Model Output Discussions 12z 30/11/16

[BLAST FROM THE PAST]

8 minutes ago, Frosty. said:

Hi Fred,

That sounds like you are not agreeing with the met office blocked anticyclonic second half of december then ?

Not entirely, I see that it will settle down calm again before the next hyper period approaching / at Xmas time.  I don't see an arctic lock out either that some are seeing...but I do see Dec on cold side of average

 

BFTP

[Tamara]

27 minutes ago, nick sussex said:

Matt H just killed Santa!  Appreciate the honesty and lack of spin. I think the post sums up a discussion we had in here the other night with Crewe Cold who I don't think is about this evening.

There are absolutely no certainties with weather modelling, and regardless of the massive investment in super computers theres simply no way currently of forecasting accurately at longer range.

I think the only recent winter which went bizarrely smoothly in terms of longer range signal was winter 2009/2010. I think its clear that our current background signals aren't as strong as that. With that in mind theres more fluidity to what we'll get and just as we might have had stronger foundations at the time of the last ECM 46 one suspects a few bricks have been removed.

We'll just have to see what transpires over the next week but Matts update might lower expectations.

 

Matts posts, and in relation to the possible outcomes have been excellently documented, along with Tony/Lorenzo and they have a very brave LRF to 'defend'. I said myself already, I don't envy trying to decipher such untested water as the variables increasingly throw at us each year.

As for managing expectations.... like others, I spend most my time on here trying to do that, right up to the present day with the best intentions..... But without writing another book about it, I wouldn't miss a beat to continue to support pushing the boundaries of longer range forecasting. If a dippy mare like me who first  learnt what GFS stood for within the last decade can try,then anyone surely can!

 

 

 

[Banbury]

47 minutes ago, nick sussex said:

Matt H just killed Santa!  Appreciate the honesty and lack of spin. I think the post sums up a discussion we had in here the other night with Crewe Cold who I don't think is about this evening.

There are absolutely no certainties with weather modelling, and regardless of the massive investment in super computers theres simply no way currently of forecasting accurately at longer range.

I think the only recent winter which went bizarrely smoothly in terms of longer range signal was winter 2009/2010. I think its clear that our current background signals aren't as strong as that. With that in mind theres more fluidity to what we'll get and just as we might have had stronger foundations at the time of the last ECM 46 one suspects a few bricks have been removed.

We'll just have to see what transpires over the next week but Matts update might lower expectations.

 

That's spot on Nick and lets be totally honest if the super computers have it wrong don't expect Matt or anyone else to be right ( no disrespect Matt ) weather will do its own thing , it doesn't take any notice of what happened in 1947 / 63/ 81 blah blah blah .........................it will always have its own way , there are never identical repeats

[cheshire snow]

Gavin P Has done his Christmas Forecast on two and WOW what a classic well worth a watch

sorry off topic  but you really have to see it,certainly make you feel a lot better than you do now.

C.S

[Ali1977]

1 minute ago, cheshire snow said:

Gavin P Has done his Christmas Forecast on two and WOW what a classic well worth a watch

sorry off topic  but you really have to see it,certainly make you feel a lot better than you do now.

C.S

Agreed, and kind of in line with the seasonal models said so I was watching it thinking it had potential - I'll ignore the fact it's the CFS.

[feb1991blizzard]

2 minutes ago, cheshire snow said:

Gavin P Has done his Christmas Forecast on two and WOW what a classic well worth a watch

sorry off topic  but you really have to see it,certainly make you feel a lot better than you do now.

C.S

He does his winter forecast tomorrow.

[IDO]

4 minutes ago, Nick L said:

A misleading post. Means at that range will always tend to cancel out to climatological norms. You need to post the anomalies.

TBH I could post the anomalous temps and precipitation and its pretty much what the charts show.

I was really highlighting the PV development rather than surface conditions as monthly means are not much help in that respect.

I was looking for trends, and what the CFS shows (been showing) is that, if we get cold it will be a front loaded winter. The PV is modelled consistently (as consistent as a CFS mean chart is) to intensify rapidly Feb, and therefore March looks hopeless for anything but a zonal westerly washout. Time is therefore not on our side and a wasted first half of December is not really helpful..

Its the current trend and may change in the days or weeks to come (or not) but it is worthy of a few thoughts, as much as the acclaimed new kid on the block, the "cold" EC32 and his older brother, who funny enough were derided last year when they were predicting the Atlantic onslaught?

