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Captain Shortwave

Model Forum Host
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Posts posted by Captain Shortwave

  1. The GFS even more progressive with disrupting the area of low pressure close to the UK

    image.thumb.png.e6661269804496ef4ffe2640737b6159.png
     

    An evolution worth watching, I think milder air will push across most of the UK at the end of the week but an easterly through the back door so to speak could be possible. Just a shame that the 850s are not conductive for snow at this point.

    • Like 1
  2. Whilst it is the worst solution the GFS does squeeze the best out of the outcome due to the fact that the first band of snow fizzles out before it turns back to rain. The UKMO looks to have been miles off with the low tracking further south. It seems to be a case of hoping in regard to the timing of the front. There is no point having the snow overnight and it being washed away by dawn for example.

    • Like 3
  3. Late next week looks very delicate and very small differences can determine whether the low deepens towards the UK or runs through the channel as a shallow feature. The UKMO keeps the low separated from the main troughing which allows a much more southerly track, the GFS on the 06z not only connects the low but the cold pooling from Scandinavia connects to the PV moving towards Greenland at the time which seems to slow the low even further and deepen in situ as there is a gap to pull WAA ahead of the low over the UK, hence the snow to rain event.

    I wouldn’t place my money on either option yet to be honest.

    GFS

    image.thumb.png.ef45ff47fcdfa12723a261ea5fc502b0.png

    Hard to spot but you can see the embedded troughing within that low extending out of Greenland.

    UKMO

    image.thumb.gif.7e02553ced20832388ad9609bc65926e.gif
     

    Much less pronounced and a more elongated and complex system. You could argue that the GFS is potentially over simplifying the set up into that one low when the reality could be a series of small systems that will gradually break eastwards.

     


    Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5030205
    • Like 1
  4. Late next week looks very delicate and very small differences can determine whether the low deepens towards the UK or runs through the channel as a shallow feature. The UKMO keeps the low separated from the main troughing which allows a much more southerly track, the GFS on the 06z not only connects the low but the cold pooling from Scandinavia connects to the PV moving towards Greenland at the time which seems to slow the low even further and deepen in situ as there is a gap to pull WAA ahead of the low over the UK, hence the snow to rain event.

    I wouldn’t place my money on either option yet to be honest.

    GFS

    image.thumb.png.ef45ff47fcdfa12723a261ea5fc502b0.png

    Hard to spot but you can see the embedded troughing within that low extending out of Greenland.

    UKMO

    image.thumb.gif.7e02553ced20832388ad9609bc65926e.gif
     

    Much less pronounced and a more elongated and complex system. You could argue that the GFS is potentially over simplifying the set up into that one low when the reality could be a series of small systems that will gradually break eastwards.

     

    • Like 3
    • Insightful 3
  5. Not really commented much because the situation later next week is pretty fragile but obviously if the low ends up too far north then the flooding risks will return with a vengeance given the chances of several hours of heavy rain if the milder air remains  in the south. Clearly the best solution is the low remaining south enough to given frontal snow with strengthening east to north easterly winds bringing showers in off the North Sea.

    The UKMO looks pretty much broadly wet for next Thursday, the GFS has snow over Scotland and the far north of England. At least the UKMO does have some heights behind the low unlike the 00z that had rapidly declining heights to the north west by the end of next week.

    • Like 3
  6. The trend is there for the Euro ridge to amplify somewhat during week 2, which should bring drier and more settled conditions to the south. At the moment there is the potential for mild or very mild conditions, however if winds do back more southerly or south easterly then we could see a bit of a chill set in again, especially at night as drier air would allow skies to clear. Still a long way off and of course the models may trend this high further north in the coming runs, which of course could lead to much more interest.

