Model Output Discussion; into 2015

[frosty ground]

Yes GFS P goes with flattening the attempt at Scandi ridging quite quickly at T144hrs.

http://modeles.meteociel.fr/modeles/gfsp/runs/2014123112/gfsnh-0-144.png?12

 

GFS Op a slower evolution with a better attempt.

http://modeles.meteociel.fr/modeles/gfs/runs/2014123112/gfsnh-0-144.png?12

Until we get closer it is difficult to assess how mobile the pattern ends up further on.

 

UKMO at t144 also thinking about Scandi ridging. 

http://www.meteociel.fr/ukmo/runs/2014123112/UN144-21.GIF?31-17

 

At least while there is this uncertainty there is room for a less zonal outlook.

 

Now over to the ECM.

Just wondering was this ridge being shown 24/48/72 hours ago...... at the appropriate times. ... 168/192/216?

We see mean charts all the time and for the last few days they have been flat....

[john mac]

Yes GFS P goes with flattening the attempt at Scandi ridging quite quickly at T144hrs.

http://modeles.meteociel.fr/modeles/gfsp/runs/2014123112/gfsnh-0-144.png?12

 

GFS Op a slower evolution with a better attempt.

http://modeles.meteociel.fr/modeles/gfs/runs/2014123112/gfsnh-0-144.png?12

Until we get closer it is difficult to assess how mobile the pattern ends up further on.

 

UKMO at t144 also thinking about Scandi ridging. 

http://www.meteociel.fr/ukmo/runs/2014123112/UN144-21.GIF?31-17

 

At least while there is this uncertainty there is room for a less zonal outlook.

 

Now over to the ECM.

So now the ukmo is on the scandi ridging!! Now this could well come to nothing but there is no denying that there is a possible trend here. At least something of interest!!

[phil nw.]

Just wondering was this ridge being shown 24/48/72 hours ago...... at the appropriate times. ... 168/192/216?

We see mean charts all the time and for the last few days they have been flat....

I noticed the ridging yesterday fg - around t168/192hrs.

The mean outputs whilst a good guide are an average of all the ens members so the overall wave pattern would become less defined further on.

The 00z mean had it from T144hrs though

 http://www.meteociel.fr/modeles/ecmwf/runs/2014123100/EDH1-144.GIF?31-12

so this has not just appeared. 

[Summer Sun]

? some snow for higher hills Pennine/N Wales areas north if GFS is correct on Saturday?

 

Yep GFS P agrees with this as well

 

[bluearmy]

Ignoring low res gfs, I am beginning to get interested in events to our east and northeast in week 2. Whilst upstream is pretty solid on the Canadian vortex and it's strong, as I said earlier, east of the meridian is less clear cut. the 12z gfsp isn't far away from encouraging SM from his hibernation with low running depressions and heights rising to our ne (coupled with a very cold Russian high to our east)

Edited December 31, 2014 by bluearmy

[Southender]

I have been watching the far reaches of lala land for a few days now and I have noticed the tendency for some energy to split from the PV and head in a SE'ly direction into France/Spain. Obviously miles away, but perhaps something to keep an eye on as we head into Mid-Jan, as a possible trigger to something more "interesting"

[mountain shadow]

UKMO at t144 also thinking about Scandi ridging. 

http://www.meteociel.fr/ukmo/runs/2014123112/UN144-21.GIF?31-17

Not much of ridge, its collapsing at that point and already positively tilted to sink. The PV is already sending a pulse of energy East which would stop any attempt at a Scandi High.

[bluearmy]

Not much of ridge, its collapsing at that point and already positively tilted to sink. The PV is already sending a pulse of energy East which would stop any attempt at a Scandi High.

Yes it would but the trend to stick a ridge north towards svaalbard is unavoidable. Unfortunately, gfsp low res kicks in as the Atlantic winds up a super low which will skew the rest of the run. I do like the profile east of the meridian by day 10. Not to be taken literally of course but again a trend and if we can get the Canadian vortex wrapped up in itself then we could be onto something. You never know.

[chionomaniac]

I think that it is worth pointing out that the latest forecast zonal conditions are completely different to last years. Then we saw a displaced polar vortex to the NA sector, leaving us in the prime position for zonality. This year we have seen the vortex split a number of times and it is forecast to do so again in the coming days. The problem being this time is that the split is unfavourable for the UK, leaving a flattened section of one of the daughter vortices in the worst position possible - across the southern aspect of Greenland.

 

The vortex is not (forecast to) split strongly enough to allow the jet stream to be prevented from crossing the Atlantic - it is poorly positioned for an Atlantic block - but well positioned for a Scandi block as the following 100hPa chart shows:

 

 

Further up the height of the stratosphere a warming is forecast to effect the Greenland daughter vortex but yet again it has not been modeled strong enough to fully knock both daughters out and so we are left with the situation where a weak tropospheric vortex can reform to our NW. We can see the vortex that we want 'knocked out' on the 30hPa chart.