[Northern Sky]

From a glass half full perspective IF the long range models prove to be wrong then let us remember that when they are showing mild weather too! In a way not having a clue what might happen in 10 days time is good thing, then at least you can always hope for something good to turn up. I think it's well documented that the background signals are more favourable than for example last year. So with that in mind let's see what winter brings.

[Banbury]

6 minutes ago, cheshire snow said:

Gavin P Has done his Christmas Forecast on two and WOW what a classic well worth a watch

sorry off topic  but you really have to see it,certainly make you feel a lot better than you do now.

C.S

Not sure he has

[feb1991blizzard]

4 minutes ago, Banbury said:

Not sure he has

Its not actually his forecast but this is what he means.

 

PS - Oh IDO I see you didn't use that run to try to back up your argument!!

Edited November 30, 2016 by feb1991blizzard

[Grimers]

The latest GFS run brings slightly colder air from the E.

  

Edited November 30, 2016 by Grimers

[bluearmy]

Bit surprised gav would make a vid off a single CFS run - perhaps he needs a soft sell to get some hits for his advertising budget!

anyway, if the demise of the accentuated ridging early next week verifies then it backs up Exeter to a fair extent and probably means mogreps was seeing things a little differently to the eps. 

[feb1991blizzard]

Just now, bluearmy said:

Bit surprised gav would make a vid off a single CFS run - perhaps he needs a soft sell to get some hits for his advertising budget!

anyway, if the demise of the accentuated ridging early next week verifies then it backs up Exeter to a fair extent and probably means mogreps was seeing things a little differently to the eps. 

No - its not his forecast, he picks the 12z CFS run every few days and just runs you through the run and describes the weather that the charts would bring at xmas, its not an actual forecast.

[bobbydog]

1 hour ago, MattHugo said:

The 12Z EC ENS are also supportive of the rather quicker arrival of a SW'ly from next Tue/Wed and whilst these can change as quickly as DET models there is a trend towards the high sinking towards the SE into the near continent within a week or so. 

As I've said before, in passing, the approach to the middle of Dec could well end up becoming a 'make or break' period in terms of how the remainder of Dec, or a large portion of it, ends up progressing. Experience has shown me that Dec is a 'long month' not just because it's 31 days!, I think you know what I mean.

However, here comes the negative thoughts as things stand; Depending on how model guidance (plus other variables) progress within the next week or so I am beginning to lean towards a possible failure in terms of northern blocking becoming dominant. Clearly a lot of the info for a blocked Dec was discussed within the Winter Forecast but this is a quickly evolving situation now and my optimism for the likes of the EC Monthly et al, to come to fruition are, overall, waning now and I think the possibility of something far more 'typical' for a Dec month is gaining some weight, but we shall see.

As ever time will tell but the next 7 to 10 days worth of model data will be crucial to determining how the first third of our winter will likely/possibly pan out. 

Regards. Matt

[snowbunting]

10 minutes ago, feb1991blizzard said:

Its not actually his forecast but tis is what he means.

 

Wow, 1995 all over again

[Singularity]

Thanks @MattHugo

I gather the EC46 is an extended version of the operational, meaning it could potentially fall anywhere within the spread of outcomes featured in the EPS?

Edit: Turns out it's ensemble based, woe est me 

As it is though, I sense a lot of whether we can trust the latest ensemble guidance rests on what GP suggested this morning; that interference from the current Indian Ocean tropical cyclone is confusing the model output for the time being. However, I'm not clear as to just how much of an impact this could be having - could it explain the lackluster stratospheric output in terms of driving a lower-level split with a favourable orientation for us (i.e. cross-polar ridge aligned very nicely), on top of the hesitancy to show more than tentative signs of upstream amplification as we reach the early stages of the period of interest (this being more directly associated with tropical forcing)?

Or perhaps that is just down to the ensembles only just reaching the period of interest. It has been a puzzling day indeed.

Edited November 30, 2016 by Singularity
I stand corrected!

[Banbury]

17 minutes ago, feb1991blizzard said:

Its not actually his forecast but tis is what he means.

 

PS - Oh IDO I see you didn't use that run to try to back up your argument!!

If Winter stopped at the time Gav ended his vid then that would do for me........................absolutely NO chance of CFS being correct

[snowbunting]

1 minute ago, Banbury said:

If Winter stopped at the time Gav ended his vid then that would do for me........................absolutely NO chance of CFS being correct

Most years I would agree with you, this year I'm not so sure.  Just a hunch. Nothing to do with models. Just a little feeling I have.

