Model output discussion - Closing in on Christmas

[Catacol]

38 minutes ago, CreweCold said:

Makes sense as we're likely to see repeated bouts of amplification. Each time we get a little closer...

Yes. This is exactly the point. Getting hung up on details at 192h seems a waste of energy to me. Instead step back and try and get the bigger picture. Amplification will continue for now, and to turn the core of winter into something special we need the vortex to be shredded. A cold snap looks likely soon after Xmas....but if it is a sustained cold spell you are after then forget run to run variability (guaranteed to inspire frustration and madness!) and look for broad scale patterns. We are gradually approaching a key point - a SSW might be as little as 3 weeks away and to get it we need trop patterns to align by maintaining amplification via AAM support and EAMT. We also need that Ural High to maintain some degree of influence. I’ll be as happy as the next person if a bit of snow is lying prior to New Year - and if this bout of amplification produces the goods then excellent. But if it doesn’t it isn’t game over because we are in a phase with sustained interest.

The time to get truly morose will be if the amplification has faded by mid January without a SSW. Renewed vortex development at that point would spell the end of a cold February. I think this is what the seasonal models latched onto, on the assumption that a major SSW doesn’t occur in a Niña context. Until we get to that point then all is good. 
 

Hard to say which way the days after Xmas will go. Historically amplification tends to be overblown - but at the same time I’m not convinced the magnitude of MJO activity is being correctly modelled and strat forcing has definitely been undermodelled and become greater nearer the time. I’d go 50/50 at the moment between a direct hit from the N with chances of snow and a deflection style hit from the NW which would mean snow only for high ground. But compared with so many seasons previous to this one I’d grab a 50/50 chance of a cold blast with both hands! Glass half full.

[Guest]

20 minutes ago, Jon Snow said:

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

We all could do with that verifying as all the gyms nationwide will be closed and I'll need some decent weather so I can carry on knackering in my ankles and knees!! 

Edited December 19, 2020 by Guest

[Frosty.]

On the face of it you may say the ECM 12z ensemble mean is Meh longer term but I think there is scope for colder shots with a NW / SE angle of attack!..maybe I’m wrong but at least I’m being positive!

[MATTWOLVES 3]

11 minutes ago, Jon Snow said:

On the face of it you may say the ECM 12z ensemble mean is Meh longer term but I think there is scope for colder shots with a NW / SE angle of attack!..maybe I’m wrong but at least I’m being positive!

Karl the more posts I'm reading of yours tonight,the more confused I'm gerrin,and I'm already a halfway house... 

The mean is a bit meh..but we may get cold shots,you might be wrong,but that doesn't matter as long as your being positive...got all angles covered there mate  

 

 

Edited December 19, 2020 by MATTWOLVES

[damianslaw]

Christmas period now coming into the reliable, but not quite there yet, this time tomorrow, will be able to say with much more confidence how the 24th-26th period likely to pan out.

In the short-term, a mid atlantic ridge will develop and usher in a colder feed from the NW, return of frost and possible wintry showers for some, so feeling much more seasonal than the past week or so. Snow most likely reserved for high ground, but not exclusively so, but it looks a rather dry outlook once uppers are conducive for snow. 

The christmas period itself looking rather chilly but dry with some frost, influence from the ridge.

After, divergences between ECM and GFS, former not showing such a strong amplified flow, but still quite a potent N/NW flow which would most likely increase chance of wintry weather in northern and eastern parts. GFS showing much more amplification with the trough dropping down through UK a bit like early December. Some cold uppers mixed in which could bring either a rain deluge or snow fest. As often happens something in the middle usually materialises, which would suggest a cold N/NW flow with a less pronounced trough feature, on the surface this would bring cold and wintry conditions.

[Ravelin]

18 minutes ago, sebastiaan1973 said:

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

With De Bilt being several hundred miles East of the South of England I'm not surprised. If you are searching for an easterly they might be of use, but with the currently modelled synoptics they are virtually useless. If there's a low dropping from the north(ish) across the UK then of course De Bilt will be showing SW or W, whilst the bulk of the UK could be getting winds from either side of N. 

[PolarWarsaw]

1 hour ago, CreweCold said:

Makes sense as we're likely to see repeated bouts of amplification. Each time we get a little closer...

Yeah....to the end of March. 

Only on the wind up. Bit of a middle ground scenario this evening, it's a shame that the 'better' synoptics long term are arising from the GFS and not the Euro's - confidence can increase when it's that way round. The GEFS are predominantly horrific. My feeling is that we may need another delay into the new year for another round of Amplification. 

I think virtually everything is on the table at the moment, which is making the model watching enthralling. 

Those wanting snow at the surface may want to look away for a while yet though. 

