Winter Model Discussion 18Z 8/1/13. The hunt for cold (is closer).

[cold snap]

well major scatter in the ens ,i was expecting a full agreement with the opeational.i was wrong.

So where do we stand?

Still in the ballance this

[Iceaxecrampon]

My main concern with the ecm is that 24 hours ago it was showing pretty much what the gfs 06z is showing this morning with a fairly mild zonal outlook. It just goes to show that no matter how excited we get with the FI eye candy, the models can suddenly bring us crashing back down to earth with a mighty bump, on balance though, I still favour a cold outlook and we already have a cold weekend in the bag.

True.

Short and sweet.

Stopped looking at FI - pointless? - although you have to sometimes start somewhere! - still astonished the METO (and todays Daily Express for that matter) aren't having any of it....

....Yet

Ian

[Dean E]

I'm always like to stay 'on the fence' when it comes to meteorology, it's what I was thought at university and will stand by that.

But even I agree that the GFS outputs today are practically a right off. There seems to be no support for the runs with all the other models going for the cold pattern. But, I've seen the GFS do this before and go out on its own, which I why I'm taking no chances before Sunday...

The SSW is still ongoing, so we can safely say, we will see some further opportunities in the coming 10 days+. I've never seen such a sudden rise in a SSW and is very 1980s 'like'.

This time next week, we could be looking at even more incredible outputs from the models, due to the SSW.

SM

[Ian Brown]

Steve M is correct, the next day or so of output is huge in terms of where the rest of the winter goes.

I’m sure the other veterans will comment, but when there has been uncertainty in the past, I can never recall the 06z coming up with the correct solution with the others then following it.

[Wivenswold]

& Just to take out that important bit- NOBODY inc the MET put ANY stock in the 06z...because its rubbish.S

I'm not sure Ian meant that exactly. With 6 hourly updates I guess the Met Office can't keep reassessing their forecasts. There may be just a practical reason for choosing to review GFS 00z & 12z outputs (i.e. timewise they match Met Office outputs), it may even be that 06z & 18z tend to verify less for whatever reason. I don't think we should necessarily discount this latest GFS run as rubbish. Even though I'd love it to be.

[WorsleySnow]

True.

Short and sweet.

Stopped looking at FI - pointless? - although you have to sometimes start somewhere! - still astonished the METO (and todays Daily Express for that matter) aren't having any of it....

....Yet

Ian

That's because the Express started building their ramp in yesterdays paper!

[fergieweather]

I'm not sure Ian meant that exactly. With 6 hourly updates I guess the Met Office can't keep reassessing their forecasts. There may be just a practical reason for choosing to review GFS 00z & 12z outputs (i.e. timewise they match Met Office outputs), it may even be that 06z & 18z tend to verify less for whatever reason. I don't think we should necessarily discount this latest GFS run as rubbish. Even though I'd love it to be.

All correct: they don't subscribe to "pub run" mythology whilst accepting the known potential weaknesses, of sorts, of 06-18z NCEP.

[Yarmy]

Unless anyone here has access to the model source, mad FORTRAN skillz, a strong familiarity with the equations of Messrs Navier and Stokes, and a desire to go through several hundred thousand lines of code then any speculation as to how the SSW is being handled is somewhat moot, I think.

[karlos1983]

Good news

@MattHugo81: Looking like distinct mild outliers the deterministic and control run of the 06z GFS - http://t.co/Uh80ws97 - good news for those cold fans.

[High Altitude]

I'm told it's something to do with EC better at modelling/sampling synoptics from N/NE etc. Can't recall all the detail I was told yesterday about it.

If the EC is better with synoptics to the N/NE, is the GFS better with synoptics from the W/NW? This being the case what model would they go with if the EC is as it is but the GFS was going with these W/NW. Is one signal or model prevalent over the other if that makes sense or will it just depend on the background signals?

[Frosty.]

True.

Short and sweet.

