Model Output Discussion

[Rollo]

Things certainly seem to be going against we cold lovers tonight but I would remind you all that these type of situations (in the sixties as I remember) were always on a knife edge and despite how things are apparently going it is my opinion that all is not lost yet,48 hours is a long time in model watching.

[robert]

I'll happily take a bet on that, work don't pay me enough!

Ok your on!

Anything making you come to that conclusion Rob?

Well I am just looking at the bigger picture

[Thundery wintry showers]

So, not an outlier, but definitely on the warm end of the ensembles.

I don't quite agree about the ensembles usually switching to fit the operationals. There were a couple of ECM runs around 20 January that showed an easterly at around T+144-168 which had only modest ensemble support, and in the end the operational fell into line with the ensembles in giving a less cold, anticyclonic outlook.

[J10]

Thankfully the ECM rune was one of the milder runs, with most going colder , slight disappointment hough with agreement in the short term between the Control and the OP run.

[La Bise]

Cripes, when you see who's been patronising above, it must have been some ding-dong 'round here. Missed it all, too busy enjoying the superb cold weather up Kinder Scout so what's the latest then? Models are not showing what they were showing yesterday...oh dear, will they behave tomorrow you think...?

[MR EXTREMES]

i dont know if its worth a mention but gp has posted in tec thread looks like we could be waiting a fair amount of time for anything wintry.

and by this time we will be fast approaching march so although always possible cold snap nothing exciting really.

[MAF]

Just wait and see the UKMO and ECM will do a U-Turn mark my words. Thursday into Friday next week will see some intense snow for a large part of the country, you have to look at the bigger picture models. Lot's and lot's of to come.

hello Robert. was wondering if you would have any input into the winter discussion this season glad to see your view is one of the cold type. plenty of hot drinks and biscuits will be needed if your U Turn comes about

[Polar Continental]

Evening all,

If memory serves and we take our minds back about a week or so, all the models were propagating an easterly, which was in the usually acceptable reliable time period and they were all very bullish. Suddenly the GFS backtracked and went for a col situation which eventually edged in the Atlantic, while the ECM and the UKMO held on to the easterly. At the time, many said on here, the GFS would backtrack and fall in line with the Euros.

But it stuck to its guns and turned out right.

The ECM and UKMO obviously did eventually gave up the easterly, but at extraordinary very short time frame, a triumph for the GFS, but we got no easterly.

Now again we have the Euros against the GFS, only the opposite scenario!!

I wonder which will be correct, some knock the GFS, but in my opinion, it usually performs admirably up to around T168, and it is my personal number one model.

The current Siberian high scenario has not been a feature since public access to the models, nor even since the advent of the Internet, even since modern super computers were built and programmed to handle the planets complex atmosphere. I think more surprises are in store, even up until Monday.

OK i may be completely wrong, but that is my opinion.

Edit: my first sentence was in error, reads correct now.

Edited January 30, 2010 by Polar Continental

[robert]

hello Robert. was wondering if you would have any input into the winter discussion this season glad to see your view is one of the cold type. plenty of hot drinks and biscuits will be needed if your U Turn comes about

Hello Maf,

Defiantly so I had better get to the shops soon before they sell out

[Thundery wintry showers]

On average the GFS is not quite as good as the ECMWF, while UKMO had performed at a similar level to GFS until the last few months, then rose to a similar level of performance to ECM but the latest plots suggest it may be dropping back towards the GFS level.

But there have been many cases in the past when the GFS has been right and the Euros have been wrong. The main reason for the ECMWF's higher accuracy, from what I've seen, is probably that when it gets the pattern wrong it tends to latch onto something that isn't too far removed from the actual outcome. GFS on the other hand is prone to "going off on one" at times.

[swilliam]

i dont know if its worth a mention but gp has posted in tec thread looks like we could be waiting a fair amount of time for anything wintry.

and by this time we will be fast approaching march so although always possible cold snap nothing exciting really.

That is not what his post says at all - a short extract

first

Models providing extremely poor guidance at the moment, most probably related to changes in the upper atmosphere and how fast warming propagates down. The time scales for this are not well defined so no surprise that blocking appears, disappears and reappeares

then

Before that, the GWO composites suggest the potential for trough disruption in the Atlantic and retrogression of highs to the North, as well as ridges pusing into the UK from the south-west (as per previous posting). A trough (or possible cut off upper low) to our east continues to look probable, as does some attempt for colder air to establish in from the NE during the second week of Feb.

and finally

So pressure building in from the south-west and slow evolution (mild to start) towards heights building across our north then north west delivering a cold snap looks the favourite before a return to high pressure over the UK towards mid month.

All he said was the effects of Strat warming would not be felt for few weeks.

[Jason T]

Hello Maf,

Defiantly so I had better get to the shops soon before they sell out

Robert,Well i truly believe that you are right i think the u turn is happening just not showing on models (YET).

[The Eagle]

Very good ECM ensembles at least so it looks like a stay of execution. In fact when I first saw those ensembles I thought they looked almost comical. Out of 50 members we happen to get one of the, if not the warmest run. And a good cluster well below freezing so the ECM op run looks unlikely. Let's see where the 18z GFS goes.

[Cecil Hogmanay Melchett]

Very good ECM ensembles at least so it looks like a stay of execution. In fact when I first saw those ensembles I thought they looked almost comical. Out of 50 members we happen to get one of the, if not the warmest run. And a good cluster well below freezing so the ECM op run looks unlikely. Let's see where the 18z GFS goes.

Exactly what i thought Eagle.

The ecm ens are fabuolous they really are.Yet again we see a milder op run which is actually getting annoying now.

