Model Output Discussion - Christmas week and beyond

[TSNWK]

5 minutes ago, MATTWOLVES said:

A displaced or stretched PV could help with a return to cold..No ssw occurred with our first cold snap..it was largely due to the Vortex being stretched! We are not locked into any kind of pattern long term unless there is a strong connect and poor placement of that Vortex..The weather is not that simple to quickly say a pattern is locked in place for many weeks. Why do you think the Met do a completely different write up every few days!

 Significant cold snaps cam develop out of thin air...check the facts from the 87 spell...it was completely unexpected in its development! I've seen many patterns over the years come out of thin air and emerge from a lost situation..You don't need to be a Professor of meteorology to put this point across! 

Thanks for response. TIme will tell I guess.

[Summer8906]

12 minutes ago, Met4Cast said:

Agreed.

The progression of January seems quite clear. Generally average/mild. Turning settled mid month onwards with HP likely to be to the E/SE. With no SSW, we'll eventually see the strat & trop coupling and I suspect an increase in the jet stream into February bringing a stormy/wet but mild period. 

Isn't that somewhat at odds with climatology though, in which February is on average the most settled and driest of the 3 winter months, and the jetstream on average tends to move north as winter moves into spring?

Edited December 27, 2022 by Summer8906

[MJB]

11 minutes ago, Met4Cast said:

Agreed.

The progression of January seems quite clear. Generally average/mild with colder spells mixed in with snow showers and an increasing risk of frost  . Turning settled mid month onwards with HP likely to be to the E/SE. With no SSW, we'll eventually see the strat & trop coupling and I suspect an increase in the jet stream into February bringing a stormy/wet but mild period. 

Not wishing to write off the entire winter season, but I would be surprised if we saw anything on the magnitude of the first half of this month.

Amended to mirror the Met forecast  

[Chesil View]

A very interesting debate going on in the last few pages. I can see where both sides are coming from. The worry of losing precious days of meteorological Winter to the current pattern and the hope that things may change via ssw or mjo driven amplification.

My only contribution would that despite the current poor synoptics. Things be they mild or cold are rarely 'locked in' as such, in a chaotic system.

Edited December 27, 2022 by Chesil View

[Met4Cast]

3 minutes ago, Summer8906 said:

Isn't that somewhat at odds with climatology though, in which February is on average the most settled of the 3 winter months, and the jetstream on average tends to move north as winter moves into spring?

February is usually unsettled in La Nina winters, the last 2 winters are case in point! 

[nick sussex]

The ECM ditches its morning tease and replaces it with a run which is underwhelming . 

The PV though doesn’t look ominous and it’s really the lack of upstream amplification which is the main problem .

I’ve seen a lot worse outputs in terms of the blob of doom and I think we should wait and see whether the MJO and reduction in zonal winds can improve colder prospects as we head into January .

 

[Daniel*]

Really at the moment we are at the height of cold hostility with strong +NAO and vortex centred over Greenland, which is firing rain and strong winds this week, also following brutal cold in US, which has further gave the jet stream a boost reminder the outlook here is much milder… the evolution of stratospheric vortex is highly uncertain going ahead. It is not looking to stay compact over Greenland. It will migrate closer to Russia and an attack will begin in eastern Siberia into early January… there is much to watch unfold away from our small little island. People have clearly lost sight of the big picture, and that is not without interest. 

[Summer8906]

17 minutes ago, Met4Cast said:

February is usually unsettled in La Nina winters, the last 2 winters are case in point! 

Ah ok. Yes, to be fair there is a significant minority of winters in which Feb is the "worst" month but not sure if there is a persistent link with La Nina. Probably one for the "winter thoughts" thread.

[Lukesluckybunch]

14 minutes ago, nick sussex said:

The ECM ditches its morning tease and replaces it with a run which is underwhelming . 

The PV though doesn’t look ominous and it’s really the lack of upstream amplification which is the main problem .

I’ve seen a lot worse outputs in terms of the blob of doom and I think we should wait and see whether the MJO and reduction in zonal winds can improve colder prospects as we head into January .

 

I agree with you there nick..its not a raging PV but it's still in its usual home,and looking hard to move!..do you think looking at the current output is it the kind of set up where wedges could appear and lead to somthing more significant..I think I have seen this type thing before?