[Scott Ingham]

17 minutes ago, Catacol said:

Yes. This is exactly the point. Getting hung up on details at 192h seems a waste of energy to me. Instead step back and try and get the bigger picture. Amplification will continue for now, and to turn the core of winter into something special we need the vortex to be shredded. A cold snap looks likely soon after Xmas....but if it is a sustained cold spell you are after then forget run to run variability (guaranteed to inspire frustration and madness!) and look for broad scale patterns. We are gradually approaching a key point - a SSW might be as little as 3 weeks away and to get it we need trop patterns to align by maintaining amplification via AAM support and EAMT. We also need that Ural High to maintain some degree of influence. I’ll be as happy as the next person if a bit of snow is lying prior to New Year - and if this bout of amplification produces the goods then excellent. But if it doesn’t it isn’t game over because we are in a phase with sustained interest.

The time to get truly morose will be if the amplification has faded by mid January without a SSW. Renewed vortex development at that point would spell the end of a cold February. I think this is what the seasonal models latched onto, on the assumption that a major SSW doesn’t occur in a Niña context. Until we get to that point then all is good. 
 

Hard to say which way the days after Xmas will go. Historically amplification tends to be overblown - but at the same time I’m not convinced the magnitude of MJO activity is being correctly modelled and strat forcing has definitely been undermodelled and become greater nearer the time. I’d go 50/50 at the moment between a direct hit from the N with chances of snow and a deflection style hit from the NW which would mean snow only for high ground. But compared with so many seasons previous to this one I’d grab a 50/50 chance of a cold blast with both hands! Glass half full.

Summed up perfectly.

No need to get hung up on individual model runs and suites. 

Its a slow burning winter of repeated snowgasms each one a little bit stronger than the last culminating in a snowmax last third of january into february 

Im just looking forward to the cigarette after (building a snowman)

[Frosty.]

5 minutes ago, MATTWOLVES said:

Karl the more posts I'm reading of yours tonight,the more confused I'm gerrin,and I'm already a halfway house... 

 

 

No worries Matt, I’ve confused myself..maybe I’ve reached the point with over 20,000 posts where model fatigue is kicking in?..preparing myself for another stupid face from Sceptical!

[Uncertainty]

50 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.

That’s right BA. Even yesterday there was still some support for genuinely flat solutions with no trough dropping down through into Europe at all. 

As @Daniel*has posted the EPS post 240 actually drive the ridge northwards back towards Greenland. 7 or 8 members produce a stonking Greenland or Griceland high and downstream trough over Europe.
 

Perhaps 20 have mid Atlantic highs of various latitudes; most producing chilly but not stellar Northwesterlies. Some remaining members have a UK high with the jet over the top. Again, as earlier in the month, barely any are full on flat zonal.

Cluster wise, there isn’t one cluster I wouldn’t snap your hand off for in a normal year, but seen as we’re in with a chance this year, it would be a shame to see this month’s Synoptics fail to deliver a decent snow event. Cluster 1 look good early and late. Cluster 4 late on looks tasty too.

The GEFS mean looks great but there are quite a few members that follow the op and drop the trough down west of the UK leading to a frustrating pattern with a west based -NAO and rain for most. On the other hand, there are far fewer flatter runs hence the more amplified look to the mean. The EPS for me are similar just delayed by a day or two.

As for the Strat I get the feeling this wave 1 attack, whilst potent, may not provide the killer blow quite yet. There was little concrete suggestion of it on the 46 and there’s nothing at the end of the Meto 30 dayer that you might expect if they were convinced an SSW was imminent. The peak temperature of the warming on the GFS has also trended down on the last few runs.

From the 0z no reversals but lots of weak, stretched vortices which should allow the present phase of trop amplification to continue.

Not sure it will last much longer than mid Jan though, I’m still seeing Ural blocking through early Jan so hopefully it’s on borrowed time. 
 

In summary loads to be excited / fascinated by at present, couldn’t be more different to many previous Xmas periods. At least, weather wise, we might have something to look forward to over the coming weeks.

 

Edited December 19, 2020 by Uncertainy

[BlueHedgehog074]

Sorry if this has already been posted, but the 12Z GFS shows a bit of back edge sleet or snow over the West Midlands and parts of Wales very early on Christmas Eve as the Southern UK Low heads further East and pulls in some colder air from the North-East

 

Despite how marginal it could be - higher ground benefitting more as well as having heavy precipitation for evaporative cooling- the charts above shows how surprise events like this, even in the shorter term, are possible. 

Still room for this little Low during Wednesday and Thursday to change a bit regarding how deep and developed it will be, and also its track. Thus affecting where any possible wintry mix from this front could end up. Seems like Southern UK is mostly the No. 1 spot for the little Low/Shortwave to track through Eastwards at the moment

 

[LRD]

4 minutes ago, Scott Ingham said:

Summed up perfectly.

