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The hunt for cold - Model discussion (late November)


Paul
Message added by Paul

If you're hunting for cold potential in the model output, this thread is for you. But if you'd like to look more widely at the models, please head over to the general model discussion thread.

This is a model related thread, so a general, frequent theme of the model output is a given, but it will not be strictly enforced:

  • Some topic drift, humorous responses etc are fine
  • Posts likely to lead the thread off on an entirely off topic tangent are not ok. For example (but not solely limited to): Posts entirely or mainly about Met Office, BBC or media forecasts with little or no model context, and posts solely asking for a weather forecast in a specific location.
  • Posts which start with something like 'I know this is off topic but ...' are not ok.
  • Posts which break the forum guidelines are not ok (eg trolling, troll-hunting, weather guilt tripping, overly defensive/aggressive, abusive, disrespectful to others)

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

As I said - up for grabs. Out to 10 days the Berlin site I think it is about as good as we can get for looking through the forecast impact at various levels of the atmosphere. 10 days out and the lower strat at 70hpa is certainly suggesting a vortex movement to Siberia, and I am beginning to wonder whether our next height rise will be more Greenland than Scandinavia when it comes later in the month (as I've said before in candid moments on this forum - I continue to find it difficult to pinpoint the exact location of the ridge/trough wave pattern) - but we don't have precise enough data yet.

ecmwf70f240.thumb.gif.dae18f093476aaa35af3430f4c0c7975.gif

Back in February we began to see the vortex disintegrate in such a way that a gathering certainty grew as to the tropospheric impacts. But we are early days still on this current event. We need another 10 days probably before we can even begin to analyse what may happen this time around.

I would like to see another wave 2 after the forecast wave 1, that would surely finish it off for most of winter

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Posted
  • Location: Winterbourne, South Glos
  • Location: Winterbourne, South Glos
7 minutes ago, Catacol said:

as I've said before in candid moments on this forum - I continue to find it difficult to pinpoint the exact location of the ridge/trough wave pattern

Runge Kutta methods for simple fast / slow waves then add some meaty multi step integrations

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire
5 minutes ago, cheeky_monkey said:

looks like a tripole that = a positive NAO signal for the winter months

No, the opposite imo.

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

Well the SSW continues to be shown on pretty much all output that goes 2 weeks, so we will have to work out what that means for our neck of the woods soon, here FV3 T348:

image.thumb.jpg.562ab51c99486f61a216a72e98c65ae1.jpg

When the heat and cold are like yin and yang,I think we can pretty much call it, but this is likely going to be a displacement SSW not a split, and that leaves much more uncertainty over what the effects will be in UK.  

So it's important to keep an eye on what will happen down here after the Atlantic eventually beats the Scandi block, which it will.  JMA T264 hints at the possibility of weather coming from the north, which I and others have considered likely for a while now:

image.thumb.jpg.98e0d774917c13167237c36ec48e4e16.jpg

Edited by Mike Poole
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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
25 minutes ago, Mike Poole said:

Well the SSW continues to be shown on pretty much all output that goes 2 weeks, so we will have to work out what that means for our neck of the woods soon, here FV3 T348:

image.thumb.jpg.562ab51c99486f61a216a72e98c65ae1.jpg

When the heat and cold are like yin and yang,I think we can pretty much call it, but this is obviously going to be a displacement SSW not a split, and that leaves much more uncertainty over what the effects will be in UK.  

So it's important to keep an eye on what will happen down here after the Atlantic eventually beats the Scandi block, which it will.  JMA T264 hints at the possibility of weather coming from the north, which I and others have considered likely for a while now:

image.thumb.jpg.98e0d774917c13167237c36ec48e4e16.jpg

What? 

Don't all SSWs start with an initial displacement? I thought it was signature that when a warming initiates it displaces and tightens the core of the vortex before causing it to split. 

Pretty sure a displacement event is what is known as a minor warming. 

Edited by CreweCold
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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
7 minutes ago, CreweCold said:

What? 

Don't all SSWs start with an initial displacement? I thought it was signature that when a warming initiates it displaces and tightens the core of the vortex before causing it to split. 

You think we are headed for a split, Crewe?  My knowledge of these events is limited to the few that I've experienced, and the ones that led to a split, e.g. February 2018 looked different to this. To me, anyway. We'll see!

Edited by Mike Poole
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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
2 minutes ago, CreweCold said:

What? 

Don't all SSWs start with an initial displacement? I thought it was signature that when a warming initiates it displaces and tightens the core of the vortex before causing it to split. 

Pretty sure a displacement event is what is known as a minor warming. 

You can have a major warming with a displacement though surely, the warming in fi now and its associated wave 1 might only knock the vortex off the pole for a short while without splitting it but if it knocks it far enough away from the pole, it will still be a technical major midwinter warming (SSW).

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

You think we are headed for a split, Crewe?  My knowledge of these events is limited to the few that I've experienced, and the ones that led to a split, e.g. February 2018 looked different to this. We'll see!

Difficult to see how the sustained assault on the vortex doesn't split it IMO. 

