Model Output Discussion - Early November Onwards

[Frosty.]

question is, will we be building sandcastles or snowmen?? B)

sandcastles..the ensembles paint a very mild picture for the next few weeks, we have been having temps of 15-18c when it should be 12c and next week should see more temps of 15-18c with a southerly airflow. This weekend looks glorious in northern britain with plenty of sun and temps around 11-13c but for england and wales it looks cloudy with some rain, even the early days of next week look cloudy but mostly dry by then with the sunshine being eroded across the north so that only nw scotland will be sunny by tuesday. Another pulse of very mild air spreading north through the middle to end of next week.

[ITSY]

my feeling based off recent days is that any HP track to the NW around the middle of the month won't be able to establish itself. I feel we're heading for an overall mild November, with VERY mild temperatures continuing till at least mid month, probably to be replaced by something more seasonally average - leading to mild conditions for the month as a whole. Here in Leeds (hardly a sunny microclimate) i've been walking around in a mere jumper for the last week - it really isn't cold at all, more springlike than anything!.

[shedhead]

sandcastles..the ensembles paint a very mild picture for the next few weeks, we have been having temps of 15-18c when it should be 12c and next week should see more temps of 15-18c with a southerly airflow. This weekend looks glorious in northern britain with plenty of sun and temps around 11-13c but for england and wales it looks cloudy with some rain, even the early days of next week look cloudy but mostly dry by then with the sunshine being eroded across the north so that only nw scotland will be sunny by tuesday. Another pulse of very mild air spreading north through the middle to end of next week.

And to be fair it's not just here either. 20c in France, 19c Germany, 18c Benelux, 16c Norway and Poland, 11c Iceland... it's very mild, if not warm, simple as. The other main concern is this pattern really isn't an easy one to break once firmly established, 4,5,6 or even 8 week spells of it are by no means out of the ordinary, so we may need a good deal of patience before we see a genuine chance of cold that many of us crave. Edited November 4, 2011 by shedhead

[Summer Sun]

Met Office have us warm right through to the end of November before temperature return to normal but there is no word of snow for even the high ground for at least the next 4 weeks.

Edited November 4, 2011 by Gavin D

[Frosty.]

And to be fair it's not just here either. 20c in France, 19c Germany, 18c Benelux, 16c Norway and Poland, 11c Iceland... it's very mild, if not warm, simple as. The other main concern is this pattern really isn't an easy one to break once firmly established, 4,5,6 or even 8 week spells of it are by no means out of the ordinary, so we may need a good deal of patience before we see a genuine chance of cold that many of us crave.

It could be a long time before the euro high loses it's grip and there is no sign of a sudden switch to cold in the foreseeable future.

[Glacier Point]

Currently, the favoured FI solution in my opinion would be the waxing and waning of the Scandi ridge with corresponding waxing and waning of the Atlantic trough. The Polar vortex is steadily increasing as the stratosphere cools and the MJO signal is weak and being overridden by stratospheric downwelling. There is no sign currently for a break in these signals.

If I could tag this on to Chion's comments..

There has been an increase in westerly zonal winds introduced by a persistent mountain torque over Asia allied to an easteward propagating MJO wave (agreed by all model solutions). This is likely to disturb the North Pacific anticyclone and introduce some eddying of the jetstream days 7-10.

How this pans out is being toyed with the medium range NWP. Some expansion of the longwave trough over the western half of North America seems favourite right now, nudging the peristent ridge over Hudson Bay further east towards the western side of Greenland.

Its interesting that even the over-progressive GFS seems to want to return to a phase 1-2 type solution for the MJO, which, depending on other factors, would tend to favour a trough solution in the Atlantic and ridge over Scandinavia, aka the reccuring pattern. The ECM is much less bullish about this happening, keeping the MJO signal very weak and therefore likely to maintain the underlying pattern of Atlantic trough / European ridge. Also worth noting that ECM ensemble spreads are rock solid on heights remaining high over Europe.

[Liam J]

last year changed suddenly from no prospects of cold, to 'proper winter'. no-one really can say for sure, but it could quite easily happen again..... "

We had strong upstream signals of a potentially cold and snowy early start to Winter 2010 over NW Europe, even as early as September this potential was highlighted. The models found it difficult to get a grip on the huge pattern change during last November which would see us plunged into severe winter weather. currently nothing to indicate anything similar occurring as early (if at all) this year.

Edited November 4, 2011 by Liam J

[chionomaniac]

If I could tag this on to Chion's comments..

There has been an increase in westerly zonal winds introduced by a persistent mountain torque over Asia allied to an easteward propagating MJO wave (agreed by all model solutions). This is likely to disturb the North Pacific anticyclone and introduce some eddying of the jetstream days 7-10.

How this pans out is being toyed with the medium range NWP. Some expansion of the longwave trough over the western half of North America seems favourite right now, nudging the peristent ridge over Hudson Bay further east towards the western side of Greenland.

