Model Output Discussion 18th Nov.2013-12z onwards.

[Cecil Hogmanay Melchett]

Im not convinced at all.

Pressure remains stubbornly high across the UK and Europe, and we can probably expect there to be an upgrade to depressions forming off the eastern seaboard scuppering any potential block retrogression.

Hopefully im wrong and tomorrow will be another step in the right direction.

[Barry12]

Hopefully this trend builds from FI and continues into reality ocean, the GFS 18Z is heading in the right direction.

[mountain shadow]

Until any Greenland amplification gets into the high resolution I'm remaining cautious.

The story of the last two weeks has been for the amplification to be much flatter and further East than initially programmed.

[bluearmy]

The extended ecm london ens are clustered cold and, looking at the anomoly charts fir the latter part of the run, this must reflect mlb delivering either a stagnant or continental feed to se uk.

[SMU]

Heres an interesting fact-

 

We have heard MUCH this month that once the high topples a swift return to SW winds would be the case, the high would topple-

 

Even Ian at the met touting the decider models returning to a SW flow- & of course the GFS modelling SW winds day in day out up until 2 days ago-

 

Well for England the last SW wind day was -

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2013111100-0-6.png  11 Nov-

 

& the next projected SW day for England is

 

ECM- No SW winds- all 10 days are dictated by mostly NW winds, occasionally veering to the west then back to NW

GFS- No SW for the next 16 days. ( 18z)

 

Interesting considering what was predicted V whats actually arrived.

S

[Mucka]

The extended ecm london ens are clustered cold and, looking at the anomoly charts fir the latter part of the run, this must reflect mlb delivering either a stagnant or continental feed to se uk.

 

 

Here they are

 

[Catacol]

Ongoing dominance of the aleutian ridge obvious at day 10 again. Berlin forecast data shows the clear ridging at 100hPa and also the location of the warming in Asia, helping pump up this ridge and continue the amplified pattern we have had through November. Notice the cold air being swept south into the USA as a result of this process but the pattern downstream then being flattened out somewhat by the strength of the vortex.

 

 

 

The vortex itself is strong. Cold temperatures still forecast out to medium range

 

helping fire up strong zonal wind speeds, probably too high to allow a high lat block to build at this stage.

 

 

In summary no change tonight still in the foreseeable - 10 day - range. NW to N incursions probable due to ongoing meridionality upstream, but until there is a change in stratospheric temperatures helping to slow down those zonal wind speeds any high pressure that starts to build north will be quickly flattened. The hoped for warming over Canada has not materialised in November, something that would have helped build our greenland high.

Edited November 26, 2013 by Catacol_Highlander

[Mucka]

Fair to say most people would be happy with the 18z control run. 

 

Winds NW, N, NE, E with snow and Ice days thrown in. Shame there is very little support for it (so far   )

[Mucka]

18z ensembles, decent for prospects of at least a cold snap but no surprise to see the control was pretty much out on its own with the severity and length of the cold.

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=253&y=84

 

and look at it for 2m temps (central England)

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=253&y=84&run=18&runpara=0&type=3&ext=1

[Snowman.]

CFS (I talk about it a lot I know) has been ringing the bell for cold for a while now nothing major fairly standard but it's still there.

[Mucka]

GFS 00z is either for the bin or it has picked up something new with powering up the Atlantic behind the Northerly. I say that because the cause is quite early in the run, an area of low pressure it develops from around 96h upstream that kills any chance of a strong ridge behind our Northerly and heights building toward Greenland.

Here it is at 120h (just ahead of the Aleutian ridge) with MetO for comparison (which doesn't have such a developed feature)

 

And again at 144h

 

 

And here it at 192h killing off any height rises toward Greenland

 

 

So given that the whole downstream pattern is affected by this feature and MetO doesn't have it, I wouldn't put any stock in the FI and the Atlantic revving up for now.

On the plus side the feature develops quite early so we should know pretty soon if this is just a rogue run or GFS is picking out something that MetO has missed.

 

Just something for folk to note before getting hung up on the mobile FI of GFS Op

Edited November 27, 2013 by Mucka

[Ali1977]

I think Ian F 's Twitter update has just put a dampened on cold prospects after next weeks temp northerly....:-(

[CRACKPOT]

I think Ian F 's Twitter update has just put a dampened on cold prospects after next weeks temp northerly....:-(

 

-and he also states 'likely' followed by a return to warmer temperatures - he didn't say a definite and he is also on about a period after T192 to T268 !! (after days 8 - 12).

 

The fact he mentions a cold snap between 8-12 days time is good but as has been said on here many times Twitter, with it's short / limited statements, you never have a full picture and this is generally open to interpretation.

 

Definitely signs of colder weather appearing they just have to creep into the reliable but we have to be patient........

 

JK

[Mucka]

GEM 00z 240h

 

 

 

 

GFS 00z ensembles.

