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The Hunt for Cold continues 02/01/19


phil nw.
Message added by phil nw.

 

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)

Message added by Paul

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Posted
  • Location: STEVENAGE, HERTS (100M ASL)
  • Location: STEVENAGE, HERTS (100M ASL)
12 minutes ago, Dancerwithwings said:

The word “Any” but how long do see as in a timeline is a cold spell.

Now you’ve also mentioned no one is gaaranteeing a cold spell, but they aren’t gaaranteeing it won’t happen either.

Agreed. No one is guaranteeing anything will or won’t happen hence the term ‘any possible colds spell’ 

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Below the UKMO at T96 hrs:

The circled red is the shortwave , the black is the low associated with the main troughing which develops upstream. That triangle is the key separation.

UN96-21.thumb.gif.073b111f27fc067526a3def91040e877.gif

We want as much distance between both, and we want the UKMO to weaken the low , this means it wont track so close to the low and be further south.

We must keep separation because if they phase then the energy will pile over the top and we wont develop a decent ridge north later. Yarmy posted the GEFS spreads  on the previous page at day 4 you can see the issues the models are having with this shortwave energy.

Edited by nick sussex
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Posted
  • Location: STEVENAGE, HERTS (100M ASL)
  • Location: STEVENAGE, HERTS (100M ASL)
12 minutes ago, Steve Murr said:

 

Lets go a whole day & not post the GFS.

Agreed....Unless it’s showing raging blizzards, in which case post away!

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Posted
  • Location: Wyke regis overlooking Chesil beach.
  • Weather Preferences: Snowfall
  • Location: Wyke regis overlooking Chesil beach.
27 minutes ago, Steve Murr said:

The problem is clear here.

To much blind faith in the GFS 'mobility' forecast.

This is the SAME GFS ( excl FV3 ) thats been wrong for the last 10 days over estimating the 'eastward' projection.

Lets go a whole day & not post the GFS.

And even with its mobility bias problems it still gets us to a nw/se jet axis at the end with the Eastern PV lobe dropping into Scandi and a pressure build behind the incoming low from the NW. 

Just another version on the sinking jet theme that was far more vigorously demonstrated on the 06z para 

The 12z GFS is certainly not as good as the 06z para but in terms of where we end up around mid month it's far from a disaster.

Edited by Broadmayne blizzard
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

To use an analogy the GFS is like an all you can eat cheap buffet ! Plenty of food but you end up with indigestion . 

Its good they provide so much free info to the public but it’s flat bias upstream is an issue . 

Edited by nick sussex
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Posted
  • Location: Solihull, WestMidlands, 121m asl -20 :-)
  • Weather Preferences: Cold and Snow -20 would be nice :)
  • Location: Solihull, WestMidlands, 121m asl -20 :-)
26 minutes ago, Yarmy said:

The GEFS are all over the shop even at T96:

https://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=96

No need to guess where the uncertainty is:

gensnh-22-1-96.png

Blimely, from Monday there are big differences 

1D376612-F289-4445-85AD-21815CEC2583.thumb.png.545d99e0ba6445fc46e167fc3f1e27fa.png

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Tonights NAVGEM is a good example of why phasing ends up a calamity !

Energy piles over the top . This is why it’s crucial this doesn’t happen . 

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Posted
  • Location: South Essex
  • Location: South Essex
1 minute ago, BlackburnChris said:

A GFS excluded thread would be a good idea actually ... 

So, exclude the model that gives us the most free data by a country mile. Hmmmmm .

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Posted
  • Location: Netherlands close to the coast
  • Location: Netherlands close to the coast
1 minute ago, BlackburnChris said:

A GFS excluded thread would be a good idea actually ... 

It is not a junk model and during winter seems to have an edge over EC, it is true that it is flat, flatter than the other models but unfortunately it turns out to be right more often than not 

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Posted
  • Location: Penkridge
  • Weather Preferences: Virgins
  • Location: Penkridge
1 minute ago, Jason M said:

So, exclude the model that gives us the most free data by a country mile. Hmmmmm .

A rule that all GFS posts are accompanied by the theme tune from the Benny Hill show should suffice.

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .
4 minutes ago, BlackburnChris said:

A GFS excluded thread would be a good idea actually ... 

Isn’t that a bit cruel ! Yes it annoys us but we’ll have nothing to moan about in the morning and night ! 

Lets not forget the ECM has hardly covered itself in glory over the last few days especially past day 6 .

 

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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20
1 minute ago, ArHu3 said:

It is not a junk model and during winter seems to have an edge over EC, it is true that it is flat, flatter than the other models but unfortunately it turns out to be right more often than not 

It verifies below the ECMWF and UKMO consistently.  It’s a decent model but there is better available.

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Posted
  • Location: Oldbury, West midlands
  • Weather Preferences: Heavy snow, Thunder storms and lightning
  • Location: Oldbury, West midlands
52 minutes ago, nick sussex said:

Everyone knows I like to moan about the outputs but in the more reliable timeframe both the GFS and UKMO have improved .

