadened to find applications in many other areas, including statistical inference, natural language processing, cryptography, neurobiology,[1] the evolution[2] and function[3] of molecular codes, model selection in ecology,[4] thermal physics,[5]quantum computing, plagiarism detection[6] and other forms of data analysis.[7] In Three Roads to Quantum Gravity cosmologist Lee Smolin provides a strong theoretical argument that, at the smallest scale, the fabric of space and time is nothing more than the exchange of discrete bits of information. If true, relativity and quantum theories are unified, and Shannon entropy could be considered physics' most basic law.

     

    http://en.wikipedia.org/wiki/Information_theory

     

    So it's "we don't know, but Shannon Entropy helps us decide how much or what we don't know…" which is a lot better than not knowing how much or what we don't know.

     

    Back to the wevver… Not a lot on the cards until February in my book, but maybe the tide will begin to turn next week.

    Edited by Iceni
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    Posted
  • Location: Swansea
  • Weather Preferences: snow, snow and more snow
  • Location: Swansea

    I listened to something on the BBC website recently that said that December was the 6th warmest since records began. January is running at similar levels so far.

     

    If you feel that this isn't worthy of being categorised as very mild, then I hope I never see a winter that you do feel worthy of this title Posted Image . Our climate is governed by relatively modest temperature swings during winter months so whilst a 2C swing might not be significant in some climate zones it sure is for us.

     

    Meanwhile back on topic.............

    the BBC forecaster said December 2013 was the 4th mildest since records began and as you quite rightly say, january is following a similar pattern at the present time.

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    Posted
  • Location: Wombwell, South Yorkshire (75m / 246ft ASL)
  • Weather Preferences: Summer Sunshine / Winter Snow
  • Location: Wombwell, South Yorkshire (75m / 246ft ASL)

    Correct me if I'm wrong, but that stat quoted by IF regarding MOGREPS support for an Easterly at the end of next week being circa. 50% caught my eye, because I am sure that is far more confidence than they had for last week's projected Easterly.

     

    I know that no model is infallible, but it is certainly encouraging that next week's potential Easterly has growing support.  The block to the NE is clearly going nowhere fast, and is far more stable and stronger than the models give it credit, and whilst the GFS 6z did not look that promising for the end of next week, I am fully expecting the 12z suite of runs to be far less progressive re the Atlantic.

     

    Every run seems to be slowly but surely correcting the patterns Westwards, and so with that in mind, I think particularly Northern and Eastern parts of the UK could be in for a snowy surprise as next week progresses.  I don't think we will achieve deep cold in the foreseeable, but as others have said, this is not required, even for a significant snow event in the middle of January, when the sun is still relatively weak.

     

    Interesting times ahead for sure, and who knows, the way some of the teleconnections are headed, February 2014 may be a month to remember for us long suffering coldies!  Posted Image

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    Posted
  • Location: NW LONDON
  • Weather Preferences: Sun, sleet, Snow
  • Location: NW LONDON

    GFS wants to attempt to link the Azores high with a high forming over Greenland. However, this is predicted to happen during the first part of February so things will chop and change a lot. There is also a deep low coming out of the eastern US which could scupper the link and ruin the block. This has been the story of the winter so far. Posted Image

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    Posted
  • Location: NR LOURDES SW FRANCE
  • Location: NR LOURDES SW FRANCE

    Hi Nick -Looking at all the NWP output over the last 24 hours we have more chance of a PM flow than a cool continental flow within T+168 perhaps with a bit of snow. Beyond that if zonality digs in again but further south, the cold can flood into central Europe opening the door to our east, with something more realistic to deliver

    how's the snow in the Pyrenees'

    Hi Russell

     

    Well anythings possible at the moment, I still feel positive that we'll get a westwards correction and the trough ejecting a shortwave se, then after that if you get the good start then the next low is more likely to deliver some snow as it heads se, the models now seem to be developing that newish route which is to bring some sort of continental flow after the second feature. In terms of the Pyrenees , well the festive period was good but then we had the foehn effect for a few days which meant it was a slushfest,the outlook now is better and a lot more snow is expected and colder temperatures.

     

    PS in terms of Phils post re the fax charts, nice to see the reverse occlusion, that's often a good sign!

    Edited by nick sussex
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    Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

    Yes that fax is a positive sign that the block is somewhat stronger.It should have been sinking by now lol-based on modeling a few days ago.

    Yes if this shift maintains then every chance the next low will track a touch further west -we can hope anyway.

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    Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

    Correct me if I'm wrong, but that stat quoted by IF regarding MOGREPS support for an Easterly at the end of next week being circa. 50% caught my eye, because I am sure that is far more confidence than they had for last week's projected Easterly.

     

    I know that no model is infallible, but it is certainly encouraging that next week's potential Easterly has growing support.  The block to the NE is clearly going nowhere fast, and is far more stable and stronger than the models give it credit, and whilst the GFS 6z did not look that promising for the end of next week, I am fully expecting the 12z suite of runs to be far less progressive re the Atlantic.

