Model Output Discussion - Into Winter

[nick sussex]

Laughable differences in the ECM later output compared to last nights run.

Not just local detail but the entire NH pattern .  Just highlights the models poor handling of the upcoming changes .

 

[mountain shadow]

Slack is the word I would use to describe the overnight input.

Certainly no proper Northerly blocking on show yet.

[That ECM]

I’d take getting to either and then see where we go.

[Ruzzi]

1 hour ago, TillyS said:

This is as zonal as I can ever recall for this time of year. We are in the midst of an Atlantic battering  .

 

47 minutes ago, TillyS said:

Thanks for your realism

 

The absence of any useful northerly blocking is incredible tbh. There’s usually something around Greenland, Iceland, Svalbard, Scandinavia at this time of year.

Come on! You really can't be serious with this? Pessimism must be high to conjur up statements like this but unfortunately they just aren't true. 

For balance of presenting fact as opposed to dramatic headline grabbers .... here is yesterday's verified chart: 

 

 

Now compare that with a genuine pessimistic chart for this time of year, aka 2004: 

 

You can see the cause for pessimism diminishes somewhat.... and further to that, we have a more amplified MJO, phase 8/1, a pending significant weakening of the strat, and a host of other favourable teleconections which I won't go in to analyse given the great job that others do so well to explain to everyone and have been giving a running commentary on. Point being, there is plenty reason for optimism beyond the 7-10 range, its not your 2004 picture painted above. 

To keep the balance of realism for maybe newer members (as I suspect the seasoned will know that you threw a few statements out with no rationale, or indeed, maybe for the controversy) ....

Here are 5 of the last 8 years for this same time of year: 

 

And here is the 3 remaining years of the last 8 years which have a slightly better viewing albeit, still don't show up the "abundant end of December northern blocking" 

 

Model fatigue can be a funny thing, but when you go back to looking for the basics, eg a roaring PV over Greenland, strong azores high or iberian high with a strongly positive NAO, or indeed strongly positive AO, a cold strat with zero warmings, an MJO in the COD and so on.... if you can tick all those boxes with no change in the forecast, only then will your statements hold credence. 

I envy the newer members this winter more than probably any before because the sheer amount of false factless based information being branded about this winter makes for a difficult read and gives a very poor foundation for learning. 

[IDO]

There is no confidence in the tPV shenanigans past D8, so my thoughts are JFF viz details, but I see little sign of any convincing northern blocking right up to D16 on the GEFS—no signs of wave amplification. Relying on wedges and an Arctic high invariably is less helpful than it is. So cold zonal relaxing to a slower zonal sine wave regime as we pass the next two weeks.

The GEFS mean is moot for details but can give us some clues as to NH patterns (D8-16):

 

The Arctic High looks like a nuisance by boxing in a pattern unhelpful for sustained high-lat heights, wedgy at best. We are on the colder side, so average temperatures to cooler. Later in the run, the possibility of N/S split as around D10, we see the westerly flow lighten up.

The real story of the last month and into the New Year is rain and storms, likely signs of the times. This winter looks to be suffering an extended version of that. As ever, I feel an impactful strat warming is the best shot of a period of cold and snow. As for the MJO signal, that hasn't impressed me in the last two years, dampened by other background signals.

I have been burnt 99% of the time with GFS over-amplification of heights in FI, so its recent output is strictly for fun. And D10 ECM, do not get me started! Fingers-crossed those with expert knowledge of an impeding amplified pattern are correct as the models are now close to mid-Jan, the mid-term.

Edited December 28, 2023 by IDO

[Lukesluckybunch]

Good ECM..but the gfs ens have trended the wrong way overnight

[That ECM]

6 minutes ago, Northern Lurker said:

That's a brilliant post Ruzzi. I couldn't agree more strongly with the final para. I've loved reading these forums nearly 20 years, however this year has been extremely disappointing.
 

There is no doubt in my mind that certain individuals post in this thread with the sole purpose of winding people up, for some reason the mods let them get away with it but it really is detracting from learning. Dozens of daily posts should be moved to the chat thread to prevent genuinely insightful posts from being washed away. 

 

Ido has put together a post which is also good for learning and well reasoned. with a less cold take.

Back to back posts with different views both of which are informative.

 

Although ido don’t give up now it’s just about to get really interesting.

[northwestsnow]

EC eps will be more revealing..

GEFS not really interested in HL blocking let's hope eps are !

[Lukesluckybunch]

BBC monthly are delaying things to mid january..even the latter part it could be,..we can't keep pushing the cold back.otherwise it rarely matearileses..we need to start seeing some good charts within day 10 ..not always day 10 plus!

[AO-]

3 minutes ago, northwestsnow said:

EC eps will be more revealing..

GEFS not really interested in HL blocking let's hope eps are !

The EPS has swung more over the last few days from one run to another. Let's hope the EC is more balanced. The fact remains that EC postponed the cold as well in the operational. But just the fact of the trough at the second of January being more South and shaped differently in the operational of EC is somewhat promising. My best guess is to put my money on EC this time because it's a rather complex situation which might be picked up better by the high resolution of EC. 

[northwestsnow]

EC mean looks good to me ..

[That ECM]

Gfs having a wobble before jumping back on.  

[Lukesluckybunch]

ECM mean isn't too bad..at 240 it does show ridging towards greenland..we need to improve this now over the next couple days

[winterof79]

32 minutes ago, Northern Lurker said:

That's a brilliant post Ruzzi. I couldn't agree more strongly with the final para. I've loved reading these forums nearly 20 years, however this year has been extremely disappointing.
 

There is no doubt in my mind that certain individuals post in this thread with the sole purpose of winding people up, for some reason the mods let them get away with it but it really is detracting from learning. Dozens of daily posts should be moved to the chat thread to prevent genuinely insightful posts from being washed away. 