 

 

However, the modeling of any stratospheric split and subsequent warmings are not easy for the models to perform - the dynamics of the whole stratosphere interacting with the troposphere have been modeled inconsistently this winter - sometimes well and sometimes not so well. We have seen the disruption to the stratosphere that we would expect in an El Nino eQBO year, but have yet to reep the rewards. However with such uncertaintity with the strat that is still 'ripe' for further disruption, we should not rule out a sudden change in tropospheric synoptics. It wouldn't take that much of a change in what is forecast stratospherically to produce this.

Edited December 31, 2014 by chionomaniac

[Polar Maritime]

Very stormy out in the run as a deep Low spins across the UK. Feeling cool to. Some big changes in tonight's output with the Arctic High much further South in turn pushing the Jet South.

 

Edited December 31, 2014 by Polar Maritime

[IDO]

I am less inclined to believe the GFS P, due to past digressions and the GEM is probably a better balance:

 

 

You can see later in FI how the bias in heights translates to blowing up of lows in FI on the GFS P:

 

 

And its D16 charts is out of the ECM D10 Hall of Fame:  

 

I think the UKMO would play out like the GEM as well. NAVGEM sort of in between: 

 

Of course the GFS op is probably to progressive with the Atlantic. Though I have to like the way the GFS P goes and you have to hope that for once it is seeing something!

Edited December 31, 2014 by i'm dreaming of...

[Polar Maritime]

Much better run for cold prospects, With Heights also pushing up into Greenland and nearly joining. A few more frames would bring a Northerly. I would expect very jumpy output over the next few days.

 

Edited December 31, 2014 by Polar Maritime

[mcweather]

I think that it is worth pointing out that the latest forecast zonal conditions are completely different to last years. Then we saw a displaced polar vortex to the NA sector, leaving us in the prime position for zonality. This year we have seen the vortex split a number of times and it is forecast to do so again in the coming days. The problem being this time is that the split is unfavourable for the UK, leaving a flattened section of one of the daughter vortices in the worst position possible - across the southern aspect of Greenland.

 

The vortex is not (forecast to) split strongly enough to allow the jet stream to be prevented from crossing the Atlantic - it is poorly positioned for an Atlantic block - but well positioned for a Scandi block as the following 100hPa chart shows:

 

viewimage.png

 

Further up the height of the stratosphere a warming is forecast to effect the Greenland daughter vortex but yet again it has not been modeled strong enough to fully knock both daughters out and so we are left with the situation where a weak tropospheric vortex can reform to our NW. We can see the vortex that we want 'knocked out' on the 30hPa chart.

 

viewimage-1.png

 

However, the modeling of any stratospheric split and subsequent warmings are not easy for the models to perform - the dynamics of the whole stratosphere interacting with the troposphere have been modeled inconsistently this winter - sometimes well and sometimes not so well. We have seen the disruption to the stratosphere that we would expect in an El Nino eQBO year, but have yet to reep the rewards. However with such uncertaintity with the strat that is still 'ripe' for further disruption, we should not rule out a sudden change in tropospheric synoptics. It wouldn't take that much of a change in what is forecast stratospherically to produce this.

Indeed Chiono. very much as the latter stages of todays 12z GFS para would suggest. let us hope this trend is our friend.

[BlueHedgehog074]

It seems to me that there seems to be a lot more high pressure over us this weekend that hoped for over the last few days.???

That's certainly true and, in a way, can show how things can change at fairly short notice. I suppose, to be fair, I probably should have mentioned in my first paragraph about the possibilities of High Pressure building back over us this weekend and also that there's always a chance of seeing further ridges of High Pressure down the line. Some seem to mention about the possibility that the weekend High Pressure system could get sucked up towards Scandinavia and help set up a chilly flow from the continent (although quickly flicking through the 12Z GFS runs, the High gets knocked to our East into South-Eastern Europe). The Scandinvian High idea is perhaps something that still can't be totally ruled out, especially if somehow Alantic Lows were to become negatively tilted and try to slide underneath the High. But do feel unsure about whether the High Pressure can really put up a strong enough fight against the mighty Greenland/Canadian Vortex to our North-West, as it kinda seems like Atlantic Lows may try break through further East through the UK.

For now, it seems the weather will be quite Atlantic dominated with the most disturbed conditions over North-Western parts, but always chances for ridges of High Pressure, just like for this weekend, to pay the UK some visits. And keep things more settled at times. I think, interestingly, what does seem to happen sometimes when the models show things flattening out in FI is to, over time, try and bring more amplification into the flow. This being especially true if a model has been too eager to flatten out a pattern.

Edit: While I'm at it, would like to wish you all a Happy New Year. :smiliz39:

Edited December 31, 2014 by DiagonalRedLine

[IDO]

GFS Mean at T138:   Control: 

[bluearmy]

IDO. I wonder if the complexity of the current situation re trop/strat coupling makes the high res of the ops a favoured route at the moment?

