Model output discussion pm 13/01/2016

[Mucka]

5 minutes ago, fergieweather said:

It's a much more longer-range and sophisticated suite designed (in no small part) to particularly undertake stratospheric diagnostics and forecast SSW events.

Thanks Ian,

So you are saying it is the most sophisticated model with regards to the strat, but does it actually  verify better or do we not have that data? 

I'm just wondering how much credence we should give GFS?

Edited January 19, 2016 by Mucka

[wishingforsnow]

Also remember that in the process of forecasting the current cold spell and many others before it there were 'good days' and 'bad days' for model trends, days when models seemed to be firming up on the idea of a cold period, then backing away from it, then it was all systems go and then Hurricane Alex was supposed to disrupt everything bring back the Euroslug and bulldozing storms  etc up and down like a yo yo so even now we can't say its definitely game over for future cold when there is so much uncertainty over the outcome for the rest of Winter.

[Singularity]

Some on here don't seem to have realised that any strat. impacts on the trop will begin to manifest at the beginning of Feb at the earliest, this being the AO trending negative with HLB beginning to gain the upper hand again. This is beyond the range of current ECM det. runs and in the far reaches of the GFS det. runs by which point the model's ability to handle the distribution of energy is hardly brilliant.

There is a flip side to this argument of course, as the strat. events look to be of a kind that risks sending much of Europe cold but leaving the UK on the fringes. That, I believe, is where we turn to the forcing from the tropics to encourage height rises to the NW with the potential to retrogress a blocking high from NE/E of the UK. As yet, GEFS hasn't picked up on the changes in AAM in response to the tropical forcing that we're looking for. Hopefully they will happen despite the model's insistence they won't - just as we've seen once or twice already this season - and that will result in some more attractive longer range output from the model.

 

In the meantime we have a balance of play between a +ve AO trend (typical precursor to SSW onset) and the continued amplification signal from the Pacific. The latter is tied in with the aforementioned tropical signals and has been messing with the model output for a long time now. 

Given the pattern looking to be in place by the start of next week, this balance will have significant effects on how far north a strong ridge of high pressure in the vicinity of the UK is able to reach. The +ve AO trend (evident in the below-left image as a rather messy affair with poleward ridges continuing to interfere) should prevent a high latitude blocking scenario, but amplification from the Pacific increases the meridionality (waviness) of the jet stream which in turn increases the chance of seeing a section of jet stream heading southeast from the Atlantic instead of northeast. Typically we see a bit of both happening simultaneously - this being a splitting (or bifurcating, to get into the lingo) jet. These are among the most troublesome features for the models to handle, and all too often they have the arm of the jet going north too strong relative to that going south. An example from the GFS 00z can be seen below-middle:

Which way things go is influenced strongly by the upstream jet; if it's weak and not too flat then the northern arm isn't favoured so much and a more pronounced split can occur, but a stronger, flatter jet (above is the 06z which shows this outcome) will tend to cut-off the southern arm and connect with the northern arm, allowing low pressure to power NE while a weak cut-off low may drift about to the south.

So lots to be resolved with respect to how that plays out. Got to go for the mo as have a call!

 

 

[bryan629]

13 minutes ago, chionomaniac said:

ECM day 10-15 anomalies couldn't be more different with a GIN trough signal!

Chio, do you think we could see similarities of March 1984 ( as per tweet) except with the synoptic possibilities 4 weeks earlier . ? 

Just had a look through the archives here....

 http://www.meteociel.fr/modeles/archives/archives.php?day=15&month=3&year=1984&hour=0&map=0&mode=0    

[tight isobar]

Flicking through the gfs 6zensembles...

There still variable support for an easterly. ..

Against the op! !!!!!

[chionomaniac]

24 minutes ago, bryan629 said:

Chio, do you think we could see similarities of March 1984 ( as per tweet) except with the synoptic possibilities 4 weeks earlier . ? 

