Model output discussion - Closing in on Christmas

[feb1991blizzard]

EPS are flatening out big time.

[BlueHedgehog074]

I think someone else covered this earlier today - I get the concern about the GFS operational run modelling Low Pressure later next week and into the week after a bit too far West. But there is also that risk of things getting too far East, and the cold, wintry, weather goes for a party over the nearby continent, or Scandinavia.

Despite the last 3 GFS runs dropping the trough around the UK area (albeit earlier runs had it a little further East) I do believe that the GFS is over-doing the Westward extent of that upper and surface Low over the UK. Seems a bit too extreme compared to what the other models show, plus the 12Z GEFS mean has the Low Pressure further East over North-Eastern UK. From my experience, like with what some have mentioned on here, I feel as though these setups more often than not get adjusted further East within time. 

For what it’s worth, synoptically, the 12Z GFS run, while not perfect, could have been a real sick bucket of a run - except perhaps it could deliver a lot of cold rain. Admittedly something a number of us would despise. However with this sort of setup, some marginal surprise wintry events are also very possible, especially over high ground. 

With how some of our last Winters have gone, it’s not too surprising to see the frustration that’s been occurring. Although saying that, people have generally been pretty good at keeping the toy throwing in check, even with what a lot of the cold weather fans have gone through. It can be easy for some of us to set our expectations too high wanting truckloads of snow and lots of cold, even when we know for an average UK Winter that is unlikely. At the same time, I don’t expect Winter’s to be constantly mild without any cold snaps/spells either

In a way, is a good thing that the setup the GFS is showing is quite far away still, as allows room for things to improve. True, things could easily get watered down. And should other models start heading the same way as the GFS then it could be a worry. But hopefully that won’t be one of those times where it all waters down, considering some of the background signals would support some amplified patterns that could favour cold weather over the UK. Just need to be in the right area for any colder conditions. Some of these things seemingly resting on where any troughs of Low Pressure drop to, along with the amount of amplification to our West upstream.

Personally, I think the GFS is overdoing things at the moment probably making things a little too amplified, especially when other models, including tonight’s ECMWF, are less amplified (but not terrible) with Low Pressure further East. 

You could argue that things could do with being more amplified on the ECMWF and especially the GEM. That of which could still always happen as models show variations of the pattern. And the way, also, they can be up and down with their outlooks.

Preferably would want something closer to the GFS, but with everything just that little bit further South-East than on that model. So are then able to tap into the colder flow from the North and East. I do get the feeling, for now, that any of the troughs to our North-West will drop close by to our East. Whether close enough to benefit us for cold and wintry weather is not certain and they can always be further West. A lot of things for the models to figure out over the next few days, so nothing is definite yet. 

Let’s hope many us can get in on some white action in the next few weeks. Not being one of those Winter’s where all the promising signs for cold and wintry weather happens too late (if at all). ️Can’t see their being a repeat of last Winter to be honest (am happy to be wrong though)

There is at least a chance for a bit of wintry weather, probably mostly for the North, and perhaps some Eastern areas towards Christmas, as well as some frost, as the flow looks to briefly turn more from the North-West or North into the middle part of the upcoming week

Edited December 19, 2020 by DiagonalRedLine

[Mike Poole]

ECM ensemble mean and spread T240:

As often the case the spread is more illuminating, that red area tip of Greenland is important, will it or won’t it?  I know some have made up their minds, but for me it is too close to call, frankly,  

[northwestsnow]

EC mean has trended the wrong way....

Clearly the flatter solutions have grown in number for the longer term...

[Allseasons-Si]

23 minutes ago, mountain shadow said:

Aye, but we've seen those Day 10 charts umpteen times already. 

When we get closer to t+0, some spoiler low appears and stops the ridge and we have to wait 4 or 5 days for the next attempt. 

And before you know it, it's May.

yes i know...

2 times a day

14 times a week

56 times a month

and 672 times a year

but i know what you mean

maybe something's a foot this time though...

is that snow>>>

 

[DEYS(Kent)]

4 minutes ago, northwestsnow said:

EC mean has trended the wrong way....

