Model Output Discussion 26/11/2012 18Z onwards

[swfc]

Hmmm gfs improves mid term.Keeps rolling this one does it not.

[TEITS]

Just as the models have flipped in the last 48 hours to show a less cold evolution, they could flip to show a colder solution once again. It is only Tuesday, and nothing is yet set in stone.

Yes we could and even at +72 we could yet see improvement.

Sometimes in the model output slight changes at say +72 have little consequence on say +144. However this isn't the case this time and if the SW is modelled further S then +144 onwards could look very different weatherwise.

[UV-RAY]

Yes its finely balanced, the GFS 06hrs run is a vast improvement on the 00hrs, this type of set up though is a nightmare to forecast.

However its really all to do with the the angle of the jet into the UK and the shortwave, there is often a tipping point, as soon as the ridge manages to back over the top of the incoming low and you keep some decent pressure in eastern Greenland then the low is stopped from making eastwards progress.

For those worried they might be too far west there is alot of changes that could happen.

There is a chance that the block will simply be to strong and keep the low out further West, I remember this happening on quite a few occasions during the 80s

[Gowon]

Ideally, you are of course perfectly correct...but folks like to vent their spleens somewhere...But why must it always be at the UKMO?

And models are called models, for a very good reason: they are models. They are not perfect facsimiles of reality!

Your guess is as good as mine.

[Weather-history]

Does anyone think the charts are like early December 2008? Remember that had low pressures coming in from the Atlantic but it was chilly and some places did see wintry precipitation.

[Weathizard]

Beautiful heights in the Arctic, despite all the negativity around this morning, having just looked at last years charts for the same day I'm now a lot more positive, now those were BAD charts, raging vortex and no chance of heights to our north. The cold will come eventually, just need to be patient. Interestingly this run is very close to being very good, as has been said won't take much but models are flipping too much to take anything post 96 as gospel

[Catacol]

I honestly dont know what all the fuss is about. Maybe some on here were expecting a flow of deepest siberian air for a week, but the ops never had that anywhere but in FI. The mean charts continue to show a flow predominantly from the north and east dominated by blocking to our NW. This isnt a change - it is consistency. The trough over the UK is modelled now a little further north on the means than was the case, probably the result of the low pressure zipping through in the early part of next week, but GP flagged up days and days ago that this energy had to go somewhere and SE was his call. Voila - SE it is. More consistency.

The MetO never updated to "snowmageddon" at any stage in their outlook, and the only alteration in the short term prognosis has been the 24 - 48 return to nearn normal temps that the low next week MIGHT bring. Note the word MIGHT because they have repeated over and over that there is considerable uncertainty about the track of that low, and experience suggests that when blocking and energy come toe to toe the models have a poor record at getting the track right. Living in the SW I have seen constant examples of low pressure systems in the past have their track altered by 50 miles or more even at 24h range.

For those interested in real model forecasting go up a few posts and look at GP's mean charts - I wont bother to post them again and add to unnecessary clutter.

Prognosis - cold. Not siberian cold, but cold. Snow chance? Certainly present. No embedded cold yet so for this week high ground only. As cold becomes more embedded over time snow chances increase for all parts with a flow from the north east bringing wintry showers, and possible attacks from the SW bringing frontal battleground events. The suggestion from SK above that the EC32 update has slider lows coming in, bringing a SE flow as they pass through certainly has my attention as a SW resident!

This was how I saw the forecast last week, and it hasnt changed a jot. Forget the detail (it will only drive you insane) and look for trends. Maybe give your local lamp post a bit of a shammy rubdown... :-)

Edited November 27, 2012 by Catacol_Highlander

[nick sussex]

In terms of the UKMO out of all the models its done better in terms of consistency, lets remember the ECM had the bloated trough over Europe, and was hopeless with the Canadian low. So two of the key features it failed on!

I know people will look at the UKMO 144 hrs output of yesterday morning but at the end of the day that might be closer to reality than any of the models.

Bear in mind if that shortwave tracks more quickly se and the ridge is even stronger you might get more trough disruption to the west.

Edited November 27, 2012 by nick sussex

[Andy H]

I honestly dont know what all the fuss is about. Maybe some on here were expecting a flow of deepest siberian air for a week, but the ops never had that anywhere but in FI. The mean charts continue to show a flow predominantly from the north and east dominated by blocking to our NW. This isnt a change - it is consistency. The trough over the UK is modelled now a little further north on the means than was the case, probably the result of the low pressure zipping through in the early part of next week, but GP flagged up days and days ago that this energy had to go somewhere and SE was his call. Voila - SE it is. More consistency.