Its interesting that even the over-progressive GFS seems to want to return to a phase 1-2 type solution for the MJO, which, depending on other factors, would tend to favour a trough solution in the Atlantic and ridge over Scandinavia, aka the reccuring pattern. The ECM is much less bullish about this happening, keeping the MJO signal very weak and therefore likely to maintain the underlying pattern of Atlantic trough / European ridge. Also worth noting that ECM ensemble spreads are rock solid on heights remaining high over Europe.

As are both the ECM and GFS 100hPa forecasts.

It is interesting because I can see an Asian MT event such as this giving a far bigger influence further downstream later on in the winter when the lower stratospheric westerly element of the QBO has diminished and wave breaking is possible to disrupt the stratosphere. How much of an effect now it will have remains to be seen as you say. Could it knock the Atlantic trough slightly further eastwards?

[Frosty.]

We had strong upstream signals of a potentially cold and snowy early start to Winter 2010 over NW Europe, even as early as September this potential was highlighted. The models found it difficult to get a grip on the huge pattern change during last November which would see us plunged into severe winter weather. currently nothing to indicate anything similar occurring as early (if at all) this year.

Spot on, there is no sign within the ensemble suites to suggest this sluggish pattern being replaced in the next month at least and the euro high will fast become a major pain but winter is still a month away so it's not a disaster yet but I think we are still paying for the early october hot spell and the lag effect will be prolonged.

[Rocheydub]

Removed.

Can't report posts from phone version of site. But message received and understood!

[rich1]

And to be fair it's not just here either. 20c in France, 19c Germany, 18c Benelux, 16c Norway and Poland, 11c Iceland... it's very mild, if not warm, simple as. The other main concern is this pattern really isn't an easy one to break once firmly established, 4,5,6 or even 8 week spells of it are by no means out of the ordinary, so we may need a good deal of patience before we see a genuine chance of cold that many of us crave.

From what i can gather that Euroblock has been around for a while now, its not as though its just arrived here yesterday as such

would nevertheless be pretty suprised if this November was anything but above average now though i do remember similar pessimism back in 2009. That November was grim, endlessly wet and well above average which lasted for the first part of December, and even the cold lovers were prophesising that to continue indefinitely and arguing the signs suggested that

A European block with a somewhat sluggish Atlantic though i maintain is not as bad as a raging positive NAO set up which was more a feature of the 90's autumns. This isnt quite the same. It wont be going anywhere quickly but would say wait a few weeks before writing a whole forthcoming season off. It hasnt started yet, though all the same would like to see some more coherent signs of a change appear. Sometimes though, they can appear almost out of the blue, in my experience of this place and in the last few years anyway

[BLAST FROM THE PAST]

Nice pattern currently, a chance of decent wind and rain events with LP projected to hit us right on. Nothing to fear about this pattern at all.

BFTP

[carinthian]

May be a bit of hope on the horizon. The present set up prolongs the warm Autumn over much of Central and Western Europe. This pattern is the worst scenario for our resort as the lifts are due to open in 3 weeks. Subscription forecasts to Austrian ZamG weather services provide the resort with multi-day trend forecasts of 30 days and beyond. The 30 day plus forecasts this year have been very good with remarkable accuracy. From about 20th November they expect the high zone to collapse with the advent of a increasing powerful westerly jet development south of 50 degrees north. This is the news the resort managements hopes for and good for cold lovers across The British Isles as well. I did note the GFS this morning had hinted at this in there outer limit progs. Lets hope this is going to be the longer term trend. All I can say at the moment, this prolonged (warm) high is better is situ now than say in 30 days time.

Back to chopping logs, may need them sometime !

C

[Frosty.]

Nice pattern currently, a chance of decent wind and rain events with LP projected to hit us right on. Nothing to fear about this pattern at all.

BFTP

Hi Fred, yes it's a nice pattern for a mild or very mild november and with nothing currently showing upstream to indicate anything different.

[Aaron]

As someone already said, better to get this pattern in November then in the middle of January, if this was January then this forum would be in meltdown mode!

[johnholmes]

I rarely disagree with chiono but in respect to this part of his post at No 71 in the Model Discussion thread I have to disagree.

I don't believe in JH's motto of comparing one days run to the same time the next. I believe that the most up to date info that is fed into each run will give the latest and probably the most accurate and up to date forecast. After all, it is not as if each run has a different programme that the data is fed into.

Why?

Well based on several years of seeing the total variability of models runs from one issue to the next, GFS is especially susceptible to this.

The 00z and 06Z issue this morning is a case in point, not that I kept a copy of either but judging by comments in the model thread that seems to have been the case. Its no an isolated instance but a fairly regular occurrence.

Chiono quotes the reason to use each run as, - ‘each run will give the latest and probably the most accurate and up to date forecast’.

One might expect this to be true in a fast changing situation perhaps but not in any fairly static set up, such as we have now. By static I am talking about the major wave length pattern around the northern hemisphere not the detail at the surface.

So why does it change so much from run to run?

