Winter Model Output Discussion 01/02/2013 12z onwards

[chionomaniac]

One of the best ways not to get drawn into the GFS pendulum swings, its overplaying of the Atlantic jet and wild FI scenarios, is to just don't look at it. I wonder how a GFS free model thread would be - certainly it would be a lot less stressful!

(Of course I can't possibly follow that advice myself!)

[Tom Montalbano]

So as we close in on the pivotal point on the closing drama for this winter we yet again have a Euros v. GFS scenario.

One of the main differences between the 2 camps is how they handle the low coming off the E.Seaboard at t120/t144.

http://www.meteociel...44-21.GIF?02-06

http://www.meteociel...1-144.GIF?02-12

http://modeles.meteo...snh-0-144.png?0

As you can see the Euros hold this feature close to Newfoundland and its track is more to the N. This has the effect of pulling the low towards the Canadian segment of the PV and, as it does so, that part of the PV just eases a touch westward away from Greenland, allowing a ridge to be thrown up from mid-Atlantic towards Iceland. ECM then goes on to start to develop height rises to our NE

GFS has this low further E and it then tracks to the NE. This flattens any attempted ridging in mid-Atlantic, although it does also develop a rise in heights to our NE, in FI.

Another fascinating period of model watching ensuing and there looks to be a battle royal in the area of the UK, in around a weeks time.

Regards,

Tom.

Edited February 2, 2013 by TomSE20

[phil nw.]

Yes it`s the Euro.models v the NA models re the evolution beyond T168hrs.

GFS and GEM going the same way bringing in the westerlies against the the much colder UK and ECM holding back the Atlantic.

We can see the differences at T144hrs with the GFS already collapsing the Atlantic ridging bringing westerly winds across to the North of Scotland compared to the Euro`s who have already started that little push back from the NE.

http://www.meteociel...1-144.GIF?02-12

http://www.meteociel...44-21.GIF?02-06

http://modeles.meteo...snh-0-144.png?0

The GFS and ECM means are not much of a guide this morning as it`s either very much milder or cold come the end of next week with no middle way but with the those differences quite close it shouldn`t take many runs before we get an agreement.

[Long haul to mild]

It's true the GFS was quicker than most to look to break down the recent cold spell...but i see this as a matter of timing only. Nothing wrong in the trend it picked up early on despite the declarations of some in the early days that the cold spell was set to endure and the "Atlantic bias" of the GFs should be ignored.

I

Think you are being a bit kind there. There were four or five snow events that would not have happened at all if the GFS has been right with its determination to bring a quick end to the cold spell.

You are right not to dismiss it entirely and even I would prefer to have it on board, but my faith in any of its output is severely weakened because it handled the last breakdown appallingly. It kept bringing in the breakdown at about T144 every single day! Eventually it was right, but that's hardly a coup in this country!

For me, the UKMO is the one to follow. For example, it was the only one of the big three that didn't completely overblow yesterday's LP. Both GFS and ECM had an extremely nasty affair which UKMO never bought into and was proved right. Trouble with UKMO is of course that it doesn't go beyond T144 which makes it hard to pick up on emerging trends.

Edited February 2, 2013 by Chalk Serpent

[SMU]

remember watch the GFS resurect that high over th next 6-8 runs- it will gradually appear out of its winter coffin!

[Tim Bland]

As I said yesterday I can happily ignore the GFS op run and will even ignore it when it has some inter run consistency. I'm yet to see the GFS be completely wrong when it has the backing of its ensembles. I can't find a single GFS ensemble that backs the ECM op, coupled with the fact that the ECM op is unsupported by its ensembles I think we have a long way to go. I would say odds on a decent Easterly are around 2/1 at the moment. I would have said less but GFS showed a glimmer of a backdown last night and ECM and UKMO are similar

[Timmytour]

Think you are being a bit kind there. There were four or five snow events that would not have happened at all if the GFS has been right with its determination to bring a quick end to the cold spell.

You are right not to dismiss it entirely and even I would prefer to have it on board, but my faith in any of its output is severely weakened because it handled the last breakdown appallingly. It kept bringing in the breakdown at about T144 every single day! Eventually it was right, but that's hardly a coup in this country!

