Jump to content

Archived

This topic is now archived and is closed to further replies.

phil nw.

Model output discussions pm 31/12/15

Recommended Posts

16 minutes ago, Catacol said:

I'm a fan Steve - but I think this post is fired rather from the hip and without sufficient thought. I wouldnt argue about the potential impact of shortwaves on the broad pattern - I remember that Dec non-easterly very well - but 3 things you have got off target here:

1. GP said ops behind 5 days in this setup are of little use. Assuming we are agreed that we are in unusual times with such a huge AAM forcing coming into the mix then I think your blast is off target. Nobody would surely say that op runs beyond 5 days are on no use at all. In fact if you scroll back through a few of Stewart's earlier posts he actually refers to them.

2. To suggest that Stewart is one of those irritating "forecasters" who waits for a clear signal and then puts out a forecast and claims success afterwards is nonsense. Maybe again you ought to scroll back through posts made in December... when EC32 was screamiing westerlies, and Knocker's anomaly charts were again and again posted up as indicating dominant westerlies... and in the midst of all that you might find the posts that challenged the modelling of the MJO... and climaxed a week or so ago with specific reference to a brief northerly phase mid Jan. Note brief northerly phase. Where was the prediction of a Greenland High in mid Jan? You are imagining it.

3. Finally note the dates on Stewart's specifics. Full NAO flip 3rd week of Jan. This was the same as was stated earlier in Dec. Third week in January. NOT next week.

 

So - without wishing to sound like the interpretative analyst that I am - you need to make sure you have your information accurately at your fingertips before firing off and describing a very respected long range forecaster with a considerable record of success as "delusional."

In this set up-  is being modelled to exactly how the atmosphere is behaving from the start point at 00z or 06z- but at day 6 the net result for the NW atlantic is the same as it generally always is - IE whatever the impacts of the AAM spike isn't enough to produce a change on the atmosphere for that specific part of the world even though at the moment there may be significant impacts elsewhere-

That's not to say that further down the line it may change for the better...

I look forward to the projected NAO flip week 3,

 

to add to my comment earlier ( & something I said to Lorenzo at the start of the Winter ) All the winter forecasts are based on analogues - Analogues & best fits that will hold SOME relevance going forward, however that best fit & relevance is only as good to the point where the overall starting points of the teleconnections are comparable to the original start point - IE because the planet is evolving at such a huge rate of change & because of the amount of factors that influence the dynamics of the atmosphere - what was once a useful match becomes insignificant due to being overwhelmed by something else - IE there are no analogues.

2 things punctuate the global weather ( this year specifically ) - Super El NINO - which will be the overwhelming factor for at least H1 of Winter, & for the fact that 'extremes' of weather are becoming more & more frequent.

So record warmth COULD swing to record cold, or record WET could swing to record dry. but it wont be forecast....

S -

Share this post


Link to post
Share on other sites
22 minutes ago, Steve Murr said:

 

So record warmth COULD swing to record cold, or record WET could swing to record dry. but it wont be forecast....

S -

You've lost me here. GP cant forecast more than 4 weeks ahead anymore for contractural reasons, but's Ed's forecast is out there from November. If we get an NAO flip in week 3 and a spell of proper cold then that will exactly match his forecast. So how can it not be a forecast? 

The weather will do what the weather will do... but surely what we are trying to do on here is make predictions? You did one yourself at a much shorter range the other day. If that had come off then would you also be saying that you hadnt forecast it - even though that was exactly what you were trying to do in the face of the general model consensus?

Was GP's correct prediction that the MJO would move through phase 6 to 7 even though the models - and some posters on here - kept saying it wouldnt.. not a forecast? 

Let's just wait and see whether GP is right... we get the transient northerly followed by an NAO flip and then I would suggest a spell of cold weather. If he is correct I for one will be stating that his forecast was correct.

And by the way I love reading your short range skilled ideas - and I love the fact that you are willing to put ideas out there that may only have a slim chance of coming off... but you see as a possible outcome. That's still a forecast by the way and please keep them coming!

