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

[knocker]

8 minutes ago, Man With Beard said:

That's very useful to know, Knocker. So do you think the EC46 was simply a couple of days late on the evolution? After all, from the weekly summary I can see a huge anomaly close to the Baltic Sea and so surely heights must be quite exceptional there on the EC46 T168-T336 period for at least 4 out of the 7 days? 

The latest T168-T240 ECM / GFS anomalies now showing the centre of the heights anomaly into the Baltic States and further into W Russia - did the corresponding EC46 show signs of this anomaly drifting east with time? Thank you for your time, I'm just trying to learn what I can and can't do with the EC46 mean weekly charts, for mine and hopefully everyone else's benefit.

At T264 it still has the strong anomaly to the east with HP centre around the southern Baltic and it more or less keeps it there whist weakening until T432 when they actually start retrogressing. So no real signs of it drifting east but of course whether this is still applicable is above my pay grade.

[nick sussex]

The differences between the GFS and ECM start within T144hrs, you'll note that the ECM keeps the PV further west with low heights not spilling so far east  , it throws some positive heights ne, the GFS doesn't do this. The UKMO is a mid solution as it does throw heights ne but not to the extent of the ECM .Given the GFS recent poor modelling in that area I'd side with a combo of the Euros.

I think we're reaching a critical point for Christmas, we must keep some high pressure to the ne to help angle the jet se, if not its hard to see a more festive Christmas weather wise.

[Frosty.]

3 minutes ago, terrier said:

To be honest I'm not really sure zonal is a good thing. Would much prefer the dry outlook we have now. Trouble with the zonal set up is for most a wet and windy affair. And could set us up for a south westerly regime in rather quick time. 

At least with zonality you have a chance of upstream amplification, especially with a disrupted pv..i like the sound of cold zonal 

[Nick L]

A sneak peek at those pretty insane wind gusts on the EC this morning...

Yes, that is in excess of 130, and yes, it is mph!

[karyo]

3 minutes ago, Frosty. said:

At least with zonality you have a chance of upstream amplification, especially with a disrupted pv..i like the sound of cold zonal 

Zonality is the opposite of an amplified pattern.

[offerman]

8 minutes ago, terrier said:

To be honest I'm not really sure zonal is a good thing. Would much prefer the dry outlook we have now. Trouble with the zonal set up is for most a wet and windy affair. And could set us up for a south westerly regime in rather quick time. 

Totally agree with you there .  This weather is actually quite nice very sunny today quite pleasant I much prefer this to what you are referring to with a wet and windy so completely agree with you . 

 

 

Zonality isn't that great for snow cold.  I do remember  several north-western cold is analogy from Canada in previous years with a cold made all the way from Canada right across the Atlantic and brought heavy snow showers in .  Whilst it was nice to see the snow soon melted so even cold is analogy isn't that great at least not in the south of the country anyway . 

[nick sussex]

If we do get the jet angled nw/se and high pressure to the ne then the unthinkable a few days ago might be possible. 

Could be a White Christmas for some favoured  locations. More likely in the north with a bit of elevation . 

Edited December 14, 2016 by nick sussex

[knocker]

The GFS not looking that clever either

[Gael_Force]

13 minutes ago, Nick L said:

A sneak peek at those pretty insane wind gusts on the EC this morning...

Yes, that is in excess of 130, and yes, it is mph!

A maybe daft question for those of you with more access to ECM data. The model first showed this potential storm at 240: what conditions does it see (at that range) to cause such sudden and intense cyclogenesis?

[Frosty.]

14 minutes ago, karyo said:

Zonality is the opposite of an amplified pattern.

Cold zonality with a nw / se aligned jet will do nicely

I will go buy a blue crayon

Edited December 14, 2016 by Frosty.

[Summer Sun]

Christmas is looking pretty unsettled now with some strong winds and heavy rain around at times

24th

25th

26th

 

 

[Ali1977]

Not a great few days for us coldies, nothing looking cold at all on the horizon neither, even the Alps are suffering so glad I'm not booked there for Xmas.

