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metaltron

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    Model output discussion - Post SSW - Will it turn cold?

    in Forecast Model Discussion

    Posted

    1 minute ago, Mucka said:

    I'm not getting the high is too far North comments at all.

    It is over Iceland, I guess that means a Greenland high is useless for cold then?

    There are many ways we can have the high at that latitude and still maintain the cold into FI and I will be amazed if some of those do not pop up in the ensembles as evidence of this.

    And at what point is it too high lat? When it is dragging in -15 uppers and giving widespread snow for a few days or in deep FI when there is a breakdown?

     

    When the high is dragging in the -15 uppers, of course. The isobars are not close enough together because the high is too far north - it's a disgrace really!

    Model output discussion - Post SSW - Will it turn cold?

    in Forecast Model Discussion

    Posted

    7 minutes ago, Quicksilver1989 said:

    A glance through the 18z ensembles at T102 suggests that support is increasing rapidly for the development of an intense Scandi high. Phase 1 of getting things set up to our NE looks like its going to succeed. 

    Next step is to not avoid any awkward shortwaves forming in the cold air to our east like a few other members have mentioned. That stopped the core of the cold air in February 2012 hitting our shores. However with an Azores low instead of a high this time we have less to worry about.
    image.thumb.png.0622011d11cb858d65b5d4a4e498921d.png image.thumb.png.e7e4bfba3a666f266e9400601436b93e.png

    Still cautious but belief is increasing this may come off.

    Being born in the late 80's I cannot remember a truly cold easterly hitting us. That has to be the best run of the internet era.

    To my eye it doesn't look like the shortwaves are the issue, rather that the high is too far north and the orientation is wrong. The high being too far north is my biggest worry looking at the GEFS ensembles. If we can get the high further south (ie over central Scandi, not the Azores!) and then retrogress it towards Greenland then I think it will drag the cold pool with it.

    • Like 2

    Model output discussion - Post SSW - Will it turn cold?

    in Forecast Model Discussion

    Posted

    3 minutes ago, Nick F said:

    None of the other medium range model output has developed a deep low over the Ukraine like GFS does, such as the EC and GEM, just the usual Genoa low, so not sure I buy this low development from GFS. Anyway, the brutal cold gets to us in the end.

    For once, it's Europe getting brutal cold and not the eastern U.S. who look to continue to torch.

    GFSOPNH18_189_2.thumb.png.4155dbd691d4754c519763618e27374a.png

    It looks like the Genoa low got caught up in the easterly, which created that low.

    Model output discussion - proper cold spell inbound?

    in Forecast Model Discussion

    Posted

    Well after this hit and run easterly, with a high pressure cell flying over Scandinavia before being sucked into the Russian high, I'm struggling to see much to be positive about in the EC ensembles (apart from the generally below average picture) - not a single ensemble run today, from the ECM, has managed to deliver maximum daily temperatures of -5 for de Bilt - you'd imagine if there was a serious chance of an easterly, then at least one run would manage it in a 15 day period.

     

     tempresult_dor4.gif

    Model output discussion - into 2018

    in Forecast Model Discussion

    Posted

    My impression has been that the UKMO has been awful this winter, especially at T144, but hopefully its right today! Anybody remember the Mid-Atlantic cut off low drama last January when the UKMO trumped the GFS/ECM, to coldies' despair, after Knocker said the UKMO looked the more likely evolution? So it is possible that the UKMO can be right against the ECM/GFS, but I think everybody would like to see the ECM agreeing later on.

    Model Output Discussion 29th December - Into mid-Winter.

    in Forecast Model Discussion

    Posted

    3 minutes ago, Chris K said:

    Not neccesarily. Same initial conditions run at a lower res, yes. But I thought that where the control is different to the operational, it is used as comparison to help to identify if a spread in the ensembles is more likely being caused by variation in the initial starting conditions, or resolution issues. It doesnt mean, for example, that one cluster should immediately be assumed to be more likely than another.

    This is because an ensemble set for one point (e.g T850 for one location) can be a 'magnified' view within an synoptic evolution, so reviewing the sets of overall synoptic patterns is required.

    Hopefully that's explained correctly!

    Ah ok so if the control and op are different then ensemble spread is most likely to be caused by resolution, whereas if they are similar the ensemble spread is most likely to be caused by starting data. Think I've got it. Thanks!

    Model Output Discussion 29th December - Into mid-Winter.

    in Forecast Model Discussion

    Posted · Edited by metaltron

    The GFS control run is more amplified than the OP this morning. I read here a few days ago that the control has the same starting data as the op but with lower resolution. So is the control meant to point out possible errors in low resolution? For example today the low resolution version of the same starting data is more amplified, so should we expect the ensembles to be biased towards amplification this morning?

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