Share this post


Link to post
Share on other sites
18 minutes ago, Catacol said:

You've lost me here. GP cant forecast more than 4 weeks ahead anymore for contractural reasons, but's Ed's forecast is out there from November. If we get an NAO flip in week 3 and a spell of proper cold then that will exactly match his forecast. So how can it not be a forecast? 

The weather will do what the weather will do... but surely what we are trying to do on here is make predictions? You did one yourself at a much shorter range the other day. If that had come off then would you also be saying that you hadnt forecast it - even though that was exactly what you were trying to do in the face of the general model consensus?

Was GP's correct prediction that the MJO would move through phase 6 to 7 even though the models - and some posters on here - kept saying it wouldnt.. not a forecast? 

Let's just wait and see whether GP is right... we get the transient northerly followed by an NAO flip and then I would suggest a spell of cold weather. If he is correct I for one will be stating that his forecast was correct.

And by the way I love reading your short range skilled ideas - and I love the fact that you are willing to put ideas out there that may only have a slim chance of coming off... but you see as a possible outcome. That's still a forecast by the way and please keep them coming!

In terms of the first paragraph- didnt know that also I dont really read anyones posts per say - when I scroll down the page I just browse whats on that page - which is why I dont quote many posts 

i dont have much time to post anymore-

but when I read stuff that I dont really agree with then I reply-

In terms of Stewarts forecast for the NAO for week 3 - well its now duly noted & I will keep an eye on it - although that in itself is onky valuable for the UK if it manifests in a cold NAO ie east based - 

i think I remember the NW forecast stated that the pattern would shift to high lattitude blocking mid to late Jan which would be as a result of stratospheric warming - so fine thats a cause & effect forecast -

but if we get high lattitude blocking but no warming then that doesnt make the forecast correct-

anyway have a good one

s

 

Share this post


Link to post
Share on other sites

Regarding the MJO no seasonal forecast that I've read  included that as having an impact on the NH pattern. 

Given that NCEP with all their resources had to rewrite their January outlook shows that this has taken many by surprise.

So sometimes variables can pop up that were previously unforeseen, starting conditions and long range forecasting don't take account of the fluidity of the atmosphere.

 

 

Share this post


Link to post
Share on other sites

Yes Nick but I have to admit the Met Office Glosea5 model (if people interpret it properly) has been rock solid since Autumn for any really significant change (via SSW)  to occur in Feb  (if there is one at all), one of the reasons (not the only one) I told my friends to expect December to be mild, Jan to be above average and Feb to be colder was that model, it has been rock solid for 2 years now and evidence that they (LRF models) are getting better.

Share this post


Link to post
Share on other sites
50 minutes ago, Steve Murr said:

In this set up-  is being modelled to exactly how the atmosphere is behaving from the start point at 00z or 06z- but at day 6 the net result for the NW atlantic is the same as it generally always is - IE whatever the impacts of the AAM spike isn't enough to produce a change on the atmosphere for that specific part of the world even though at the moment there may be significant impacts elsewhere-

That's not to say that further down the line it may change for the better...

I look forward to the projected NAO flip week 3,

 

to add to my comment earlier ( & something I said to Lorenzo at the start of the Winter ) All the winter forecasts are based on analogues - Analogues & best fits that will hold SOME relevance going forward, however that best fit & relevance is only as good to the point where the overall starting points of the teleconnections are comparable to the original start point - IE because the planet is evolving at such a huge rate of change & because of the amount of factors that influence the dynamics of the atmosphere - what was once a useful match becomes insignificant due to being overwhelmed by something else - IE there are no analogues.

2 things punctuate the global weather ( this year specifically ) - Super El NINO - which will be the overwhelming factor for at least H1 of Winter, & for the fact that 'extremes' of weather are becoming more & more frequent.

So record warmth COULD swing to record cold, or record WET could swing to record dry. but it wont be forecast....