Where do we look next for possibilities, well the high over Europe isn't going anywhere and it isn't going to give us a cold Easterly, I think we know that.  I actually think cold zonality is about the best we can do around the xmas period, beyond then we need some luck, and hopefully we can shift a lump of PV far enough East to develop opportunities for some Atlantic or Canadian WAA.  

After the last few years this isn't great, but at least there isn't rain and gales hitting our shores just yet.

 

Edited December 14, 2016 by Ali1977

[Man With Beard]

Although I'm not feeling too confident about any model output right now, it's worth mentioning that the 06Z GEFS has a number of potential easterlies at T168 e.g.

        

... though by T240 the Atlantic has pushed most of them away.

[terrier]

3 minutes ago, Summer Sun said:

Christmas is looking pretty unsettled now with some strong winds and heavy rain around at times

24th

25th

26th

 

 

Those charts look horrible. Looks akin to something we saw leading to Boxing Day last year. Would much prefer what we are seeing now. Compared to wet windy cold zonal. 

[knocker]

36 minutes ago, Gael_Force said:

A maybe daft question for those of you with more access to ECM data. The model first showed this potential storm at 240: what conditions does it see (at that range) to cause such sudden and intense cyclogenesis?

I don't know why cyclogenesis occurred in this instance but some observations if I may.  This storm appears east of Newfoundland at T180 997mb. ByT192 it's mid Atlantic and at 969mbs. From here there is very strong NE jet (165Kts) and the low tracks along the cold side of this to be smack bang over the Faroe Islands at T216 938mb.

Edited December 14, 2016 by knocker

[karyo]

26 minutes ago, Frosty. said:

Cold zonality with a nw / se aligned jet will do nicely

I will go buy a blue crayon

It might last for a day or so if you are lucky and then back to southwesterlies.

So from cold rain to mild rain. lol

[bluearmy]

14 minutes ago, Man With Beard said:

Although I'm not feeling too confident about any model output right now, it's worth mentioning that the 06Z GEFS has a number of potential easterlies at T168 e.g.

        

... though by T240 the Atlantic has pushed most of them away.

I think the gefs post day 8 are a fairly crude tool for detail because of their resolution after that timescale.

No surprise to see the Atlantic pile through that weakish looking blocking based on the position at day 8.

mobility certainly seems to be in the ascendency and there is some catching up to do from the likely blocked xmas scenario we were looking at - just how long that persists for ??  There are some that would tell you that once this zonality gets in we are looking at four weeks - poppycock! 

[johnholmes]

18 minutes ago, knocker said:

I don't know why cyclogenesis occurred in this instance but some observations if I may.  This storm appears east of Newfoundland at T180 997mb. ByT192 it's mid Atlantic and at 969mbs. From here there is very strong NE jet (165Kts) and the low tracks along the cold side of this to be smack bang over the Faroe Islands at T216 938mb.

?? NE'ly jet old fella?

[knocker]

2 minutes ago, johnholmes said:

?? NE'ly jet old fella?

Not so much of the old. Yes perhaps could have been worded better as i meant blowing towards the NE which of course means a SW jet in normal parlance.

[blizzard81]

24 minutes ago, bluearmy said:

I think the gefs post day 8 are a fairly crude tool for detail because of their resolution after that timescale.

No surprise to see the Atlantic pile through that weakish looking blocking based on the position at day 8.

mobility certainly seems to be in the ascendency and there is some catching up to do from the likely blocked xmas scenario we were looking at - just how long that persists for ??  There are some that would tell you that once this zonality gets in we are looking at four weeks - poppycock! 

That last sentence is probably the bravest comment I have read on this forum lol. 

[EastAnglian]

How many different versions of the Christmas period have the models shown this week? Why the sam hill should this version be any more crediable? I don't think anybody said four week for zonality, apologies if they did but in my experience it does last some time, hope I am wrong won't be the first or last time! 

