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Model Output Discussion 01/09/17


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

    Just to explain a bit more re the ECM/GFS differences.

    If you look at the ECM 00hrs for T96 and T120hrs.

    You can see the one low in the northern jet stream and the shortwave running ne from the southern, the ECM phases these into one deeper low, this is what you want to see:

    ECH1-96.thumb.gif.1ae4eae1f6a383aa3b2cf8e3c7f39ff4.gif

    ECH1-120.thumb.gif.5d4c7715dda566e325d759ec238bc4e4.gif

    Now if you look at the GFS 06hrs  T90 and T114hrs charts, you have the shortwave in the southern stream but see what happens at T114hrs:

    gfsnh-0-90.thumb.png.478bc8569336f7177a902287c88ae185.png

    gfsnh-0-114.thumb.png.f1d9ef4fd1be038f2b994cd2ab003774.png

     

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    Good morning Gang ,Its great to be back reading the Posts on Net weather .My Wife passed away two weeks ago ,she had Pancreatic Cancer which spread ,but enjoyed life since she was diagnosed back in Ap

    Good afternoon gang ,its nice to be back reading all the posts again ,although i have been lurking .(Thanks to all friends on here for my much appreciated messages over the loss of my wife recently ,T

    So sorry to hear that mate Dont want to clutter up this thread but im sure i speak for everyone in wishing you the very best and hope you will be ok.

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    Posted
  • Location: st albans
  • Location: st albans

    Eps clusters don’t offer great support for a sustained cold spell that might bring countrywide snowfall as there isn’t what I would call consistency from run to run. 

    Whilst the mean and anomolies look good I am still to be won over on how week 2 might progress from a coldie perspective.

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    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
    5 minutes ago, bluearmy said:

    Eps clusters don’t offer great support for a sustained cold spell that might bring countrywide snowfall as there isn’t what I would call consistency from run to run. 

    Whilst the mean and anomolies look good I am still to be won over on how week 2 might progress from a coldie perspective.

    Yes bit of a lottery from D10 onwards. But I was drawn to the D8 cluster chart. That's an extremely strong signal for a Euro trough, and it would be a pretty huge modelling error if there isn't some sort of trough when D0 arrives:

    ec-ens_nat_z500scenarios_2017112200_192.

    Pretty consistent for Europe with yesterday's clusters for the same time:

    ec-ens_nat_z500scenarios_2017112112_204.  ec-ens_nat_z500scenarios_2017112100_216.

    Good chance of a flow between N and E by T192, then - but will it draw in enough cold for snow? 

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    Posted
  • Location: Strood, Kent, 19 feet above sea level
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Strood, Kent, 19 feet above sea level

    The EPS clusters at 216 are encouraging all pointing to very blocked pattern across the Atlantic. Nothing mild at this time frame at all.

    216.thumb.png.9672fb23b4033d50dd66eedee611663e.png

    Moving onto 324 we start to see much less confidence with a real variety of solutions, though there are still some ensembles keeping things cold and blocked, one cluster turns things wet and the other dry, so still very much to play for.

    324.thumb.png.d283f275b14f7ef0698b408b00e6eaa2.png

    Lets hope the GFS can resolve the shortwave issue tonight and we get back to cross model agreement. We don't want to see the UKMO/ECM suddenly backing off.

    Edited by Daniel Smith
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    Posted
  • Location: st albans
  • Location: st albans
    8 minutes ago, Man With Beard said:

    Yes bit of a lottery from D10 onwards. But I was drawn to the D8 cluster chart. That's an extremely strong signal for a Euro trough, and it would be a pretty huge modelling error if there isn't some sort of trough when D0 arrives:

    ec-ens_nat_z500scenarios_2017112200_192.

    Pretty consistent for Europe with yesterday's clusters for the same time:

    ec-ens_nat_z500scenarios_2017112112_204.  ec-ens_nat_z500scenarios_2017112100_216.

    Good chance of a flow between N and E by T192, then - but will it draw in enough cold for snow? 

    I’m always wary of Euro low heights MWB - the form horse is generally for them to be downgraded and for the upper ridge to force them a little further from the uk. Whilst I agree the signal is very strong, exactly where those low heights end up (they clearly won’t verfiy on such a large scale as those maps indicate) and how unstable the upper airflow is across the uk remains the question. The earlier spread posted showed the preferred area to be central France day 7 and then curving around anti clockwise to be Czech Republic day 10. 

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    Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
    18 minutes ago, Man With Beard said:

    Yes bit of a lottery from D10 onwards. But I was drawn to the D8 cluster chart. That's an extremely strong signal for a Euro trough, and it would be a pretty huge modelling error if there isn't some sort of trough when D0 arrives:

    ec-ens_nat_z500scenarios_2017112200_192.