S -

Hi Steve, regarding the reference to the analogs, yes I remember in the early stages of the run up to winter thread some discussion around analogs for this winter, indeed both Ed and I after reviewing a lot of analogs eventually discarded them as they didn't feel right, nor did they display the particular evolution we thought would take place.

Interestingly, none highlighted the uber cold vortex, and in some Nino cases quite the opposite. wrt. to the Winter forecast yes the regime shift was predicated for January on a stratospheric event, one which may still happen albeit delayed in the face of aforementioned strong vortex. There is some irony that blocking and regime shift timing is on the table via trop led activity, moreover there is a stratospheric disconnect evident this season whereby the lower vortex is more receptive than the seemingly impenetrable middle layer, as ever we watch and learn.

For the close range though, yes, I think we can use the MJO analogs and the AAM ones, especially where these are shuffling the NH deck. Afterall these are not completely literal, the charts I posted over the last week can be reviewed as directional for potential evolution. Am nowhere near GP or T knowledge level of the GWO or AAM evolutions as it's a helluva subject to get to grips with. So, the composites or looking for starting points where the atmosphere is a mirror I think is a good place to work from, is it the magic bullet for forecasting, no. Does it attempt to provide insight, yes.

Your model knowledge is without question by those in here who follow your posts Steve, insightful and educative. Stewart provides the same level of insight into a different arena. Both compliment everyone's ultimate aim to learn and understand more. Both bring elements to the table, and although there is something of a debate today, both compliment each other.

Share this post


Link to post
Share on other sites
On 31/12/2015 at 3:06 PM, Steve Murr said:

So to repeat what I just added over on TWO

bin all the GFS & ECM suites 

 

1 hour ago, Steve Murr said:

I think ignoring shortwaves and the ops in this setup is delusional. 

 

 

I'm confused

Share this post


Link to post
Share on other sites

The points being made recently in various posts about short term micro details within the reliable approach >arrival period of a cold snap/spell are completely valid. No-one has at any point, or is now, disputing that whatsoever.

Stewart certainly wasn't disputing that particular point. Its possible to look at the shorter term picture as part of the bigger longer term picture - and in that context the short term analysis in terms of micro details is less important and less relevant. Which is a gist of what was said.

The posts that are made from GSDM/teleconnection basis are not attempts to micro forecast or replace micro forecasting. These are macro longer range guidance tools to assist assessing evolution of hemispheric weather patterns, and pinpointing when changes in these may become apparent.  On that basis they have much value. After all, micro assessment cannot be carried out ahead of getting the relevant macro pattern in place first

I think it is entirely possible to co-operate constructively in debate over these aspects, rather than compete over them, and,  more of relevance feel the need to compete over one another and spoil what can/could be a very interesting and rewarding discussion devoid of one-upmanship :)

I think we best not confuse the upcoming amplification with what may follow. The longer term guidance discussion is attempting to link how the initial amplification may be part of an evolution into a longer term more sustained cold pattern as described. On the other hand, assessing detail of shortwaves within the closer term approaching amplification will obviously become increasingly relevant on approach to it - as the models pick these up and determine the spatial distribution of cold air advection southwards next week.

However, with respect to the conversation this morning, the debate centred around how this initial salvo may be just a stage towards a proper engaged and connected switch of the Annular Mode - in terms of determining when the NAO might switch to complete the process.

For these purposes, there is certainly no need to agonise over shortwave distribution - as the whole process from the upcoming Atlantic amplification to evolvement of the pattern further on can be looked on seamlessly. That means, getting the macro pattern in place first, and then letting the micro details take care of themselves afterwards.

There has never been any suggestion at any time that using teleconnections and GSDM tools are some kind of wholesale replacement for each and every aspect of model output study and analysis. All have complete relevance, and all have their place.

Lets not confuse them for whatever purpose - and in this way let contributions about both the short term, and longer term prognosis, from those who can contribute something of one or other (or both!) have their place without unnecessary urges to compete for some phantom prize at the end of it all:)

The end never comes anyway - the weather and weather patterns are in endless flux balancing the atmospheric budgets. On that basis alone, chasing human tails is completely futile:)

Enjoy:)

Share this post


Link to post
Share on other sites

The one good thing in all this is that anybody putting forward a forecast on here will not go to jail or lose his or her shirt if it goes wrong.