Clearly the flatter solutions have grown in number for the longer term...

Is that a mean chart for 10 days away? Don’t look for trends, positive or negative, using those...

[That ECM]

3 minutes ago, Allseasons-si said:

yes i know...

2 times a day

14 times a week

56 times a month

and 672 times a year

but i know what you mean

maybe something's a foot this time though...

is that snow>>>

 

Maths not your strongest quality?

[snowice]

43 minutes ago, nick sussex said:

The options on the table seem to be cold to varying degrees in the medium term .

Which is a lot better than some of the horrors that coldies could have been subjected to .

The run upto Christmas and the day itself also still has a degree of uncertainty in terms of depth of cold and the chance of any snow .

Overall as much as I’d like to wheel out my crunchy snow and ice day alert, that has to wait but  the outputs are still very encouraging . 

Amber lights ready

[Jeremy Shockey]

ECM 12z Ensemble mean 

A very good mean for 24th and 25th. After that too much scatter but plenty to be excited about. IMO

[Allseasons-Si]

7 minutes ago, That ECM said:

Maths not your strongest quality?

Unfortunately,...NO 

Geography is.

Edited December 19, 2020 by Allseasons-si

[Mike Poole]

Clusters from ECM T192-T240:

Cluster 1 is the one we want.  Cluster 2 looks a bit weird from current situation.  We don’t want cluster 3.  

[stodge]

11 minutes ago, feb1991blizzard said:

EPS are flattening out big time.

Any idea why?

My first thought is the response to the first slight warming is to push the PV back to Canada where it can fire up the Atlantic jet. The second much more substantial warming begins after Boxing Day and peaks on the 30th effectively splitting the strat and far FI has a hint of warming over America which would be fascinating.

Perhaps the EAMT signal isn't as strong as some envisaged.

 

[Daniel*]

14 minutes ago, northwestsnow said:

EC mean has trended the wrong way....

Clearly the flatter solutions have grown in number for the longer term...

Maybe in that snapshot in time It’s pretty promising  when you see beyond  

 

[Mike Poole]

4 minutes ago, stodge said:

Any idea why?

My first thought is the response to the first slight warming is to push the PV back to Canada where it can fire up the Atlantic jet. The second much more substantial warming begins after Boxing Day and peaks on the 30th effectively splitting the strat and far FI has a hint of warming over America which would be fascinating.

Perhaps the EAMT signal isn't as strong as some envisaged.

 

I don’t think so, I think there is a two way split in possible evolutions from here, it either does the Greenland high or it doesn’t. That’s down to the upstream evolution.   And obviously mean plots will be a blend of those two scenarios which are quite different.  

Edited December 19, 2020 by Mike Poole

[bluearmy]

16 minutes ago, feb1991blizzard said:

EPS are flatening out big time.

 

15 minutes ago, Mike Poole said:

ECM ensemble mean and spread T240:

As often the case the spread is more illuminating, that red area tip of Greenland is important, will it or won’t it?  I know some have made up their minds, but for me it is too close to call, frankly,  

The spread reflects mid Atlantic ridging into that area - doesn’t necessarily lead to a colder outcome for the U.K. but the clusters tell a better story than the mean. 

what the 12z runs have done is indicate that the upstream amplification will probably be there to send the trough nw/se .....we won’t get a handle on that for a few more runs yet but hopefully there’s some cross model agreement before too long

good to have some interesting trop patterns to look at whilst also watching gfs op now showing a tech SSW by day 15.

[Scott Ingham]

4 minutes ago, stodge said:

Any idea why?

My first thought is the response to the first slight warming is to push the PV back to Canada where it can fire up the Atlantic jet. The second much more substantial warming begins after Boxing Day and peaks on the 30th effectively splitting the strat and far FI has a hint of warming over America which would be fascinating.

Perhaps the EAMT signal isn't as strong as some envisaged.

 

Or the ECM has spat out a run from cluster 3 of the clusters. 