No need to get hung up on individual model runs and suites. 

Its a slow burning winter of repeated snowgasms each one a little bit stronger than the last culminating in a snowmax last third of january into february 

Im just looking forward to the cigarette after (building a snowman)

Trouble is I'm getting to the age where I can't last the pace with slow burning, building snowgasms and want to get to a snowgasm quite quickly as there is a risk that, leaving it too long, we won't get to a snowgasm at all and the rest of the winter will be spent trying to sleep off the anti snowmax. Of course, with the right visual stimulation and teasing, prospects might be better but it won't take much to put me off

Ahem, anyway on to the charts and the GFS spaghetti is still looking good despite it now struggling to cook down in the short term

[Allseasons-Si]

5 minutes ago, Scott Ingham said:

Summed up perfectly.

No need to get hung up on individual model runs and suites. 

Its a slow burning winter of repeated snowgasms each one a little bit stronger than the last culminating in a snowmax last third of january into february 

Im just looking forward to the cigarette after (building a snowman)

Only joking Scott

it's nice to have another addition to the MOD family

[SnowSalah]

I havnt got time to read all 11 pages.. is the summary for a snow lover good or bad today?

[LRD]

1 minute ago, SnowSalah said:

I havnt got time to read all 11 pages.. is the summary for a snow lover good or bad today?

Bad

But also good. My hunch is don't expect much this next 10 days - after that, however...

[Scott Ingham]

9 minutes ago, LRD said:

Trouble is I'm getting to the age where I can't last the pace with slow burning, building snowgasms and want to get to a snowgasm quite quickly as there is a risk that, leaving it too long, we won't get to a snowgasm at all and the rest of the winter will be spent trying to sleep off the anti snowmax. Of course, with the right visual stimulation and teasing, prospects might be better but it won't take much to put me off

Ahem, anyway on to the charts and the GFS spaghetti is still looking good despite it now struggling to cook down in the short term

What you need to appreciate is this winter we have something in our beds and if we fail to get it up (the Greenland high) we will surely explode at the end when the SSW kicks in. 

Could be worse last year the only thing we had to look at were Tight isobars top shelf magazines

[mountain shadow]

39 minutes ago, Jon Snow said:

On the face of it you may say the ECM 12z ensemble mean is Meh longer term but I think there is scope for colder shots with a NW / SE angle of attack!..maybe I’m wrong but at least I’m being positive!

No two ways about it. That's an awful mean.

Anyone expecting a bitter cold Northerly based on GFS products in the next three weeks is going to be very disappointed. 

[Windysun1]

53 minutes ago, Roger J Smith said:

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.

Mr R J Smith knows a thing or 2 or 3

[Glaswegianblizzard]

8 minutes ago, LRD said:

Bad

But also good. My hunch is don't expect much this next 10 days - after that, however...

Rinse and repeat for the rest of winter....

[Frosty.]

The cfs shows a Northerly in low res (FI)

[Skullzrulerz]

1 minute ago, Glaswegianblizzard said:

Rinse and repeat for the rest of winter....

Couldn't of said this any better 

[LRD]

1 minute ago, Windysun1 said:

Mr R J Smith knows a thing or 2 or 3

There is absolutely nothing scientific in what I'm about to say but I 'feel' that something of interest will happen in the next fortnight for cold lovers. Perhaps the models have picked up a signal but are being too quick with it (oooooh, matron)

However, I have a feeling Xmas Eve and Xmas Day cold might be upgraded short term, but followed by mid-term disappointment before an uptick in cold lovers fortunes around the turn of the year

[Allseasons-Si]

Considerably more downstream troughing East'n  USA on the 18z ICON...

18z 120 v's 12z 126

 

[Scott Ingham]

People are writing off the post Christmas period off of the back of a couple of bad (and not really bad in the grand scheme of things) ecm runs.

Chill out look at it scientifically we still have a very good ticket to the lottery. According to the clusters the ECM has a very minor majority going for something similar to the GFS. The ukmo doesnt go out far enough and the most consistent model in all of this the GFS is signposting a very interesting cold period. 

Itll never be any different on here will it hahaha 

Edited December 19, 2020 by Scott Ingham

[LRD]

3 minutes ago, Glaswegianblizzard said:

Rinse and repeat for the rest of winter....

Whatever. I could be wrong, I could be right. It's only weather for Christ's sake. I'm sure you'll be the first to point out if/when it goes wrong and claim some sort of pyhrric victory (unless you like mild winters and it won't be pyrrhic at all). I'd be more worried about the climate more than the weather to be honest. But the current outlook at least gives interest - which is more than most of the last 7 or 8 winters have done