It highlights just how complex our atmosphere is and just how difficult it is to predict - all attempts to do so should be welcomed - not ridiculed!

Relax, the weather will do what it does and there's damn all we can do about it! Anyway, it doesn't look as if there is any return to mild on the extended ECM mean for 850 temps: that's a pleasing picture at fifteen days ahead. :)

ec-ens_millikort_mslpmean_t850mean_t850s

Share this post


Link to post
Share on other sites
1 minute ago, feb1991blizzard said:

Yes Nick but I have to admit the Met Office Glosea5 model (if people interpret it properly) has been rock solid since Autumn for any really significant change (via SSW)  to occur in Feb  (if there is one at all), one of the reasons (not the only one) I told my friends to expect December to be mild, Jan to be above average and Feb to be colder was that model, it has been rock solid for 2 years now and evidence that they (LRF models) are getting better.

What happens if there's a wintry spell without a SSW? And I don't remember any of the ECM 32, Glosea, Mogreps picking up on the Russian block, positive PNA, or change to a negative AO

The main background variable that's changed in the last few weeks is the MJO, yes there are other smaller factors but it's clearly destructively interfered with the El Niño. NCEP have clearly admitted they were wrong with their January forecast and have placed the reason on the MJO.

 

Share this post


Link to post
Share on other sites
1 minute ago, feb1991blizzard said:

Yes Nick but I have to admit the Met Office Glosea5 model (if people interpret it properly) has been rock solid since Autumn for any really significant change (via SSW)  to occur in Feb  (if there is one at all), one of the reasons (not the only one) I told my friends to expect December to be mild, Jan to be above average and Feb to be colder was that model, it has been rock solid for 2 years now and evidence that they (LRF models) are getting better.

With respect, whilst that model may of been consistent in its prediction, please don't give hope to people by saying February may deliver because if it doesn't, somebody on here will say, "I'm fairly confident March will deliver" judging by what this model/teleconnection or whatever is saying. 

Don't get me wrong, I respect the long term signals and all the various factors that goes behind the weather patterns but I have already read about a prediction earlier on in the season that mid December could be promising for cold lovers and we all know how that turned out! Now I'm hearing maybe mid to the latter part of January may produce the goods and it remains to be seen whether that be the case or not but if it doesn't, then for me and perhaps others, it will be rather tiresome hearing these potential long term predictions which may favour cold weather. 

On the here and now, the pattern is different to that of December, obviously the NAO being the main obvious one but lets not fool people by saying just because the NH pattern has changed, it means cold weather could be on the way because it does not work like that, seen many NAO type patterns before and the UK can still be stuck in an Atlantic rut and that what it is at the moment and that has not changed from what I can see. 

However there is the potential WAA up to Greenland but as you can see, it could end up being half hearted attempt and the Northerly as a result is slacker, not as cold and much drier in terms of PPN amounts than it could of been. I have seen it many times before unfortunately however its still quite a long  way off without worrying too much about the details. 

Share this post


Link to post
Share on other sites

I get what Steve says here wrt teleconnections and making a long range forecast - in that the further away you move from the start point, the greater the unknowns, and the more messy the picture becomes. Almost to the point where the forecast isn't valuable. The massive El Nino this year at least gave everyone a head start for the first half of winter, an it panned out how most thought it would, albeit on an extreme level with the warmest and wettest month ever recorded here, and similar things happening in the east of the USA. I'm certainly looking forward to what's ahead for winter part II, it sure as heck isn't going to be like the first half!

Share this post


Link to post
Share on other sites
Just now, nick sussex said:

What happens if there's a wintry spell without a SSW? And I don't remember any of the ECM 32, Glosea, Mogreps picking up on the Russian block, positive PNA, or change to a negative AO

The main background variable that's changed in the last few weeks is the MJO, yes there are other smaller factors but it's clearly destructively interfered with the El Niño. NCEP have clearly admitted they were wrong with their January forecast and have placed the reason on the MJO.