    Pretty consistent for Europe with yesterday's clusters for the same time:

    ec-ens_nat_z500scenarios_2017112112_204.  ec-ens_nat_z500scenarios_2017112100_216.

    Good chance of a flow between N and E by T192, then - but will it draw in enough cold for snow? 

    That impressive beard should keep you warm:D

    I'm sticking with the king /daddy of the models, the ECM...I see plenty to be encouraged about as things stand!

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    This platform is hilarious. Just days ago the GFS was completely off just a couple of days out while the ECM/UKMO were more on the money. This time the ECM/UKMO are showing the cold and people are fully backing the GFS for some reason. One things for sure, I'd rather have the ECM/UKMO showing cold and the GFS showing mild than the other way round. Plenty to be optimistic about imo. GFS has been an embarrassment to its programmers the last couple of winters. Hopefully a similar situation here! 

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    Posted
  • Location: New Ash green 150M / 500 FT
  • Location: New Ash green 150M / 500 FT

    So a pidgeon step from the 06z but not enough to satisfy a full morph over to the euros

    remember we are not to worried if there 'isnt' a major block through Greenland-

    just enough of a wedge to swerve the jet back SE when the atlantic throws a bit more energy east-

    GFS PTB 17 is a good example

    http://www.meteociel.fr/modeles/gefs_cartes.php?code=17&ech=6&carte=1&mode=0

     

    also NAVGEM 06z which is american goes close to the euros

    remember its not the initial height of the 552 line but the stability of the wedge into the pole that steers the jet away from the UK..

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    Posted
  • Location: st albans
  • Location: st albans
    18 minutes ago, ZK099 said:

    This platform is hilarious. Just days ago the GFS was completely off just a couple of days out while the ECM/UKMO were more on the money. This time the ECM/UKMO are showing the cold and people are fully backing the GFS for some reason. One things for sure, I'd rather have the ECM/UKMO showing cold and the GFS showing mild than the other way round. Plenty to be optimistic about imo. GFS has been an embarrassment to its programmers the last couple of winters. Hopefully a similar situation here! 

    They are ?

    If the GFS really was an embarrassment to its programmers then we would look at it as we do NAVGEM or one of the other less known models. It’s verification isn’t so far behind the other models but granted it isn’t generally quite as good. 

    if we had MOGREPS to look at then we would probably look less at gfs but we don’t so we do !! 

    Gfs has it’s bias’ and we should look at the output knowing this and making interpretations/adjustments accordingly.

    Edited by bluearmy
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    Posted
  • Location: Strood, Kent, 19 feet above sea level
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Strood, Kent, 19 feet above sea level
    5 minutes ago, frosty ground said:

    graphe4_1000___-21.9811320755_64.4939271

    Pressure over Iceland.......

    Nice and clear in the extended then..

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    13 minutes ago, bluearmy said:

    They are ?

    If the GFS really was an embarrassment to its programmers then we would look at it as we do NAVGEM or one of the other less known models. It’s verification isn’t so far behind the other models but granted it isn’t generally quite as good. 

    if we had MOGREPS to look at then we would probably look less at gfs but we don’t so we do !! 

    Gfs has it’s bias’ and we should look at the output knowing this and making interpretations/adjustments accordingly.

    Agreed, but in winter in particular it performs quite poorly compared to Euros. Not sure about other seasons but in my experience the GFS regularly gets it wrong in winter. 

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    Posted
  • Location: Strood, Kent, 19 feet above sea level
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Strood, Kent, 19 feet above sea level

    The GFS isn't "that" different from the other models. But one minor change in the way it handles the shortwave energy around Greenland has big impacts further down the line. A very small change may not make a big impact hemispherically but it can do for us down on the ground, in this tiny corner of the world.

    The GFS IS one of the top performing models, I think it seems more "mental" because it runs 4 times a day and goes out further than the other models, if it ran twice a day and only went to 240 like the ECM then we would probably see more consistency, but running 4 times a day allows all the flip flops and minor changes to become very much apparent. 

    The ECM has it's flaws too, often going insane on the amplification only to massively water it down in subsequent runs, "that ECM" comes to mind.

    EDIT: The posts I was replying to have been removed so now I just look like a madman 

    Edited by Daniel Smith
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    Posted
  • Location: Purley, Surrey
  • Location: Purley, Surrey

    TWO refugee here! Didn't think the outlook was that severe for the servers to go down!

    Disappointing 06z run, hopefully just a wobble

    Edited by Jan 87
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    Posted
  • Location: Wendover, Buckinghamshire
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Wendover, Buckinghamshire

    For those who dismiss the GFS here are some statistics of the correlation of geopotential height at 500hpa at T144 over the North Atlantic. In recent times the GFS is a tiny bit worse then the UKMO and ECM.