Stopped looking at FI - pointless? - although you have to sometimes start somewhere! - still astonished the METO (and todays Daily Express for that matter) aren't having any of it....

....Yet

Ian

Hi Ian,

Yes the latest meto update is painting a very wintry picture next week with snow mentioned several times, an upgrade for cold/snow from yesterday and very much in line with the Ecm 00z operational run, the further outlook, on balance, remains the same..cold. It's not surprising because most of the models apart from the gfs is showing a cold wintry spell from sunday onwards.

[Lynxus]

Well Ive trawled though the GFS ENS at 06Z for T144 and only 2 runs support the ops run wrt the atlantic lows and total flatterning, most keep pressure much higher and the mean where the 980mb low in the atlantic at T144 is a full 30mb higher at 1010mb.

Seen enough to put that run in the very unlikely pile.

Ive said it before, I will say it again..

GFS is very much Atlantic driven. Most of its data show the Atlantic pushing through. This will always show up in situations like this with progressive Atlantic lows and their positioning.

Also, As others have stated. The GFS 06z doesn't have as much data as others ( Balloon data ) This alone will skew the results a little.

ECM still seems happy.

Time will tell. If we still have a half decent agreement later today then game on. If not, Then i fear we may be doomed. Doomed i tell ye .. I'm positive we will still see something.

[pyrotech]

So often the GFS has been the only model to pick up on a cold signal and then slowly other models fall into line and pick up on the same trend only for the GFS to then drop it and we all scream outlier. Although this may be the case i've lost count of the times that it's been the first model to backtrack only for the others to follow suite. Having said that it normally goes from an ice age scenario at the height of its cold trend to a medieval warming type output in its next before finally settling on something inbetween - and for the UK this usally means a damp squib. Please don't be the case again. My emotions can't take much more of this!

Gfs is also well known for finding a trend and dropping it closer to timeframe and then bringing it back at last minute. I am certainly not worried by this change in GFS . I personally find the 06z the worst run anyway but the Gfs is very volatile and normally seems to have covered every possable outcome in fi before it gets to reliable timeframe. Its a useful tool for searching for trends but on its own its unreliable. I suggest the trend over last few days is cold, it has now dropped that only to bring it back again soon.

[TEITS]

So really today we have the complete opposite of yesterday with regards to the GFS/GEFS. Im not going to be a hypocrite though because the way the GEFS control follows the OP makes me nervous and like I said last night I prefer to see cold operationals than ensembles.

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=315&ext=1&y=77&run=6&runpara=0

Still you could argue that todays operationals are following yesterdays ensembles and hopefully later today the 12Z will follow some of the 06Z ensembles.

[BLAST FROM THE PAST]

Having re-read RJS discussions again [HE HAS THE WARMEST SPIKE BACK END OF MONTH but up and down anyway], thinking back to what happened in December [we had GFS with greeat runs, then ECM came with the PERFECTION run with GFS then immediately dumping with ECM then following]. This build up has almost been precisely the same albeit we have differing tele signals. As a betting man I would put money on the ECM retreating.

Re all models being against the GFS, Well if one looks at the hemispheric view posted earlier then it is IMO clear that the overall pattern is broadly similar. Just the UK Atlantic locale that's different?

So on that basis I am a tad concerned for the further outlook [for Jan cold longevity only] and will not be surprised to see other models retreat today. Whether that is the right solution or not, I'm talking mainly models here at this point...but confidence has been dented.

BFTP

Edited January 9, 2013 by BLAST FROM THE PAST

[tonbridgemole]

Would love this to come off

[Alexis]

• the GFS 6z is a clear mild outlier

• the GFS often 'appears' to pick up trends first because it runs 4 times a day

[Frosty.]

GFS 06z op run goes straight into the wheely bin

Meto side with ecm and all the other models showing

[bluearmy]

interestingly, the gefs suite recovers amplification post T200 which sort of says to me that the atmosphere is predesposed to it and if we wont get shortwave spoilers each time heights try and build.