The MetO never updated to "snowmageddon" at any stage in their outlook, and the only alteration in the short term prognosis has been the 24 - 48 return to nearn normal temps that the low next week MIGHT bring. Note the word MIGHT because they have repeated over and over that there is considerable uncertainty about the track of that low, and experience suggests that when blocking and energy come toe to toe the models have a poor record at getting the track right. Living in the SW I have seen constant examples of low pressure systems in the past have their track altered by 50 miles or more even at 24h range.

For those interested in real model forecasting go up a few posts and look at GP's mean charts - I wont bother to post them again and add to unnecessary clutter.

Prognosis - cold. Not siberian cold, but cold. Snow chance? Certainly present. No embedded cold yet so for this week high ground only. As cold becomes more embedded over time snow chances increase for all parts with a flow from the north east bringing wintry showers, and possible attacks from the SW bringing frontal battleground events. This was how I saw the forecast last week, and it hasnt changed a jot.

Now that is a good post! Some of the posts on here are unbelievable, but this post gives a balanced view of what is happening over the next few days.

[bluearmy]

i cant quite believe some of the rubbish posted on here this morning. hopefully, in a few weeks time, some of you will realise your mistake. the models are only showing you a virtual representation of what could happen over a period of time. its up to you to work out, looking at all the available data, what that means (and i acept we dont have access to all available data). if you are not 'qualified' enough to do that correctly then dont go blaming the models. if you are getting over excited without cause, then dont blame the models. the best model for this upcoming period has been ukmo. the forecasts issued by exeter have been good. (so far).

TEITS has made some very informed posts over the past few days. if i were inexperienced at judging the output, i would be looking at those. i know there is an appetite for posting charts to support your viewpoint but any chart is just some numbers in a computer. you are responsible for judging the value of that chart. if you arent sure, then trust the pro forecasters in this country whose view you can see every day on their website. meto.gov.uk. it may not be in as much detail as you'd like but thats because no one knows exactly whats going to happen.

now back to virtual world of models and i note some very positive indicators on this morning ens and spreads. i would expect the north of the uk to have a very cold first half of dec and some areas will see quiet a bit of snowfall. as is NORMAL in a uk winter, judging where that snowline will be (and it will morve north and south at times) is going to be the issue.

[pyrotech]

Yeah but its 'their' computer and it cost the tax payer a hell of a lot of money. Mind you it probably spends most of its number crunching time working out AGW scenarios fifty years down the road.

Wow i rarely see such anger at the models on here, normally people on here have some understanding of the complications involved in our atmosphere.

We are talking about one of the most complex and diverse sciences, even worse for us in UK with warm seas surrounding us, Cool or cold European mass to our otherside etc etc, Can i remind you of a few things

Firstly Meto have not ramped about snow, thats been done my some on forums, not Meto.

Media (newspapers ) also ramped this us, again not by Meto

Infact Meto did what we should do, compare everything they see.

Even when their model got consistant they still used the other tools available, then instead of forecasting with their hearts they used their brains.

All the WX computers cost millions, and they all make mistakes, it a number crunching program and these things are constantly being adjusted for performance.

Like a sports car for a race, you take it out and run it, then constantly retune and adjust for better and better performance.

May i suggest that although the UKMO-GM MAY have got this wrong, that so have any users on here that followed its progrress on modified SPC and ukmo model. How many times do you need to be told never follow just one model, one run. You watch accross models, watch runs from same time and compare all, Also most of this has been in fi, its called fantasy island for a reason. Meto have done just that, they looked accross models and anylized what they saw.

Lastly your putting down a model for failing before it failed, we are still days away, maybe we should wait.

Edited November 27, 2012 by pyrotech

[carinthian]

Good Morning,

Just spoke to the Met Guys who provide our customized forcasts. It is interesting how they view the up and coming cold spell and overall developments. As it seems some snowfall is probabale for parts of the UK with retention of a European cold block. The Euriopean trough becoming a feature over the weekend with low development early next week to SW of the UK and to evenually centre over France . To my eyes, I think they are refering to a slider low coming against the cold block.

Will try and update when they fax their charts later today.

C

[Southern Storm]

A long way out at 180 things would be looking very good if that short wave just north of scotland bugger off, and we arrived here because of small correction in the early timeframe! Still a lot to play for.

