Model output discussion - 5th December 2016 - Into Winter we go

[IDO]

2 minutes ago, Nick L said:

I'm not debating whether it's cold or mild, I'm correcting you when you said it was the maximum at 6pm only. And yes, I'm sure.

When I look at the GFS on meteociel they have 2m temps for the actual time period: http://www.meteociel.fr/modeles/gfs/royaume-uni/temperatures-2m-hd/3h.htm and I assumed wetter was the same! Thanks for correcting me.

[Methuselah]

Apart from some occasional frost and/or fog patches darn sarf and some rain in the NW, things look excruciatingly bland to me...For how long can nothing continue?

[knocker]

2 hours ago, Singularity said:

Despite appearances at 850 hPa, only the yellows over N. Ireland and Scotland represent mild conditions at the surface (it's the mild sector of a low getting entrained into the circulation). The yellows to the south are upper level 'warmth' generated by interaction of the SE flow with the Alps - at the surface it's proper chilly.

I'm sorry I'm not really following that. Whilst I agree with the north south split regarding the surface temps in the UK it looks to me down to the different air structure within the circulation of the high pressure with SE flow over England and SW over Scotland. I'm puzzled as to the location of the mild sector of a low that gets entrained?

 

 

Edited December 10, 2016 by knocker

[booferking]

I would bank that right now over this high malarkey and yes even  the SOUTH EAST gets snow and the cold shot last up to the big day.

[Carl46Wrexham]

5 minutes ago, booferking said:

I would bank that right now over this high malarkey and yes even  the SOUTH EAST gets snow and the cold shot last up to the big day.

Uppers look a bit too marginal for my liking. Higher elevations would doubtless do well. Cold rain for the rest of us. As for that bottom chart which shows snow over large parts of the country, all i will say is that I have yet to see a single one of those charts turn out accurate. Even at 48 hours out they are wildly inaccurate.

[Jeremy Shockey]

 

Temperatures potentially trending colder from 15th / 16th away from this current mild period 

 

Edited December 10, 2016 by Jeremy Shockey

[karlos1983]

Probably the poorest set of gfs ensembles we've had for a while. None going with any form of "deep" cold apart from 1 blip in the middle of the run which looks a bit rogue in nature.

let's hope for an improvement on the afternoon runs!

[ManiaMuse]

32 minutes ago, Ravelin said:

Right, I'm gonna break the rules myself just to say, Mods, break out the 'ban hammers' cos I'm fed up of trawling through dross in this thread. One liners, mild or not mild arguments, to BBQ or not BBQ etc. There's been enough warnings already, time to get tough or its going to be a very long winter irrespective of what the weather brings. 

+1

As a lurker who doesn't understand most of the technical posts but still enjoys reading them anyway to get an idea of which way things may be swinging, it's getting really annoying having to sift through all the petty bickering and overly optimistic/pessimistic one liners that don't add anything to the thread.

(Yes I'm aware this post is also breaking the rules so warn/ban me if needs be)

[bobbydog]

Looking at the GEFS for Christmas eve/day, which at that range is as realistic as looking at the Op, quite a few showing a cold flow. Some showing nasty storms and a few even showing snow. With the current model uncertainty, any one of them could be the outcome by Christmas.

Also, not one of them is showing what I would consider "mild" even the ensemble mean is showing around 4°C on Xmas day.

Edit- I missed one. One of them is showing mild.... only one....

Edited December 10, 2016 by bobbydog

[Mucka]

What can we do when almost the entire GFS suit flip flops from blocked to mobile run to run?

The 00z was possibly the strongest signal yet for blocking Christmas week and then the 06 comes along and could be among the weakest.

I can certainly see where the MetO forecast is coming from though, high to the East and trough to the West but no undercut/low heights into Europe, so no real snow prospects. That has been the pattern for December, plenty of promise but all unrealised.

No doubt the 12z set will be much keener on building heights North and blocking again in FI. All very frustrating tbh.

If I had to take a wild stab at Christmas weather I would say temps around average in the North, perhaps a little below in the SE, mostly dry.

