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Model output discussion 25th Jan - The final third of winter beckons..


Paul

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  • Location: Warsaw, Poland. Formerly London.
  • Weather Preferences: Four true seasons. Hot summers and cold winters.
  • Location: Warsaw, Poland. Formerly London.
    2 hours ago, blizzard81 said:

    We must remember this is the 18z though. We have been here so many times before, only to be let down in the morning. At least it is Friday though lol.

    On a plus note the old wives tale about the pub run being useless is exaggerated.  On another note the limit of the forecast skill of nwp is currently about six days with a notable drop off in verification at the latter end of that time frame. So whether GFS 12, 18, 00 etc or ECM and UKMO and GEM and JMA et al, the picture for the UK for the end of next week is far from decided. To paraphrase a very wise forum member @Ed Stone the weather will do what the weather will do, regardless of our fretting 7 days out. Ending on a completely unscientific note I really would love to see the UK get a taste of proper continental winter. So fingers and toes crossed the "upgrades" continue.

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
    22 minutes ago, Seasonality said:

    On a plus note the old wives tale about the pub run being useless is exaggerated.  On another note the limit of the forecast skill of nwp is currently about six days with a notable drop off in verification at the latter end of that time frame. So whether GFS 12, 18, 00 etc or ECM and UKMO and GEM and JMA et al, the picture for the UK for the end of next week is far from decided. To paraphrase a very wise forum member @Ed Stone the weather will do what the weather will do, regardless of our fretting 7 days out. Ending on a completely unscientific note I really would love to see the UK get a taste of proper continental winter. So fingers and toes crossed the "upgrades" continue.

    Aye but where do you draw the line on that one? I say this because what happens at day 7, for example, (outside of the sharpest forecast skill) can be determined by what happens at day 4 (within the sharpest forecast skill range). It's not as simple as you make out and when we're dealing with dynamic and complex physics an arbitrary cut off point usually doesn't mean a lot.

    Personally I will look at day 4 with scepticism when an easterly is progged...

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    Posted
  • Location: Cyprus and North east Swindon. 104 ASL
  • Location: Cyprus and North east Swindon. 104 ASL
    9 minutes ago, The Eagle said:

    00z not so positive at 87hrs. Atlantic exerting more influence. We need an undercut.

    It's pretty similar to me at 144 which is great news backing the pub run

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    Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
    2 minutes ago, Ali1977 said:

    It's pretty similar to me at 144 which is great news backing the pub run

    Yes another cracker, UKMO not so good though, not as good a cold pooling to draw on.

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

    There are differences this run....Scandi heights slightly further S and that straight E'ly seen on the 18z days 7&8 may turn more SE'ly as the high is orientated differently. Still all variations on a theme though.

    We're actually in a SSE'ly by day 7....though not a warm one at this point!

    gfsnh-0-168.png

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    Posted
  • Location: Banbury
  • Location: Banbury
    1 minute ago, CreweCold said:

    There are differences this run....Scandi heights slightly further S and that straight E'ly seen on the 18z days 7&8 may turn more SE'ly as the high is orientated differently. Still all variations on a theme though.

    At the range we are discussing they are small, 6z will show something different, its the general set up we should be v happy with

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    Posted
  • Location: Cyprus and North east Swindon. 104 ASL
  • Location: Cyprus and North east Swindon. 104 ASL
    5 minutes ago, CreweCold said:

    There are differences this run....Scandi heights slightly further S and that straight E'ly seen on the 18z days 7&8 may turn more SE'ly as the high is orientated differently. Still all variations on a theme though.

    We're actually in a SSE'ly by day 7....though not a warm one at this point!

    gfsnh-0-168.png

    Yeah true, still cold but the highis losing its shape, lets see what happens when Injected with Atlantic WAA - if it happens!!

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
    1 minute ago, Ali1977 said:

    Yeah true, still cold but the highis losing its shape, lets see what happens when Injected with Atlantic WAA - if it happens!!

    It's a common theme starting to creep in to the modelling, earlier and earlier (the HP losing it's shape). The UKMO is actually quite awful at day 6 for this with the 'sagging high' cutting off the cold feed fairly quickly

    UN144-21.GIF?03-05

    At this rate we might need another attempt at positioning the high favourably (to get a proper snowy easterly) but it would have to be timed meticulously to avoid the Atlantic overpowering the block and sinking it.

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    Posted
  • Location: Cyprus and North east Swindon. 104 ASL
  • Location: Cyprus and North east Swindon. 104 ASL

    Not sure how the ENS will be, hopefully holding the high in place in a bit better. This extremely cold blob in Scandy is growing though - another battle 

    IMG_4144.PNG

    Cur this Atlantic trough off and cold would rapidly flood in as pressure rebuilds over Scandy 

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
    2 minutes ago, Ali1977 said:

    Not sure how the ENS will be, hopefully holding the high in place in a bit better. This extremely cold blob in Scandy is growing though - another battle 

    IMG_4144.PNG

    Wow if only we could pull all that westwards!

    gfsnh-0-234.png

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    Posted
  • Location: Cyprus and North east Swindon. 104 ASL
  • Location: Cyprus and North east Swindon. 104 ASL
    4 minutes ago, CreweCold said:

    Wow if only we could pull all that westwards!

    gfsnh-0-234.png

    Although now beyond reliable, I think the cold will win. Not as good as the pub run but blocks are in place for some good upgrades over the next few runs.

