Model output discussion - Jan 3rd onwards

[Paul_1978]

10 minutes ago, steveinsussex said:

70% said who?

He’s referring to the fact that in 66.6% of cases SSWs lead to cold, but in 33.3% of cases they don’t. (They might not be the exact figures but that’s the gist of it). 

[joggs]

35 minutes ago, Tamara said:

A seasonal absentee by-stander in all this - but a one-off offering from me.

Its a pity that this post is getting taken apart in some quarters, because hypothetically it *could* promote some interesting discussion if the snow goggle biases were put away for a moment.

This winter has seen a much greater disconnect of the atmosphere to the La Nina base state than anticipated. Intense seasonal bias confirmation processes customarily disguise this, but if one is prepared to stay detached from that, it has been something of a surprise to the neutral diagnostic elements enthusiast. 

What is meant by this disconnect? In simplest terms, much greater poleward rossby wave propagation has taken place than under a more 'connected' and stable w/QBO La Nina  low angular momentum regime in early winter would usually provide. The autumn itself, heading into the first few weeks of winter, saw (overall)  a much more typical EL Nino type presentation, with a downstream configuration that until the festive period did not, mostly apart from a brief period, feature the expected sub tropical Atlantic ridging and instead a configuration of warm air advection processes c/o an amplified Atlantic trough and downstream European ridging. This alignment ultimately provided the feedback catalyst to assist  the wave breaking that has instigated instability of the polar field, albeit reversal of zonal winds are restricted closer to 10mb level.

Interestingly, global relative angular momentum has been slowly falling since the festive period and continuing into the first days of January.

 

 

The Global Wind Oscillation, a phase plot depiction of wind-flow inertia between the tropics and extra tropics has slowly slipped towards the La Nina attractor phases - reflecting greater harmony with the ocean base state.  

 

The effects of falling momentum are to switch greater inertia into the polar jet from upstream. The initial manifestation of this c/o the weakness across the polar field has been for the usual feed of this inertia to proceed eastwards closer between 50 and 60N to be somewhat roadblocked, and instead looped around the pole and create the blocking structures close by to the NNE and linked to the amplification of the more Nina-esque Atlantic ridge.

However, the difficulty comes with how these blocking structures respond to continued displacement/split processes within the polar field at the same time as angular momentum continues to fall ( *in the shorter term absence of any westerly inertia supplied by tropical forcing)  and much more closely match the underlying base state. This is where the post under reply holds the interest I was mentioning at the beginning and should be treated with better respect

It is perfectly conceivable, at least for a time, for polar jet energy to make greater inroads eastwards at mid latitudes, as the polar field continues to re-organise and as the period of time approaches where zonal winds, at least temporarily, are increased within the lower stratosphere and troposphere boundary. Not to any great levels  by any means, as the overall structures continue to look weak and unstable-but enough to allow a more westerly induced pattern to prevail, at least for a time, with a more traditional Nina-esque Atlantic ridge centred close to the west or south west and ebbing and flowing within the bandwidth of displaced vortexing to the NE.

*The further wildcard is intraseasonal MJO forcing. In keeping with w/BQO Nina-esque regimes, and linked to known periodicity timelines for high frequency activity - it is worth watching out for signs of an eastward convective parcel progression attempting to negotiate the Pacific later in January or possibly into February.    A further variable that could see a sudden and quite dramatic surge in atmospheric angular momentum, tipping the resultant synoptic patterns even more their head.     Impossible obviously to know where and when these may set up hemispherically at this stage - but high impact synoptics are conceivable with very large temperature boundaries across the mid latitudes.

That is all for another time. Perhaps.  Closer to home, putting preference biases completely aside, whatever they maybe - from a neutral meteorological point of view its a very tricky time for numerical modelling ahead which encompasses the ensemble suites and representative upper air anomaly charts . The overriding diagnostic (GWO tropical>extra tropical momentum relationship vs a very disjointed polar field)  susceptible to highly erratic global wind-flow patterns at the tropopause boundaries and creating precipitous jumps in synoptic patterns, at mid latitude,... in either direction.

Falling momentum and weak high frequency MJO activity for the foreseeable future (* above caveat aside ) does weight probabilities towards a more typical sub tropical regime and polar jet flow arcing around this. At the same time and as can be seen, there are very hard to keep tabs of pockets of weak inertia popping op at relatively short notice closer to 60N which quite easily could stall westerly inertia and create subtle eddies within the jet which build very weak 'cold' ridges and derail the movement of troughs from west to east and restrict warm air advection

At present, no outcome is to be discounted or dismissed out of hand, and any discussion should be unclouded by bias preferences and be open minded to the even greater than usual uncertainties. That is not sitting on the fence - its honest objectivity in the face of highly sensitive factors that require a watching brief ,rather than any impetuous call for the sake of wanting to appear confident in appealing to a specific popular outcomes.

