Model discussion - hunt for cold - Christmas countdown

[Ali1977]

There’s no denying the disappointment after this last week but we still have lots in our favour - notably the lack of any major PV to our North on any model at day 10, and the METO long range. Just a case of waiting , and hoping something will pop up in the medium range rather than have to track it in from day 15 as this is really painful - especially when it falls apart last minute!! 

[Duane S.]

Of course, we all know we can’t take one aspect in isolation (take the very promising wave 2 chart I posted just now).

So us humans then naturally lean towards cumulative weighting, our brains can easily cope with that.

Imagine each of the following as a 6 sided dice, with the higher the number rolled individually, the better for us and cold prospects…

MJO phase 

E-QBO phase

ENSO state

Solar cycle

As a snapshot right now, you’d probably score something like a…

6 (decent amplitude, long lasting P7)

5 (descending easterlies)

4 (Moderate La Nina, looking like being more E based)

5 (heading out of minimum but still low, despite recent outbreaks)

If the average thrown is 14 then we score a very impressive 20. Sure, our chances have definitely improved on paper.

The problem, and it is what are brains cannot cope with, is conflict and interference BETWEEN these drivers (and if only it was only this 4 dictating our weather! ). There will always be varying degrees of overlap within that 4, despite them all being capable of being fairly primary drivers in themselves. You will have unknown tipping points all over the place. Throw in the numerous other atmospheric nuances, and  that can change the path sufficiently upstream (and thus on to a different path downstream) without us ever knowing exactly why.

I know there are analogues that show various combos through the years, but I’ve never been that convinced by them. They are a good guide as to potentially increased opportunities but often little else. Certainly not in the context of the UK and with a warming planet thrown in.

It may be this winter a score of 5,5,2,5 would give us our best winter in 11 years. But that exact same state (impossible but for example’s sake) next winter would result in an average winter, because of other interfering factors. Too mind boggling to comprehend.

 

Personally, I suspect we neglect AAM too much (did a drop in net global serve notice on this cold spell?). Certainly for my part, my understanding is not sufficient (Tamara in particular is excellent at interpreting these).

Hey ho. It’s all good fun! 

[Singularity]

2 hours ago, mountain shadow said:

Yeh. This is the learning point for me from this. The MJO is essentially useless.

I mean, where exactly is the tropical wave that was supposed to aid colder weather?

It’s not essentially useless, it’s just not a ‘magic bullet’ that guarantees certain outcomes for Northern Europe. 

MJO phase 7 drives building northward of high pressure across Western Europe, potentially far north enough for a cold easterly to affect places like southern UK. That’s almost happened in the past few days, but the Atlantic trough hasn’t quite behaved as was needed this time.

We’re now seeing a bit of phase 7 / phase 8 forcing that moves the high northwest, but the forcing isn’t strong enough to produce a large Greenland High (models did overdo it a bit when in the 5-8 day range), so we’ve still needed the Atlantic trough to behave in the right way. It really could have done so, the fine margins have been very evident in the recent model swings.

Now, the AAM cycle is inevitably headed through the lower AAM segment (as +mountain torque events have temporarily scrubbed out the tropical +frictional torques) , so the MJO phase 7/8 forcing sequence is essentially being reset. Round 2 is lining up, kicking off in the final days of this year with high pressure looking to build north from Europe (models likely not resolving the progress of this very well at the mo).

This reset doesn’t show on the MJO RMM plots. Bottom line is, you can’t consider the MJO alone, the whole tropical-extratropical cycle (represented by AAM/GWO) is important. Much as Tamara was emphasising a week or two ago.

Which reminds me, the strongly negative PDO is worth considering. It likely underpins the near-term extreme cold western Canada, warm most of USA pattern and this may have influenced the Atlantic trough behaviour in a manner that worked against the polar jet shifting south of the UK. How exactly, I’ve not yet researched.

Edited December 23, 2021 by Singularity
PDO

[Staffmoorlands]

14 minutes ago, Ali1977 said:

There’s no denying the disappointment after this last week but we still have lots in our favour - notably the lack of any major PV to our North on any model at day 10, and the METO long range. Just a case of waiting , and hoping something will pop up in the medium range rather than have to track it in from day 15 as this is really painful - especially when it falls apart last minute!! 

The Met Office long range suggests a cold start to January then much milder weather from mid-month. Along with their seasonal 3 month forecast, I would suggest they are not expecting much in the way of wintry weather this season sadly

[blizzard81]

39 minutes ago, karyo said:

All the models look poor this morning but the ECM is particularly hard to swallow with the ominous rise of pressure over Iberia! We have seen this happen many times in recent years, this is a very stabborn high and the models are very good at handling it once it appears. 