[bluearmy]

10 minutes ago, Singularity said:

Thanks @MattHugo

I gather the EC46 is an extended version of the operational, meaning it could potentially fall anywhere within the spread of outcomes featured in the EPS?

Just a thought - after all, isn't EPS barely getting into that critical period as of this time, much as with GEFS?

As it is though, I sense a lot of whether we can trust the latest ensemble guidance rests on what GP suggested this morning; that interference from the current Indian Ocean tropical cyclone is confusing the model output for the time being. However, I'm not clear as to just how much of an impact this could be having - could it explain the lackluster stratospheric output in terms of driving a lower-level split with a favourable orientation for us (i.e. cross-polar ridge aligned very nicely), on top of the hesitancy to show more than tentative signs of upstream amplification as we reach the early stages of the period of interest (this being more directly associated with tropical forcing)?

Or perhaps that is just down to the ensembles only just reaching the period of interest. It has been a puzzling day indeed.

The ec 46 is an extension of the eps, not the op ? 51 members

[nick sussex]

9 minutes ago, Singularity said:

Thanks @MattHugo

I gather the EC46 is an extended version of the operational, meaning it could potentially fall anywhere within the spread of outcomes featured in the EPS?

Just a thought - after all, isn't EPS barely getting into that critical period as of this time, much as with GEFS?

As it is though, I sense a lot of whether we can trust the latest ensemble guidance rests on what GP suggested this morning; that interference from the current Indian Ocean tropical cyclone is confusing the model output for the time being. However, I'm not clear as to just how much of an impact this could be having - could it explain the lackluster stratospheric output in terms of driving a lower-level split with a favourable orientation for us (i.e. cross-polar ridge aligned very nicely), on top of the hesitancy to show more than tentative signs of upstream amplification as we reach the early stages of the period of interest (this being more directly associated with tropical forcing)?

Or perhaps that is just down to the ensembles only just reaching the period of interest. It has been a puzzling day indeed.

This was NCEP's MJO update done yesterday:

The RMM-based and CPC velocity potential-based MJO indices continue to indicate an intraseasonal signal with the enhanced phase over the eastern Indian Ocean. A pair of Kelvin waves over the eastern Indian Ocean and western Pacific are apparent in the OLR field, and these features may be contributing to the amplitude of the indices.

Dynamical model forecast solutions generally predict a weakening of the MJO index, although many GFS and ECMWF ensemble members depict renewed eastward propagation of the enhanced phase to the Maritime Continent by the end of Week-2.

Due to the complex pattern in the global tropics, the future evolution of the intraseasonal signal is uncertain.

Midlatitude MJO impacts over North America would depend heavily on the evolution of the tropical convective pattern. Persistent West Pacific convection would favor a colder North American solution, while a slower evolution over the Indian Ocean and western Maritime Continent would favor ridging.
 

The complex pattern they mention in the global tropics might be in relation to what GP mentioned.

[Singularity]

5 minutes ago, bluearmy said:

The ec 46 is an extension of the eps, not the op ? 51 members

Ah right, thanks ba. There are so many tools these days I sometimes get a bit muddled up 

So I fall back on the model confusion idea, which does appear to have legs based on Nick S' helpful reply (cheers to him too!).

[Ali1977]

At 162 better WAA from Alaskan side and different position of the low at a southern tip of Greenland - not sure if this will help height rise out of N Canada but it looks a bit flatter over there. Different looking run but can't say for which side it turns towards just yet.

All mid range so nothing to worry about anyway - all about FI trending.

Edited November 30, 2016 by Ali1977

[lorenzo]

1 hour ago, Johnp said:

This isn't a dig at Matt at all, as I happen to think it's better to update forecasts as new data becomes available rather than stand by them and watch them fail ...but

Doesn't that make a complete mockery of seasonal forecasts?

Great question -  allows me to highlight a couple of aspects of our seasonal forecast which try to address this - 

a) the preface which described the view taken across the community on any type of seasonal forecasting. 

b) the title - a Winter of Wildcards - well we've got plenty that can throw a spanner in the works of the NWP output, not withstanding the internal workings of the vortex itself this season.

c) the summaries - a concise, honest analysis of where things are heading and where we have been, an evolving roadmap as it were.