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

FWIW I think catacol expects a split too, reading between the lines, as he talks about 'striking the heart of the vortex'. I'd suggest that's only possible with a split. I could be wrong though. 

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

Difficult to see how the sustained assault on the vortex doesn't split it IMO. 

Your right in that often the displacement leads to a split - 2013 i think it was shredded it completely if i remember.after inintial wave1

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
Just now, feb1991blizzard said:

Your right in that often the displacement leads to a split - 2013 i think it was shredded it completely if i remember.after inintial wave1

Yes was going to post 2013 image. Started off similarly from what I've seen. 

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
6 minutes ago, CreweCold said:

FWIW I think catacol expects a split too, reading between the lines, as he talks about 'striking the heart of the vortex'. I'd suggest that's only possible with a split. I could be wrong though. 

Actually I hope you are right.  Would certainly firm up prospects for the heart of winter.  But I'm cautious at the moment.

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

Oh and here is when the GFS started latching on to the SSW earlier this year

Related image

you sure it wasn't later than that?

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
Just now, feb1991blizzard said:

you sure it wasn't later than that?

The actual SSW happened later...but there's no guarantees that this one won't happen later than what is shown at present...

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
3 minutes ago, CreweCold said:

Oh and here is when the GFS started latching on to the SSW earlier this year

Related image

Remember it well, but this looks different to me...

image.thumb.jpg.e5f78b5d7e9b81420d5c95541006a874.jpg

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
3 minutes ago, Mike Poole said:

Remember it well, but this looks different to me...

image.thumb.jpg.e5f78b5d7e9b81420d5c95541006a874.jpg

If anything, the chart you've posted looks more directed towards the heart of the vortex than the GFS initially went for earlier this year.

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
3 minutes ago, CreweCold said:

If anything, the chart you've posted looks more directed towards the heart of the vortex than the GFS initially went for earlier this year.

Are you saying you expect this event (if it happens!) would be more explosive than the Feb one?  I can't see that, to be honest, I still think the PV will end up displaced.

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
Just now, Mike Poole said:

Are you saying you expect this event (if it happens!) would be more explosive than the Feb one?  I can't see that, to be honest, I still think the PV will end up displaced.

No, that's not what I'm saying.

I'm saying that the chart you've posted, shows a more impactful warming than the chart I posted from earlier this year does. Bear in mind, I posted a 384 hr GFS chart from when the model first cottoned on to the warming.

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
1 minute ago, CreweCold said:

No, that's not what I'm saying.

I'm saying that the chart you've posted, shows a more impactful warming than the chart I posted from earlier this year does. Bear in mind, I posted a 384 hr GFS chart from when the model first cottoned on to the warming.

Well so did I, but with the chart you posted, the heat is right bottled up, with the current charts, it is happy power sharing the hemisphere?  Better wrap this up soon, this time of night, before I start talking out of the wrong end!!  If that hasn't already happened 

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

Well so did I, but with the chart you posted, the heat is right bottled up, with the current charts, it is happy power sharing the hemisphere?  Better wrap this up soon, this time of night, before I start talking out of the wrong end!!  If that hasn't already happened 

Hahaha, I'm by no means a strat expert!

Guess we'll just have to wait and see what transpires and take note of what those with better understanding impart to us! 

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Posted
  • Location: Solihull, Midlands. (Formerly DRL)
  • Weather Preferences: Sunshine, thunder, hail & heavy snow
  • Location: Solihull, Midlands. (Formerly DRL)

Speaking about the heart of the Vortex, it’s ❤️ would probably stop beating should those GFS Stratosphetic warming charts come off like that!

Particularly so if they were to somehow improve further.

But if not, maybe we’ll just have to feed the Polar Vortex lots of fat, greasy, McDonalds burgers! Then its ❤️ could be in trouble! ☠️

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Posted
  • Location: Calgary, Canada. Previously, Saffron Walden (Essex/Herts border), United Kingdom
  • Weather Preferences: Continental:Warm dry summers, cold snowy winters
  • Location: Calgary, Canada. Previously, Saffron Walden (Essex/Herts border), United Kingdom

Deleted

Edited by CanadaAl
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Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

Such a laughable difference from UKMO 12z to 00z doesn’t look any good for undercut but nowhere near as progressive to 12z with doomed Scandi block, seemingly a lot of struggle in this area.

ED61708F-7484-41C6-B8F2-C6D6C962EFFF.thumb.jpeg.c50199bd89a1992d91f9dcb820a12279.jpegE63F7689-8B0F-40C3-BAA5-A7C022FC31DD.thumb.gif.c20c70d2bed0ff3e34bf3089523f4b48.gif

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Posted
  • Location: Santry, Dublin, Ireland. 50 metres ASL.
  • Location: Santry, Dublin, Ireland. 50 metres ASL.

GFS 00z out to 120, certainly a lot less progressive than the 18z at 126 was. Doubt it will make too much difference as the Atlantic looks poised to plow in through. Will watch up to 144 then go back asleep!

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