 

Edited December 10, 2016 by Mucka

[Banbury]

Starting to see a bit of agreement out to the 17th ( next weekend looks chilly ) after that it could go absolutely anywhere and I mean anywhere . I'd favour something around average rather than brrrrrrrr or mild

Edited December 10, 2016 by Banbury

[Snow Grain]

46 minutes ago, booferking said:

I would bank that right now over this high malarkey and yes even  the SOUTH EAST gets snow and the cold shot last up to the big day.

That would bring breezy weather with rain for most.  Great if you want a white Christmas on Ben Nevis.

[johnholmes]

What can we do when almost the entire GFS suit flip flops from blocked to mobile run to run?

Quite simply stop following each run out into far F1 and compare like with like at these extended times.

Edited December 10, 2016 by johnholmes

[Catacol]

44 minutes ago, booferking said:

I would bank that right now over this high malarkey and yes even  the SOUTH EAST gets snow and the cold shot last up to the big day.

Well - maybe... but polar north westerlies for low lying areas usually means wind and cold rain. Pretty grim and I would suggest more grim than a frosty block. Right now we need to wait patiently for the locale of the block to shift because it has setup in the worst possible place for us. But it is a very strong block and the suggestion towards Christmas is that it will move north. A strong block - even a Rex block to start with as Knocker referred to previously- gets us tantalisingly close to proper battleground Synoptics as per 1991 or 1996 or perhaps even a bitter feed as per 1987. For that reason I very much hope we will not end up under marginal NW air streams.

Dont see it happening anyway. The key now is patience and whether the GWO can stay away from orbits 1-3. As I posted last night the GEFS keeps seeing the Nina footprint hitting the atmosphere but so far this season it hasn't. If that is maintained then the current modelling of a U.K. Block will be undercooked. If the ENSO disconnect can continue to work in our favour then the block ought to be much higher lat than that.

im still very excited by this winter. Most positive feel for many years. So much that can still go right for coldies. The ongoing misery and negativity of some posts frankly has no place in 2016/17 when background drivers are so good. First 10 days of December has brought some pretty painful reading to this thread with toys strewn everywhere. Let's see what the next 10 days brings........

 

[booferking]

27 minutes ago, Snow Grain said:

That would bring breezy weather with rain for most.  Great if you want a white Christmas on Ben Nevis.

Ireland scotland wales most of england would see snow inland away from the coast but im not going to debate a chart that is 12-13 days away in fi.

Edited December 10, 2016 by booferking

[swfc]

given the outlook im guessing arguments ete over temps in fi shows what a state the nhp is in atm.

id be hoping for a reset in the current set up ie a good nnw blow with wintry showers ete.sick of this euro type blocking sticking around .also the ski industry looks in dire straights atm and needs this change imo

[Nouska]

4 minutes ago, Mucka said:

What can we do when almost the entire GFS suit flip flops from blocked to mobile run to run?

The 00z was possibly the strongest signal yet for blocking Christmas week and then the 06 comes along and could be among the weakest.

I can certainly see where the MetO forecast is coming from though, high to the East and trough to the West but no undercut/low heights into Europe, so no real snow prospects. That has been the pattern for December, plenty of promise but all unrealised.

No doubt the 12z set will be much keener on building heights North and blocking again in FI. All very frustrating tbh.

If I had to take a wild stab at Christmas weather I would say temps around average in the North, perhaps a little below in the SE, mostly dry.

 

If you look at the last ECM46 ensemble mean chart (Christmas week) for 500-1000 thickness - you can see why models are having such difficulties in solution. Such a narrow corridor between quite extreme thickness values and just tiny oscillations in the pattern give very different outcomes as surface conditions.

It could be some time before this is resolved.

[nick sussex]

Its like after the Lord Mayors show today after some brief excitement last night from the GFS 18hrs run. Once again a rampant jet and too flat upstream pattern at the crucial timeframe scuppers chances of a Scandi high.

Looking at the ECM ensembles theres a small cluster of solutions that have the high further north. Apart from that very little interest upto day ten.

 

 

[Hanny]

1 hour ago, knocker said:

I'm sorry I'm not really following that. Whilst I agree with the north south split regarding the surface temps in the UK it looks to me down to the different air structure within the circulation of the high pressure with SE flow over England and SW Scotland. I'm puzzled as to the location of the mild sector of a low that gets entrained?