    This could be a snowy freezing FI as Scandy high is building and trough is being cut off.

    IMG_4145.PNG

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
    4 minutes ago, Ali1977 said:

    Although now beyond reliable, I think the cold will win. Not as good as the pub run but blocks are in place for some good upgrades over the next few runs.

    This could be a snowy freezing FI

    Pointless analysing it as so different to last run...may not even get that far if UKMO is on the money. We'll just have to wait and see. But yes, at 264 hrs there is a chance to link the N Atlantic and Svalbaard heights

    gfsnh-0-264.png

    EDIT: and on cue...

    gfsnh-0-300.png

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

    This is more like it...shame it's 300 hours plus...

    gfsnh-0-336.png

    gfsnh-0-372.png

    Leaching our cold air from Scandi rather than running the risk of importing it from the Balkans!

    gfsnh-1-348.png

    gfsnh-1-360.png

    Heights generally lower too so more precipitation likelihood for more people

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    Posted
  • Location: Hernia Bay
  • Weather Preferences: Heavy Snow
  • Location: Hernia Bay

    This is one run the general theme is easterly in some shape or form. On this particular run the Atlantic is displaying it's bravado against the cold block but in general it's been beaten back in prior runs. We can hope that this run is not a trend setter but more at odds with previous runs and other model outputs 

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

    Longer term, CFS continues with its (I'm guessing) SSW driven March. Brilliant continuity from when I was last checking it 2/3 weeks ago. Fits in brilliantly with longer term GFS 0z. Not seen this level of consistency from CFS since March 2013, another SSW driven month.

    cfsnh-4-3-2017.png?06

    Could be some fun and games to be had next 6 weeks or so...

    cfsnh-1-3-2017.png?06

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    Posted
  • Location: Chisinau, Moldova.
  • Location: Chisinau, Moldova.

    The GFS 0z is quite nice for the UK from T130 or so, which is good to see it getting to such a range. Nothing overly prolonged, though, but nice to see something creeping closer, as opposed to further away.

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

    Control run follows the op to an extent in FI, keeps us in the game and holds blocking at a higher latitude than the 18z did

    gensnh-0-1-276.png

    Opportunities galore from there

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    Posted
  • Location: King’s Lynn, Norfolk.
  • Weather Preferences: Hot and Thundery, Cold and Snowy
  • Location: King’s Lynn, Norfolk.

    00z runs have got off to a cracker once again. GEM is a belter with an endless train of -12 to -16 uppers from the UK to the Ukraine and beyond! 

    GFS is similar to the previous 18z, then slams that floating PV over Russia right into scandi, which we tap into in FI

    UKMO is also on the right path up to 120hrs, getting us into the cold feed, which is the main thing. Question marks about the orientation of the high over scandi should come after we have the cold in place, God willing. 

    Now to await the ECM

    Happy Friday! 

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    Posted
  • Location: Cambridge, UK
  • Weather Preferences: Anything out of the ordinary!
  • Location: Cambridge, UK

    Pretty good again this morning. A lot is going to hinge on how the initial flow gets here - if it gets cut off early, then the cold pool will decay much faster, and it could take a second attempt to send the massive cold our way.

    gefsens850London0.png

    The crunch point appears to be on the 8th - which is the point at which the flow starts to properly feed in from the continent....either very very cold, just plain cold, or chilly. The ensemble mean is now below -5 for 3/4 days, which is a good sign. Also a good number of runs reloading at the end. We await the ECM eagerly!

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    Posted
  • Location: Chisinau, Moldova.
  • Location: Chisinau, Moldova.
    Just now, mb018538 said:

    Pretty good again this morning. A lot is going to hinge on how the initial flow gets here - if it gets cut off early, then the cold pool will decay much faster, and it could take a second attempt to send the massive cold our way.

    gefsens850London0.png

    The crunch point appears to be on the 8th - which is the point at which the flow starts to properly feed in from the continent....either very very cold, just plain cold, or chilly. The ensemble mean is now below -5 for 3/4 days, which is a good sign. Also a good number of runs reloading at the end. We await the ECM eagerly!

    Personally expecting changes from the ECM in the near term, inside 5 days. It was quite slow bringing the cold into Europe on the 12z compared to its 0z and other model output. 

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
    21 minutes ago, Seasonality said:

    Um, I know that, my point was pretty clear and my post written in clear English, sorry if you didn't understand I'll try to make it easier for you next time.

    In the models here is a chart that is easy to grasp. Lovely cold pool at 144h. 

     

    gfs-1-144 (3).png

    UW144-21 (3).gif

    It was a genuine question...not a dig at you but if you want to reply in that tone then fair enough. I know full well what you were saying but I was questioning the premise. 

    In my eyes a notable decrease in forecasting skill at day 6 won't manifest in the output until days 7&8 and increase thereafter due to the snowballing of the butterfly effect?

    It's all a moot point anyway given that we often see fairly significant changes in the 72-96 hrs range.

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