Edited December 27, 2022 by Lukesluckybunch
Adding

[stodge]

Evening all

We've been here before many times and we'll be here again many times.

This is traditional North West European winter weather - Atlantic based but with HP to the south. After what was for many (though not all) a decent December cold spell (and if you get 14 memorable days out of 90 you're doing well) we are back to normal.

It may get even milder if the HP ends up over Iberia and we get a more South South Westerly feed. The rainfall figures scream positive alignment:

A deluge for anywhere facing south west otherwise not too bad and temperatures above average.

How do we break out of this? Not easily - attempts to build heights into Scandinavia are thwarted by the strength in the jet which flattens any heights and turns a possible high latitude block into a classic mid-latitude.  Maybe we'll get a bit of help with some negative alignment of the trough if the HP pulls back into the Atlantic but that will be transient. 

Continued warming on the Siberian side serves only to keep the PV on the Canadian side and as @CreweColdhas opined, we may well be into proper coupling of the strat and trop before too long. We could get an SSW but there doesn't seem much prospect currently though it may look different in a couple of weeks. 

The other possibility is we may have had our cold and snow this winter and the next time it'll get cold is when we'll all be clamouring for spring warmth - the weather's like that, capricious at times.

 

[lassie23]

32 minutes ago, MATTWOLVES said:

You may joke about this..but its exactly what I pointed out earlier..mid Jan and Feb will be gone..then come March it will be...the teleconnections for next winter look poor also..And this scenario will play out until a meteor hits the earth and we enter another ice age.

Every little bit of positives i had are now being eaten away bit by bit.

I bid you goodnight..

I've had enough now.

I had snow in December, the first snow in ages, after a series of snowless winters, so I will take that. Winter can do what it wants now, it is still better than the last few put together, had some ice days too in London which is rare. January is usually the month of mild weather and Atlantic junk so I still think February will be our best chance of snow. I thought a scandi high might form mid month, but that is unlikely at the moment. I hope you see some snow before winter is out Matt.

[dan dan]

I'm interested to know if there were signs of the Dec cold spell from looking at this chart? Or would this be the kind of chart that any cold for the following 4 weeks would be written off? Also, did the last cold spell arrive from a period of zonality or was it well modelled prior? TIA

[Cold Winter Night]

The 12z EPS ensemble places the high resolution run in the least amplified cluster 192-240h (18 members).
The other 24+9 members point towards a calm High in our area.

More along those lines in the extended, 264-360h, with slightly more ridging in the East Atlantic, and with the 4th cluster (9 members) as most interesting, involving a Scandi High that is getting undercut by low heights over Europe and from the Atlantic.
No sign of a traditional +NAO, but no sign of deep cold either.

[RhHh]

6 minutes ago, lassie23 said:

I had snow in December, the first snow in ages, after a series of snowless winters, so I will take that. Winter can do what it wants now, it is still better than the last few put together, had some ice days too in London which is rare. January is usually the month of mild weather and Atlantic junk so I still think February will be our best chance of snow. I thought a scandi high might form mid month, but that is unlikely at the moment. I hope you see some snow before winter is out Matt.

Ditto that. Had zilch measurable snow here since March 2013 until December 11th 2022. Onwards to the next snow,whenever that may be.

[Mike Poole]

One thing there is plenty of in here today is over-confidence, I would suggest.  I would be the first to admit, the outlook is not good for cold weather prospects in the UK for the foreseeable, and a lengthy period of mild weather is probably the correct call.  But equally, I’m not seeing a raging vortex of doom over Greenland, so until the strat and trop vortexes really do couple properly, and they may well do, but until that happens there are other paths the weather could take during the remainder of winter, which is still over 2 months. 

ECM clusters T192-T240, and there are 3:

Fairly simple, cluster 2, the euro high stays where it is, cluster 1 (favoured) mid lat block including UK, cluster 3 block extends to higher latitudes.

T264+

Clusters 1,2 and 4 of some interest here.  

 

[nick sussex]

18 minutes ago, Lukesluckybunch said:

I agree with you there nick..its not a raging PV but it's still in its usual home,and looking hard to move!..do you think looking at the current output is it the kind of set up where wedges could appear and lead to somthing more significant..I think I have seen this type thing before?