[jvenge]

2 minutes ago, EastAnglian said:

How many different versions of the Christmas period have the models shown this week? Why the sam hill should this version be any more crediable? I don't think anybody said four week for zonality, apologies if they did but in my experience it does last some time, hope I am wrong won't be the first or last time! 

Well, stating the obvious, but the closer you get to the Christmas period, the more trustworthy the output will become ;-)

 

 

[EastAnglian]

8 minutes ago, jvenge said:

Well, stating the obvious, but the closer you get to the Christmas period, the more trustworthy the output will become ;-)

 

 

Yes of course but agreemant from model to model would be nice let alone run to run. Clutching at straws I hope the next model runs go back to the cold and frosty Christmas of the weekend, but a certain gentlemans law would indicate that the most unpalatable outcome is most likley.   Glass half empty and all that.

Edited December 14, 2016 by EastAnglian

[bluearmy]

17 minutes ago, blizzard81 said:

That last sentence is probably the bravest comment I have read on this forum lol. 

It may be the case - poppycock refers to them stating they know it to be so !

[Catacol]

42 minutes ago, Ali1977 said:

Not a great few days for us coldies, nothing looking cold at all on the horizon neither, even the Alps are suffering so glad I'm not booked there for Xmas.

Where do we look next for possibilities, well the high over Europe isn't going anywhere and it isn't going to give us a cold Easterly, I think we know that.  I actually think cold zonality is about the best we can do around the xmas period, beyond then we need some luck, and hopefully we can shift a lump of PV far enough East to develop opportunities for some Atlantic or Canadian WAA.  

After the last few years this isn't great, but at least there isn't rain and gales hitting our shores just yet.

 

Yep - fair assessment I think. GLAAM currently anchored in a very neutral orbit 

and MJO also not influening the pattern sufficiently for amplification. It is forecast to become more impactive - but the progression has been painfully slow and any impact now looks post Xmas

Meanwhile vortex reformation continues apace - as far down as 70hpa we not have a much more defined circulation and this is continuing to propagate downwards

 

Altogether not a pattern conducive to high lat ridging in the foreseeable. I wont be getting too excited about a NW polar flow in Xmas week. Cold rain for me - and years of model watching suggests it will be cold rain for most as the extremes of the current run get watered down by the lovely warm bath of the atlantic. Unless you are on high ground only an easterly component to the wind direction is necessary for anything other than transient excitement.

However raising the white flag for the pre Xmas period isnt to say that all is grim. The pacific forcing expected is still there somewhere on the horizon. To be plain - I would rather a cold pattern hit in January than in December (both of course would be even better! - but let's not be greedy....) and so if the next 30 - 60 day cycle of the MJO is a little delayed then that is not necessarily a bad thing. As has been pointed out by others, ALL of our greatest winters and spells in the past have been January/February (Dec 2010 the one exception I can pluck out of memory) and so there is still much to play for.

So - in terms of timing my own personal forecast of a fortnight ago is in the bin... but in terms of process not yet. However two things do actually need to happen! Firstly pacific forcing needs to return. We wait on this. Secondly I would very much like to see a return to the potential for trop led wave breaking to disrupt the vortex once again. Here my expertise is basic, and over on the Strat thread Inheritus was sounding less than enthusiastic about prospects for a SSW... but we dont need a full SSW for cold: a disruption such as we have just had that has brought upwards of 2 weeks of blocked conditions is enough to weigh the dice in favour of blocked patterns once again. If I understand trop led wave assaults on the vortex at all then we want an aleutian low and high pressure in Western Russia - rather like this. Anyone with greater skill than I - please feel free to comment. I'd appreciate the extra gloss in this area.

 

So - my eyes now firmly focused on the post Xmas pattern. Here's hoping Santa's sleigh and all his reindeer can whip the pacific into life so that we can get a block in place (in the right spot this time) with a vortex experiencing enough grief at the trop level to prevent an atlantic charge.