Essentially in doing things in this manner it allows us to acknowledge the wildcards, chaos theory and unforeseen characteristics of a UK Winter, and provide some further retrospective and forward analysis. In itself I feel that is a step forward from publishing a simplistic temp map saying the whole of Iberia will be warm or Scandi cold etc etc. If we can analyze how winter started then acknowledge the changes - the hope is this leads to better understanding next time around etc etc.

Right now the vortex is getting a neat injection of steroids and has reminded itself that it is a winter player, using some sporting analogies - it's a boxer that's already gone 6 rounds with a Canadian Warming heavy weight and now the zonal wind increase (moving to football) is like a supersub brought on at 60 minutes to rescue a one-nil down position. We have some incredible intensification ahead in u wind across 70-90 and 60-80 - really sharp increase in vortex recovery - however we cannot see how this resonates across the whole trop - strat column in the current NWP output.

It is fair to say the models go off at tangents when there is a regime shift  - vortex relocation of any kind , and an increase in u winds from meandering like a stream to a full on torrent will be tricky to resolve in layers of modelling.  After all that, throw in some jet bifurcation and the tropics and you get the idea - a whole lot will be in flux for a period whilst this acceleration to climatology plays out..

Tomorrow is the first day of Winter proper.. to me it's already been a more interesting year. December is indeed a long month, but this year a fascinating journey..

[nick sussex]

7 minutes ago, Singularity said:

Ah right, thanks ba. There are so many tools these days I sometimes get a bit muddled up 

So I fall back on the model confusion idea, which does appear to have legs based on Nick S' helpful reply (cheers to him too!).

I have more! This from the Global Tropics Hazard page, yes I know I should get out more! lol

The RMM-based MJO index weakened during the past week after eastward propagation of the index ceased. The amplitude of the CPC velocity potential based MJO index has weakened as well. A pair of Kelvin waves (KW) is evident over the Maritime Continent and West Pacific, and the latter KW appears to be constructively interfering with an equatorial Rossby wave (ERW). The resulting enhanced convection over the West Pacific is likely interfering with the projection of the lower frequency intraseasonal signal on the MJO indices. Dynamical model MJO index forecasts generally depict a weak signal over the next several weeks, with some GFS and ECMWF ensemble members suggesting renewed MJO activity over the Indian Ocean to the Maritime Continent by Week-2. Given the competing convective signals over the eastern Indian Ocean and the West Pacific and continued influence from the low frequency La Nina base state, the future evolution of the global tropical convective pattern is unclear.

This is the link it generally adds a bit more detailed info to the normal NCEP MJO update, theres much more in the link concerning Tropical cyclones etc.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ghazards/

 

 

Edited November 30, 2016 by nick sussex

[Ali1977]

3 minutes ago, lorenzo said:

Great question -  allows me to highlight a couple of aspects of our seasonal forecast which try to address this - 

a) the preface which described the view taken across the community on any type of seasonal forecasting. 

b) the title - a Winter of Wildcards - well we've got plenty that can throw a spanner in the works of the NWP output, not withstanding the internal workings of the vortex itself this season.

c) the summaries - a concise, honest analysis of where things are heading and where we have been, an evolving roadmap as it were.

Essentially in doing things in this manner it allows us to acknowledge the wildcards, chaos theory and unforeseen characteristics of a UK Winter, and provide some further retrospective and forward analysis. In itself I feel that is a step forward from publishing a simplistic temp map saying the whole of Iberia will be warm or Scandi cold etc etc. If we can analyze how winter started then acknowledge the changes - the hope is this leads to better understanding next time around etc etc.

Right now the vortex is getting a neat injection of steroids and has reminded itself that it is a winter player, using some sporting analogies - it's a boxer that's already gone 6 rounds with a Canadian Warming heavy weight and now the zonal wind increase (moving to football) is like a supersub brought on at 60 minutes to rescue a one-nil down position. We have some incredible intensification ahead in u wind across 70-90 and 60-80 - really sharp increase in vortex recovery - however we cannot see how this resonates across the whole trop - strat column in the current NWP output.

It is fair to say the models go off at tangents when there is a regime shift  - vortex relocation of any kind , and an increase in u winds from meandering like a stream to a full on torrent will be tricky to resolve in layers of modelling.  After all that, throw in some jet bifurcation and the tropics and you get the idea - a whole lot will be in flux for a period whilst this acceleration to climatology plays out..

Tomorrow is the first day of Winter proper.. to me it's already been a more interesting year. December is indeed a long month, but this year a fascinating journey..

Would you still punt for a cold mid to late Dec ?