Model Output Discussion - 12th December Onward

[Summer Sun]

Firstly tomorrow mornings snow fall

In the run up to the big day we get a brief cold spell from the north-west

Maybe snow for the higher areas in the north

http://www.wetterzen...s/Rtavn1921.png

New Years eve

http://www.wetterzen...s/Rtavn3841.png

http://www.wetterzen...s/Rtavn3842.png

A long way off I know but maybe a sign of a change come 2012?

[Robbie Garrett]

Edited December 15, 2011 by Robbie Garrett

[Frosty.]

Firstly tomorrow mornings snow fall In the run up to the big day we get a brief cold spell from the north-west Maybe snow for the higher areas in the north http://www.wetterzen...s/Rtavn1921.png New Years eve http://www.wetterzen...s/Rtavn3841.png http://www.wetterzen...s/Rtavn3842.png A long way off I know but maybe a sign of a change come 2012?

I agree with chio and kold about the building blocks to proper cold meaning some short term pain although there is no real suggestion of a very mild spell lasting weeks and weeks as say the winter of 1988-89 which was pure garbage.

[phil nw.]

We often come out of cooler zonal to a milder setup as the jet axis resets from a NW-SE to a SW-NE trajectory with pressure rising from the South West.

As other seasoned model watchers have said this has been on the cards and considering the strength of the vortex has been a longer time coming than most thought.

All recent output and longer term modelling has pointed to the Azores high paying us a visit with the jet moving north.

The question now is how far north it will get-12Z GFS shows a very flat pattern going to next week putting us in a mild South Westerly flow whereas the UKMO shows buckling of the jet and ridging much further north,Here at T144 to compare

http://www.wetterzentrale.de/pics/Rtavn1441.png

http://www.wetterzentrale.de/pics/Rukm1441.gif

Still uncertainty leading up to Xmas whether we can see that High closer so at least we get some surface cold.

Meanwhile a cold few days to come untill early next week with some polar air around,a bit of snow for some and night frosts.

[SP1986]

I've never really been convinced about Stratospheric warming forecasts, that's not because I'm trying to instill doubt into the situation, but because I recall in both the winters of 2006 and 2007, stratospheric warming was widely called for, in a similar stance to now, where the conditions where mostly Atlantic dominated (not necessarily warm), yet it looked great, lots of calls for a cold second half to winter much as now, yet those winters failed to deliver.

I'm not sure whether that implies that the forecast is not always very accurate or whether Stratospheric warming is not always conducive to cold weather, but I always approach stratospheric warming/cooling with a fair bit of scepticism.

What we can see at the moment though is a fairly typical classic Atlantic pattern.. a cool zonality period ending, with a mild zonality period trying to set up - I'm not convinced that mild zonality will get a foothold, but certainly I can't foresee any easterly influence this side of the new year. I think I would sit on the fence and go for average conditions moving into January if I had to choose.

[ChartViewer]

As certain members have said this is a mild theme for Xmas and beyond and now really set in stone......Possible mild theme into Jan here

http://www.netweather.tv/index.cgi?action=charts;type=home;sess

http://www.netweather.tv/index.cgi?action=charts;type=home;sess

http://www.netweather.tv/index.cgi?action=charts;type=home;sess

http://www.netweather.tv/index.cgi?action=charts;type=home;sess

Hih Pressure to our South...shocking for coldies....Suspect this cold go into Jan and wouldnt be out of place as a suedo Bartlett

[chionomaniac]

I've never really been convinced about Stratospheric warming forecasts, that's not because I'm trying to instill doubt into the situation, but because I recall in both the winters of 2006 and 2007, stratospheric warming was widely called for, in a similar stance to now, where the conditions where mostly Atlantic dominated (not necessarily warm), yet it looked great, lots of calls for a cold second half to winter much as now, yet those winters failed to deliver.

I'm not sure whether that implies that the forecast is not always very accurate or whether Stratospheric warming is not always conducive to cold weather, but I always approach stratospheric warming/cooling with a fair bit of scepticism.

From what I have found out over the last few years, SP is that it is far more complex than stratospheric warming equals cold. I have found that those most sceptical about stratospheric/ tropospheric interactions are those that know least on the subject.

As has been stressed many times before that a very cool stratosphere is not conducive to high latitude blocking. A far warmer stratosphere opens up the playing field in this respect to a far greater extent. If the stratosphere warms up then we will have a far better chance of a disturbed polar vortex whether or not we see a SSW. Combine this with the wave interactions that propagate back and forward between the troposphere and stratosphere then we are heading into a period with far greater blocking prospects than the one we are going through now.

[SMU]

http://www.meteociel.fr/ukmo/run/UN144-21.GIF?15-17

noone want to comment on the UKMO tonight

Chart of the day that

S

[ChartViewer]

As some members called it correctly Mild theme into Xmas day and child Bartlett beyond into Jan 2012

Edited December 15, 2011 by ChartViewer

[Summer Sun]

As some members called it correctly Mild theme into Xmas day and child Bartlett beyond into Jan 2012

Beyond next week is hard enough to predict so don't even worry about going in to 2012 that's a long way off in weather terms.

