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Hunt For Cold: Model Discussion - Heading Into Christmas


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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3 hours ago, nick sussex said:

You’d better hope for a quick trop response because I fear we’ll be bored into submission soon.

You are right SSW s can cause models a lot of problems , we’ve seen that in the past

Hi Nick, it's unnecessarily gloomy on this thread.  I haven't got time for a full update today but the "tropical response" that you, me and many other coldies are hoping for is looking extremely promising. Even if we do not see a major SSW (and it's almost nailed on - with just type and impact timing uncertainties to be ironed out) the next tropical Nino surge with +ve poleward AAM (atmospheric angular momentum) and +ve GLMT (global mountain torque) and particularly +ve EAMT (east Asian mountain torque) are set to fall into place towards the end of December favouring a pattern reset which is already underway.  Currently it has just fallen to strongly -ve relative AAM tendency, -ve GLMT and -ve EAMT and are all about to bounce back (they must do to restore equilibrium) and surge upwards with rapid responses.  Almost every winter this catches out the models which do not take anywhere near enough account of these key drivers. It would be looking good for colder patterns anyway through January but the timing of this, with the progress towards a very early SSW (with a full split looking increasingly likely) and the MJO seemingly set to be playing ball too (week 2 just adjusting again to a higher amp pass through phases 5, 6, 7 on the cards), I'm particularly bullish about a prolonged cold spell in much of Europe (including the UK) gathering momentum in early January.

This and the last 2 winters have seen only brief periods of "zonal" or really flat patterns and "mostly" weaker and displaced jets.  2016/17 saw an extraordinary amount of MLB but with little HLB.  2017/18 saw periods of both MLB and HLB throughout (November to April) culminating with a rising of AAM, the torques, a spike in EAMT (through late Jan and early Feb with the usual time lagged responses) all helping to trigger the SSW and also helping the MJO advance through its maritime phases at increasing amp to go on to reach near record amp in phase 7 assisting the blocking pattern.  The SSW impacts, once the wind reversal reached the surface, spread very rapidly westwards from Siberia/N Asia.  That happened with a less favourable "Nina" pattern.  This year we have a weak El Nino trying to establish itself - considered to be the most favourable ENSO phase for encouraging SSWs (but not too strong like the 2015 super Nino which blasted the global patterns into oblivion). The tropical Pacific SSTs are all indicative of a Nino event but there has been "until just now" a problem with ocean-atmosphere coupling. The imminent surge in AAM and the current higher amp MJO in the Maritime phases should strongly favour full coupling. The lower troposphere layers will look highly conducive to SSW impacts without the propagating problems that we've seen in some recent years (perhaps the best since 2009/10 - also with solar minimums but no two events are alike and I hate using analogue years when we have impacts from global warming and reduced Arctic ice extent to throw into the mix).

The models are likely to struggle for several more days and then we should see some major changes as they start to increasingly sniff out the impacts from the pattern reset and the upcoming broad scale changes leading to an increasingly -veAO and -veNAO as we head into January.  A split SPV (stratospheric polar vortex) SSW is likely to produce considerable HLB and widespread Arctic cold spilling out towards the mid latitudes, including the UK.  Even a displaced SPV which has come under such persistent attacks could produce the goods this time.  Overall, the next week should reveal what lies ahead.  If ever there was a time to consider what drives the model output, then this is it. The interaction of the key teleconnection processes on the stratosphere and the troposphere are coming together nicely.   

In Feb 2018 GFS had several op runs for about 7 days ahead with barrel lows of sub 930 mb showing up just off the southern tip of Greenland. A week later that area had over 1030mb - so just a small error of over 100mb and all due to the pattern reset which GFS and the other models had been struggling with.  I noted this in this morning's GEFS 0z run as a perfect example of "What NOT to expect": 

 23x1.thumb.PNG.1ef56ee703e95ba33660400bb5eb08f8.PNG   

That's a record breaking Aleutian or Bering Sea LP.  This is perturbation 2 for next Sunday - just for fun. With 925mb shown, I would say that the CP would be nearer 922mb or 923mb.  The existing NPAC record (excluding tropical cyclones and hurricanes) is 925mb set on October 25th, 1977 at Dutch Harbor, Alaska. That's the "official" record but I believe that there have been several unofficial readings of 924mb with one as recently as December 14th, 2015 during the peak of the super El Nino.  An Aleutian low is quite possible but one like that is quite simply complete fantasy.  The whole GEFS panel is all over place and covers almost every possible outcome.  That should bring home to all of us that we're in a reset period with extreme model uncertainty.