Just had a look through the archives here....

 http://www.meteociel.fr/modeles/archives/archives.php?day=15&month=3&year=1984&hour=0&map=0&mode=0    

I think that would depend on whether we see a significant enough displacement of the vortex. The GFS over the last couple of weeks has reeled us in with the promise of an SSW that would occur just after each run ceases - but in fact, even though a warming and displacement look likely, we are not seeing the full monty SSW in any closer timeframe. Seems to be a pattern over the last 3 winter - the nearly SSW winters....

[SxK]

27 minutes ago, chionomaniac said:

I think that would depend on whether we see a significant enough displacement of the vortex. The GFS over the last couple of weeks has reeled us in with the promise of an SSW that would occur just after each run ceases - but in fact, even though a warming and displacement look likely, we are not seeing the full monty SSW in any closer timeframe. Seems to be a pattern over the last 3 winter - the nearly SSW winters....

I suspect the fact that Glosea is not seeing any SSW into well into Feb tells us everything we need to know. 

That said the stress on the vortex should still open up some opportunities for colder interludes while we await the big daddy SSW. Lets just hope it is not too late for our winter. 

[Mair Snaw]

Wasn't the cold and snow at end of March 2013 due to a late SSW?? So a Mid Feb SSW isn't the end of the world for the UK... but as has already been said by many today an SSW does not always mean cold weather for the UK in the same way that we dont need an SSW for UK cold many a cold spell has happened without one..

[Paul_1978]

4 hours ago, Ed Stone said:

Please folks, can we keep on-topic...This isn't the Tomasz Shaffernacker interpretation thread.

To be fair when a screen grab of a forecast is posted and the models don't necessarily reflect it then it is model related, as we are discussing the relationship between the forecast and what the models are showing. However Ian F has quite kindly now clarified the forecast position. 

[fergieweather]

1 hour ago, SxK said:

I suspect the fact that Glosea is not seeing any SSW into well into Feb tells us everything we need to know. 

That said the stress on the vortex should still open up some opportunities for colder interludes while we await the big daddy SSW. Lets just hope it is not too late for our winter. 

Well, it actually tells us very little: at this particular juncture.
We need to consider how:

- Broad support does exist for substantial weakening (and displacement) of the stratospheric PV later this month
- Whilst no conclusive or compelling signal currently exists (barring a minority of GS5 ENS) for this to develop into a SSW in defined sense by early Feb, that doesn't wholly rule it out
- Irrespective of this, handling of tropospheric developments into medium range continue to show some key variance and are certainly not without interest; e.g., the broadly more mobile set of 00z EC-ENS versus higher incidence of blocked ones in both GFS and MOGREPS; plus there's no 'done deal' on progression being assured beyond D5 in e.g. 00z UKMO-GM Parallel. 
- As noted so many times before, beware tendency in all models for creep towards climatology in further reaches of output

Cheers

 

[Tom Jarvis]

Is there any idea on how gp's torpedo is going when was it expected to hit. 

[SLEETY]

so no cold for two weeks ,but after that noone can say ,so guess we just have to wait out next two weeks,plenty of winter left yet,even march can be good,like 2013

 

[Severe Siberian icy blast]

6 minutes ago, SLEETY said:

so no cold for two weeks ,but after that noone can say ,so guess we just have to wait out next two weeks,plenty of winter left yet,even march can be good,like 2013

 

Sleety please can you share with us all how you can make such a statement?  

Anything beyond 5 days is up for grabs.  From mild southwesterlies to screaming northerlies .

The Models are up and down more times that a brides nighty. 

All we no is its gonna turn milder briefly from Fri,  how long for nobody knows . 

 

[jvenge]

15 minutes ago, Severe Siberian icy blast said:

Sleety please can you share with us all how you can make such a statement?  

Anything beyond 5 days is up for grabs.  From mild southwesterlies to screaming northerlies .

The Models are up and down more times that a brides nighty. 