     

    Every run seems to be slowly but surely correcting the patterns Westwards, and so with that in mind, I think particularly Northern and Eastern parts of the UK could be in for a snowy surprise as next week progresses.  I don't think we will achieve deep cold in the foreseeable, but as others have said, this is not required, even for a significant snow event in the middle of January, when the sun is still relatively weak.

     

    Interesting times ahead for sure, and who knows, the way some of the teleconnections are headed, February 2014 may be a month to remember for us long suffering coldies!  Posted Image

     

    i would just like to add, "the forseeable" is at the moment, a very short period of time.....

    Edited by bobbydog
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    Posted
  • Location: NR LOURDES SW FRANCE
  • Location: NR LOURDES SW FRANCE

    Yes that fax is a positive sign that the block is somewhat stronger.It should have been sinking by now lol-based on modeling a few days ago.

    Yes if this shift maintains then every chance the next low will track a touch further west -we can hope anyway.

     

    I'm quite impressed by that block  not wanting to get pushed around by the angry PV over Canada! That reverse colluded front is a bloody nose for the upstream energy but its only the first round. I wonder whether the blocking will send for reinforcements from that Arctic lobe of higher pressure?

     

    These types of patterns are the most frustrating because of such a narrow margin between success and failure in terms of cold and snow potential.

    Edited by nick sussex
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    Posted
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl
  • Weather Preferences: Winter synoptics.Hot summers.
  • Location: Kirkburton, Huddersfield - 162.5mtrs asl

    Yes that fax is a positive sign that the block is somewhat stronger.It should have been sinking by now lol-based on modeling a few days ago.

    Yes if this shift maintains then every chance the next low will track a touch further west -we can hope anyway.

    I posted the same this morning see below but the early crew see what they want to see sometimesPosted Image

     

    Posted Today, 07:11

    This fax chart illustrates the formation of heights to our s/e

    http://www.meteociel...fax84s.gif?15-0

    Not three bad really

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    Posted
  • Location: North of Glasgow 105 msl
  • Location: North of Glasgow 105 msl

    Hi Russell

     

    Well anythings possible at the moment, I still feel positive that we'll get a westwards correction and the trough ejecting a shortwave se, then after that if you get the good start then the next low is more likely to deliver some snow as it heads se, the models now seem to be developing that newish route which is to bring some sort of continental flow after the second feature. In terms of the Pyrenees , well the festive period was good but then we had the foehn effect for a few days which meant it was a slushfest,the outlook now is better and a lot more snow is expected and colder temperatures.

     

    PS in terms of Phils post re the fax charts, nice to see the reverse occlusion, that's often a good sign!

    I don't quote much on this thread, but looking at all the NWP it appears an interesting but not exciting next 128hrs -the fax this am was still IMO too far east and tonight could be looking in the mirror! 

    however I think we are moving in the right direction... very slowly and a change will happen from the NW and later deeper cold from the east in mid Feb.

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    Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

    I'm quite impressed by that block  not wanting to get pushed around by the angry PV over Canada! That reverse colluded front is a bloody nose for the upstream energy but its only the first round. I wonder whether the blocking will send for reinforcements from that Arctic lobe of higher pressure?

     

    These types of patterns are the most frustrating because of such a narrow margin between success and failure in terms of cold and snow potential.

    Yes i was just flicking through the NH mean charts Nick just for an overall trend and the semi retreat of that Greenland vortex continues until about days 8/9

    http://www.meteociel.fr/modeles/ecmwf/runs/2014011600/EDH1-192.GIF?16-12

    http://modeles.meteociel.fr/modeles/gens/naefs/run/naefsnh-1-0-192.png?0

     

    before it's starts to reassert itself and wants to bring the Atlantic back over the Azores High.

    A long way out though and in the meantime this comparative lull in the jet is keeping us all wondering how much more that block can develop before that happens.

    Edited by phil nw.
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    Posted
  • Location: Solihull, WestMidlands, 121m asl -20 would be nice :-)
  • Weather Preferences: Cold and Snow -20 would be nice :)
  • Location: Solihull, WestMidlands, 121m asl -20 would be nice :-)

    Cooler run from GFS 06z here is the 8 day temperature anomlay

     

    Posted Image

     

    With very cold temps at present over Scandinavia atm, I'm sure the heights over Scandinavia will just get stronger and them pinks on your chart SS will be become more prominent

     

    These are some of the latest/live temperature mins from Sweden at present,

     

      Vajmat

      min

      -33.0°C

      Latnivaara

      min

      -32.3°C

      Kvikkjokk Arren.

      min

      -32.0°C

      Nedre soppero

      min

      -31.2°C

      Nainakka

      min

      -29.7°C

      Karesuando A

      min

      -28.8°C

      Gallivare

      min

      -28.0°C

      Nattavaara

      min

      -27.7°C

      Rensjoen

      min

      -27.4°C

     

    Posted Imagehttp://www.snow-forecast.com/maps/dynamic/scand?over=pressure&type=lapse

    Edited by Dancerwithwings
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    Posted
  • Location: Newbury, Berkshire. 107m ASL.
  • Weather Preferences: Summer:sunny, some Thunder,Winter:cold & snowy spells,Other:transitional
  • Location: Newbury, Berkshire. 107m ASL.