 

 

Sorry to jump out of the learners amateur wilderness, please may say that the above is a great example of how to be be polite but constructively challenge another post in such a way that us lesser knowledgeable readers can both learn and understand.

This is a great site as a learning resource with both professionals and very knowledgeable enthusiasts.

It is a shame that some posts have been disrespectfully bullish or demonstrating a little knowledge becomes dangerous when posted based on opinion and not facts.  

Bottom line is that we are ALL learning but at different levels both professionals and enthusiasts alike. 

Moderators sorry for off topic post.

Many thanks to you all.

[Timmytour]

13 hours ago, Timmytour said:

The GFS 18z has had me picking toys up off the floor to put back into the pram again......

I came down this morning to find they'd all been chucked out again!!

The models are doing the okey cokey with mild/cold solutions at the moment. Just as it wasn't worth getting too excited with one promising looking run, it's not worth getting too despondent over one run switching away from that promise. I often find that promise sniffs its way into the models thinking and that what shows up as 1 run in four,becomes one in three,becomes one in two and then is all of  sudden in a realistic time frame with a lot of backing....

[Dangerous55019]

At the risk of being ripped limb from limb for fetching the CFS into whats going to happen in two weeks time, lets have a look at it...
(And before anyone says it, I know that the CFS can be about as reliable as trying to hit 180 on a rotating dart board, but I actually do find it a very good model when looking for 'trends').
... The first image shows the week encompassing Christmas day, and you can see high pressure centred to the north of the UK. This would give us easterly or south easterly winds, but there is a low pressure area just off the coast of Ireland
The second image is from the CFS daily run, and we can see high pressure over to the North east of the UK with quite a vigorous area of low pressure just off the coast of Ireland... This would give us South easterly to southerly winds on the day itself.
And finally lets have a look at the GFS (06z) for the big day itself... This is actually very similar to what the long range CFS is showing, but with a really impressive dartboard low off the coast of Ireland.

My take on the situation is that I think Christmas day itself will see high pressure domination over much of the UK, with winter sunshine; there might be some overnight frost, but no easterly, and no snow unless you're in the highlands of Scotland.
Sorry if that's not what you want to hear (or see), but that's what I'm seeing. 

And my gut instinct is that this will be quite close to the mark.

[bluearmy]

Can we talk about anomalies

a high anomaly north of the uk needs to be intense to represent a proper area of high heights as standard climatology has fairly low heights in that area. Conversely, a weak looking high anomoly south of the uk could easily represent white high heights as we would usually find quite high heights to reside there.

looking at the CFS chart above, the high anomoly is north of the uk and this then weakens as we head south into Europe. The reality of this would be a fairly large area of highish heights spread from e Greenland down to se Europe. tough to say exactly where it's strongest at 500hpa but what's certain is that it wont be that large an area come verification. Coldies would want to see it further north and non existent further south allowing a flow east of south and strong enough to advect cold west. The circular shape of most intense variation from normal could offer a clue as to where it may be favoured but we have no idea of if the ridge will extend west towards greeny or se into Europe.  as ever, the heights over Europe are IMO critical to chances of deep cold and snowfall. 

Mucka, not sure I see the GEFS flip flopping that much. They are moving the position of most intense anomoly around but the broad theme is blocked around w Europe. 

[SMU]

Afternoon All-

well the first nineth of winter has passed & thus far apart from the x2 nights of very seasonal frosty weather at the start of the month its been all down hill from there, at the end of tomorrow we will be circa +1c above on CET & nothing in motion to stop it- I would be revising my guess ( sadly ) for this month to a landing zone of between 6-7.5 at this stage :(-

Anyway, in terms of modelling the status quo is still evident with an airmass up from the south / south west / west across the next 10 days - no SE airmass? - well we get the wind 'maybe' but the airmass is a long way behind.

Here is the closest the continental air gets 

its way back over germany -

later in the week we get a smidgeon of a wave over the UK & as a result some colder polar air gets held at the surface for England into next weekend- so possibly some frost then under the inversion-

Whats important to remember though from the inversion is that we can get a cold inversion & a warm one - & post next weekend we have some VERY warm air moving into Ireland & Scotland - penetrating ESE with time

So that temporary cold air trapped at the surface will be mixed out-

Next 7-8 days then mild/ very mild with 2 days of chill in the air. -

Chances of anything better ( from the East ) less than 10%- theres no undercut or any suggestion of that developing- even todays  UKMO 00z 144 that has been touted as good is infact warm & wet with no undercut.