I think that looks unlikely with the current set up unfortunately. We’ll need to be a bit patient and wait to see how things play out with the MJO and reduction in zonal winds .

 

[Cheshire Freeze]

16 minutes ago, dan dan said:

I'm interested to know if there were signs of the Dec cold spell from looking at this chart? Or would this be the kind of chart that any cold for the following 4 weeks would be written off? Also, did the last cold spell arrive from a period of zonality or was it well modelled prior? TIA

The December spell was advertised weeks and weeks in advance.

[Kasim Awan]

Just now, CreweCold said:

The December spell was advertised weeks and weeks in advance.

What a poor spell for snow apart from the odd lucky spot in the south. Not a great sign going forward as imo that shows the atmosphere isn't predisposed to correctly alligned troughs / tilts to produce widespread snow this winter. Last big frontal snow event was 4th Feb 2012.

[dan dan]

Just now, CreweCold said:

The December spell was advertised weeks and weeks in advance.

Thanks CC, was this shown in the models (ECM/GFS) Or the anomaly charts/longer range?

[RhHh]

15 minutes ago, Kasim Awan said:

What a poor spell for snow apart from the odd lucky spot in the south. Not a great sign going forward as imo that shows the atmosphere isn't predisposed to correctly alligned troughs / tilts to produce widespread snow this winter. Last big frontal snow event was 4th Feb 2012.

Scotland have done pretty well up to now.

[Drifter]

31 minutes ago, dan dan said:

Thanks CC, was this shown in the models (ECM/GFS) Or the anomaly charts/longer range?

No, I really don’t think it was . Happy to be proved wrong with actual charts or forecasts. 

[bluearmy]

1 hour ago, minus10 said:

Last word on this but ...im sure i am not going mad here .. is it not the case that the op is the high resolution run, the control is the low resolution run and all the ens are peturbed low res runs...the mean is the mean of all of them...

Correct

1 hour ago, dan dan said:

I'm interested to know if there were signs of the Dec cold spell from looking at this chart? Or would this be the kind of chart that any cold for the following 4 weeks would be written off? Also, did the last cold spell arrive from a period of zonality or was it well modelled prior? TIA

 

39 minutes ago, dan dan said:

Thanks CC, was this shown in the models (ECM/GFS) Or the anomaly charts/longer range?

Apart from the teleconnective indications, the two week ens were pretty good.  The below from 15 days out. I have plenty of others and the archives of ens output are on meteociel 

 

Edited December 27, 2022 by bluearmy

[mountsbaysnow]

I've got a suspicion that the charts being churned out this last week or so are gonna back track as quick as when we have fi charts dashed at the final hurdle. Just a hunch. 

 

[bluearmy]

I do find it a little odd that there is surprise at the coupling. more than a week ago it looked pretty clear that there was going to be a coupling between strat and trop as the forecast strong upper strat sent a downwelling  wave into the trop.  There was some discussion as to whether the trop was itself responsible for the pos AO and that was upwelling into the strat. Could be the case but it found the downwelling wave headed to meet it so the pos AO was re in-forced 

similarly, the strat weakening in week 2 is clearly predicted and has been for some time. How weak it goes and just how displaced currently unknown.  And whether it has an effect down in the strat we also wait to see. 

[chionomaniac]

2 hours ago, CreweCold said:

If anyone wants my opinion (and I know plenty won’t), there will not be a fruitful pattern for the UK in terms of widespread or sustained cold until if/when a SSW occurs.

We look likely to see some kind of wave 1 displacement event (with magnitude unknown at this point), however this will most likely not bear fruit for the UK. If we can follow up the displacement with more warming then we could see a SSW but that may not be until late January. If we don’t see a QTR from that then it could be back end February until we see anything of note…

Those ‘writing off’ January are not as crazy as they sound.

That’s not necessarily true. For two reasons. 
One that even if we get a displacement SSW, then it is hard to get this to propagate and then disrupt our side of the hemisphere. 
 

But…two, we can benefit from a scandi high that is often a precursor to this set up. 
 

But as ever, the Strat interaction with the trop and vice versa are all important at this turning point in winter.