    Or, "we don't know"?

     

    I.e. the Model suites don't know or us mere mortals can't interpret them. Perhaps the NWP outputs couldn't care less for us good folk on the ground in the UK. Trying to predict the climate/weather when the weather is ever-changing makes model watching even more fascinating than usual. What I don't understand (this is not directed specifically at the poster) is the necessity for pointing the blame at the models themselves NOT bringing us what we want, there is a requirement for us humans to attempt to understand how, why and what timeframe the NWP outputs aren't getting the picture. Right now, due to Ms "Shannon" wotsaface, the scatter of surface solutions would be at a very early timescale, much earlier on than would be normal in less chaotic situations. Posted Image

     

    Back to watching what the models have in store for us but always remembering the background signals are mixed (will the PV shift to somewhere more pleasant for coldies, will it split before January is out?) and have been for many a day. Hopefully model consensus on the impending Easterly potential will be resolved over the coming 24 to 48 hours. EYES DOWN. Posted Image

    Edited by gottolovethisweather
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    Posted
  • Location: Newbury, Berkshire. 107m ASL.
  • Weather Preferences: Summer:sunny, some Thunder,Winter:cold & snowy spells,Other:transitional
  • Location: Newbury, Berkshire. 107m ASL.

    Just to add to my post above, if you check Phil NW's wonderful post earlier, the timescale at which the model suites struggle, at least in part due to "Shannon" wotsaface may be even sooner than I considered previously.

     

    http://forum.netweather.tv/topic/79043-model-output-discussion-10th-jan-onwards/?p=2897321

     

    By viewing the Fax Charts provided Posted Image and further to Phil's analysis, there may be a pleasant surprise change within t+96 hours or thereabouts from what was forecast only six hours earlier on the GFS or 12 hours previous on other outputs. Not forgetting these Faxes are plotted surface charts and it's what is above us at H500 level or higher that eventually accounts for our weather at the surface. Posted Image

    Edited by gottolovethisweather
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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    Just to add to my post above, if you check Phil NW's wonderful post earlier, the timescale at which the model suites struggle, at least in part due to "Shannon" wotsaface may be even sooner than I considered previously.

     

    http://forum.netweather.tv/topic/79043-model-output-discussion-10th-jan-onwards/?p=2897321

     

    By viewing the Fax Charts provided Posted Image and further to Phil's analysis, there may be a pleasant surprise change within t+96 hours or thereabouts from what was forecast only six hours earlier on the GFS or 12 hours previous on other outputs. Not forgetting these Faxes are plotted surface charts and it's what is above us at H500 level or higher that eventually accounts for our weather at the surface. Posted Image

     

    one very minor crib, only the actual is from a plotted chart the rest are the man/machine mix of forecast outputs.

    But as you suggest and phils' post indicated Exeter have shifted the frontal zone a shade west in their latest Fax output although this is not yet reflected in any forecast output that I have seen.

    Very interesting and your comment re the 500mb level is a fascinating area to watch.

    Edited by johnholmes
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    Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

    Have noticed a big pattern change being shown for the western half of North America and the eastern Pacific...we see that limpet like ridge migrating north into Alaska and the arctic..this may in turn aid pressure to rise across Greenland and force the jet south..its a long way out still but is a similar pattern developing here that is akin to Dec 2010.

     

    Yep - agree, though a northerly of the 2010 magnitude would be a lot to ask for. But it is beginning to come together. As said before - zonal winds falling, vortex currently squeezed and then set to be bashed, (hopefully) main centre of stressed vortex heading east. The weather makes fools of us all often, but so far the NetW forecast put together by Chio is on track for the most part.

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    Posted
  • Location: Newbury, Berkshire. 107m ASL.
  • Weather Preferences: Summer:sunny, some Thunder,Winter:cold & snowy spells,Other:transitional
  • Location: Newbury, Berkshire. 107m ASL.

    one very minor crib, only the actual is from a plotted chart the rest are the man/machine mix of forecast outputs.

    But as you suggest and phils' post indicated Exeter have shifted the frontal zone a shade west in their latest Fax output although this is not yet reflected in any forecast output that I have seen.

    Very interesting and your comment re the 500mb level is a fascinating area to watch.

     

    Thanks JH, good to know I'm learning day by day. Yes, come to think of it, you have often stated that the Faxes are with added human input, I kind of didn't make that clear. Posted Image  Anyway, this is our starting point guys regarding the Jetstream and H500 profiles.

     

    Current NH Jetstream position and flow.

     

    post-7183-0-80851100-1389886986_thumb.pn

     

    Current H500 profile.

     

    post-7183-0-85852100-1389886971_thumb.pn

     

    The coldest T850s are out to our NE and NNE right now and today is nearer average at the surface hence the greener blue H500s over the UK. Just where we go from here will be revealed over the coming hours but I advise folk focus on the timescales aforementioned and only take latter output as hints as to where the trend might lead deeper into final third of January.

    Edited by gottolovethisweather
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