Model Output Discussion 18/11/2012 12Z onwards

[Continental Climate]

18z is going to be totally different from the 12z even by t120 the jet looks different this is the 18z at 120 http://www.wetterzentrale.de/pics/Rtavn12015.png

This is the 12z 12 hours later http://www.wetterzentrale.de/pics/Rtavn13215.png

[Jonan92]

Escandi developing in the 18z run. Shortcut rising from UK?

[Continental Climate]

GFS is quickly becoming a little bit of a joke, does any other model chop and change so much?

To me its no better than nogaps

[Snowman.]

Looks like the GFS is going on yet another route here!

Really the differences between GFS runs at only 120hrs are laughable,compare this to the earlier 12hrs over the eastern USA, unbelievable!

This does look closer to the UKMO so maybe this is a good sign! Here we see the phasing of those two lows upstream and we have a mini northern Scandi high popping up aswell!

Damn it!

Beat me to it

Anyway look at T144

Then 12z

Almost completely different.

Edited November 18, 2012 by SN0WM4N

[cold snap]

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=150&mode=0&carte=1

Much better this at 150 could be a decent run this

[Weather Boy]

It does seem like we have been anticipating a cold pattern for some considerable time.

We have to remind ourselves that a pattern change to something less mobile was never expected untill near month end.

We have been teased a few times with some attempts by certain runs to bring this change closer but they have been dropped nearer to real time.

We are now starting to see that change being modeled within the next 10 days now-indeed the 12z ops were in quite good agreement at T240 that the persistent trough finally shows signs of warming out with pressure rising near the UK.

Pretty unanimous from the GEFs for this change too.

http://www.meteociel...&mode=6&ech=240

The 2m temps on the GFS ens also continue to show the cooling trend to month end.

We have to see where we go from there as to whether some deep cold comes our way.

If the vortex continue to be put under pressure as we go in December our chance will come when those blues(low heights)move further away from Greenland.This would enable the anticipated Atlantic blocking to push much further north diverting all the jet energy south and allow a more stable cold pattern to establish.

An excellent post if I may say so Phil. I have highlighted what I think is the most important point, albeit a somewhat basic and obvious one. Drawing all the strands together, given the sheer persistence of hints of blocking and non-Atlantic driven weather for quite some time ago now, I think it is unlikely that this is not going to happen early next week (i.e. w/c. 26 November). The timeframe is now semi-reliable but in my mind the writing has been on the wall for quite some time due to the sheer persistence of the signals across all the models at some stage. Yes, there have been wobbles, but there are always are with major pattern changes.

I therefore find it difficult to comprehend the reticence of the METO in still only labelling this one of a range of possibilities. I'm not denying that it could be completely wrong, but at this stage and at this range, that surely has to be unlikely.

BUT

I am not suggesting that we are all going to be buried in a foot of snow come 1 December. Far from it. As we all know, northern blocking does not equate to cold weather and still less equates to snow, especially so early in the season. Given the proximity of the high, it seems to me that the most likely medium-long term solution is for mainly dry weather, and even where there is precipitation, given the very early stage of the season and the lack of cold on the continent, I would expect that to mainly be confined to northern parts with some elevation.

What quite rightly gets Steve Murr (who obviously knows miles more than me) excited is the possibility of how the current cold forecast may develop in time. Of course, at this point, it could easily be that the cold is a flash in the pan for a week or even less with just a few hard frosts and/or fog and then it is back to the Atlantic train as we are going to see this week. Steve for example clearly thinks otherwise and I am not one to contradict him. But I do not recall seeing any model at sensible range that gives us significant snowfall and so for the time being, I think that we should look to see cold synoptics from about T+240 or so and beyond that it is necessarily speculation to an extent.

I'm looking forward to seeing how it develops but at the moment it is all up in the air save for some fairly low temperatures at the end of the month.

[weather_it_will]

Chalk and cheese... and..

We have a ridge. Where will it end?

[Ice BIast]

This what you're looking for Steve?

[Continental Climate]

Ha by 162 we have an easterly of sorts albeit not a very bone chilling one http://www.wetterzentrale.de/pics/Rtavn1621.png pretty big changes between each run now and almost in the semi reliable time frame as well

[January Snowstorm]

I've a feeling the next 24hours is going to come up with some awesome charts.

18z run is going in the right direction

A pattern change is coming and Winter '12/13 is about to tighten it's grip!

[BlueHedgehog074]

GFS clearly had too many drinks from zee model pub again. Seems to be a reasonable Easterly starting to arise from it with that undercutting spirally low.

Edited November 18, 2012 by DiagonalRedLine

[Grimsby Snow Lover]

gfs really struggling at the mo.

The fact that each run is throwing out different scenarios suggests to me that a change is definitly brewing, how cool/cold is yet to be realised.

