Model Output Discussion. 3/12/2022. How cold will it get?

[Metwatch]

The GFS 6z was a good example of the trough modelled out in the azores going from having a positive tilt to a negative tilt.

(A negatively tilted trough tilts horizontally, parallel to surface, from the north west to south east)

This would increase frontal snowfall risk as it meets against the blocking ridge, with milder air essentially being squeezed out should it verify.

Edited December 4, 2022 by Metwatch

[Methuselah]

This is turning into a trick one, and the 06Z seems to be going off on its own with all those incoming lows and milder weather... Yesterday's 06Z wasn't all that great either? But at least next weekend still looks okay!

    

    

    

And, as to the question of longevity -- I'm not even sure it's a useful question, just yet: predicting how an individual model-run might play out is not the same as knowing what the weather will do... 

[Bricriu]

5 minutes ago, Tamara said:

.And very often there are finely balanced situations which call for saying so. This is a voluntary weather forum - not a derivatives section of the stock market. No-one gets paid or is compelled to say anything, but most especially something they don't believe and when they think there is not enough evidence to make any definitive prediction. All this 'falling on sword' speak is a little excessive and in my opinion unnecessary and perennial childish one-upmanship. The answer is to use the ignore facility. It is not a utopia, but it helps.

The modelling evolution is playing out precisely as described in previous summaries. Indeed, the battleground convergence I talked about is going to become tighter and tighter pinned down focus around NW Europe around, and beyond, the 10-day focus. There remains exactly the fork in the road I described at least twice in posts as foreseen last week - attritional forcing of sub-tropical air to the south, meeting the cold dense arctic air to the north. As suggested almost a week back when this modelling was still outside any discernible range, 'high impact' weather events were muted. I don't think that was sitting on the fence - the various permutations are now coming into view on NWP. But the truth points to more than one potential high impact weather event - not soley snow potential for the UK

The completion of the retrograde pattern will inevitably force a re-set and new momentum following from upstream. That much can be asserted. The periodicity of the -ve EAMT is a guideline for this. Starting a few days back, the retrograde sequence has the coming week still to play out. Then upstream momentum, of some measure should return.

I continue to think that ultimately following attritional battleground forcing (and a very wet and muggy period of weather in my SW Europe locality) there will be something of a lifting of the cold air from the south for parts of NW Europe, including obviously the UK. Clearly the further south one is most likely to see this. 

A downstream ridge building from the sub tropics into Iberia (following the low-pressure sequence) could well then build northwards. Much a similar sequence as occurred from last weekend and early last week.

As stated in the last post - it is a case of how any energy put back from the sub-tropical -ve NAO jet regime into the polar jet then interacts with this process and how much unstable-ve zonal wind inertia remains at higher latitudes. This sensitive balance of opposite forcing, meaning the difference between a European mid latitude ridge and Atlantic trough, or a re-connection of a northward building ridge to arctic high pressure and cold pooling. No-one if they were to be honest knows any one answer to this - beyond what their bias tells them to see. How far this cold pooling is dislodged through attrition is finely balanced and falling on a sword is really neither compulsive nor mandatory.

These practices should never be attempted unattended and unsupervised. Consult an adult.

So basicially  are you saying that anyone that utters phrases like cold is locked / no way back for the Atlantic is unwise, no matter how appealing individual runs might be to those of us who want snow and prolonged cold weather, given the delicate balance between the transfer of energy around the globe and how easily it can alter the weather a majority of us would like to prevail?

[1947s coming]

9 minutes ago, Neilsouth said:

IF GFS keeps doing these dartboard lows, it will keep going in the BIN!  Why does this model keep doing this year in year out?

It will change closer to the actual time , but it’s now negatively tilted and could slide under the block. If so that could allow the cold from the east to move west , the high to move into scandi and start to pull the vortex chuck ready to drop down to the east  and feed from it. In my opinion Wednesday the models might have this sorted , let’s get the cold in first then watch the models change again . It really wouldn’t surprise me at all if we have a repeat of summer but now the blocking is to the north. Summer gave us record heat , are we ready for possibly record breaking cold. It’s certainly not the usual start and winter set up we are used to or the models 

[MATTWOLVES 3]

However this cold snap plays out regarding surface temps and snowfall I'm not sure,but looking at the longer range ensembles there's quite a bit of noise for the Notrthern Hemisphere to remain completely out of sorts to what we would normally expect at this time of the year. So I would say the chances of further inroads of cold will be with us for a decent chunk of the month! 

