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

[Jonathan Bollen]

Look at this in FL a eastly never saw it coming but at least it shows on the Gfs model. 

[That ECM]

All three at t144 have the ridge starting to build out west. Let's hope we can see this at t72 then it may well be game on. At last output excitement. Personally wouldn't worry about what is shown after this time. 

Edited December 23, 2016 by That ECM

[booferking]

The ECM is good @ 192hr when compared to gfs run but fails to deliver @ 216hr but hold on it has another go @ 240hr.

When comparing the low on canadian lobe the GFS 192 it is more intense and further South helping WAA.

The trend is there lets see were this takes us over the next few days.

Edited December 23, 2016 by booferking

[MR EXTREMES]

7 hours ago, TEITS said:

The runs this evening come as no surprise to me which is why I mentioned the Iceland SLP GEFS mean a few days ago, and why we should keep an eye on that. As I said a couple of days ago what is being suggested instinctively looks right to me whereas I never bought into all the hype during late November.

At least we now have some eye candy to follow which makes a nice change.

So the 12Z GEFS mean for Iceland was 1010mb. I fancy this will rise to 1040mb in around 7 days time.

and tetis you where saying good call 1045mb

 

[Iceberg]

Well I've been busy with Christmassy things over the last day or so and missed most of the models, but I see that things continue well. 

Please excuse this first part but I was shouted down as the first part of January couldn't possible hold any potential. There wasn't any chance of the Atlantic being blocked as we enter the beginning of January. 

Well the models could still be wrong as it's a prediction 10 days out but they are now more clearly showing the potential. Gfs, gfs ens and ecm. Remember it's only the trend we need to look until it gets to t144 and the trend is very nice indeed. 

[knocker]

The ecm also has HP amplifying NE with the deep upper trough to the west and the cut off upper low apparently not an insignificant player. Thus the run ends with a quite an intense high pressure cell centred about 500Km west of Cornwall. The exact orientation of this, always assuming that this anywhere near correct of course, will dictate the upper flow

[Blessed Weather]

Back on Weds fergieweather posted that the DECIDER product was indicating the potential for High pressure to set-up west of Ireland, bringing "increased risk of NW'ly flow early into New Year". And that morning the GFS 06z chart started to show such a set-up which I posted in the Alps thread.

The GFS has continued to show this since Weds, but with a trend to move both High and subsequent N/NW (and now NE) flow further west. So this morning's 0z output from GFS has some consistency to the story and at last I sense the UK might be in with a shout of seeing some very cold air and dare I mention snow.

You can see the trend from the GFS output below. Early Jan charts from 21st, 22nd and today 23rd:

[carinthian]

1 minute ago, Blessed Weather said:

Back on Weds fergieweather posted that the DECIDER product was indicating the potential for High pressure to set-up west of Ireland, bringing "increased risk of NW'ly flow early into New Year". And that morning the GFS 06z chart started to show such a set-up which I posted in the Alps thread.

The GFS has continued to show this since Weds, but with a trend to move both High and subsequent N/NW (and now NE) flow further west. So this morning's 0z output from GFS has some consistency to the story and at last I sense the UK might be in with a shout of seeing some very cold air and dare I mention snow.

You can see the trend from the GFS output below. Early Jan charts from 21st, 22nd and today 23rd:

Malcolm, that last chart is great for the UK cold and Euro ski resorts. Looks snowy as well and almost in the reliable time span. Lets hope ECM run this morning shows the same at 240t. When you off to the Alps ?

C

[northwestsnow]

Gfs shows a decent block to the North west but ECM no where near as good, much flatter, however i wasnt expecting this opportunity so its fascinating viewing!

[bluearmy]

quite a complex set of scenarios to drive the ridge and then amplify it enough to avoid the gem solution this morning. 

At the moment, looks like we could get lucky for a cold shot and whether that is sustained via mid altlantic ridge or scandi ridge are both options. However, could end up a standard toppled as upstream retains the strength to flatten the pattern.

the envelope is wide this morning but for once it isn't just a brown one! 

[northwestsnow]

5 minutes ago, bluearmy said:

quite a complex set of scenarios to drive the ridge and then amplify it enough to avoid the gem solution this morning. 

At the moment, looks like we could get lucky for a cold shot and whether that is sustained via mid altlantic ridge or scandi ridge are both options. However, could end up a standard toppled as upstream retains the strength to flatten the pattern.

the envelope is wide this morning but for once it isn't just a brown one! 

Any musings as to the cause of this Atlantic amplification blue.Looking forward to stewarts thoughs if he finds time to post...