[chionomaniac]

How close to getting that WAA up the west side of Greenland?

It wouldn't take much difference in the future to have that bang on.

[Grimsby Snow Lover]

How close to getting that WAA up the west side of Greenland?

It wouldn't take much difference in the future to have that bang on.

Is the WAA needed to help support a Greeni High Chino?

[Zakos]

The fact that each run is throwing out different scenarios suggests to me that a change is definitly brewing, how cool/cold is yet to be realised.

Definitely agree. The models are clearly struggling with the pattern change ahead, massive differences on the GFS 12z/18z very early on in the run.

I think there is a very strong signal for northern blocking, a great change is going to take place, but the models are seemingly having great difficulty in predicting where the pressure cells will be situated etc...

One thing is for certain, this week will give some very entertaining model watching, lets hope this is not the models teasing us. All to play for at this stage

[chionomaniac]

Is the WAA needed to help support a Greeni High Chino?

Yes, and the Greenland land mass is perfect to help this

[fergieweather]

I therefore find it difficult to comprehend the reticence of the METO in still only labelling this one of a range of possibilities."

Because innumerable public bodies and populace rely on their steer and that's exactly why they are meeting tomorrow to review things in light of latest seasonal output etc. Lest us forget that they don't have the luxury of discussing a raft of outcomes on a forum, with no media backlash or loss of public and commercial confidence if it all goes pear-shaped! I think their steady and measured approach thus far to some very conflicting NWP output has been exactly as one would hope for from scientists who cannot express any cold or mild preference or bias in their analyses.... they have huge responsibility.

[cold snap]

Because innumerable public bodies and populace rely on their steer and that's exactly why they are meeting tomorrow to review things in light of latest seasonal output etc. Lest us forget that they don't have the luxury of discussing a raft of outcomes on a forum, with no media backlash or loss of public and commercial confidence if it all goes pear-shaped! I think their steady and measured approach thus far to some very conflicting NWP output has been exactly as one would hope for from scientists who cannot express any cold or mild preference or bias in their analyses.... they have huge responsibility.

Must be under huge pressure right now at met office thanks for your input

Excellent 18z gfs wouldn't take much to upgrade this further

[Grimsby Snow Lover]

Could well have snow falling outside when the Christmas tree goes up if charts like this verify in a couple of weeks. Different the the previous run I know but the overall trend kind of remains it that the Atlantic is looking fairly quiet.

http://www.wetterzentrale.de/pics/Rtavn3361.png

[bobbydog]

Because innumerable public bodies and populace rely on their steer and that's exactly why they are meeting tomorrow to review things in light of latest seasonal output etc. Lest us forget that they don't have the luxury of discussing a raft of outcomes on a forum, with no media backlash or loss of public and commercial confidence if it all goes pear-shaped! I think their steady and measured approach thus far to some very conflicting NWP output has been exactly as one would hope for from scientists who cannot express any cold or mild preference or bias in their analyses.... they have huge responsibility.

exactly. especially with the national newspapers' tendency to latch on to the words of any old amateur forecaster and proclaim them as front page headlines!

[JP1972]

Looks like the GFS is going on yet another route here!

Really the differences between GFS runs at only 120hrs are laughable,compare this to the earlier 12hrs over the eastern USA, unbelievable!

This does look closer to the UKMO so maybe this is a good sign! Here we see the phasing of those two lows upstream and we have a mini northern Scandi high popping up aswell!

And let's be honest right here and now.

Differences and disagreement is why we should all be hopeful that change is on the way, and change for the better if you're a coldie lover.

At the risk of piddling folk off, November 2010 and December 2009 both had similar pre-cursors where the models were all over the place in the run up to a decent cold spell.

[Jonan92]

Huge change in this run, big improvement but I have always considered the 18Z run as the "crazy" run of the day, it usually shows the most spectacular outlooks

[AWD]

NAE shows some very strong winds around Ireland & Western facing coasts early next week;

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=pslv&HH=36&PRINT=1&ARCHIV=0&PANEL=0&INFO=0&WMO=

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=pslv&HH=48&PRINT=1&ARCHIV=0&PANEL=0&INFO=0&WMO=

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=uv10&HH=36&PRINT=1&ARCHIV=0&PANEL=0&INFO=0&WMO=

[cold snap]

Could well have snow falling outside when the Christmas tree goes up if charts like this verify in a couple of weeks. Different the the previous run I know but the overall trend kind of remains it that the Atlantic is looking fairly quiet.

http://www.wetterzentrale.de/pics/Rtavn3361.png

Yes snow at the end it just makes the Stella run

12z was slow,18z is a fast solution chalk and cheese

Steve m where are you?

Edited November 18, 2012 by cold snap

[Cloud 10]

Steve m where are you?

At the controls of the 18z.