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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: Bournemouth
  • Weather Preferences: Dry mild or snow winter. Hot and humid summer.
  • Location: Bournemouth
Just now, MattStoke said:

Hmm. GP said to expect the heights to our north east to put up a fight and to not be fooled by any output that shunts it away. Guy seems to have a crystal ball.

David Beckam “golden balls” GP Crystal balls

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex
10 minutes ago, carinthian said:

There we have it. Cold air advected from the Northern European Plain at 120t . 

C

UW120-7.gif

What are your Met guys in Austria saying at the moment Carinthian, any updates?

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

Looks as if - GFS-wise, at any rate - the overnight/early morning runs' usual eastward 'realignment' has been offset by the 12Z's customary westward 'correction'...?

A very transient snow event, for some lucky eastern members? Very possibly...A reason not to concentrate on what happens immediately following Xmas? No. IMO...

As JH keeps saying: comparing 00Zs/06Zs with 12Zs/18Zs is futile...:santa-emoji:

Edited by Ed Stone
Aris about face...
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Posted
  • Location: Home: Chingford, London (NE). Work: London (C)
  • Weather Preferences: Winter: cold and snowy. Summer: hot and sunny
  • Location: Home: Chingford, London (NE). Work: London (C)
30 minutes ago, Banbury said:

Some realism for any newbies

HP is holding off the Atlantic but a strong bitter Easterly isn't on the cards , the most favourable option is something from the West eventually with average temps IMO of course 

UKMO 144 has the Atlantic held off so a chilly breeze from Europe .

 

gfs-1-84.png

gfs-1-90.png

No one is suggesting we are in for a deep cold, convective easterly. What is possible is a snow event based on an undercutting low pressure system pushing up against a colder block. You don’t need deep cold 850 temps to get snow in these situations. 

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Posted
  • Location: West Dorset
  • Weather Preferences: Warm summers, Snowy winters.
  • Location: West Dorset
2 minutes ago, danm said:

No one is suggesting we are in for a deep cold, convective easterly. What is possible is a snow event based on an undercutting low pressure system pushing up against a colder block. You don’t need deep cold 850 temps to get snow in these situations. 

Debatable but what you do need is the 0 minimum dew points.

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Posted
  • Location: Home: Chingford, London (NE). Work: London (C)
  • Weather Preferences: Winter: cold and snowy. Summer: hot and sunny
  • Location: Home: Chingford, London (NE). Work: London (C)
2 minutes ago, Stuie W said:

Debatable but what you do need is the 0 minimum dew points.

Yes agree you need 0 to sub zero dew points. However you don’t need -10c 850s in those situations. Zero to -2c can sometimes do the trick as long as we have the dew points on side. 

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Posted
  • Location: West Dorset
  • Weather Preferences: Warm summers, Snowy winters.
  • Location: West Dorset
6 minutes ago, danm said:

Yes agree you need 0 to sub zero dew points. However you don’t need -10c 850s in those situations. Zero to -2c can sometimes do the trick as long as we have the dew points on side. 

True but I am not seeing that scenario in this setup. I`d be much happier with -8 850`s 1st.

Edit: It is looking like the dew points are only going to come with the colder air.

dew points.JPG

Edited by Stuie W
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Posted
  • Location: Hertfordshire
  • Weather Preferences: SNOW AND FREEZING TEMPS
  • Location: Hertfordshire
10 minutes ago, Stuie W said:

True but I am not seeing that scenario in this setup. I`d be much happier with -8 850`s 1st.

Edit: It is looking like the dew points are only going to come with the colder air.

dew points.JPG

But isn’t that dew points chart from the gfs ? And if so it’s no where near as good UKMO , so they might be lower than that . 

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Posted
  • Location: West Dorset
  • Weather Preferences: Warm summers, Snowy winters.
  • Location: West Dorset
Just now, ICE COLD said:

But isn’t that dew points chart from the gfs ? And if so it’s no where near as good UKMO , so they might be lower than that . 

It is but just highlighting the point mate that without the colder air in situ the dew points are not there.

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

Well for the first time I think we get a view of what happens after the progged warming, unsure yet if it is an official SSW, here GFS T324, with temps above +4:

image.thumb.jpg.17b52dba24f32ee9830721e7fd2b4a9a.jpg

 And it leaves us like this at the end of the run

image.thumb.jpg.c5e309abb7281719d8c9335ff6df99f6.jpg

Well disturbed vortex, in a good way? time will tell!

Edited by Mike Poole
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Posted
  • Location: Netherlands close to the coast
  • Location: Netherlands close to the coast
1 minute ago, Mike Poole said:

Well for the first time I think we get a view of what happens after the SSW, here GFS T324, with temps above +4:

image.thumb.jpg.17b52dba24f32ee9830721e7fd2b4a9a.jpg

 And it leaves us like this at the end of the run

image.thumb.jpg.c5e309abb7281719d8c9335ff6df99f6.jpg

Well disturbed vortex, in a good way, time will tell!

Gfs is not very reliable for strat forecasts at that time frame, only from around 168h out does the forecast have any credibility. Every winter this signal for a warming is there at the end of a run

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
6 minutes ago, Weather-history said:

GFSOPNH12_324_1.png

GFSOPNH12_324_42.png

Polar vortices at the tropopshere and stratosphere look under stress on the 12z run

Which might just tie-in with the very cold uppers, to our NW and NE, shown on the GFS 12Z?

Netweather GFS Image

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
2 minutes ago, ArHu3 said:

Gfs is not very reliable for strat forecasts at that time frame, only from around 168h out does the forecast have any credibility. Every winter this signal for a warming is there at the end of a run

I would go a lot further than that - i've never seen a clear SSW bust at 240 on any model. the warmings at the end are always gone within a couple of runs if they have no credence.

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Posted
  • Location: Longton, Stoke-on-Trent.
  • Location: Longton, Stoke-on-Trent.

GFS finishes with some height rises to our north west, like Catacol has been saying, and the flow from a northerly quarter again,

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