Perhaps the list below is at least part of the answer, and no I have no idea why relatively small changes in variable data as opposed to the basic data on every run, create such large differences in the output.

http://forum.netweather.tv/topic/35985-what-data-does-the-gfs-use/

That is to me a fairly comprehensive reason to take the same time run each day and compare. Obviously, if you are involved in day to day forecasting in the range 1 day to 10-15 days you need to check each run. For the vast majority on here, especially those with little meteorological experience be that from the web or from other sources, then the end result is apparent for all to see. Ups and downs in the model thread as successive runs show, or don’t show, what a particular poster wants/hopes to see-the rollercoaster ride as it’s sometimes referred to.

So my advice, great respect that I have for the input from chiono, is take one run each day and see how the last day and the next compare. IF they are consistent over that time scale then it’s much more likely, not certain by any means though, that GFS is not far off the mark. Even then, compare its output to the other main models, be it out to T+144 or 240. Again if they are all showing a similar version, then even more confidence can be given to its output.

Further to that, if they in turn have solid support from the 500mb anomaly charts, out to T+240, then another level of confidence can be added, and so on through the various teleconnections taking us out to 15-20 days or so.

Just remember though it can still go pear shaped; readers of several winters ago, at, I think, the T+48-72 will remember the so called ‘beast from the east’ being CERTAIN to arrive, only for it to disappear into thin air.

Meteorology is a science but it’s also got a touch of black art in it!

Edited November 4, 2011 by Paul
Inserted link

[Pennine Ten Foot Drifts]

What you seem to be suggesting John is that in effect, at least on a very subtle level, the GFS is not four runs a day of the same model but one run a day of four different models ?

[johnholmes]

What you seem to be suggesting John is that in effect, at least on a very subtle level, the GFS is not four runs a day of the same model but one run a day of four different models ?

No not really that large but the subtle changes it seems to provoke, for instance one run has more upper air data from aircraft than another, another more METARS than another. The basic input of data is dealt with the same way for each run-basic physics for meteorology using complex maths equations.

I'm puzzled why these subtle differences cause such swings from one run to another. Of course it may be some factor but chatting via e mail to NO/NASA and to folk I still know in UK Met they do not seem to have anything definite to add. Mind you its a couple of years since I exchanged e mails so things may have changed in that time.

[Paul]

What you seem to be suggesting John is that in effect, at least on a very subtle level, the GFS is not four runs a day of the same model but one run a day of four different models ?

It's definitely the same model, uses the same physics on every run and so on. The only difference is that there are differing amounts of some of the data types going into each run - for instance the 06z run may have less upper air data from the atlantic because there are less flights over the atlantic at that time of day.

[Dale Leigh_6487]

This pattern carn't go on for ever give it 2 weeks and i'm sure we will all be looking forward to something more seasonal. I listen to the experts on here ie john Holmes etc. the knowledge and expertase they bring to the forum is great. be patient guys and gals winter will come.

[wimblettben]

Removed post

Edited November 4, 2011 by Paul
Please use this thread for discussion of the models not just to whine about the weather currently.

[johnholmes]

It's definitely the same model, uses the same physics on every run and so on. The only difference is that there are differing amounts of some of the data types going into each run - for instance the 06z run may have less upper air data from the atlantic because there are less flights over the atlantic at that time of day.

Paul have you got that link as to what goes in and when please-I seem to remember you repeated it sometime early last winter but I cannot find it?

Edited November 4, 2011 by Paul
Removed reply to already removed post

[Paul]

Just ended up deleting about 10 posts made this pm, can we keep this thread to the models please....

Paul have you got that link as to what goes in and when please-I seem to remember you repeated it sometime early last winter but I cannot find it?

I added it to your post for you

[chionomaniac]

I knew you would reply to this John!!

One can always agree to disagree but I think it is worth discussing and is model related. Keeping this discussion to the GFS, I was under the impression that the data variation from run to run was almost insignificant compared to what is inputted. It is with this respect that I feel that one should look at every run with the latest being the most accurate. One should look at overall FI solution of every run to get an accurate picture as possible to what is the likely outcome. Why would the operators of the GFS bother running the programme 4 times a day if they too believed that it is just better to look at only one of them?

To me it makes better sense to combine the output of every run and ensemble direction. One can see where divergence from one solution to another begins when doing this and work out for oneself up to which point the run can be trusted!

edit: Oh and to add further following Paul's insert if you concentrate on one run then you may inadvertently concentrate on the poorest run . I know that the data is compared somewhere to evaluate each run.

Edited November 4, 2011 by chionomaniac

[gottolovethisweather]

As per my earlier post, now deleted?

PPS! The trough shown below is still present on the 12z as well, so maybe it's onto a trend. I'll await the tomorrow's 06z with interest. The most interesting aspect of this situation is how, thereafter, it allows an introduction of much colder pooling air into continental europe.

Watch this space methinks!

Cheers

gottolovethisweather

Edited November 4, 2011 by gottolovethisweather