So then the rest of Dec, Im afraid I dont share Any of GPs thoughts on the high retrograde west - ( im pretty sure it was forecast to already be in the models ) but its a very low end chance for at least +9 days..

As ive posted the expectation ( for me ) is the 'burst' in 10 HPA zonal winds stratospheric will propergate downwards this week & next - with a forecast peak of approx 40 & 45 M/S - ( remember the december ave is about 30-35 across the piste. ( todays is along the upward curve @33.4M/S

Is there a disconnect / non propergation - NO !

The next 7 days from 12 hours to 168 clearly shows the increased speeds propergating downwards in 60N - 

it would be clearer if the scaling on those were ^^ in 5 M/S not 10 !

In terms of the pattern, the vortex is modelled to be stronger & stronger, although because its come from a lowish base its still slightly displaced from its usual position but generally from our quadrent the jet is riding up over iceland & dropping back SE over central europe seen nicely here

 

Therefor the conclusion is much the same as it was 3-5 days ago, continued westerlyness for 10-12 days at least poss longer- no retrograde ( as per some forecasts ) & no easterlies !

chances as follows:

*Westerlies to day 10 or a deviation there of: 70%

*Pattern backing sufficient enough pre day 10 to advect some sub <14c thetas from the SE about 20% 

*Snow cold arriving from an Easterly 10%

 

Finally a word on the GLOSEA/ECM Long rangers - I as have many others have been critical of what the output was, more especially recently as they both continued to tout northern +VE pressure to the North of the UK-

however in retrospect for December its done quite well- 

Here are the height anomalies for the first week of Dec-

so with the core of the focus from Ian being that +VE anomalies would be North of the UK - you could say its been a moderate success ( so far )

whats missing - & something that maybe if it shows again we need Ian to comment on isnt so much the +VE to the North but the troffyness ( is that a word!) to the South & East as part of the forecast was to highlight westward propergation of cold air towards the UK from the East, so personally I think a score of 7/10 early doors on that one for the glosea / EC outputs.. !!

Also did we get an answer from Adam S on why the seasonal models are essentially ignoring the zonal wind burst in favour of more of the same ? @fergieweather

 

Are there any positives today, well just the one for me - the GFS ensembles ( whilst theres no mean ) have just flattened the peak of the zonal wind burst now around day 12-16 with a few members dipping off- We know the OPs have indicated a few chances of a SSW from that time so thats something to monitor over the next 48-72 hours -

In terms of blocking projections- much the same, the velocity of the westerly wind will make it very difficult for any cross polar blocking & any MLBs with high wave amplitudes so no possibility of any true GH, best we get later on is slight atlantic amplification or some higher amplitude on the scandi high to force the cold west more... Low chance of a white Xmas at the moment...

Cheers 

S

@Dangerous55019 Todays CFS 00z CFS control have the peak of the zonal burst first few days of Jan then minor possible minor warmings at that timeline on both with the zonal wind dropping to November levels again second & third week of Jan - allowing the higher probability of HLBs again - S

Edited December 10, 2016 by Steve Murr

[musician]

1 hour ago, ManiaMuse said:

+1

As a lurker who doesn't understand most of the technical posts but still enjoys reading them anyway to get an idea of which way things may be swinging, it's getting really annoying having to sift through all the petty bickering and overly optimistic/pessimistic one liners that don't add anything to the thread.

(Yes I'm aware this post is also breaking the rules so warn/ban me if needs be)

Agreed. I'm trying to learn more from those far more knowledgeable than myself but have to trawl through reams of bickering instead of backing up thoughts with models. Its become so bad that if I don't see a chart I tend to disregard the one-liners. PLEASE lets return to serious discussion! 

[Timbo]

i have a feeling that over the next few days the models will move more towards a proper Scandy High, this then allowing a cold pool to develop and move Westwards into the South of the UK

East Anglia could be seeing a proper white Xmas with frequent snow showers.

Watch this space and watch a turn around in the models starting tomorrow