 

True but if you look at even the record breaking EL Nino of 1997-98, the spring was cold + There maybe a wintry spell without an SSW  but it will be a toppler / temparory episode and wont skew the temperature monthly anomalies to such an extent that you can disregard the GLOSEA5 output when doing a hindcast review, Sustained Northern blocking will not occur as a purely tropospherical pattern in Late Jan - Mid Feb this year.

Share this post


Link to post
Share on other sites
9 minutes ago, Geordiesnow said:

With respect, whilst that model may of been consistent in its prediction, please don't give hope to people by saying February may deliver because if it doesn't, somebody on here will say, "I'm fairly confident March will deliver" judging by what this model/teleconnection or whatever is saying. 

Don't get me wrong, I respect the long term signals and all the various factors that goes behind the weather patterns but I have already read about a prediction earlier on in the season that mid December could be promising for cold lovers and we all know how that turned out! Now I'm hearing maybe mid to the latter part of January may produce the goods and it remains to be seen whether that be the case or not but if it doesn't, then for me and perhaps others, it will be rather tiresome hearing these potential long term predictions which may favour cold weather. 

On the here and now, the pattern is different to that of December, obviously the NAO being the main obvious one but lets not fool people by saying just because the NH pattern has changed, it means cold weather could be on the way because it does not work like that, seen many NAO type patterns before and the UK can still be stuck in an Atlantic rut and that what it is at the moment and that has not changed from what I can see. 

However there is the potential WAA up to Greenland but as you can see, it could end up being half hearted attempt and the Northerly as a result is slacker, not as cold and much drier in terms of PPN amounts than it could of been. I have seen it many times before unfortunately however its still quite a long  way off without worrying too much about the details. 

But whats wrong with doing a forecast, whether it comes from a novice like me or a pro, surely that's what these forums are all about - opinion.

Share this post


Link to post
Share on other sites

We should see models and teleconnections as eyesight. Teleconnections are a view from far away where everything is a bit blurred but an overall pattern can be seen, when it comes to the models the nearer to 0Z hours the closer it gets until it is completely in focus.

 

In this regard, teleconnections show me the blurred pattern, shortwaves at 180 don't interest me, as the overall pattern is still coming into focus, now a shortwave at 48hrs is more than likely going to happen as the model focuses ever closer on the final picture.

Share this post


Link to post
Share on other sites

There is still uncertainty on a more westerly pattern setting up later next week after a few days of much colder air according to the professionals; that to me says the charts of a few days ago showing more blocking are still possible.

Let's hope for an afternoon evening of upgrades towards longevity of cold, along with driers weather for all....We would all like to keep any zonal type weather away, whatever your preferences.

Share this post


Link to post
Share on other sites

Do we want all this cold weather..... if you think about it with all the rain the north have had it will turn into one massive ice rink:rofl:

Share this post


Link to post
Share on other sites
Just now, Flash Elvis said:

Do we want all this cold weather..... if you think about it with all the rain the north have had it will turn into one massive ice rink:rofl:

It would give the moisture way below more time to run off provided we didn't get one of them battleground marginals that deliver a huge dumping followed by a rapid thaw of course.

Share this post


Link to post
Share on other sites
16 minutes ago, Ali1977 said:

There is still uncertainty on a more westerly pattern setting up later next week after a few days of much colder air according to the professionals; that to me says the charts of a few days ago showing more blocking are still possible.

Let's hope for an afternoon evening of upgrades towards longevity of cold, along with driers weather for all....We would all like to keep any zonal type weather away, whatever your preferences.

gensnh-9-1-228.png

Lets hope by tonight we will be seeing the polar vortex looking like this.

On a more serious note and as a newbie to commenting on this forum (although I have been lurking for some years) most of the gefs ensembles have a complete northern hemisphere change occurring..