This is purely speculation and it may not play out that way such is the chaotic side of things. Beyond that who knows! Even the best of the best do not have the answers.

@sheikhysorry mate...and this gif is for your nan mate..where hopefully she will beam a shining light down upon you and make sure you keep this place entertained. Bless ya.

Edited December 4, 2022 by MATTWOLVES

[swfc]

19 minutes ago, Bricriu said:

So basicially  are you saying that anyone that utters phrases like cold is locked / no way back for the Atlantic is unwise, no matter how appealing individual runs might be to those of us who want snow and prolonged cold weather, given the delicate balance between the transfer of energy around the globe and how easily it can alter the weather a majority of us would like to 

I think some of the output on the nhp have been pretty impressive. The usual caveats apply and as on most occasions for the UK being and island is subect to use swings. I don't totally follow the more incremental back ground signals but I suspect Tamara has a good hold on the complexity going forward. It's turning cold with some snow"esp the north"but the longer term is not for me to have a punt at ie trends etc

Edited December 4, 2022 by swfc

[chionomaniac]

Good to see the signal is still present for the strong wave 1 upper Strat event. 
 

I will keep monitoring this to see if we can get a full blown SSW down the line

[Methuselah]

Mmmmm... My main 'worry' is that, since the FV3 came along, the GFS has been rather good regarding warm-ups in FI. So, I'll no' be binning it just yet? But, being a coldie at heart, I can't say as I like it...

    

[Skullzrulerz]

Don't really know what to say about the models this morning.

Cold does seem to be better in the short term, yet these lows that almost come out of nowhere seems to be a big spanner in the way of things.

While understandably in the medium to long term, breakdowns are here and there but remain in the minority.

The majority of the UK is set to receive these even colder conditions sometime mid next week, but for the Southwest and parts of Wales it's not looking likely at this time.

No point even discussing snowfall till it reaches a nowcast/short range.

[blizzard81]

38 minutes ago, Tamara said:

.And very often there are finely balanced situations which call for saying so. This is a voluntary weather forum - not a derivatives section of the stock market. No-one gets paid or is compelled to say anything, but most especially something they don't believe and when they think there is not enough evidence to make any definitive prediction. All this 'falling on sword' speak is a little excessive and in my opinion unnecessary and perennial childish one-upmanship. The answer is to use the ignore facility. It is not a utopia, but it helps.

The modelling evolution is playing out precisely as described in previous summaries. Indeed, the battleground convergence I talked about is going to become tighter and tighter pinned down focus around NW Europe around, and beyond, the 10-day focus. There remains exactly the fork in the road I described at least twice in posts as foreseen last week - attritional forcing of sub-tropical air to the south, meeting the cold dense arctic air to the north. As suggested almost a week back when this modelling was still outside any discernible range, 'high impact' weather events were muted. I don't think that was sitting on the fence - the various permutations are now coming into view on NWP. But the truth points to more than one potential high impact weather event - not soley snow potential for the UK

The completion of the retrograde pattern will inevitably force a re-set and new momentum following from upstream. That much can be asserted. The periodicity of the -ve EAMT is a guideline for this. Starting a few days back, the retrograde sequence has the coming week still to play out. Then upstream momentum, of some measure should return.

I continue to think that ultimately following attritional battleground forcing (and a very wet and muggy period of weather in my SW Europe locality) there will be something of a lifting of the cold air from the south for parts of NW Europe, including obviously the UK. Clearly the further south one is most likely to see this. 

A downstream ridge building from the sub tropics into Iberia (following the low-pressure sequence) could well then build northwards. Much a similar sequence as occurred from last weekend and early last week.

As stated in the last post - it is a case of how any energy put back from the sub-tropical -ve NAO jet regime into the polar jet then interacts with this process and how much unstable-ve zonal wind inertia remains at higher latitudes. This sensitive balance of opposite forcing, meaning the difference between a European mid latitude ridge and Atlantic trough, or a re-connection of a northward building ridge to arctic high pressure and cold pooling. No-one if they were to be honest knows any one answer to this - beyond what their bias tells them to see. How far this cold pooling is dislodged through attrition is finely balanced and falling on a sword is really neither compulsive nor mandatory.