The shortwave energy in the Atlantic though is turning into a real problem for the models , no agreement on that.

I know I’ve been droning on about phasing for days but it’s key this doesn’t happen , and we want a weak shortwave . The UKMO gets there but if it’s shortwave was weaker it’s day 6 would have been better .

We need as much distance between the shortwave and upstream deep low as possible to increase the margin of error.

HI Nick any chance you could draw a diagram of the offending shortwave and what we need it to do. When I look at it i just see many low pressure systems as I learn the finer detail. Would be great for Novices to keep an eye on also. Thanks for your great posts well appreciated.

 

Edit you just did it lol. Thankyou

Edited by snowangel32
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Posted
  • Location: Kensington
  • Location: Kensington
1 minute ago, ArHu3 said:

It is not a junk model and during winter seems to have an edge over EC, it is true that it is flat, flatter than the other models but unfortunately it turns out to be right more often than not 

No matter what time of year  it never has the edge over the Ecm.  For me no model has covered itself in glory this winter but the GFS in particular has been woeful  it comes out 4 times a day which is why most look at it  but for me its ranked fourth in weather consistency.    

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
5 minutes ago, feb1991blizzard said:

Its just not downwelling properly, thats the problem.

So long as the actual weather is downwelling okay, all should still be alright?;)

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

5 gef clusters at day 6

https://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cz50&HH=144&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

sums up the uncertainty,in fact 8 clusters at day 10!

The only fairly consistent trend seems to be a Sceuro trough and the High receding into the Atlantic eventually as the jet tends to a more nw/se axis,not a mild pattern and could easily turn colder.More amplification of that high would release the cold south,there lies the uncertainty.

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Posted
  • Location: South Essex
  • Location: South Essex
Just now, Skyraker said:

A rule that all GFS posts are accompanied by the theme tune from the Benny Hill show should suffice.

We could also exclude ECM because it tends to over amplify leading to fantasy easterlies. Maybe exclude GEM, ICON, NAVGEM and JMA because they are all a bit useless. METO tends to be good up to 120 but the 144 charts are often not good so we could bin that as well. 

Not saying that it doesn't have its weaknesses but so do all the other models. The more data the better. METO may not use GFS as a first line model but I doubt they would just automatically bin it. Also peeps are assuming its wrong in bringing in a short period of mobility before the pattern quickly re amplifies. It may yet be proved right.

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .
Just now, snowangel32 said:

HI Nick any chance you could draw a diagram of the offending shortwave and what we need it to do. When I look at it i just see many low pressure systems as I learn the finer detail. Would be great for Novices to keep an eye on also. Thanks for your great posts well appreciated.

Top of the page , the offending shortwave is there . In a nutshell you want that weaker and further south . The key thing though is it remains seperated from the other low circled black .

If you have a phasing this does two things it helps to pull the low further east , it also stops our limpet high to the south from extending a ridge nw . We want the shortwave to run east and then turn more se , if it remains clear of the upstream low the limpet high will ridge through the gap . Then we want the low left behind to elongate north south.  This means it’s amplifying , this then helps to draw the ridge further north ahead of that .

 

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Posted
  • Location: Mill Corner East Sussex, 55m asl
  • Weather Preferences: snow,thunder,tornados
  • Location: Mill Corner East Sussex, 55m asl

Well,we all know it wont play ball

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Posted
  • Location: Hull
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Hull
2 minutes ago, Jason M said:

We could also exclude ECM because it tends to over amplify leading to fantasy easterlies. Maybe exclude GEM, ICON, NAVGEM and JMA because they are all a bit useless. METO tends to be good up to 120 but the 144 charts are often not good so we could bin that as well. 

Not saying that it doesn't have its weaknesses but so do all the other models. The more data the better. METO may not use GFS as a first line model but I doubt they would just automatically bin it. Also peeps are assuming its wrong in bringing in a short period of mobility before the pattern quickly re amplifies. It may yet be proved right.

Indeed it does make me laugh, if the GFS was showing a screaming easterly and the ECM was showing a sinking high everyone would be complaining about the ECM.

The ECM is slightly better then the GFS but the GFS should be considered in its own right...

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Posted
  • Location: Oldbury, West midlands
  • Weather Preferences: Heavy snow, Thunder storms and lightning
  • Location: Oldbury, West midlands
2 minutes ago, nick sussex said:

Top of the page , the offending shortwave is there . In a nutshell you want that weaker and further south . The key thing though is it remains seperated from the other low circled black .

If you have a phasing this does two things it helps to pull the low further east , it also stops our limpet high to the south from extending a ridge nw . We want the shortwave to run east and then turn more se , if it remains clear of the upstream low the limpet high will ridge through the gap . Then we want the low left behind to elongate north south.  This means it’s amplifying , this then helps to draw the ridge further north ahead of that .

 

Yh i just saw it mate. So many posts so quick lol. Just shows the fine margins getting cold and snow to the UK. Shortwave has to be my New swear word lol. Thanks again.

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