More runs needed. No need to get too high when things are going well or too low when things arent going great. 

Its model watching. Its the weather. I still favour the GFS for reasons mentioned earlier 

[feb1991blizzard]

1 minute ago, stodge said:

Any idea why?

My first thought is the response to the first slight warming is to push the PV back to Canada where it can fire up the Atlantic jet. The second much more substantial warming begins after Boxing Day and peaks on the 30th effectively splitting the strat and far FI has a hint of warming over America which would be fascinating.

Perhaps the EAMT signal isn't as strong as some envisaged.

 

Not sure tbf, i really am concentrating on the top of the strat (rightly or wrongly), so i hope that EAMT event is strong, last few runs have shown a stretched vortex at 10mb but not nearly a split, which it was showing a near split a few runs ago, i say near split because i don't class these as a split. 

 

Todays as you'll see is a downgrade.

There is a reversal or near reversal at 1mb but i wont be popping the corks until i see a proper split with 500 to 1000 miles in between the daughter vortices and heights over Greenland in the mid strat.

[Frosty.]

Oh my, the cfs isn’t looking very wintry next month..but fear not, the opposite will probably verify!

[Tim Bland]

Look at the snow risk for Plymouth on 28th / 29th  at sea level !
 

P.S re the EPS I’ve lost count how many times in the last month they have ‘awesome’ only to not verify so me reason think they are correct this time

Edited December 19, 2020 by Tim Bland

[feb1991blizzard]

4 minutes ago, bluearmy said:

 

The spread reflects mid Atlantic ridging into that area - doesn’t necessarily lead to a colder outcome for the U.K. but the clusters tell a better story than the mean. 

what the 12z runs have done is indicate that the upstream amplification will probably be there to send the trough nw/se .....we won’t get a handle on that for a few more runs yet but hopefully there’s some cross model agreement before too long

good to have some interesting trop patterns to look at whilst also watching gfs op now showing a tech SSW by day 15.

Definitely interesting trop wise but as you can see by Mike's post that the uncertainty lessens the further you go North to Northern Greenland so again until the SSW, it just looks to me that the atmosphere isn't primed for very high lat blocking, its happening time and time again, but still snow threat of some description in the meantime while we wait.

[MATTWOLVES 3]

31 minutes ago, Mike Poole said:

ECM ensemble mean and spread T240:

As often the case the spread is more illuminating, that red area tip of Greenland is important, will it or won’t it?  I know some have made up their minds, but for me it is too close to call, frankly,  

Yes Mike,those charts look decent to me. And I'm not to concerned with the ECM ens...a fair amount of spread even though at face value the mean 850s have increased..just viewed the extended to day 14,and they do fall away again. Know complaints from me.

Edited December 19, 2020 by MATTWOLVES

[DavidS]

12 minutes ago, Daniel* said:

Maybe in that snapshot in time It’s pretty promising  when you see beyond  

 

 

13 minutes ago, Daniel* said:

Maybe in that snapshot in time It’s pretty promising  when you see beyond  

 

When you consider what we’ve had for the last few winters, that is a cracking mean.

[sebastiaan1973]

De Bilt plume. Things are not looking good. Sadly. Winddirection from most members is SW or W.

[Skullzrulerz]

41 minutes ago, feb1991blizzard said:

EPS are flatening out big time.

They are updated daily are they not ?

[Roger J Smith]

To the extent that there have been downgrades on some models, I can't remember a decent cold wintry spell (for the UK) where there isn't at least one downgrade run or series of runs about this far out, 6-8 days. Seems like a part of the process. Not that a downgrade is therefore proof that good things are about to develop. It could also be a downgrade trend without reverse, seen a few of those also. 

There's a rather volatile looking evolution over the eastern U.S. on 24th-25th, all guidance shows a strong cold front, some develop a secondary low that runs almost due north from the Carolinas to western Quebec. How that actually goes may have a major influence on how the west-central Atlantic ridge responds. 

I would say the best scenario would be establishment of cold 28th to 1st then battleground lows 2nd to 5th. That could give a lot of snow.