The sun remains very active (www.spaceweather.com). In fact, solar activity in this cycle is exceeding the forecasts and it looks like we will reach solar maximum much quicker than first thought. This is particularly disappointing for me, because the last solar cycle gave us two good winters (2008/9 & 2009/10) and it looks like this one has failed to even give us one! 

 

Yep, I'm convinced that increased solar activity has played its part in this dramatic turnaround. Multiple CME's being ejected from the sun these last couple of days towards earth. Perfect timing, as ever. 

Edited December 23, 2021 by blizzard81

[mountain shadow]

10 minutes ago, Singularity said:

It’s not essentially useless, it’s just not a ‘magic bullet’ that guarantees certain outcomes for Northern Europe. 

MJO phase 7 drives building northward of high pressure across Western Europe, potentially far north enough for a cold easterly to affect places like southern UK. That’s almost happened in the past few days, but the Atlantic trough hasn’t quite behaved as was needed this time.

We’re now seeing a bit of phase 7 / phase 8 forcing that moves the high northwest, but the forcing isn’t strong enough to produce a large Greenland High (models did overdo it a bit when in the 5-8 day range), so we’ve still needed the Atlantic trough to behave in the right way. It really could have done so, the fine margins have been very evident in the recent model swings.

Now, the AAM cycle is inevitably headed through the lower AAM segment (as +mountain torque events have temporarily scrubbed out the tropical +frictional torques) , so the MJO phase 7/8 forcing sequence is essentially being reset. Round 2 is lining up, kicking off in the final days of this year with high pressure looking to build north from Europe (models likely not resolving the progress of this very well at the mo).

This reset doesn’t show on the MJO RMM plots. Bottom line is, you can’t consider the MJO alone, the whole tropical cycle (represented by AAM/GWO) is important. Much as Tamara was emphasising a week or two ago.

Hi Singularity. Yes, I know not to put all the eggs in one basket when it comes to the MJO in isolation but we are seeing a long standing MJO phase 7 wave, which really should have delivered more. You're saying an Atlantic trough 'misbehaving' can overcome MJO forcing with ease. That makes no sense to me, whatever is driving the trough (whether the PV or something else) is clearly of more importance than the MJO.

[Frostbite1980]

6 minutes ago, Staffmoorlands said:

The Met Office long range suggests a cold start to January then much milder weather from mid-month. Along with their seasonal 3 month forecast, I would suggest they are not expecting much in the way of wintry weather this season sadly

However seasonal models or the Met cannot forecast things like SSW more than 2 weeks out at best which could turn a mild winter into an average/below average temp winter. That is something we need to watch IMO

[mountain shadow]

Just now, blizzard81 said:

Yep, I'm convinced that increased solar activity has played its part in this dramatic turnaround. Multiple CME's being ejected from the sun these last couple of days towards earth. 

There is little evidence for this. Some of our best winters have come during periods of very high solar activity, so there is no direct correlation. 

[damianslaw]

The theme of 2021 continues Atlantic struggling to make inroads across the UK. Instead fronts look like stalling and trough held limped to our west. Can't remember a year with such little mobile zonal flow. 

 

[Eagle Eye]

1 hour ago, NewEra21 said:

 

Like most of us, I'm sure our girlfriends, wives, boyfriends etc etc just don't understand our thrill of the chase for cold. So it's a pleasure to share all of the ups, downs and the pain with you guys.

 

Don't make me sadder than I already am lol, I've been telling all my friends that I've been chasing snow and giving snow chances, many of them might have taken it as absolutes, it better magically snow I don't have the heart to tell my crush that it's not going to snow  

I too am glad that we had the chase, it kept me and I'm sure many others going in the long road up to Christmas and I wouldn't mind chasing a SSW around my birthday as well.

In the meantime a bit of Rossby wave chasing won't do much harm, we might getting a better outcome that way with a little change 

[sheikhy]

More undercut at 48 hours from gfs!!!!sorry i cant resist!!

[Battleground Snow]

The GFS is sliding the low a tad more at 54 hours, why am I still doing this to myself haha

@sheikhy

Edited December 23, 2021 by Battleground Snow

[mushymanrob]

7 minutes ago, mountain shadow said:

Hi Singularity. Yes, I know not to put all the eggs in one basket when it comes to the MJO in isolation but we are seeing a long standing MJO phase 7 wave, which really should have delivered more. You're saying an Atlantic trough 'misbehaving' can overcome MJO forcing with ease. That makes no sense to me, whatever is driving the trough (whether the PV or something else) is clearly of more importance than the MJO.

Id have thought the Atlantic trough was being fuelled by the huge high west of greenland drawing down arctic sourced air into the north atlantic where sea surface temperatures are higher then normal .. i dont know... just surmising.