    I want cold and snow as much as everyone else but until we get cross model agreement we must proceed with caution. We can't dismiss a model when it shows what we don't like!

    cor_day6_HGT_P500_G2NHX.png

    Edited by Quicksilver1989
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    Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL
    3 minutes ago, Quicksilver1989 said:

    For those who dismiss the GFS here are some statistics of the correlation of geopotential height at 500hpa at T144 over the North Atlantic. In recent times the GFS is a tiny bit worse then the UKMO and ECM.

    I want cold and snow as much as everyone else but until we get cross model agreement we must proceed with caution. We can't dismiss a model when it shows what we don't like!
     

    Have to agree with that. But I think we should see what the 12z show, if the GFS still isn't budging, at that point I would probably be inclined to take stock! 

    The UKMO from memory has had to backdown on occasion last year in similar situation, I'm by no means sold by it's output yet!

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    Posted
  • Location: Tyrone
  • Location: Tyrone
    9 minutes ago, Quicksilver1989 said:

    For those who dismiss the GFS here are some statistics of the correlation of geopotential height at 500hpa at T144 over the North Atlantic. In recent times the GFS is a tiny bit worse then the UKMO and ECM.

    I want cold and snow as much as everyone else but until we get cross model agreement we must proceed with caution. We can't dismiss a model when it shows what we don't like!

    cor_day6_HGT_P500_G2NHX.png

    Yep and that tiny bit of worst difference makes a big difference down the line.

    Edited by booferking
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    Posted
  • Location: Wendover, Buckinghamshire
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Wendover, Buckinghamshire
    3 minutes ago, booferking said:

    Yep and that tiny bit of difference makes a big difference down the line.

    Problem is the block is already under pressure at T144 on the GFS 06Z, and leads to it sinking. At T144 GFS has a correlation of 0.81 and UKMO 0.84, it will only make a very small difference in later frames because the butterfly effect is random and affects all models. In the most recent runs GFS has actually verified a tiny bit better then UKMO.

    For what its worth I'm still optimistic of some sustained northerlies but the GFS shouldn't be dismissed.

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    Posted
  • Location: New Ash green 150M / 500 FT
  • Location: New Ash green 150M / 500 FT

    Thats the NH - its almost pointless looking at those stats as the impacts that we are looking at are under a microscope in 1 spot...

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    Posted
  • Location: Wendover, Buckinghamshire
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Wendover, Buckinghamshire
    10 minutes ago, Steve Murr said:

    Thats the NH - its almost pointless looking at those stats as the impacts that we are looking at are under a microscope in 1 spot...

    My mistake, but shouldn't that same general pattern appear everywhere?. For example the PNA region the same themes appear..., also in the tropics, what would make our region different? (genuine question :))

    cor_day6_HGT_P1000_G2PNA.png

    cor_day6_HGT_P1000_G2TRO.png

    Edited by Quicksilver1989
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    Posted
  • Location: New Ash green 150M / 500 FT
  • Location: New Ash green 150M / 500 FT

    In the olden days there was a plot for pole / North atlantic was well

    06z & 18z was woeful on these - hence my distain for these runs...

    They are not available any more :(

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    Posted
  • Location: Netherlands close to the coast
  • Location: Netherlands close to the coast
    13 minutes ago, Quicksilver1989 said:

    My mistake, but shouldn't that same general pattern appear everywhere?. For example the PNA region the same themes appear..., also in the tropics, what would make our region different? (genuine question :))

    cor_day6_HGT_P1000_G2PNA.png

    cor_day6_HGT_P1000_G2TRO.png

     

    You can compare model verification here, you can look at different regions and parameters 

    http://apps.ecmwf.int/wmolcdnv/

     

     

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    Posted
  • Location: Wendover, Buckinghamshire
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Wendover, Buckinghamshire
    Just now, Steve Murr said:

    In the olden days there was a plot for pole / North atlantic was well

    06z & 18z was woeful on these - hence my distain for these runs...

    They are not available any more :(

    Ah yeah that was the other thing I was curious about was the time of the day which the model is run.

    For what its worth I've looked at reanalysis models for my PhD, I know things like how they are put together but the performance in specific regions is something I'm less familiar with but the smaller amount of data assimilation around the Greenland area makes forecasting variations there a bit harder.

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    Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
    1 minute ago, Quicksilver1989 said:

    Ah yeah that was the other thing I was curious about was the time of the day which the model is run.

    For what its worth I've looked at reanalysis models for my PhD, I know things like how they are put together but the performance in specific regions is something I'm less familiar with but the smaller amount of data assimilation around the Greenland area makes forecasting variations there a bit harder.

    But have you analysed the annual Yuletide shortage of balloon data, QS?:D

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