Model output discussion 24/01/21

[Tim Bland]

Bootyfull ️

[IDO]

We see how the gfs op has changed over the last few runs. The 12z from yesterday and the 06z (ditto 0z):

The high exiting the esb cuts through a low, creating a cut-off trough in the Atlantic on the latest runs, but last night the high slid further SE and did not dissect that low from the trough. This of course will suppress any nascent wedge building to our north, as it shows. The ecm has also reverted to the cut-off trough on the 0z where as the GEM and para keep to yesterday's gfs modelling of this development:

On the gfs 06z this again delays the change to a colder flow from the NE until T300, but never quite makes it with the severe cold uppers due to the west based developments in FI. Another pivot point? Will this again go the wrong way and further delay that colder solution? 

Edited January 27, 2021 by IDO

[Tim Bland]

1 hour ago, ALL ABOARD said:

ECM with snow for part of Wales, the Midlands and South West England on Sunday 

See attached mean below as well

GFS, however more of rain to snow event as the low slides.   

Place your bets 

Snow depths only show a trace across western areas with more substantial falls reserved for welsh hills. Depths further north are either there now or from tomorrow 

[Griff]

12 minutes ago, Ice Day said:

Well these are much better runs that the overnighters.  At this point we are only looking at the broad synoptics as the real interest is out in FI.  But, we are seeing the height rises to the north appearing as per yesterdays MO update,  We will see some stonkers and some stinkers over the next few days; either could be the net result.  However, another cold chase is underway, I'm up for it!

Oh, and the Para is a doozy at 276

100% agreed, hanging on each and every run as gospel will cause anxiety and exhaustion. 

Spot on, things are going to swing between good and bad until it works things out. Chances are the signal might fade, but wouldn't it be great if this counted down, I'm very keen to see what the gem says later  

[Scandinavian High.]

Looks like bomb as gone off up top parts of vortex every where..

[Scandinavian High.]

7 minutes ago, IDO said:

We see how the gfs op has changed over the last few runs. The 12z from yesterday and the 06z (ditto 0z):

The high exiting the esb cuts through a low, creating a cut-off trough in the Atlantic on the latest runs, but last night the high slid further SE and did not dissect that low from the trough. This of course will suppress any nascent wedge building to our north, as it shows. The ecm has also reverted to the cut-off trough on the 0z where as the GEM and para keep to yesterday's gfs modelling of this development:

On the gfs 06z this again delays the change to a colder flow from the NE until T300, but never quite makes it with the severe cold uppers due to the west based developments in FI. Another pivot point? Will this again go the wrong way and further delay that colder solution? 

And what’s betting next run uk will be in freezer . very encouraging Heights building to north of uk lots of my changes to come.

[That ECM]

Still many of interest. 

[Froze were the Days]

To put it succinctly Its a real struggle getting any decent cold towards our shores into February as the ecm is currently showing with low pressure keeping the cold to our north and north east though GFS runs juggle with cold shots at times...I know what model I'd trust towards day 10 so the search goes on. Potential there but that's all it is.

And the posts that keep whacking out these perturbation charts...I just don't understand it, they never come to fruition.

Edited January 27, 2021 by Froze were the Days

[nick sussex]

Sometimes you get repeated attempts to develop a high to the n/ne before it finally lands close enough to the UK to direct the cold sw wards .

As long as you keep that amplified wave digging the cold into the central USA your downstream pattern will want to carve energy se either through or to the west of the UK.

This normally then sees high pressure developing to the ne of that troughing associated with that se push of energy .

 

[Methuselah]

I'm nae interested in details but, there could be a potential 'elephant in the room', as the 06Z closes out: another burst of air, originating from >20C T850s, could be pushing north through Eastern Europe and perhaps even on into Scandinavia; something that seems to happen more and more often, these past few years:

    

But, at least the cold pool already in place, over Scandi, is several degrees colder than it was, at the beginning of the month...

Edited January 27, 2021 by General Cluster
Clarification

[Cold Winter Night]

1 minute ago, General Cluster said:

I'm nae interested in details but, there could be a potential 'elephant in the room', as the 06Z closes out: another burst of >20C T850s could be pushing north through Eastern Europe and perhaps even on into Scandinavia; something that seems to happen more and more often, these past few years:

    

But, at least the cold pool already in place, over Scandi, is several degrees colder than it was, at the beginning of the month...

Your chart has 5c T850's in Eastern Europe, -15c and lower in Scandinavia and the >20c is in Libya?

[Turnedoutniceagain]

Ramping up nicely for Sunday

 

[Anthony Burden]

GFS chopping and changing but it is encouraging to see the cold scenario keep returning,

my take it won’t be long before northern blocking starts to show more strength in establishing.

[Kentspur]

41 minutes ago, Tim Bland said:

Snow depths only show a trace across western areas with more substantial falls reserved for welsh hills. Depths further north are either there now or from tomorrow 

Looks about right ECM was the best model last weekend

Edited January 27, 2021 by Kentspur

[johnholmes]

3 minutes ago, Anthony Burden said:

GFS chopping and changing but it is encouraging to see the cold scenario keep returning,

my take it won’t be long before northern blocking starts to show more strength in establishing.