For me, the UKMO is the one to follow. For example, it was the only one of the big three that didn't completely overblow yesterday's LP. Both GFS and ECM had an extremely nasty affair which UKMO never bought into and was proved right. Trouble with UKMO is of course that it doesn't go beyond T144 which makes it hard to pick up on emerging trends.

I know what you are saying on its consistent 144 approach to breaking down the cold spell. But you know i think in hindsight it wasn't so far of the mark?

i have to say the recent spell with its snowfall was great for me from an IMBY perspective, but one aspect of it was that it never really did get that cold...it was certainly strange to have snow lying for 13 days and yet not have lakes and ponnds frozen to the degree a dog would be safe walking on it.

So i think the GFS did pick up on the fact that the cold was never entrenched to the level that others modelled it to be, and it was this, rather tthan an Atlantic bias, which kept it modelling a six day breakdown. Certainly I can't remember the GFS producing the kind of 1947 type charts ECM seemed to produce on a few runs which never materialised either.

[snowking]

Very interested to see the 0z ECM ensembles this morning (havn't had a chance to take a look at the 2m mean mapping yet) given that yesterday's 12z suite for Birmingham, whilst still rather diluted beyond Feb 8th, did show quite a big swing in the members towards cold.

Ill offer up a bit more analysis a little later on, but I think at this juncture it's still wise to hold fire with any thoughts of a following E/NE pattern - we saw the GFS say no to this a good 3-4 days before the euro's back in the December Debacle, and whilst I wouldn't give the GFS too much credit for predicting the recent breakdown (because it predicted the breakdown so many times on so many different dates during the last cold spell that on the law of averages alone it had to be right eventually!) I would certainly keep in mind for now that we all (myself included) assumed that it was 'pulling a GFS' - ie overblowing the Atlantic energy - and we all ended up with rather eggy faces (met office included!). Finally, the GFS, for what it's worth, is currently the best verifying model in the northern hemisphere at day 10.

The one bit of light at the end of the tunnel is the messiness once again of the GFS ensemble suite!

SK

Edited February 2, 2013 by snowking

[chionomaniac]

ECM freebie today shows Euro 500hPa and 850's.

Days 9 and 10 look good!

(Edit remember the lines are 500 hpa heights not slp isobars and indicative of an upper trough with greater instability)

Edited February 2, 2013 by chionomaniac

[nick sussex]

As I said yesterday I can happily ignore the GFS op run and will even ignore it when it has some inter run consistency. I'm yet to see the GFS be completely wrong when it has the backing of its ensembles. I can't find a single GFS ensemble that backs the ECM op, coupled with the fact that the ECM op is unsupported by its ensembles I think we have a long way to go. I would say odds on a decent Easterly are around 2/1 at the moment. I would have said less but GFS showed a glimmer of a backdown last night and ECM and UKMO are similar

I wouldn't worry about not finding a GEFS member backing the exact synoptics, its how many curve the jet with this heading south around the periphery of the high to the west.

So really its the trend that's important.

[Long haul to mild]

I know what you are saying on its consistent 144 approach to breaking down the cold spell. But you know i think in hindsight it wasn't so far of the mark?

i have to say the recent spell with its snowfall was great for me from an IMBY perspective, but one aspect of it was that it never really did get that cold...it was certainly strange to have snow lying for 13 days and yet not have lakes and ponnds frozen to the degree a dog would be safe walking on it.

So i think the GFS did pick up on the fact that the cold was never entrenched to the level that others modelled it to be, and it was this, rather tthan an Atlantic bias, which kept it modelling a six day breakdown. Certainly I can't remember the GFS producing the kind of 1947 type charts ECM seemed to produce on a few runs which never materialised either.

Yes, a valid point. Whilst I still think the GFS is not be relied upon too much because of its tendency to break things down way too quickly, it never did get as cold as some other models showed.

The truth, as always, was somewhere in the middle!!

[shaky]

remember watch the GFS resurect that high over th next 6-8 runs- it will gradually appear out of its winter coffin!

Lol!!fingers crossed!!

[Ali1977]

I think the GFS will jump onboard with the ECM now...:-)

[BLAST FROM THE PAST]

Very quick one, ECM absolute blinder, 192 to 240 will lead to feb 86 scenario and deep and prolonged cold. wen continue to improve folks...see you tomorrow.