Once again ,thank you Tamara. Hope alls well.

[Cleeve Hill]

40 minutes ago, Tamara said:

A seasonal absentee by-stander in all this - but a one-off offering from me.

Its a pity that this post is getting taken apart in some quarters, because hypothetically it *could* promote some interesting discussion if the snow goggle biases were put away for a moment.

This winter has seen a much greater disconnect of the atmosphere to the La Nina base state than anticipated. Intense seasonal bias confirmation processes customarily disguise this, but if one is prepared to stay detached from that, it has been something of a surprise to the neutral diagnostic elements enthusiast. 

What is meant by this disconnect? In simplest terms, much greater poleward rossby wave propagation has taken place than under a more 'connected' and stable w/QBO La Nina  low angular momentum regime in early winter would usually provide. The autumn itself, heading into the first few weeks of winter, saw (overall)  a much more typical EL Nino type presentation, with a downstream configuration that until the festive period did not, mostly apart from a brief period, feature the expected sub tropical Atlantic ridging and instead a configuration of warm air advection processes c/o an amplified Atlantic trough and downstream European ridging. This alignment ultimately provided the feedback catalyst to assist  the wave breaking that has instigated instability of the polar field, albeit reversal of zonal winds are restricted closer to 10mb level.

Interestingly, global relative angular momentum has been slowly falling since the festive period and continuing into the first days of January.

 

 

The Global Wind Oscillation, a phase plot depiction of wind-flow inertia between the tropics and extra tropics has slowly slipped towards the La Nina attractor phases - reflecting greater harmony with the ocean base state.  

 

The effects of falling momentum are to switch greater inertia into the polar jet from upstream. The initial manifestation of this c/o the weakness across the polar field has been for the usual feed of this inertia to proceed eastwards closer between 50 and 60N to be somewhat roadblocked, and instead looped around the pole and create the blocking structures close by to the NNE and linked to the amplification of the more Nina-esque Atlantic ridge.

However, the difficulty comes with how these blocking structures respond to continued displacement/split processes within the polar field at the same time as angular momentum continues to fall ( *in the shorter term absence of any westerly inertia supplied by tropical forcing)  and much more closely match the underlying base state. This is where the post under reply holds the interest I was mentioning at the beginning and should be treated with better respect

It is perfectly conceivable, at least for a time, for polar jet energy to make greater inroads eastwards at mid latitudes, as the polar field continues to re-organise and as the period of time approaches where zonal winds, at least temporarily, are increased within the lower stratosphere and troposphere boundary. Not to any great levels  by any means, as the overall structures continue to look weak and unstable-but enough to allow a more westerly induced pattern to prevail, at least for a time, with a more traditional Nina-esque Atlantic ridge centred close to the west or south west and ebbing and flowing within the bandwidth of displaced vortexing to the NE.

*The further wildcard is intraseasonal MJO forcing. In keeping with w/BQO Nina-esque regimes, and linked to known periodicity timelines for high frequency activity - it is worth watching out for signs of an eastward convective parcel progression attempting to negotiate the Pacific later in January or possibly into February.    A further variable that could see a sudden and quite dramatic surge in atmospheric angular momentum, tipping the resultant synoptic patterns even more their head.     Impossible obviously to know where and when these may set up hemispherically at this stage - but high impact synoptics are conceivable with very large temperature boundaries across the mid latitudes.

That is all for another time. Perhaps.  Closer to home, putting preference biases completely aside, whatever they maybe - from a neutral meteorological point of view its a very tricky time for numerical modelling ahead which encompasses the ensemble suites and representative upper air anomaly charts . The overriding diagnostic (GWO tropical>extra tropical momentum relationship vs a very disjointed polar field)  susceptible to highly erratic global wind-flow patterns at the tropopause boundaries and creating precipitous jumps in synoptic patterns, at mid latitude,... in either direction.

Falling momentum and weak high frequency MJO activity for the foreseeable future (* above caveat aside ) does weight probabilities towards a more typical sub tropical regime and polar jet flow arcing around this. At the same time and as can be seen, there are very hard to keep tabs of pockets of weak inertia popping op at relatively short notice closer to 60N which quite easily could stall westerly inertia and create subtle eddies within the jet which build very weak 'cold' ridges and derail the movement of troughs from west to east and restrict warm air advection

At present, no outcome is to be discounted or dismissed out of hand, and any discussion should be unclouded by bias preferences and be open minded to the even greater than usual uncertainties. That is not sitting on the fence - its honest objectivity in the face of highly sensitive factors that require a watching brief ,rather than any impetuous call for the sake of wanting to appear confident in appealing to a specific popular outcomes.