[SnowBallz]

Hiya

I have very limited knowledge of models and their likely outcomes, so could someone please give me a biginners description of an outlier, a short wave and a toppler please?

I know there's a learners area but a bit short of time at the moment and I'm sure you guys will be able to give a perfect explination!!

Thanks Guys

Hope this helps, with a bit of context for you too:

Outlier

Technically, it's a term which mathematicians - like moi - or statisticians attach to a reading which doesn't tie-in with the rest; a bit of a black sheep which has got lost somewhere. In meteorology, the term 'outlier' is be used in the context of assessing support for the various model runs. These model runs (sometimes up to 50 different ones) are compiled into ensemble charts, so that they can be visually analysed against one another. It is at this point that you'll see those 'black sheep', where a run goes off on one, relative to the rest. In the main, those are then discarded as outliers, ie: runs without support of the collective suite.

Shortwave

Essentially, these are embedded flow disturbances which disrupt the overriding synoptic pattern. In meteorology, it's wise to bear in mind two patterns: the overriding parental one (zonal, blocked, etc...) but then there is also a child meso pattern, which is often most influenced by shortwave disturbances. Shortwaves are notorious for their synoptically subtle influences which - once amplified - can, and often do, completely change a pattern. To spot them, look for little hook/kinks in the isobars. But shortwaves are not always bad news, and sometimes synoptically you need them, in order to progress or move to a more advantageous pattern. But timing and location is absolutely crucial, and this is what can cause such utter frustration. Nick S loves a good shortwave

Toppler

A term only ever used in reference to Northerly's. Essentially, a 'toppler' is a short-lived - or even non-existent Northerly - which is synoptically spoilt by high pressure ridging from the Atlantic. A toppler can, nonetheless, 'produce the goods' - only that it's short-lived (perhaps 24-36hrs) and often belies a fairly mobile pattern. Not the best winter synoptic, although I'd hazard a guess they're fairly common for the UK; at least, more common than, for instance, an Easterly flow - which, by contrast, is characteristically colder and has much more longevity associated with it.

Hope that helps you - and indeed others - with a few of the myriad of meteorological terms.

SB

[offerman]

This is exactly what i was on about yesterday. Charts said cold, but i said don`t get to excited as it could all change as december proved. Atlantic just seems very strong this year and always winning out. There will be brief cold spell sat-Mon but look like Atlantic will win out longer term.

Hope i`m wrong though.

[Frosty.]

Having re-read RJS discussions again [HE HAS THE WARMEST SPIKE BACK END OF MONTH but up and down anyway], thinking back to what happened in December [we had GFS with greeat runs, then ECM came with the PERFECTION run with GFS then immediately dumping with ECM then following]. This build up has almost been precisely the same. As a betting man I would put money on the ECM retreating.

Re all models being against the GFS, Well if one looks at the hemispheric view posted earlier then it is IMO clear that the overall pattern is broadly similar. Just the UK Atlantic locale that's different?

So on that basis I am a tad concerned for the further outlook [for Jan cold longevity only] and will not be surprised to see other models retreat today. Whether that is the right solution or not, I'm talking mainly models here at this point...but confidence has been dented.

BFTP

By a clear rank mild outlier? come on fred, cheer up, deep cold is coming, the words of netweather and the majority of the 00z models with the biggest plus being the even more wintry met office upgrade hot off the press.

Edited January 9, 2013 by Frosty039

[Met4Cast]

• the GFS 6z is a clear mild outlier

• the GFS often 'appears' to pick up trends first because it runs 4 times a day

Trouble is, the GFS had been a cold outlier for several runs against it's ensembles

[Alexis]

Trouble is, the GFS had been a cold outlier for several runs against it's ensembles

Not to any great degree though? And it wasn't without support.

[garbagebags]

Trouble is, the GFS had been a cold outlier for several runs against it's ensembles

It does unfortunately apear to be more substantial than just a "blip" or "wobble". However, Im still taking comfort in the other models.