    • Like 6
  7. All we can do now is hope for the best. The cold air should be starting to dig in now, a cold one with a widespread frost.

    image.thumb.png.3f9caeaa9c9fcec0884a2b97302ae57b.png
    Generally -1 or -2c tonight

    Tomorrow looks cold with temperatures only getting a little above freezing.

    image.thumb.png.990a5b364f1a276df77022de7b1ad9b8.png
     

    1c, perhaps 2/3c in sheltered spots. It will feel cold and this is pretty much the range of the temperatures for the whole of the week. It is a shame that there doesn’t appear to be anything of note in terms of precipitation, potentially the system affecting the north could bring some patchy sleet/snow in the north of the region and likewise the same could happen with the low moving through northern France for southern areas. I am hoping something will crop up that could give something decent more widely.

    • Like 3
    • Thanks 1
  8. 3 minutes ago, Neilsouth said:

    @Paul Is mod section broken?

     

    Warning issued by A.J

    July 15, 2014

    Content moderated - 2 days

    Your content will need to be approved by a moderator

    Haven't posted in that section or broken any rules in that group for awhile, as seen by 2014 Lol

    Just a temporary thing on all posts, see Paul’s post in the model thread.

    • Thanks 1
  9. A toppler by definition is a lea northerly in a generally mobile westerly pattern, as such it is more amplified than your bog standard PM airmass behind a set of Atlantic weather systems, but it is not sustainable for more than 24-48 hours. The pattern for this week certainly doesn’t illustrate this, the collapse of the blocking signal comes about because of events above the troposphere (the stratospheric vortex gets pushed the the north west of the UK by the strong warming event and that downwells resulting not only in the transfer of tropospheric low heights from the north east to the north west, but lowers pressure in general over the arctic (Feel free to correct any inaccuracies I might have spewed here).

    It is likely that we will see some more mobile whether, but how this comes about in reality is still a little up in the air (aka how far north or south the jet stream will lie), however once the current cold spell and breakdown Synoptics are out of the way, we may start to see promising output again from the models once they shake the “forever zonal” default state they seem to be in just at this moment.


    Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5011423
    • Like 3
  10. Good model agreement (at the very least) on temperatures struggling to get much above freezing throughout next week (Monday to Friday). The risk of frontal snow in the south and deep arctic cold for everyone else where something g could crop up at any time. 
    A breakdown look likely during the following weekend unless the models start to pick up complications in regards to the jet moving northwards again.

    • Like 5
  11. Some very strange goings on around day 4 in the ensembles. The cause of this appears to be a shortwave appearing on the core low heights over Scandinavia that passes fairly close to the east coast of Scotland, this appears to enhance the depth of cold sweeping down the eastern side of the country.

    Just posting one ensemble to show this;

    image.thumb.png.4c4fcb3cb3b46e398ba70621190d2780.png

    Note the kink east of Scotland on here.

    So lets see if any other models showed this;

    ECM

    image.thumb.png.51a7fb6476b608462afde1507cd9046e.png

    It is sort of there to the north of Scotland, but it gets more absorbed into the part low. It might be worth keeping an eye on because a shallow system with embedded frigid air appears and heading close to the UK could be the surprise we were hoping for.


    Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5007944
    • Like 2
  12. 3 minutes ago, Mike Poole said:

    JMA clean at T96 too:

    IMG_8467.thumb.gif.e032ece2cbd5020c3b4f3eae17449abe.gifIMG_8468.thumb.gif.b63b283c5b474b15f4517d5d779b68d3.gif

    Similar evolution to ECM after, possibly more snow.  I think we are now in a good position at T96.

    But I think the period T120-T168 is not yet nailed on any of the models.  I think the move to deflate the ridge and close the separation of the two lobes is overstated by the models, and will maybe take place slower or even not at all.  

    Worth noting the JMA brings organised precipitation down from the north west as the channel low clears eastwards (thanks to another secondary low developing over the north of the UK), which would likely deliver a snow event.

    image.thumb.gif.54c89fdaddbcd1c1a7e73c8294da836a.gif

    Heights look very low and the airmass will be very cold. Lots of potential but it would be nice to see the models picking something up more broadly.

    • Like 5
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