If I have time, I'll elaborate on some of this during the Christmas holiday. Meanwhile, I'll wish everyone a very Merry Christmas, a Happy New Year and a period of absolutely fascinating model watching.  David   

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Posted
  • Location: portsmouth uk
  • Weather Preferences: extremes
  • Location: portsmouth uk
2 hours ago, DiagonalRedLine said:

Interestingly, that extended EPS chart looks kinda similar to this analogue/composite chart @Glacier Point posted over a week ago in the Stratosphere Temperature Watch Thread. 

E05765B1-F254-4333-AD58-6D07829D75A9.gif.66fcb025dab9343a1f248a3e91d769f6.gif

Seeing High Pressure developing more to the West of the U.K with possible chillier air filtering down from a Northerly sort of direction seems a plausible route to head in. Especially considering the above. 

Indeed I believe glacier point was looking at around start of January.

Good call I'm punting for the 7th but might go boobs up but I don't think so.

I'm wondering now if last February warming is the start of a run of more 80s style winter's.

To be honest I would never underestimate our climate in many ways.

It's easier to forecast the weather on Jupiter than it is on earth.

We are very unique 

Edited by Paul
Testing due to error on page
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Posted
  • Location: portsmouth uk
  • Weather Preferences: extremes
  • Location: portsmouth uk
2 minutes ago, Jonathan Rhodri Roberts said:

Does this mean it could be bad news snow-wise in Europe? 

image.jpeg

Yeah merge over this side of the pond I reckon.

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Posted
  • Location: Solihull, Midlands. (Formerly DRL)
  • Weather Preferences: Sunshine, thunder, hail & heavy snow
  • Location: Solihull, Midlands. (Formerly DRL)
24 minutes ago, MR EXTREMES said:

Indeed I believe glacier point was looking at around start of January.

Good call I'm punting for the 7th but might go boobs up but I don't think so.

I'm wondering now if last February warming is the start of a run of more 80s style winter's.

To be honest I would never underestimate our climate in many ways.

It's easier to forecast the weather on Jupiter than it is on earth.

We are very unique 

That would be nice to think that 80’s Winters start becoming more of a thing again. Wasn’t around for those Winters, but have heard some great wintry tales about them.

Feels as though as some said in the past, that the SSW back then appeared to shake up the atmosphere and provided us some rather extreme weather conditions. Such as that super chilly Easterly and the very warm, dry weather in Summer.

Indeed, the uniqueness of our island can make the weather here unpredictable at times. Even when the models show blocking conditions, for example, the U.K can be right on the edge of the cold weather a blocking High could unleash! 

Edited by DiagonalRedLine
Correcting mistakes
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Posted
  • Location: Wyke regis overlooking Chesil beach.
  • Weather Preferences: Snowfall
  • Location: Wyke regis overlooking Chesil beach.
3 minutes ago, Weather-history said:

Matt Hugo has pulled up Judah Cohen over this, why always GFS

I think he has got a point, why doesn't Cohen look at all the models? Michael Ventrice looks at ECM charts.

Hi WH. I have made this point before as well 

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

Cohen is part of a wider issue that exists because GFS is the most widely, freely available and easily accessible model on the web; outside of scientific circles and, as Cohen proves, even within them to some extent, it gets a lot more publicity than ECM despite being inferior on numerous levels.

The problem is currently amplified by the fact that GFS is lacking most substantially at the levels of the atmosphere that are most important with respect to what we see taking place next month.

Sadly, the nature of science means that 100% certainty is extremely rare - so we can't guarantee that GFS is getting things wrong because of it's shortfall on stratospheric resolution and should therefore be discounted without question. I for example can only advise putting it aside for the time being. I'd say there's an 80% chance this is the case, but that's still a 1 in 5 chance of a disastrous (for reputation) failure by ECM and (based on what I've seen shared around) GloSea5.