All we no is its gonna turn milder briefly from Fri,  how long for nobody knows . 

 

Agree with your sentiments in general, but you must admit, more than a "brief" period of mild is currently the favoured, not that it means it will or won't happen. At the same time, can't really write the next two weeks off either.

[Snowman.]

19 minutes ago, jvenge said:

Agree with your sentiments in general, but you must admit, more than a "brief" period of mild is currently the favoured, not that it means it will or won't happen. At the same time, can't really write the next two weeks off either.

The future is looking blocked. With that in mind anything can happen.

Edited January 19, 2016 by SN0WM4N

[Mucka]

This looks like it may be a little more interesting. Deeper atlantic trough and cut off low developing over Scandinavia/Russia

 

[northwestsnow]

19 minutes ago, Mucka said:

This looks like it may be a little more interesting. Deeper atlantic trough and cut off low developing over Scandinavia/Russia

 

Too much umph in the Atlantic im afraid mucka- little chance of anything nice for our little island looking at that chart in isolation..

Edited January 19, 2016 by northwestsnow

[Mucka]

7 minutes ago, northwestsnow said:

Too much umph in the Atlantic im afraid mucka- little chance of anything nice for our little island looking at that chart in isolation..

There won't be any quick routes to cold as far as I can see but the building blocks are much better this run.

Check out how much closer the cold air to the East is comparative to the 06z and the lower heights in N Europe,

 

Still a chance of an FI easterly here.

Edited January 19, 2016 by Mucka

[karlos1983]

6 minutes ago, northwestsnow said:

Too much umph in the Atlantic im afraid mucka- little chance of anything nice for our little island looking at that chart in isolation..

for pure eye candy, if that low between the uk and Norway slips under the high, things would look interesting.

@192, for some reason I can't copy images.......

and she is going at 198.  

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=0&ech=204&carte=1 

 

 

Edited January 19, 2016 by karlos1983

[northwestsnow]

1 minute ago, Mucka said:

There won't be any quick routes to cold as far as I can see but the building blocks are much better this run.

 

Still a chance of an FI easterly here.

Im with you bro

If we can lose that fodforsaken euro high we might be in business.

[wishingforsnow]

5 minutes ago, northwestsnow said:

Too much umph in the Atlantic im afraid mucka- little chance of anything nice for our little island looking at that chart in isolation..

What we need is to see emerge in the models (hopefully) is the heights over Europe are brought down for any significant cold spell to come. But apart from that there is potential and to me, with that cold over Europe not far away it shouldn't be too hard to bring it over to the UK as opposed to December when there was no cold potential anywhere. 

[Snowman.]

3 minutes ago, karlos1983 said:

for pure eye candy, if that low between the uk and Norway slips under the high, things would look interesting.

@192, for some reason I can't copy images.......

and she is going at 198.  

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=0&ech=204&carte=1 

 

 

Having the same issue.

[Froze were the Days]

27 minutes ago, Mucka said:

This looks like it may be a little more interesting. Deeper atlantic trough and cut off low developing over Scandinavia/Russia

 

Show me a chart without strong heights in the reliable time frame to the south over Europe then the faith will begin - been the problem for a good 6/7th's of the winter so far and what went before.

[SLEETY]

1 hour ago, Severe Siberian icy blast said:

Sleety please can you share with us all how you can make such a statement?  

Anything beyond 5 days is up for grabs.  From mild southwesterlies to screaming northerlies .

The Models are up and down more times that a brides nighty. 

All we no is its gonna turn milder briefly from Fri,  how long for nobody knows . 

 

it would take time for a cold pattern to develop again,it cant just turn cold again overnight the atmosphere has to turn to a cold pattern again,but lots of time left 

[karlos1983]

success at +210 , shame so far way, but trends and friends and all that 

2 minutes ago, SN0WM4N said:

Having the same issue.

Maybe we are in the naughty corner? Everyone elses seems to working fine.