Model output discussion - another cold spell on the horizon?

[Allseasons-Si]

ICON 180...

[Kasim Awan]

1 minute ago, Battleground Snow said:

Could work out later on?

It's frustrating to see the first attempt limited by the Azores / Iberian high. 

[Mucka]

Just now, Kasim Awan said:

It's frustrating to see the first attempt limited by the Azores / Iberian high. 

Are you sure you are not looking at the 18z?

GFS 00z is not as you describe Kasim.

[Kasim Awan]

2 minutes ago, Mucka said:

It seems pretty inconsistent run to run to me, like a broken watch it will be right some of the time as a happy accident.

UKMO and GFS aren't so far apart

Are you looking at the right charts?

 

Would be more confident in the North Easterly if the initial amplification were to be cleaner though, anything over 200 hours is really just for fun at the moment. 

[Kasim Awan]

Just now, Mucka said:

Are you sure you are not looking at the 18z?

GFS 00z is not as you describe Kasim.

No, it is, in the more reliable time frame which we're monitoring (144-200h) it fails the initial retrogression, keeps too much HP over Iberia which prevents both amplification and a cold wedge forming over the UK. 

[Mucka]

Just now, Kasim Awan said:

Would be more confident in the North Easterly if the initial amplification were to be cleaner though, anything over 200 hours is really just for fun at the moment. 

True but GFS is game over for the Atlantic by 168.

As previously posted, so long as we get the amplification the Scandi trough will do the rest.

[Battleground Snow]

Gem at 144.

I think an improvement an all models this morning is a fair assessment, but with lots of detail yet to be worked out.

Let's hope that pesky ECM drops the quick topple scenario later!

[Kasim Awan]

1 minute ago, Mucka said:

True but GFS is game over for the Atlantic by 168.

As previously posted, so long as we get the amplification the Scandi trough will do the rest.

I don't buy the amplification as a guarantee the flow will be optimal in the UK post 168h. For this a cleaner amplification is needed, shortwaves in the wrong position will prevent enough HP being sent north west, and keep a milder air mass influence. The GFSP is an example of this too. Again, please don't presume I am disregarding a cleaner amplification & potential further route to prolonged cold, these are still on the table given an initial awful attempt at Iberian high retrogression. 

[Mucka]

5 minutes ago, Kasim Awan said:

No, it is, in the more reliable time frame which we're monitoring (144-200h) it fails the initial retrogression, keeps too much HP over Iberia which prevents both amplification and a cold wedge forming over the UK. 

I'm not sure what you mean.

As far as I would understand retrogression would be for high pressure to move NW, like a classic Scandi high retrogressing to Greenland, and we have never been looking at that scenario.

It has always been Atlantic ridge and deep trough moving S/SW into Scandi bringing NE floa and it was always programmed for around alst 1/3 Jan.

Obviously we are seeing very different things.

Edited January 11, 2021 by Mucka

[Kasim Awan]

Just now, Mucka said:

I'm not sure what you mean.

As far as I would understand retrogression would be for high pressure to move NW, like a classic Scandi high retrogressing to Greenland, and we have never been looking at that scenario.

It has always been Atlantic ridge and deep trough moving S/SW into Scandi bringing NE and it was always programmed for around alst 1/3 Jan.

Obviously we are seeing very different things.

If you run all output at present from 0h to 160h you will see the high moving from east (Europe & Iberia) towards southern Greenland. This is retrogression. 

[Battleground Snow]

Pretty nippy here on the OP, its gone back to yesterday mornings solution of -20 uppers lurking in Scandinavia

 

[Ali1977]

WOW, much much better runs this morning. LOOK at that cold pool coming from over in Scandinavia

Edited January 11, 2021 by Ali1977

[Mucka]

4 minutes ago, Kasim Awan said:

I don't buy the amplification as a guarantee the flow will be optimal in the UK post 168h. For this a cleaner amplification is needed, shortwaves in the wrong position will prevent enough HP being sent north west, and keep a milder air mass influence. The GFSP is an example of this too. Again, please don't presume I am disregarding a cleaner amplification & potential further route to prolonged cold, these are still on the table given an initial awful attempt at Iberian high retrogression. 

Ah I see you mean Iberian high displaced . You are just using terminology I would usually reserve for another scenario so that clears things up some.

The way I see it the trough digging SW is going to do that job for us just so long as it is given time to with enough blocking in the Atlantic.

It was always going to be a bomb from 168/192 for that reason IMO

 

Of course we are not there yet but so long as we get the upstream amplification and that low is cut off then all the other rubbish should just move E and phase with the trough.

Edited January 11, 2021 by Mucka

[northwestsnow]

Kaboooooom.

 

[Daniel]

That's got to be one of the best runs this season?! SSW really likes teasing us

[Kasim Awan]

1 minute ago, Mucka said:

Ah I see you mean Iberian high displaced . You are just using terminology I would usually reserve for another scenario so that clears things up some.

Yeah, it depends as what you would class to be the main process here. I would class it as both retrogression & amplification. The key variable here is how much of the Iberian high is transferred north west, up to Greenland. If it retains a more significant latitude like on the GFSP 00Z, this may produce a greater risk of snow events as the jet is displaced further north within a cold flow. Further south and it's more of a showery NE feed. 

[Allseasons-Si]

2 minutes ago, northwestsnow said:

Kaboooooom.

 

I second that...

 

[Ali1977]

Unbelievably cold if this came off, possibly historic. Let’s see how cold this gets but at day 12 we have -12c uppers clearing the West coast 

[Battleground Snow]

I wish I knew what caused the models to have less stellar runs yesterday, but hopefully whatever the signal was doesn't return. A true Greenland high on the para here

 

[Ali1977]

Make that -14c uppers clearing the West coast

This could hit -18c into the East...what’s the record ????

[Daniel]

Wow! Look at that greeny high on gfs para. Cold air surging into the UK aswell.

little to west based but a lot better than its previous runs. 

Edited January 11, 2021 by Daniel

[Scott Ingham]

18 minutes ago, Kasim Awan said:

No, it is, in the more reliable time frame which we're monitoring (144-200h) it fails the initial retrogression, keeps too much HP over Iberia which prevents both amplification and a cold wedge forming over the UK. 

Kasim greenie heights arent being modelled any later its same time frame as yesterday haha

Unbelievable morning for upgrades.

Steve will be happy to see his cut off high back in the game across the board!

[Allseasons-Si]

Look north,....

 

 

[Ali1977]

This is just getting silly now, all pretty much in FI these boom charts but it’s probably as severe a cold spell as you’d ever see and about to be topped up from the North.

I’m not sure something so severe would help the emergency services with COVID if it did come off !!

 

[Kasim Awan]

2 minutes ago, Barmada_Casten said:

Chances are very, very high sadly. At least 95%.

Not really - good chance the Azores high will be phased out over time with this pattern, even if initially it is somewhat of a limiting factor as @Mucka pointed out.

As @Scott Ingham pointed out, the model bias favours the GFS in the Greenland amplification department, so I'm fairly confident that the ECM at half 6 will make a move towards increase easterly vectors around D4-7. In theory this will increase efficiency of the retrogression, amplification.