 

Certainly some eye candy here and there but still nothing overall to have us believe a cold spell is more likely than a cold snap.

Signal for at least cold snap still firming up though.

 

I would give anything for p4 to be right, it is the holy grail for snow fans but I would settle for p9 

 

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=256&y=93

http://www.meteociel.fr/cartes_obs/gens_display.php?x=259&y=99&run=0&runpara=0&type=3&ext=1

 

Decent BOM

 

Edited November 27, 2013 by Mucka

[Polar Maritime]

Lot's of PM shots showing on the GFS and snow for the whole of the UK by the 5th and continuing for a few days into FI,  A good start to Winter showing this morning.

 

[Great Plum]

The GFS 0Z ensembles are still looking positive for a cold snap after 3rd Dec...

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Notice as well how the mean reduces the milder blip before...

A few days ago, the south east was forecasted to be widely 11-13c today by the models - the met office expect a top temperature of 8 today here in Reigate...

In all seriousness, considering the 'vortex that is looking all vortexy' (thanks Lorenzo!) and other factors, the fact that we are running below average with a possible cold snap on the way is probably the best we can expect at the moment... And it's not even winter!

[Ian Brown]

http://www.meteociel.fr/modeles/ecmwf.php?ech=216&mode=1&map=0&archive=0

 

This looks a decent blast from the ECM.

[Mucka]

http://www.meteociel.fr/modeles/ecmwf.php?ech=216&mode=1&map=0&archive=0

 

This looks a decent blast from the ECM.

 

 

Yes best ECM so far

 

[Mark Neal.]

A very interesting ECM, best of the season so far?! 

 

If we are to get a cold snap lets hope it will bring some snow with it and make the most of what is a poor outlook for HLB,It does prove that we can still get some interesting wintry synoptics even if they aren't long-lasting! (supposedly)

[Ali1977]

Ready to reload another Northerly at the end of the ECM looking at it.

[Mucka]

[Iceberg]

I think Ian F is going out that far simply as the cold snap being forecasted isnt down to teleconnections or large blocs, but is simply a synoptic response due to the backing pattern. Due to that its a far assumption that any cold snap will not be prolonged. ECM shows a flat upper pattern. The one possibility is that we have a roll of the dice that does set up prolonge cold, as the backing pattern continues a few days or a week after the cold snap.

 

Good positioning for the cold snap from ecm and gfs as it develop the low on the eastern seaboard more, which in turn strengths the high and pushes the pattern eastwards. Biggest problem has to be that everything is too far west and lows form in the warmer sectors keeping the cold air further north and west of the UK. Or the high moves across too quickly giving a brief 12 hrs of cold and potential snow.

 

Far too early to look at this detail as it needs to be within T120 to pick up the secondary lows as the cold moves down. But pleasent charts for December.

[SMU]

Morning, So ECM produces a stella run- just trumped by the GEM at 240 which is similar to last nights control run.Some disparity between the ECM & GFS this morning though - GFS not seeing much in the way of polar heights where as the ECM solid in the formation ( again 3rd run on the trot ) of a significant -AO index.The ECM at 240 sees a polar low zipping SE which would bring snow for many - but at this mere conjecture-Based on what *May* happen though the opportunity for a northerly with deep low heights (unstable) seems to be presenting itself and more importantly some signals that a disconnect between the stratospheric vortex and tropospheric pattern may be in the offering-Still similarities to the start of Dec 81 which has been regularly dismissed, but I will keep posting it as its my idea-SPS a comment on ian fs twitter ( I havent read it ) that the DECIDER models have been pretty wrong thus far in there assessments of the pattern returning to all things normal which is rather like the volatile nature & inaccuracies of the ECM DET 32

Edited November 27, 2013 by Steve Murr

[EML Network]

FINALLY we have some form of heart hearted agreement about the possibility of a slightly more accentuated cold ''snap'' that could just deliver the goods as we head toward the middle of next month. 

 

I used those words above purposely because that's all anyone can read into a chart that is at 240 +

 

It's already been posted above but hows this for eye candy ?

 

 

What encourages me this morning is that we have both the ECM and GFS singing from the same song sheet which is to drop that deep low south into Scandinavia or over the UK (as shown above)

 

If this comes to pass there is a tiny window of opportunity for us to latch onto a more prolonged cold spell, but for that to happen everything else has to play ball around us and we would indeed need to be most lucky. 

 

Of course the other option is that the low passes overhead so to speak and we end up pretty much give or take, as we are now. 

 

The Atlantic looks like it might be wakening up soon in any case, so at least we'll have something to talk about it would seem, it could be the strength of the wind, or it could be chasing a cold spell into + 120 . 

Anything is better than what the charts have been throwing at us this past week and a half !!

 

If nothing else, it's given a glimmer of hope for something more interesting as we head into the middle of Dec. 

[That ECM]

Frosty is going to explode when he sees the latest runs!!