Why are the ops always the milder option?Thats the way it seems with ecm recently?

[lukemc]

Hi,

Intresting seeing all these twists and turns from the models today but one think I must make clear is that IMO this is not a normal "modern" winter in terms of the synoptics and I would think that a prolonged period of mild zonality would have been likley going by tonights charts in past winters (e.g. before last winter) but this winter is different and even if we got a UKMO/ECM type pattern setting up do you think it could flip back to a cold scenario quicker than many on here think - epecially with all that cold to our east?

Also if the ECM or the UKMO where to verify as programmed, would it be the case that it would not just be mild for the UK, but also much of mainland Europe too including those parts that have had severe cold until very recently?

I also have a question - in early December I heared people on here comment that a cold outcome would be more likely because thier is no strong Polar Vortex over Greenland - what is the state of play with regard to the PV now? I would think that as long as we have no organised PV in the Greenland area a cold outcome would always be more probable?

And do you think that GPs earlier call of a mild (or even very mild) febuary could actually be close to the mark now, and looking at tonights models do you think it could go the same way as 1982 or 1997 rather than 1963 or 1947 etc?

Luke

[kev238]

Its odd how we seem to be getting one of the coldest runs from the GFS and one of the warmest with ECM.

There is so much divergence it is highly unlikely any of the solutions offered is accurate!

[nick sussex]

Amid all this hysteria and wrist slashing, can someone vaguely sane please give me a completely balanced appreciation as to how the models can flip flop so severely?

I understand there will always be variations in runs, but not five minutes ago Mr Murr was waxing down his skis in anticipation, then two seconds later people are digging out their T-shirts...

The main features of the current set up is a strong Siberian block trying to push sw and a strong jet stream, the models have to decide where the main energy goes from the jet, south or north, in these situations theres a fine line between success and failure for the easterly. The GFS, JMA and GEM take more energy south, the UKMO and ECM take more energy north,if you look at the ECM at 144hrs you can see two ways forward, with as we've seen major differences to the UK. The block wants to move sw but theres a small window of opportunity for the block to ridge west aswell and influence the UK, once the jet energy heads north and over the advancing block its game up for cold as the jet will sink this, so even though theres a negative AO you'll have the high sinking and a separate ridge heading west towards Greenland but the UK stuck underneath with low pressure heading east.

Theres really no middle ground in this type of set up, so its either mild sw'erlies or cold east to se'lies. Sorry I'm rambling but in a nutshell the reason for the sudden switches is more energy being pushed eastwards and where the models decide to take most of this, north or south, hope that helps.

[I remember Atlantic 252]

but doesn't the 0perational have more chance of verifying, or is it just an ensemble? thought that was why it was the 0p, could get worrying if the 0ps are always mild

[Jason T]

Well getting quite alot of rollercoaster rides lately, We are just in a no mans land with the models at the moment, but i think that will be short lived.

[andymusic]

Well getting quite alot of rollercoaster rides lately, We are just in a no mans land with the models at the moment, but i think that will be short lived.

The models have done this many times before when they are unsure - then - as if by magic - they get back on the rails again - patience for the result will pay dividends

Edited January 30, 2010 by andymusic

[Cloud 10]

Here are the extended ensembles for the 12z ecm.

The operational is looking a bit silly compared to the ensemble mean and especially the control run!

[The Eagle]

Right 18z coming. We should know very quickly if any big changes are going to occur on this run (before 72hrs) to match the ECM.

[chris78]

The main features of the current set up is a strong Siberian block trying to push sw and a strong jet stream, the models have to decide where the main energy goes from the jet, south or north, in these situations theres a fine line between success and failure for the easterly. The GFS, JMA and GEM take more energy south, the UKMO and ECM take more energy north,if you look at the ECM at 144hrs you can see two ways forward, with as we've seen major differences to the UK. The block wants to move sw but theres a small window of opportunity for the block to ridge west aswell and influence the UK, once the jet energy heads north and over the advancing block its game up for cold as the jet will sink this, so even though theres a negative AO you'll have the high sinking and a separate ridge heading west towards Greenland but the UK stuck underneath with low pressure heading east.

Theres really no middle ground in this type of set up, so its either mild sw'erlies or cold east to se'lies. Sorry I'm rambling but in a nutshell the reason for the sudden switches is more energy being pushed eastwards and where the models decide to take most of this, north or south, hope that helps.

very helpful thanks so people amazed and criticising the difference between models are missing the poinnt that a subtle change leads to very different outcomes? Makes the hysteria look even mader

[Blizzardo]

Definite setback tonight for those looking for an extended cold spell. What I'm looking for over the next couple of days is what model has the best handle on the northern blocking and how the renewed energy in the Atlantic develops.

It seems that the GFS shuts the door on the low pressure moving north immediately while the ECM seems to leave it open - at 120 hours I dont see whats stopping he Siberian block extending a bit further west and linking better with the heights over Greenland.

My own feeling has been that over the last 18 months or so the models have initially overdone the energy in the Atlantic so small differences here could make big differences down the line.

The UKMO has never really bought the big easterly over the last few days while the GFS has been pretty consistant in going for a very cold and snowy scenario. The ECM has swung one way and now the other so I was disappointed to see its output tonight.

However, I still think its on a knifedge.

Edited January 30, 2010 by Blizzardo

[cooling climate]

Just seen the ECM run and I must say I did not expect both Euro models to struggle so

much with this upcoming pattern change, what a coup for the GFS model.

Having said that it is only the period t96 to t144 where they are misinterpreting the

movement of the energy in the Atlantic and this is having a knock on effect for the

rest of the run.

They should be fully on board by the end of tomorrow though.