BFTP

[TEITS]

One of the best ways not to get drawn into the GFS pendulum swings, its overplaying of the Atlantic jet and wild FI scenarios, is to just don't look at it. I wonder how a GFS free model thread would be - certainly it would be a lot less stressful!

(Of course I can't possibly follow that advice myself!)

Spot on CH.

If I think back to all the drama over the years of following the models it has often been the GFS that has been mainly responsible. If we only had access to the UKMO we would of had alot less stress over the years. However we wouldn't have as much to discuss though!

As for the current debate whether the GFS is right or the ECM/UKMO? Well for me its a no brainer which to back at the moment because the GFS has been rubbish this winter. The only thing its got right was the demise of our last cold spell.

06Z is showing a shift W.

Remember this run has the most E bias of all the GFS runs. I learn't this last winter and continues to be the case.

[Nick F]

Yep, wouldn't be surprised to see GFS to slowly edge towards ECM determisitic, the NCEP model has been rather slow to catch onto these colder evolutions. Looking at the EPS, the determisitic certainly not an outlier with the northeasterly developing, sufficient support for it.

[MR EXTREMES]

and guess what there is only slightly afuther shift west by the gfs 6z or it could be slowing the evolution its been showing for the last gew days.

[Pixel]

Very quick one, ECM absolute blinder, 192 to 240 will lead to feb 86 scenario and deep and prolonged cold. wen continue to improve folks...see you tomorrow.

BFTP

Happy Groundhog Day !!

I'll be watching the Russian highs later..

the development and its effect is very interesting.. hope the shape works out for us in this little Island for some snow in the cold (-:

Have finally given up looking at the GFS beyond T 90 after all these years. The ECM and UKMO seem less stressful, A realisation many have come to this winter (-:

[SMU]

Remember people 6-8 runs-

I will give it to tomorrow 12z & the GFS will look exactly like the ECM-

then as said the only question is how far the cold gets west

S

[Methuselah]

I think it's a wee bittty unfair to blame the GFS...I'd put it down more to that our all-prevasive desire for snow often clouds our reason:

The spread between what the individual ensemble-members show, after about T+144 or so, really ought to be enough to demonstrate the futility of posting Perterbation-X,Y or Z, as if it had any real meaning??

[TEITS]

This is such a typical GFS run. What I mean by this is it never suddenly switches but slowly with each run changes the outlook. If you want to see the clearest shift W then don't look at the UK but look between Greenland towards N of Scandi.

http://www.wetterzen...s/Rtavn1321.png

Programmers of the GFS need to sort this out!

Steve beat me to it.

Edited February 2, 2013 by THE EYE IN THE SKY

[Jason M]

Remember people 6-8 runs-

I will give it to tomorrow 12z & the GFS will look exactly like the ECM-

then as said the only question is how far the cold gets west

S

To be fair, nobody can accuse you of fence sitting :-)

[Weathizard]

Steve Murr back to Mr Positive, I like it.

As for the latest model drama, the GFS even early on in this run has made a back track towards the Euros even within the 120 time frame. After this I trust the GFS 0%, especially with short waves around Iceland after its recent shocking handling of this area. I think the GFS has been appauling this winter in the short term especially.

[Stu_London]

I'm not buying an Easterly. Reasons

1) Ec op a relative outlier vs its ensembles.

2) UKMO looks ok but not on board.

3) GFS op and control not buying in one bit.

4) GEM not interested

5) ECM to bullish with easterlies all winter.

6) GFS modelled last breakdown correctly (albeit delayed) whilst ECM was showing Day after Tomorrow stuff

7) GFS got yesterday's complex system right first.

GFS has modelled Tuesday's system beautifully - super consistent for about 10 days.

[Frosty.]

The way the GFS is so easily dismissed by some for its "Atlantic bias" bemuses me.

Probably because it showed a breakdown of the last freeze 72 hours before it eventually did end, 3 whole days error and the ecm and ukmo had been going for the extended cold throughout, the gfs had to back down. As steve said last night, the gfs has an eastward bias and it handles cold blocking over the uk and europe poorly. The Ecm 00z is a fantastic run for prolonged very cold snowy prospects and would have similarities to feb 1986 which was a very cold blocked month.