Love your input Tamara. 
Don’t be a stranger - looking forward to your next instalment.  

[swfc]

Subtle changes coming on ec I suspect 144 hrs

[Scott Ingham]

19 minutes ago, steveinsussex said:

So Atlantic based lows and ‘normal winter conditions’ more favoured....

 

disappointing news 

Temporarily with a caveat that this season has seen short term rises in aam from pockets of inertia around 60n which get modelled at short range. I believe Matt Hugo has a tweet about this. Also the ssw has the effect of disrupting westerly energy and creating home grown amplification. The interesting element is the low base state aam interacting with high pressures carved by ssw. This is extremely hard enough to model to as she says not give any confidence to any side of the camp. Warm or cold.

The thing that may tip things in our favour is the expected movement of an mjo cycle into the western hemisphere back end of january which could bring us out of -aam into +aam. 

So in summary

Short term westerly momentum potentially hitting a brick wall against the ssw, pockets of easterly winds from autumn at 60n and an active mjo wave.

Basocally end of january is 50/50. Both camps in the game as her last paragraph suggests.

So the post of "normal winter conditions favroured" wasnt the over riding message no

Edited January 6, 2021 by Scott Ingham

[SMU]

Not bad...

[Griff]

1 minute ago, Steve Murr said:

Not bad...

Can't be, not 10 days away  

[Man With Beard]

Clutching at straws but definitely more heights towards Greenland than normal at D15

 

 

[TSNWK]

3 minutes ago, Steve Murr said:

Not bad...

Agreed and of interest is that even at 120 the heights were forming towards Iceland unlike this morning..

[swfc]

3 minutes ago, Griff said:

Can't be, not 10 days away  

FI 144 hrs. Its building better heigths

[Blessed Weather]

No more discussing Met Office videos in here please. Use the Moans/Chat thread. Thank you.

[Daniel*]

More competition between air masses evident. Still favour U.K. to be milder but next weeks weather isn’t totally straightforward likely more settled. 

[Battleground Snow]

Para v ECM at 168

 

[winterof79]

Be gone with you PV 

[Vikos]

Maybe those rules apply also at your island for cold winters

-Colder winters tend to have a "mild" phase around mid January, "warm" winters do it the opposite way and have cold spells then

-Inversion cold is underrated, west-drifts overrated by GFS

-short zonal periods are often a sign of significant changes in the NH-Patterns

Edited January 6, 2021 by Vikos

[Griff]

2 minutes ago, Battleground Snow said:

Para v ECM at 168

 

Good to see ecm is finally playing catch up as it seems to twice a week. 

[Notty]

ECM -v- GFS(P) at T+192

[TSNWK]

Was not expecting this T192.. I thought that disruption low  to our north west that was a barrel ball about to flatten it at 168.

and where did that trough come from over the North Sea.

 

[Griff]

2 minutes ago, Notty said:

ECM -v- GFS(P) at T+192

Thing is if it was the GFSP I'd be making bold claims about heights rises around about now, not so sure here though, but I like it. 

[swfc]

3 minutes ago, TSNWK said:

Was not expecting this T192.. I thought that disruption low  to our north west that was a barrel ball about to flatten it at 168.

and where did that trough come from over the North Sea.

 

Looks a bit suspect 192 onwards 

[winterof79]

A flexing of the Scandi muscles 

 

Edited January 6, 2021 by winterof79

[Griff]

 

[chris55]

52 minutes ago, Tamara said:

A seasonal absentee by-stander in all this - but a one-off offering from me.

Its a pity that this post is getting taken apart in some quarters, because hypothetically it *could* promote some interesting discussion if the snow goggle biases were put away for a moment.

This winter has seen a much greater disconnect of the atmosphere to the La Nina base state than anticipated. Intense seasonal bias confirmation processes customarily disguise this, but if one is prepared to stay detached from that, it has been something of a surprise to the neutral diagnostic elements enthusiast. 

What is meant by this disconnect? In simplest terms, much greater poleward rossby wave propagation has taken place than under a more 'connected' and stable w/QBO La Nina  low angular momentum regime in early winter would usually provide. The autumn itself, heading into the first few weeks of winter, saw (overall)  a much more typical EL Nino type presentation, with a downstream configuration that until the festive period did not, mostly apart from a brief period, feature the expected sub tropical Atlantic ridging and instead a configuration of warm air advection processes c/o an amplified Atlantic trough and downstream European ridging. This alignment ultimately provided the feedback catalyst to assist  the wave breaking that has instigated instability of the polar field, albeit reversal of zonal winds are restricted closer to 10mb level.