 

Ditto over the last two years sadly

[mulzy]

8 minutes ago, northwestsnow said:

EC mean looks good to me ..

Yes, it's decent.  Just need to watch the heights to the south (don't shoot me!)

[Ali1977]

8 minutes ago, northwestsnow said:

EC mean looks good to me ..

Very good, I think it’s all still on for 7th is of Jan - and I think the UKMO even at the 3rd is close to a snow event in the south with this !! 
Models are clearly struggling with the strat changes - my fingers are crossed for no downgrades on the METO text later - and a swing back towards a SSW 

[weathercold]

1 hour ago, TillyS said:

Thanks for your realism which, sadly, is right on the money with the models at the moment. 

The best thing to do for the snow-starved southerners is to take a trip to somewhere wintry if you can. You don’t even have to go that far or spend much: Scotland has been seeing some heavy snowfall on and off and we’re getting to the point now where milder interludes won’t melt it all from the mountains.

The force of the Atlantic is as great as I can recall at this time of year and it’s going to take a while to calm or divert the jetstream sufficiently to establish blocking where we need it. The absence of any useful northerly blocking is incredible tbh. There’s usually something around Greenland, Iceland, Svalbard, Scandinavia at this time of year.

Slightly perplexed by your summary to be honest. The force of the Atlantic is very common for our shores and there are many examples of a strong jet stream across our locale at this time of year, not sure why you are so surprised by this?

There is northern blocking across scandi next week with locations such as Helsinki, Stockholm going deep into negative temperature territory during the day with lots of blocking. I think your post is misleading.

[Hotspur62]

Just a quick one hopefully someone can answer.If models are showing a possible SSW around 4-7 January isn’t there a time lag of about 10-14 days before we feel effects of this if we are lucky enough to feel the effects coldwise(about 60% chance?).Would that mean we would be looking at 15th January before any chance of cold weather?Remember something of 2018 BFTE but can’t exactly remember all details.Do we still have a chance of colder weather before then with the teleconnections etc?I am more confused than ever now after 12 years of being on this forum as this season seems to be so many different views on things I am confused.com!

[IDO]

As expected, the ECM op at D10 is moot as the op run is an outlier early on in the run via at least two metrics:

One for the bin highlighting the uncertainty with taking op runs seriously beyond D7-8.

The De Bilt shows that the mini-wave in the Atlantic on the D10 mean will have more significant colder benefits to the east of the UK:

 

Let us see where the 12z takes us.

 

 

Edited December 28, 2023 by IDO

[northwestsnow]

Yesterday day 9 mean

todays day 10 mean

[Ali1977]

4 minutes ago, northwestsnow said:

Yesterday day 9 mean

todays day 10 mean

Much better into Greenland , and around the tip of Greenland with the Atlantic hitting the blockers

[bluearmy]

4 minutes ago, Hotspur62 said:

Just a quick one hopefully someone can answer.If models are showing a possible SSW around 4-7 January isn’t there a time lag of about 10-14 days before we feel effects of this if we are lucky enough to feel the effects coldwise(about 60% chance?).Would that mean we would be looking at 15th January before any chance of cold weather?Remember something of 2018 BFTE but can’t exactly remember all details.Do we still have a chance of colder weather before then with the teleconnections etc?I am more confused than ever now after 12 years of being on this forum as this season seems to be so many different views on things I am confused.com!

The models have trended away from a ssw in the technical sense where it reverses at 60N 

however, they are still reversing the flow high up at latitudes above 70N - it’s a sig warming but not an actual ssw 

so we can expect a generally neg AO signature for some time to come because that reversal wave will continue to drift down into the trop - usually there are three or four repeats with 14/17 days in between (approx) 

your question about lag times is relevant - usually we would expect a wave to downwell 10/14 days later after the reversal first appears at the top of the strat. But on this occasion we already have a neg AO  in the trop so any downwelling wave would simply reinforce  that.
There looks to be a rapid downwelling likely in this instance so no wait and our issue is getting that wave far enough south once it arrives in the trop. Hence the general consensus that 60N is important for the reversal to get down to. 

We do have a potential issue in some  modelling where the reversal wave will push down the residual positive flow ahead of it into the trop and you’ll see a temporary increase in zonal flow at 500 hpa. I’m afraid we just have to wait a while to see how that will actually play out 

if you run through this view of the gfs op then you will see how and where the blues (neg zonal flow) are currently in the atmosphere and how they are expected to evolve. Remember that the lower down you go the less reliable the forecast becomes. In theory, higher up in the strat is supposed to be less chaotic - suspect that isn’t the case over the next couple weeks! 

Vertical cross u-mean + EPflux

WWW.WEATHERISCOOL.COM

 

[Mike Poole]

ECM clusters this morning, T192-T240:

Roughly equal split between the two, cluster 2 has the stronger ridging into Greenland by day 10, cluster 1 looks weaker but of the same idea.

After that, there are 5 clusters, all of which show blocking of some sort.  Clusters 2, 3 and 5 look to have the blocking very well positioned for the UK.  Cluster 1 retains high pressure over UK and south, which is less good, looks a bit messy that one.  

All in all, picture at this timeframe similar to yesterday’s 12z.

Edited December 28, 2023 by Mike Poole

[Marting]

The ECM ensembles still bringing us down and down on the temps over the next week. Not sure what has occurred with the GEFS so far this morning 

[phil nw.]

Morning all,

Unfortunately a couple of off topic posts have been removed.

Just a reminder people are entitled to different views on the models as long as they are supported in the outputs.

Please report any problems to the team rather than complain in off topic posts.

Thanks.