A genuine question.

What is your reason for saying that, what proof is there of this happening please?

 

[Lampostwatcher]

3 minutes ago, Kentspur said:

Looks about right ECM was the best model last weekend

Hopefully as it's 4 days away it may change in your favour lol

[Kentspur]

Just now, Lampostwatcher said:

Hopefully as it's 4 days away it may change in your favour lol

I know this was posted yesterday, I have a good memory when it comes to snow events here, and all of these years with lengthy days of -AO I've been around to witness we had atleast 1 decent snow event down here in the SE so I'm sure it will come eventually, or else it will go down as the most unluckiest winter ever!

[mountain shadow]

6 minutes ago, Kentspur said:

I know this was posted yesterday, I have a good memory when it comes to snow events here, and all of these years with lengthy days of -AO I've been around to witness we had atleast 1 decent snow event down here in the SE so I'm sure it will come eventually, or else it will go down as the most unluckiest winter ever!

Or, that the AO in itself is not a main player, we need that Neutral / East based -NAO too.

[SqueakheartLW]

My favourite cold charts from GFS and GEM 00z runs

GFS Member 28

GFS Member 29

GEM Member 12

GFS Extended Member 6

Scenario Time - GEM 00z Member 5

A good scenario here on the 00z GEM run this morning and the main question here is .....

How the hell do we get cold from this starting situation?

+246 hours

Nothing too noteworthy here to start off with with some colder air just retreating away to the north as low pressure and milder air starts pushing up from the south and this chart currently screams "winter is over now"

+312 hours

By 312 hours we are under +5 to +10 uppers and at this point it looks like there's no way back to a colder route from here but look east and there's colder air dropping down into eastern Europe at this time and WWA is beginning to take place

+342 hours

By 342 hours the UK is still under the milder air mass but the WWA is under full swing now and notice how the high pressure has also pushed northwards too. This is now opening the doors to a potential beasterly to get going

+360 hours

By 360 hours the WWA has done its work and has helped to blow up a decent area of northern blocking and this is forcing the low pressure areas to dive underneath this so cutting off the source of milder air and colder air is now moving across the North Sea and towards the UK as the winds back into the east

+372 hours

By 372 hours the winds have gone round fully to the east and the -5 isotherm has cleared most of the UK by this stage and the -10 isotherm isn't far away now and an increasingly strong biting beasterly is getting going and no doubt snow showers are blowing in off the North Sea

+384 hours

By 384 hours and the end of the run the -5 isotherm has completely cleared the UK and the -10 isotherm has got a bit closer too. Also the blocking looks to be even more set in too. A proper beasterly is now in full swing here and even colder air is lurking further to the east here ready to move in if the pattern can stick.

[Man With Beard]

GEFS mean at T276. That surface Scandi High is growing run by run. I tend to get excited when the mean hits 1030mb.

The cautionary note is that the ECM mean built a large high over the South of Europe by D15. Would suggest we might not get a cut-off Scandi High for long. But it's early days

Edited January 27, 2021 by Man Without Beard

[Griff]

5 minutes ago, Man Without Beard said:

GEFS mean at T276. That surface Scandi High is growing run by run. I tend to get excited when the mean hits 1030mb.

The cautionary note is that the ECM mean built a large high over the South of Europe by D15. Would suggest we might not get a cut-off Scandi High for long. But it's early days

Thank you, I really value these kinds of posts (even when they bring bad news), because they cut through the chaos and noise.

[weathermadbarnsleylad]

10 minutes ago, Griff said:

Thank you, I really value these kinds of posts (even when they bring bad news), because they cut through the chaos and noise.

Yes excellent post mate thanks 

[weathermadbarnsleylad]

17 minutes ago, Man Without Beard said:

GEFS mean at T276. That surface Scandi High is growing run by run. I tend to get excited when the mean hits 1030mb.

Excellent post thanks 

[sebastiaan1973]

1 hour ago, Man Without Beard said:

GEFS mean at T276. That surface Scandi High is growing run by run. I tend to get excited when the mean hits 1030mb.

The cautionary note is that the ECM mean built a large high over the South of Europe by D15. Would suggest we might not get a cut-off Scandi High for long. But it's early days

Yes it does. But is it a real 'cold delivery service'? In the ENS I don't see powerful Scandihighs as a result of heat advection from south to north. As e.g. in February 1991.

Edited January 27, 2021 by sebastiaan1973

[Kentspur]

59 minutes ago, mountain shadow said:

Or, that the AO in itself is not a main player, we need that Neutral / East based -NAO too.

Yes that's a very good point I always prefer a strong negative East based -NAO over a strong -AO. But its definitely best to have both at once also, also Scandi highs tend to give us the goods down here which we've not really seen this winter

Edited January 27, 2021 by Kentspur