Interestingly, global relative angular momentum has been slowly falling since the festive period and continuing into the first days of January.

 

 

The Global Wind Oscillation, a phase plot depiction of wind-flow inertia between the tropics and extra tropics has slowly slipped towards the La Nina attractor phases - reflecting greater harmony with the ocean base state.  

 

The effects of falling momentum are to switch greater inertia into the polar jet from upstream. The initial manifestation of this c/o the weakness across the polar field has been for the usual feed of this inertia to proceed eastwards closer between 50 and 60N to be somewhat roadblocked, and instead looped around the pole and create the blocking structures close by to the NNE and linked to the amplification of the more Nina-esque Atlantic ridge.

However, the difficulty comes with how these blocking structures respond to continued displacement/split processes within the polar field at the same time as angular momentum continues to fall ( *in the shorter term absence of any westerly inertia supplied by tropical forcing)  and much more closely match the underlying base state. This is where the post under reply holds the interest I was mentioning at the beginning and should be treated with better respect

It is perfectly conceivable, at least for a time, for polar jet energy to make greater inroads eastwards at mid latitudes, as the polar field continues to re-organise and as the period of time approaches where zonal winds, at least temporarily, are increased within the lower stratosphere and troposphere boundary. Not to any great levels  by any means, as the overall structures continue to look weak and unstable-but enough to allow a more westerly induced pattern to prevail, at least for a time, with a more traditional Nina-esque Atlantic ridge centred close to the west or south west and ebbing and flowing within the bandwidth of displaced vortexing to the NE.

*The further wildcard is intraseasonal MJO forcing. In keeping with w/BQO Nina-esque regimes, and linked to known periodicity timelines for high frequency activity - it is worth watching out for signs of an eastward convective parcel progression attempting to negotiate the Pacific later in January or possibly into February.    A further variable that could see a sudden and quite dramatic surge in atmospheric angular momentum, tipping the resultant synoptic patterns even more their head.     Impossible obviously to know where and when these may set up hemispherically at this stage - but high impact synoptics are conceivable with very large temperature boundaries across the mid latitudes.

That is all for another time. Perhaps.  Closer to home, putting preference biases completely aside, whatever they maybe - from a neutral meteorological point of view its a very tricky time for numerical modelling ahead which encompasses the ensemble suites and representative upper air anomaly charts . The overriding diagnostic (GWO tropical>extra tropical momentum relationship vs a very disjointed polar field)  susceptible to highly erratic global wind-flow patterns at the tropopause boundaries and creating precipitous jumps in synoptic patterns, at mid latitude,... in either direction.

Falling momentum and weak high frequency MJO activity for the foreseeable future (* above caveat aside ) does weight probabilities towards a more typical sub tropical regime and polar jet flow arcing around this. At the same time and as can be seen, there are very hard to keep tabs of pockets of weak inertia popping op at relatively short notice closer to 60N which quite easily could stall westerly inertia and create subtle eddies within the jet which build very weak 'cold' ridges and derail the movement of troughs from west to east and restrict warm air advection

At present, no outcome is to be discounted or dismissed out of hand, and any discussion should be unclouded by bias preferences and be open minded to the even greater than usual uncertainties. That is not sitting on the fence - its honest objectivity in the face of highly sensitive factors that require a watching brief ,rather than any impetuous call for the sake of wanting to appear confident in appealing to a specific popular outcomes.

So for the laymen, and as many have been suggesting ....

Westerly regime next week

SSW impacts still unclear. 

Going beyond next week chances for high pressure wedges setting up to the north or east pulling in a much colder flow. 

La Nina foundation conflicting SSW signals. 
 

as ever.....more runs needed  

 

 

[MATTWOLVES 3]

Things are gerrin exciting on those ens..that means I'm getting excited...I hope all of you are getting excited..we need to be excited about something. Over 1000 deaths today...gutting...all my heart felt sympathy to those involved. 

And just to finish hopefully another blow to the Vortex in the coming days with a secondary warming...Stay safe folks.

 

 

[Snowjokes92]

Hi all. Are the hints of ridges building,on the ecm for example in FI enough to keep us in the gam?. Not trying to be negative i have been a bit on fence last couple days. Thats even when I know how volitile models can be during SSW Events. Just hope we can keep these adjustments coming

Hope all is well with everyone. Last fews days just been a bit fed up with all the stuff going on at minute, struggled to motivate myself, let alone keeping a proper eye on the models. Just been a few flicks and reads on here. Anyhow, hopefully see some clarity soon within the models 

Edited January 6, 2021 by Snowjokes92