To further this with the recent comments from Ian f regarding any uncertainty I think that this could be the most positive stage of winter so far from a coldies perspective. 

Any help if im incorrect regarding the ensembles would be gratefully appreciated and would help me a lot.

 

Share this post


Link to post
Share on other sites

Regardless of the above discussions.

It's hardly a bad outlook at all. Yes it's not turned out at the moment like that ECM run where the Atlantic heights joined up with the Arctic. But even with this mornings relatively more disappointing op run, it's still going to turn much colder and drier in the mid term. Frosts at night with temperatures struggling only a couple of degrees above freezing in the day for most. Its a massive improvement on the recent pattern and still time for improvements. We all know too well that it's quite possible that we see an upgrade in the pattern again by 7pm tonight. Plus reading some of the posts from earlier, it seems we have all the reason to be optimistic in the longer term.

8-14 from ECM

image.thumb.png.f8f30bf3a42b8fd7c203522a

Colder and Drier. How cold though? We'll probably know in a couple of days.

Share this post


Link to post
Share on other sites
1 hour ago, RAIN RAIN RAIN said:

 

I'm confused

because at that point ALL the models had ALL the energy moving NE - when infact the probability would be that some broke away SE- in turns out that not enough went SE - but the energy that has has had a net result of a swing of 8c @850 HPA for London - & for that alone the models were effectively useless for the English weather prediction.....

In lamens terms we have gone from mild rain to cold rain- not quite to snow.....

If you refer to the post earlier where is showed the actual change or projection from day 6 of the GFS to the now day 2 chart then you should 'unconfuse' yourself  : )

 

Share this post


Link to post
Share on other sites

It really isn't a case of Macro V Micro because one is more valuable for generalisations and long term pattern forecasting and the other for short term and detailed local forecasting (local in this sense means UK weather).

You can't predict long term patterns at the micro scale and you can't predict detail at the macro.

Forecasting the upcoming weather for the UK day 5 to 10 days requires a micro approach for me. That doesn't mean we take every operational run as gospel (as fun as that is) but we do take note of developing trends, especially where there is cross model support.. In that regard the Atlantic ridge has very much been toned down and a Greenland high now looks like a remote possibility though personally I would wait until tomorrow before writing it off completely.

If that is the case then we are looking for any longevity from either a reload of the WAA to the West or the ridge toppling toward Scandi - that is the micro out to day 10 which suggest a cold snap the North but then a messy spell with either renewed MLB or HLB and cold from there or a return to a more mobile flow for a time at least.

This mornings UKM looks like it would give a renewed attempt at forcing WAA toward Greenland post day 6 though  the forcing may well take that more toward Iceland.

Look at the low off US East coast day 6, that would give the second push but it wasn't modeled by ECM or GFS this morning so I will be interested to see if sticks with that and what the angle of amplitude might be. Comparisons 144 UKMO, ECM, GFS

Modele UKMO - Carte prévisionsModele UKMO - Carte prévisionsModele UKMO - Carte prévisions

Certainly it seems we will need more than one bite at the cherry to get the sort of amplification we need for a prolonged cold spell but regardless of how things pan out it will be fascinating viewing (and reading). Winter weather fans really deserve some cheer so fingers crossed for improved output this afternoon, especially from GFS.

Share this post


Link to post
Share on other sites

Indeed, Mucka - the two approaches complement one another...And that is why, perhaps, the UKMET usually outfoxes less-mindful amateurs such as us?:)

Share this post


Link to post
Share on other sites

Well what a discussion beforehand. I'm in both camps but imo what it boils down to is it any good for UK and Ireland.  And I think that posters post in here with the intention that our shores will be directly affected by the change?  Yes great NH pattern with cold blocking is great for the purist, but of little use generally day to day if it misses us and important if it's down to SW development.  On the fence? Yep.  

still a good ' edge ' today.  

Interestingly 06z showing that more than one bite is needed.

 

BFTP

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.

×
×
  • Create New...