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Posted
  • Location: Wyke regis overlooking Chesil beach.
  • Weather Preferences: Snowfall
  • Location: Wyke regis overlooking Chesil beach.
49 minutes ago, Ed Stone said:

06Z GEFS ensemble...I make that eight members ending below -5C...?

GEFS Ensembles Chart

Not quite the famous GFS 850's ensembles cliffplunge of late November 2010 but it's an improvement on the recent cross.

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

As Emperor Caligula himself might have said, as he perused the GFS at T+120: I don't think that's Agrippa!;)

Netweather GFS Image

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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20

The NWP runs are very flat this evening.  Longer term who knows but another step back in the short to medium term.  Can ECM save the day again? Lets’s hope so!

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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20
12 minutes ago, The Eagle said:

UW144-21.GIF?23-17

As you were on the UKMO day 6. Or "weapons grade depression" as it's also known  

Dreadful ‘heart of winter’ chart!

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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20
4 minutes ago, Banbury said:

How much vinegar did YOU have on your cornflakes this morning lol

What do you want me to say brother?  That is a dreadful chart - period.  Compared to the 0z ECM massive step back.

Sadly your comment adds nothing to the discussion.

 

Edited by mulzy
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Posted
  • Location: Brighton, East Sussex
  • Location: Brighton, East Sussex

I was literally about to say the same thing^ it’s pointless, we all know there’s no cold in the next 10 days, keep moaning about changes nothing!

Liking the trend at day 9/10, starting to become very interested in that HP cell

C58F5D91-66E5-4895-A22E-415B5386208B.png

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Posted
  • Location: Hampstead / Cambridge
  • Location: Hampstead / Cambridge
3 minutes ago, Weathizard said:

I was literally about to say the same thing^ it’s pointless, we all know there’s no cold in the next 10 days, keep moaning about changes nothing!

Liking the trend at day 9/10, starting to become very interested in that HP cell

C58F5D91-66E5-4895-A22E-415B5386208B.png

Too much activity in North America to force enough (or any) WAA up the eastern seaboard. Might take longer to evolve into something useful for us, this run...

Edited by ITSY
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Posted
  • Location: Barnet
  • Location: Barnet

To me, the models are starting to firm down on the idea of the high over the UK gradually moving west/nw after 200 hours +. 

As it edges westwards the pv begins to force its way southwards into Europe leaving uk under some kind of northerly. 

That’s the starters 

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Posted
  • Location: Brighton, East Sussex
  • Location: Brighton, East Sussex
1 minute ago, ITSY said:

Too much activity in North America to force enough (or any) WAA up the eastern seaboard. Might take longer to evolve into something useful for us, this run...

At this stage it’s only tentative signs but if we continue seeing the shift westwards and the PV is impacted by the SSW and begins to weaken/move I’m struggling to see anywhere else it can go aside from... you know where!

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Posted
  • Location: Banbury
  • Location: Banbury
18 minutes ago, mulzy said:

The NWP runs are very flat this evening.  Longer term who knows but another step back in the short to medium term.  Can ECM save the day again? Lets’s hope so!

To be perfectly honest Bro, the above adds nothing to the discussion either, at the time of posting GFS was out to 180 and UKMO was complete at 144 - timeframes when nothing is expected .

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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill
5 minutes ago, bluearmy said:

Ok - this is the hunt for cold thread - there is no ‘cold’ showing in the next week to ten days so theoretically, anyone commenting on the model output for the next ten days and saying how rubbish it is re cold should be in knockers thread?? 

Just a bit fed up with posters telling me that the next weeks ‘flat’ output is flat - we know !  (It’s actually not that flat )

The problem is it is flatter than the 06z run, compare:

gfsnh-0-234.thumb.png.0d38e301e259fa15675f2c34f67e74ab.pnggfsnh-0-228.thumb.png.e4e82da3aa9a0f97a0bade2af9367512.pnggfsnh-0-264.thumb.png.7ac59c32df0a52f09927f69f9af8235e.png

The Pacific Ridge is flatter than the 06z. This means that the Atlantic trough on the 12z is stronger so the next wave goes under rather than cut through the trough. That was the trigger for Atlantic heights and the migration west of the UK high! So big changes by D11 and further delays...

...Its a surprise as the background signals are to the contrary.

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