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


Paul
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Message added by Paul

Please only post model discussion in this thread. 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

Thank you!

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Posted
  • Location: Pershore
  • Location: Pershore

    The much talked about SSW has taken place, but as Nick blogged about a few days ago, it doesn't always mean cold for the UK. The signs are good though (if you like cold that is), and the model output is showing a lot of northern blocking currently. It's set to be a really interesting time to follow the models if nothing else, so please carry on the discussion here. 

    As ever, please keep it to model discussion only in this thread.....

    Want to view the model outputs?
    You can get all the major ones here on Netweather:

    GFS
    GEFS Ensembles
    ECMWF
    ECMWF EPS
    NetWx-SR
    NetWx-MR
    Met-Office
    Fax
    GEM
    GFS Hourly

    Snow forecast and precip type
    Model Comparison
    Global Jet Stream
    Stratosphere

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    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

    And so we get into "squeeky-bum" time with the SSW and its impacts on the models.

    Anyone looking for consistency in the fine details will be disappointed if they compare yesterday's UKMO T144 with today's T120:

    UW120-21.GIF?13-17  UW144-21.GIF?12-12

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    Posted
  • Location: Windsor
  • Weather Preferences: Snow and cold
  • Location: Windsor
    4 minutes ago, Man With Beard said:

    And so we get into "squeeky-bum" time with the SSW and its impacts on the models.

    Anyone looking for consistency in the fine details will be disappointed if they compare yesterday's UKMO T144 with today's T120:

    UW120-21.GIF?13-17  UW144-21.GIF?12-12

    Not a good start this evening with the GFs following in the same vein ?

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    Posted
  • Location: oldham
  • Location: oldham
    4 minutes ago, Man With Beard said:

    And so we get into "squeeky-bum" time with the SSW and its impacts on the models.

    Anyone looking for consistency in the fine details will be disappointed if they compare yesterday's UKMO T144 with today's T120:

    UW120-21.GIF?13-17  UW144-21.GIF?12-12

    gfs-0-120.png?12

    GFS agrees 

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    Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

    UKMO. GEM and GFS all flatter this evening?

    Never easy is it?

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    Posted
  • Location: Rotherham
  • Location: Rotherham
    1 minute ago, frosty ground said:

    Before we get toys thrown about the GFS is not to different from the 06z

    gfs-0-126.png?12 12z vs 06z gfs-0-132.png?6

    Heights are 200miles further south. It's not a great start. It's delays well see if all routes lead to cold soon

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    npsh500.pngnpsh500.png

    hgt300.pnghgt300.png

    Arctic ridge better toward the pole than the 06z and jet cutting south a little further west. Small tweaks so far.

    h500slp.pngh500slp.png

    Today has so far seen the old solution of the Azores High building a ridge to Scandinavia put aside in favour of it being overrun by a low that then cuts down through Norway - thanks to that curve of the jet down south - and so acts as a 'trigger low' for the easterly as heights rise across Scandinavia from the north. This 12z run from GFS seems to be trying for yet another way forward though, as the low doesn't separate from the main Atlantic trough and we're looking to rely instead on the increasing heights down from the Arctic plus above in the stratosphere to disrupt the main trough.

     h500slp.png

    A hint of that going on as of +135 (tiny low in the N Sea). 

    Not as fun as the 06z but UKMO is keen to give this idea the thumbs-down with the low separating very cleanly indeed;

    UW144-21.GIF?13-17

    It's handled the Atlantic trough pretty strangely but that push of heights from the SW should interact with the forcing from the SSW to build a Scandi high by Tue/Wed.

    Clearly, some details sorely in need of resolving before we can start expecting the easterly to land on any particular day.

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    Posted
  • Location: North East Cotswolds, 232m, 761feet ASL
  • Location: North East Cotswolds, 232m, 761feet ASL

    I’m not sure what the GFS is doing here, it looks like the blocking high could be flattened which is a bit of a shocker!!

    edit - wrong , looks like a WAA reload will fix that

    Edited by Ali1977
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    Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

    Phase 1 is a fail I'm afraid on both UKMO and GFS with the ridge being overrun.

    gfsnh-0-156.png?12

    That means for any cold we would have to wait for the Atlantic to reamplify.

    While that may be the case it is obviously much better to get the initial ridge because the next chance is again in FI and that could go wrong too.

    Nothing to say the models won't switch back to the more amplified pattern they showed this morning so no need to panic yet but also no point pretending the output is not worse than this morning for cold lovers.

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    Posted
  • Location: North East Hampshire
  • Location: North East Hampshire
    3 minutes ago, Daniel* said:

    There is very little difference the trigger low is missing so a less quicker route but we’ll get there I’m sure.

    I'd call that quite a big difference.

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    Posted
  • Location: oldham
  • Location: oldham
    2 minutes ago, Ali1977 said:

    I’m not sure what the GFS is doing here, it looks like the blocking high could be flattened which is a bit of a shocker!!

    edit - wrong , looks like a WAA reload will fix that

    gfs-0-156.png?12gfs-0-168.png?12

    Exactly the high is building again.

    No quick route to cold, but no flattening high either.

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    Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL
    3 minutes ago, Johnp said:

    I'd call that quite a big difference.

    Perhaps but looking at it broadly it’s not hugely different minor adjustments equate to big impacts on resultant surface conditions. The AO definitely seems more negative on this run...

    0A541CB3-B292-429E-90F8-2827B4D44DE7.thumb.png.a49786ca8d1f0fd4c73b05525b34449d.png

    Edited by Daniel*
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    Posted
  • Location: Warsaw, Poland. Formerly London.
  • Weather Preferences: Four true seasons. Hot summers and cold winters.
  • Location: Warsaw, Poland. Formerly London.

    The cold air is obviously restricted further east on this run, then again it may just be a mild outlier or a rogue run. Lets see where it goes from here.

    gfsnh-1-180.png

    gfsnh-1-186.png

    Edited by Paul
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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    npsh500.png npsh500.png

    While it's still making progress toward a similar outcome (trough breaking down, some of it likely headed for W. Asia with blocking to N of it), this run is a bit out of kilter with the other models terms of how much the Atlantic trough advances NE days 4-6, so is worth viewing with high(er than usual) suspicion.

    It's pretty much a reversion to the 00z run, which was followed by the quicker 06z run (in terms of cold air arrival from east).

     

    UN144-21.GIF?13-17

    Here's UKMO top-down at day 6. Looks alright when taking into account the fact that the focus of heights is ready to shift from SW to NE of the UK - but true to say, it could easily have been better with the shape of the Atlantic trough.

    Edited by Singularity
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    Posted
  • Location: oldham
  • Location: oldham
    2 minutes ago, Singularity said:

    npsh500.png npsh500.png

    While it's still making progress toward a similar outcome (trough breaking down, some of it likely headed for W. Asia with blocking to N of it), this run is a bit out of kilter with the other models terms of how much the Atlantic trough advances NE days 4-6, so is worth viewing with high(er than usual) suspicion.

     

    UN144-21.GIF?13-17

    Here's UKMO top-down at day 6. Looks alright when taking into account the fact that the focus of heights is ready to shift from SW to NE of the UK - but true to say, it could easily have been better with the shape of the Atlantic trough.

    Worth Noting the Low has slipped south on the UKM whilst on the GFS it went back north west.

    Edited by frosty ground
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