[Great Plum]

Interesting that the 12z was consistently one of the mildest members on the ensembles... Might not be as mild!

Forgot to put link to ensembles: http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

[Osbourne One-Nil]

No one's called anything correctly yet, so how about those of you trying to point score and outdo each other stop, talk about the models and stay on topic?

[Cheshire Freeze]

A milder spell probably is a reasonable call, I'm actually surprised its taken this long to show its hand again onn the models, the cool zonality certainly had some staying power.

I view this set-up with the HP ridging up as a part of the long term evolution towards something FAR colder in Jan, and it maybe worth people reading the Stratosphere thread to see that we have got some fairly good developments starting to be strongly hinted at that goes along with the idea of a much colder 2nd half to the winter.

Yes, I think it's a question of when rather than if at this time. I think it's looking favourable for an Azores-Siberian high link up at some point in the not too distant future. The 144 UKMO highlights the potential

[Weather-history]

http://www.meteociel...44-21.GIF?15-17

noone want to comment on the UKMO tonight

Chart of the day that

S

I looked at it and my first thought was so what?

[Cheshire Freeze]

I looked at it and my first thought was so what?

As I've said before, that ridge being drawn north towards Svalbard is often a pe-cursor to an eventual easterly. This a strong possibility, especially if warming of the strat can gain momentum as it appears to be doing at the minute and if we can shift that PV west.

Edited December 15, 2011 by CreweCold

[Cecil Hogmanay Melchett]

As I've said before, that ridge being drawn north towards Svalbard is often a pe-cursor to an eventual easterly.

I doubt very much there will be much in the way of excitement on the ukmo run.

I'd wager the azores high will get flattened very quickly thereafter.

[UV-RAY]

As some members called it correctly Mild theme into Xmas day and child Bartlett beyond into Jan 2012

It becomes very tedious reading comments like this. When Xmas is upon us then by all means make comments like the above.

IMO a lot remains undecided with the positioning of the High.

[SP1986]

From what I have found out over the last few years, SP is that it is far more complex than stratospheric warming equals cold. I have found that those most sceptical about stratospheric/ tropospheric interactions are those that know least on the subject.

As has been stressed many times before that a very cool stratosphere is not conducive to high latitude blocking. A far warmer stratosphere opens up the playing field in this respect to a far greater extent. If the stratosphere warms up then we will have a far better chance of a disturbed polar vortex whether or not we see a SSW. Combine this with the wave interactions that propagate back and forward between the troposphere and stratosphere then we are heading into a period with far greater blocking prospects than the one we are going through now.

Indeed I know very little about it, I've never really thought about learning about it as such. I am sure that Stratospheric warming can have an input in producing conditions that may favour cooler conditions, but my experience on those two winter I mention above was one of 'it doesn't always'. But I do understand a warmer stratospheric profile can bring about the potential for more blocking.

I suppose my post was more about the chances rather than the credibility, if you understand where I'm coming from.. I'll probably do a bit more reading up on the Stratosphere!

[wolvesfan]

http://www.meteociel...44-21.GIF?15-17

noone want to comment on the UKMO tonight

Chart of the day that

S

Couldn't that ridge fuel a pressure rise to scandi?.

[Cheshire Freeze]

I doubt very much there will be much in the way of excitement on the ukmo run.

I'd wager the azores high will get flattened very quickly thereafter.

Maybe this time yes. The interest is in the 14-21 day timeframe IMO and is something that Simon Keeling of Weatheronline has also made reference to. It also correlates well to GP's thoughts as we progress into January with heights on the increase to the east rather than the south.

[karyo]

As I've said before, that ridge being drawn north towards Svalbard is often a pe-cursor to an eventual easterly. This a strong possibility, especially if warming of the strat can gain momentum as it appears to be doing at the minute and if we can shift that PV west.

The warming of the stratosphere will take some weeks to make its presence felt on the troposphere.

Karyo

[Weather-history]

As some members called it correctly Mild theme into Xmas day and child Bartlett beyond into Jan 2012

I seem to recall you saying no low level snow in the south until at least mid-January and I gave you example why you can't say that with confidence. Now there is a distinct possibility but even I'm not going to say I correctly called it only 12 hours out let alone 14 days out.

Edited December 15, 2011 by Mr_Data

[SMU]

I looked at it and my first thought was so what?

heights building north as opposed to east on the GFS-

look at the GFS 144

http://176.31.229.228/modeles/gfs/run/gfsnh-0-144.png?12 totally different & a flat jet-

Its a pity there is no 168 UKMO chart

S

[Cheshire Freeze]

The warming of the stratosphere will take some weeks to make its presence felt on the troposphere.

Karyo

It really depends on other factors. If you've read the Strat thread it is looking likely that any warming will have a quicker effect than the average strat warming.

[SP1986]

To be fair the high pressure has been fairly consistent over the past 2-3 runs, but even then, that means absolutely nothing, as we saw with the storm earlier this week! Can't really see anything develop; re: an easterly this side of Christmas though, the jet may be a little strong for it. That's not to say it won't develop into January though - which is a possibility as we go into the month.