[karlos1983]

@Ali1977 when did you say you were travelling away 

if it was me, I'd start thinking of an excuse. You never know, maybe the weather will stop you getting to the airport 

Joking aside, I am getting cautiously optimistic now, ECM upgrade seems to have been a good one, it seems to have performed pretty well of late. Not getting carried away as this is still way to far out, but the signs are good! 

 

Edited December 23, 2016 by karlos1983

[sorepaw1]

Nice looking charts the 18z and 00z.

Hope it's still showing Christmas day  within T+156hrs.

if it pulls of New year travelling could become hazardous. 

[mountain shadow]

I would urge great caution in believing any model output showing a proper Greenland High, I see nothing to support it teleconnectily.

A brief or decent ridge seems likely but we have seen even these get toppled East in the past.

Cautiously pessimistic are my watch words!

[Iceberg]

Re why we get amplification for me it's two reasons why we have potential. 

Firstly at t220 if you draw a line from us to Alaska then most of the pv (trop) is to the east of this line. 

Secondly we have the high dragging cold air into the mid states, this forms low pressure but with no strong pv to push it out, the result it a waa push allowing the ridge to build in the Atlantic. The lack of pv over Greenland then also allows it to ridge northwards as per the waa build. 

The spaners are a pv fragment over Greenland causing the block to collapse before it get started with the waa will only enhance. And the cold air digger further east in the states. 

[Banbury]

I wont buy into anything at the minute until the 21:55 weather shows something.

Greenland ENS............................id go steady guys if I was you

[Blessed Weather]

Dr Cohen tweeted last evening about the GFS 18z 500mb height anomaly showing a great set-up for North America. Well it's still there on this morning's 0z run and it doesn't look too shabby for the UK either with a big height anomaly over Greenland and the lobe of vortex (polar low) 'trapped' over North America.

@mountain shadow wise words of caution!

 

[Summer Sun]

 

Edited December 23, 2016 by Summer Sun

[KTtom]

24 minutes ago, mountain shadow said:

I would urge great caution in believing any model output showing a proper Greenland High, I see nothing to support it teleconnectily.

A brief or decent ridge seems likely but we have seen even these get toppled East in the past.

Cautiously pessimistic are my watch words!

Well, the weather hasn't been playing ball with teleconnections so far this winter, lets hope it doesn't start now! ....Wild cards???

[northwestsnow]

2 minutes ago, Summer Sun said:

 

Well a north wester might produce in early jan , sounds like the op was one of the flatter solutions...

[karlos1983]

8 minutes ago, Summer Sun said:

 

23 reasons to be extremely cautious then  for me! Usually I would be saying 28 reasons to be optimistic but We've been here once or twice before this season 

Edited December 23, 2016 by karlos1983

[Frosty.]

The Gfs 00z wishes everyone on netweather a white new year!

Edited December 23, 2016 by Frosty.

[bluearmy]

Worth scanning the ECM spread on days 9 and 10 ...........

the eps thereafter draw the scrussian trough low anomolys sw across Europe to our south - early days but with the mid Atlantic ridge firming up run by run the risks of the less cold evolution are dropping whilst the chances of a wintry early 2017 increase

[knocker]

One musn't forget the other player in this and that's the Russian lobe of the vortex which seems to be intensifying and the east European trough moving W/SW. How important will this be if the amplification, caused presumably by the Pacific wave train and the Aleutian HP ridging into the Arctic, is but transient and the Atlantic flow becomes flatter which the ext mean EPS is indicating?

[LRD]

50 minutes ago, mountain shadow said:

I would urge great caution in believing any model output showing a proper Greenland High, I see nothing to support it teleconnectily.

A brief or decent ridge seems likely but we have seen even these get toppled East in the past.

Cautiously pessimistic are my watch words!

I agree that folk should always treat longer range modelling with caution but can't agree with your reasoning. There is obviously something that's being fed into the computers (and the way they are interpreting this info/data) to make them churn these projections out... regardless of what teleconnections are or are not saying (and also regardless whether or not these forecasts verify). So the computers are seeing some scientific reason to come to the current conclusions they're coming out with - positive teleconnections or not. As I say they might not verify but that doesn't mean they should be dismissed - if the models are throwing certain scenarios out, then, by definition they must be possible

If that makes any sense at all!

However, I do suspect things might be watered down nearer the time as often happens but I obviously hope they don't and, indeed, 'upgrade' (for ice, snow and cold)

Edited December 23, 2016 by LRD