 

[nobble]

31 minutes ago, Battleground Snow said:

Motivation at rock bottom to continue the chase today, but I'm sure we will be back when an eastlerly appears at day 10,

Nobody seems to have a conclusive answer to why the heights drained so fast from Greenland, that was the killer of the  touted cold spell, if the jet had remained to the south it would have kept Iberian heights at bay, at least for a while.

The gem does still have a transient snow event boxing day, but even this you would say is a rank outsider.

Enjoy Xmas guys

Nailed on that # believe

[sheikhy]

Just now, Battleground Snow said:

The GFS is sliding the low a tad more at 54 hours, why am I still doing this to myself haha

@sheikhy

Good timing my fellow midlander!!!!listen man these little could make a difference for us to see a little snow in the next 48 hours!!

[Singularity]

18 minutes ago, mountain shadow said:

Hi Singularity. Yes, I know not to put all the eggs in one basket when it comes to the MJO in isolation but we are seeing a long standing MJO phase 7 wave, which really should have delivered more. You're saying an Atlantic trough 'misbehaving' can overcome MJO forcing with ease. That makes no sense to me, whatever is driving the trough (whether the PV or something else) is clearly of more importance than the MJO.

The trough isn’t locked into particular behaviour right down to the timing of secondary lows swinging etc, the atmosphere is too chaotic for that - but your comment has reminded me that the very negative PDO may be a plausible influence skewing probability toward the unfavourable outcomes.

MJO-wise it’s critical to appreciate that longer duration doesn’t mean more forcing indefinitely. The atmosphere attempts to balance itself sooner than later (AAM dropping, as it will this coming week, meaning we are only just ‘in the game‘ and probably not going to ‘win’), at which point we look to see if the MJO will force AAM back up again before it decays. Current signs are, there’s a good chance of that happening as we head into 2022.

If we’d had a more swiftly (but not rapidly!) moving MJO through 7-8, chances are, it would have aligned well with the AAM climb to produce a more emphatically -NAO spell. On the other hand.

Edited December 23, 2021 by Singularity

[damianslaw]

What's the betting any next cold snowy spell will appear in a short timescale rather than something long drawn out like the last 10 days. Very likely but when that will be who knows.. but I feel this winter will be one where best never to hang Hope's on anything until within 96 hr sometimes 72 hr timeframe. 

[Gowon]

It's very sad to see how close we was to a white Christmas

 

[jules216]

This Christmas dráma is just insane. I highlighted my location in respect of T850hPa on 25th lunch tíme. The difference between SW and NE of Slovakia is a mere 11C according to latest Icon I am in about -4 uppers. Just ,2 days ago there was model agreeement full scale that I be under +2 uppers like SW Slovakia. Ridiculous drama

 

[jellybaby1969]

As we try and digest why the cold and snow didn't arrive..many folk come to the conclusion that the models struggle with blocking patterns. But  are they really struggling ? Are they not just showing the difficulty and the battle of one airmass against another ? Hence the unpredictable model output. Think about as a tug of war between to fairly equal teams..v difficult to predict an outcome until one team or force collapses.

[bluearmy]

1 hour ago, Man With Beard said:

Yep, ECM was the closest once down to D5, after all.

Finally I can accept there's no way back from this morning, white Christmas is off sadly.

Sliders are a nightmare. It seemed for all the world that this was going to slide but it failed - by the skin of our teeth.

To me, the fact we lost any CAA very early on in this episode meant that any potential snowfall was likely knife edge anyway. Even if we’d had a slider I would have worried that the air wouldn’t have been cold enough to deliver in the way we crave. Remember the adage - get the cold in first!  (And preferably for more than half a day) 

also, Ukmo uppers are surely questionable - they seemed way lower than other models with v similar solutions 

[shawty1984]

26 minutes ago, Staffmoorlands said:

The Met Office long range suggests a cold start to January then much milder weather from mid-month. Along with their seasonal 3 month forecast, I would suggest they are not expecting much in the way of wintry weather this season sadly

I'll never understand this. Christmas day is on Saturday and we've only just found out what's happening on Wednesday/Thursday. Why do people even then look at something 3 weeks away. 

[mbrothers]

On 23/12/2021 at 10:03, shawty1984 said:

I'll never understand this. Christmas day is on Saturday and we've only just found out what's happening on Wednesday/Thursday. Why do people even then look at something 3 weeks away. 

U tend to find it’s usually the same people too.

[BLAST FROM THE PAST]

2 hours ago, mountain shadow said:

Yeh. This is the learning point for me from this. The MJO is essentially useless.

I mean, where exactly is the tropical wave that was supposed to aid colder weather?

India.  True

 

BFTP

[blizzard81]

I bet the models don't back down on that ever inflating Iberia high . You have to laugh. Humour is the only way to get through it.