These practices should never be attempted unattended and unsupervised. Consult an adult.

@Eagle Eye Its ok, don't worry - it was not aimed at you... Keep up your excellent thirst for knowledge and applying it. A great example a young member could set

For my part, I was discussing certain developments with Chio. I wasn't speaking with anybody else in mind on this forum whatsoever. I was speaking from a purely personal perspective. I like making calls sometimes. It's part of the fun for me and if that comes across to some as being childish then so be it. I don't see it that way. 

[Lincs Observation]

Just now, blizzard81 said:

For my part, I was discussing certain developments with Chio. I wasn't speaking with anybody else in mind on this forum whatsoever. I was speaking from a purely personal perspective. I like making calls sometimes. It's part of the fun for me and if that comes across to some as being childish then so be it. I don't see it that way. 

For what is worth I agree with you on this, although I respect Tamara’s musings the line about being childish was a bit uncalled for imo. 
 

it’s a hobby guys let’s not forget that, leave the nibbles at the Christmas tree eh.

LO

[Uncertainty]

For all the mid range uncertainty, day 15 on both the GEFS and EPS are remarkably similar. Troughs over N Alaska, France and Eastern US. 

 

Notwithstanding what comes before, not a bad position for coldies heading into the Xmas period…

[Cambrian]

3 degrees at noon here today and a stiff easterly breeze, already very definitely a different phase of weather.

It’s a real pleasure to view the charts at the moment, and even more groovy with these awesome hi-tech new worldly gifs. Yup.  (Tip - please wear spectacles if required). 

6z GFS ensemble mean - a play in two parts:

Part 1 - the drop (day 1-8)

  

Mean T850 isotherm at -4 degrees through the south coast. Beautiful, needs no more words than already eloquently provided over the last few days by the tremendous contributors to this awesome thread. 

Part 2 - the flux (day 9-15)

The cold air partly relents only to very likely reinforce southwards in the post-run period. This setup is potentially a lot more interesting than frigid cold, with pulses of low pressure having a go, probably only partly succeeding, and then moving into the continent, it’s the kind of pattern that could ultimately result in successive southward pushes of colder air around their northwestern flank in any case.

On the 6z mean, the centre of the low slowly grinds its way north through the UK and Ireland, then east into the North Sea with the possible re-establishment of a northerly by day 15, even on this slightly less cold run. The Siberian PV lobe is also taking on a helpful orientation to support a further northerly with a push of lower heights towards Svalbard.

  

And look at the T850s, it’s the same point about flux, never gets above freezing, say typically -1 to -5. The zero degree isotherm pushes down again to the south of France by the end, with the -4 coming down south over Scotland. 

It’s good to look at what the models actually show. 

At the moment : Cold air parked up. Long stay cold spell. 

And frontal systems / low pressures pushing up from the south into that! 

A Sunday like this is a real gift for us lot. Enjoy…..big time.

Edited December 4, 2022 by Cambrian

[Eagle Eye]

@TamaraI think that falling on the sword, at least in my case, is more used to show a big call that the cold is favoured long-term here, I don't think it's really used in a childish manner. I suppose it's a bit childish to not elaborate further but that's the nature of making these big calls. Its more to do with living by the sword versus dying by the sword. I'm half agreeing with you, its sort of childish but more to do with passion than anything. We all see ourselves overcome by passion at some time and then will stick to our word if its backed up by some teleconnections.

[Methuselah]

13 minutes ago, Eagle Eye said:

@TamaraI think that falling on the sword, at least in my case, is more used to show a big call that the cold is favoured long-term here, I don't think it's really used in a childish manner. I suppose it's a bit childish to not elaborate further but that's the nature of making these big calls. Its more to do with living by the sword versus dying by the sword. I'm half agreeing with you, its sort of childish but more to do with passion than anything. We all see ourselves overcome by passion at some time and then will stick to our word if its backed up by some teleconnections.

Indeed we do, EE: I used to make them by the shedload, but, alas, the 1963 redux I kept predicting has, for some mysterious reason, never materialised... That ECM was the final nail in my James Madden coffin!

Edited December 4, 2022 by Ed Stone

[phil nw.]