I wouldnt bother with gfsp past day 10. Like I said the broad profile at that timescale interests me. Likewise the ECM later at day 10. No detail, just general trends which seem to reflect a propensity to raise SLP and heights when the vortex has departed an area.

perhaps Ian had a point earlier when he posted that Exeter weren't convinced the strong zonal signal would make it to 2 weeks unabated?

[Jason M]

GEFS are making more of the ridge again at 120 hours. See example below

 

http://www.meteociel.fr/modeles/gefs_cartes.php?code=20&ech=120&mode=0&carte=0

 

I do think its a false signal though, as the last three or four sets have arrived at some reasonable looking day 5 charts. That said, I've not seen one ensemble fail to collapse the ridge over the last few days, and at 5 days out I'd expect at least one or two runs to make something of the situation. Its a bit like the possible easterly for this week, where at their best the charts just needed that one further little nudge north, but they backed away at that stage. I think the same is happening here.

 

Edit: Just noted IDO's post. Really, the 120 hour mean would have been a bit more useful alongside the 138.

Edited December 31, 2014 by Jason M

[A.J]

forget the GFS, ECM & MOGREPS output.........I've just got a very expensive subscription to the new PHROAR model, and it looks full of wintry promise to me

 

 

I'll fetch me coat

 

 

Happy New Year Folks!! 

[mulzy]

GFS Mean at T138: gens-21-1-138.png  Control: gens-0-1-138.png

 

Interesting that the Balkans likely to get cold - very La-Nina like....

[Mucka]

Well at least that was a decent end to the GFSp in deepest FI.

One or two members offering just a glimmer of hope of the Atlantic train being slowed within the 10 day timeframe but very much the minority - still we have to start somewhere and any signal will likely start off very weak and build rather than we see a sudden flip on one ensemble set.

There is at least a signal for increased chance of more amplification past day 8 and so colder air could be dragged further South even in a relatively mobile ridge/trough scenario.

If a straw is all you have then you may as well use it.

[IDO]

IDO. I wonder if the complexity of the current situation re trop/strat coupling makes the high res of the ops a favoured route at the moment?

I wouldnt bother with gfsp past day 10. Like I said the broad profile at that timescale interests me. Likewise the ECM later at day 10. No detail, just general trends which seem to reflect a propensity to raise SLP and heights when the vortex has departed an area.

perhaps Ian had a point earlier when he posted that Exeter weren't convinced the strong zonal signal would make it to 2 weeks unabated?

 

I agree that we have the unknown re trop/strat coupling. But how do we know what the relationship is until we get a clear signal that the warming is direct to the trop? At the moment we have two waves of Atlantic/Euro ridges that have sent WAA towards the Scandi area:

 

 

This has provided a delay for the PV to our NW from over running the ML. 2/3 days ago the GFS had given less credence to these ridges and the PV spilled east quicker. Therefore is the baby Scandi ridge a strat/trop response or did the models just under-estimate the strength of the ridges from the south? At the moment I suspect the latter. At D8 the general trend is there to see:

 

 

But of course as you say if the strat/trop response is effective and is direct then the GFS ops are the best bet, but maybe not the GFS P.

[MR EXTREMES]

Many a winter we seen a Scandinavia ridge build and believe me when it's there it don't get moved on easy.

A Greenland block is certainly not going to happen but Scandinavia ridge will only be decent if lower heights to our South and into Southern Europe and se Europe.

But it's shown every year that Scandinavia heights are robust and long standing.

Of coarse it might not build or if it does it might be to Far East.

But background singles do offer the slightest chance although weak chance but better than no chance.

If I were to take the models at face value tonight I would say we need something concrete by mid month or I'd be inclined to say feb for another shot.

[Chris K]

forget the GFS, ECM & MOGREPS output.........I've just got a very expensive subscription to the new PHROAR model, and it looks full of wintry promise to me

 

1920x1080.jpg

 

I'll fetch me coat

 

 

Happy New Year Folks!! 

 Even the snow on the nearby tree has started to melt

[pointswest]

forget the GFS, ECM & MOGREPS output.........I've just got a very expensive subscription to the new PHROAR model, and it looks full of wintry promise to me

 

1920x1080.jpg

 

I'll fetch me coat

 

 

Happy New Year Folks!! 

Better take more than a coat there.....she looks trouble to me!! HNY!!

[MR EXTREMES]

forget the GFS, ECM & MOGREPS output.........I've just got a very expensive subscription to the new PHROAR model, and it looks full of wintry promise to me

 

[url=https://forum.netweather.tv/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=235998]1920x1080.jpg[/

 

I'll fetch me coat

 

 

Happy New Year Folks!!

That's what I call strat warming I'm bit chilly tonight send her my way lol