I have just been out for my daily walk and I could already feel the edge to what is still a modest easterly.

I am just anticipating how cold it will be by Thursday as the Arctic air arrives right down to the south coast and then beyond.

Snow chances in quite a number of locations by the weekend by the looks,starting in the north by Tuesday.

On the wider view with the NH pattern the blocking will move around and the Atlantic will inevitably try to attack the underbelly of our cold trough.

At least by then we will have a very cold surface for the fight.

There are too many options to honestly punt on the outcome but a battleground snow event is looking more likely next week.

At least after all the anticipation we know the cold and some snow is coming this week.

[Penrith Snow]

30 minutes ago, Josh S said:

For all the mid range uncertainty, day 15 on both the GEFS and EPS are remarkably similar. Troughs over N Alaska, France and Eastern US. 

 

Notwithstanding what comes before, not a bad position for coldies heading into the Xmas period…

Without being too picky I would like to see the high pressure anomaly centred over Greenland rather than Baffin Island as it runs the risk of a west based -NAO

Andy

[Mark wheeler]

Forget the rest everyone. The Nasa model has got this one nailed

[Ben Sainsbury]

12 minutes ago, Ed Stone said:

Indeed we do, EE: I used to make them by the shedload, but, alas, the 1963 redux I keep predicting has, for some mysterious reason, never materialised... That ECM was the final nail in my James Madden coffin!

Hahaha, that's a name I haven't heard in a while and Exacta Weather too! Might need their old enthusiasm if the models take a turn for the worst tonight! Admittedly, I can't see that happening and I do expect the dartboard low to begin to ease off over the next few models runs, but still!

Edited December 4, 2022 by Ben Sainsbury

[Ali1977]

Just now, Mark wheeler said:

Forget the rest everyone. The Nasa model has got this one nailed

I said this yesterday, it’s all over this set up I wish/hope 

[Pembroke Dangler]

16 minutes ago, Mark wheeler said:

Forget the rest everyone. The Nasa model has got this one nailed

Well I happen to hold this model in high regard (when colder weather is showing ) even if the met office don’t. Would be a lovely way to keep the cold coming and with the kinky flow plenty of snow showers moving east to west and very cold nights nationwide. 

[V for Very Cold]

18 minutes ago, Ali1977 said:

I said this yesterday, it’s all over this set up I wish/hope 

I don’t care about the verification stats when I see this 

[Sweatyman]

13 minutes ago, Pembroke Dangler said:

Well I happen to hold this model in high regard (when colder weather is showing ) even if the met office don’t. Would be a lovely way to keep the cold coming and with the kinky flow plenty of snow showers moving east to west and very cold nights nationwide. 

well if the big low moves east nicely and not as strong then charts will start looking like this ..

[MATTWOLVES 3]

47 minutes ago, Eagle Eye said:

@TamaraI think that falling on the sword, at least in my case, is more used to show a big call that the cold is favoured long-term here, I don't think it's really used in a childish manner. I suppose it's a bit childish to not elaborate further but that's the nature of making these big calls. Its more to do with living by the sword versus dying by the sword. I'm half agreeing with you, its sort of childish but more to do with passion than anything. We all see ourselves overcome by passion at some time and then will stick to our word if its backed up by some teleconnections.

Are but mate you still are a child legally speaking so all is forgiven!

Sorry....couldn't resist! There's nowt wrong with sitting on the fence in this thread or committing to making a call on how you see things playing out...thats all part of the fun of being a lover of weather. The pros have to make a call on severe conditions for the safety of the public,and if they get it wrong...Trust me they get slaughtered for it! On the other hand if many of us on here get it wrong...the only thing affected is our egos!

Tams has her style which I respect her immensely for and others have a different style and may not agree! But hey how many experts and amateurs from every walk of life agree with one another! Even the best Doctors are constantly in dispute over which form of treatment works,and which does not.

All part of the fun. This place is gr8 yeh a little head strung at times but analysis overall is unrivalled.

It's nearly Xmas and times are difficult for many of us...never get to downhearted over anything regarding weather...we love it yes..but it need not control our lives.

Onwards and upwards for a juicy set of 12s.

[Battleground Snow]

Interesting 06z ECM is control looking to cut off the high like the gem did, that low looks a bit ominous though, anything after 144 is FI atm.