Edited November 27, 2012 by thunderman24

[weather eater]

I hate to bang on but I refer back to my earlier post, you cannot trust the models post 120hrs, any of them, not just the UKMO. Personally I think the models do a fine job, its people’s expectations of what they can deliver that’s the problem. 06z creeping out now and small changes early on from the 00z, it remains to be seen what the cumulative effect of these will have over the coming days.

[Catacol]

I must be completely imagining the split vortex and the cold spell that is about to ensue.

Just because we are not seeing a glowing orange beacon over Greenland does not imply no blocking.

The GEFS mean height and temperature anomalies continue to advertise a well defined trough signature across Europe throughout the 15 day period with temperatures well below average. Whether this is the '2010 factor' at work I don't know but we must consider that this is late November and early December and we are looking down the barrel of a sustained cold spell, unusually so for the time of year.

Looking at short to medium term those small scale adjustments in the track of the low driving down from the NW continue almost on every run so by the time we get to 2-3 days out, could wel be interesting, especially with the trough engrained over Europe.

Looking further ahead, we have the strong teleconnector in the North Pacific and downstream ridge over the North Atlantic south of Greenland. That essentially keeps us locked in a cold puddle of air for the duration. The AO looks on the negative side too which is a bonus for December as far as I'm concerned given other factors.

Thanks Stewart. That's the nearest to exasporated frustration I have sensed in your posts probably ever. Some posters on here cant see the wood for the trees...

[Paul]

This is the model thread and not the random take your anger out at the Meto/GFS/evil anti snow fairies/whatever else takes your fancy because the 6 feet of snow you expected, due to only reading the bits in forecasts/model posts that you wanted to see is unlikely to materialise thread. So please can we get back to discussing the model output and maybe pop some of those toys back in the pram.

Thanks

[Aiden2012]

6z looking good at the end

[Dean E]

As other members are saying, heights in the Arctic are just perfect, Svalbard has the heights. Its still a very good model output.

One thing to remember, this is the 06z so its always one to take with a pitch of salt!

SM

[bobbydog]

This is the model thread and not the random take your anger out at the Meto/GFS/evil anti snow fairies/whatever else takes your fancy because the 6 feet of snow you expected, due to only reading the bits in forecasts/model posts that you wanted to see is unlikely to materialise thread. So please can we get back to discussing the model output and maybe pop some of those toys back in the pram.

Thanks

[Southender]

I'm liking the idea of SE'ly diving systems out of Greenland.

Very risky, but the rewards could be epic. As the 6z run shows.

A scenario to keep an eye on over the next week or so.

Edited November 27, 2012 by Shrimper

[bobbydog]

.

Edited November 27, 2012 by bobbydog

[492]

Thanks Stewart. That's the nearest to exasporated frustration I have sensed in your posts probably ever. Some posters on here cant see the wood for the trees...

Another thing that has to be taken into consideration is that the Artctic high which is already in position is currently driving very cold air towards Scandinavia and ultimately northern Europe and the UK. Once this cold is established it becomes much more difficult for the Atlantic to make inroads into the UK and shortwaves are inclined to run southeastwards into France and into the European trough.

[Nick F]

Good Morning,

Just spoke to the Met Guys who provide our customized forcasts. It is interesting how they view the up and coming cold spell and overall developments. As it seems some snowfall is probabale for parts of the UK with retention of a European cold block. The Euriopean trough becoming a feature over the weekend with low development early next week to SW of the UK and to evenually centre over France . To my eyes, I think they are refering to a slider low coming against the cold block.

Will try and update when they fax their charts later today.

C

Morning C, yes be interesting to see how far south the jet and associated low(s) sliding down from the NW get later this weekend and early next week. It seems the trend is slightly further south with each run.

On the 06z GFS, we still have milder air creeping in from the west across Sern Britain on Sunday, given the angle of approach of Atlantic fronts from the west, but on this run we have the threat of snow across northern Britain as the fronts arrive, where the cold air looks to remain more entrenched.

Measuring up the NWP and their ensembles this morning, IMO turning unsettled from the west Sunday then staying unsettled next week. Perhaps staying cold across the north with hill snow and snow to lower levels at times, less cold in the south with rain more likely. But with the caveat of uncertainties weekend onward wrt to the margin between rain/snow/sleet - which could move south or north and vary in altitude over certain areas dependent on how far south/north the NW-SE aligned jet decides to track.

Edited November 27, 2012 by Nick F

[Dean E]

Another thing that has to be taken into consideration is that the Artctic high which is already in position is currently driving very cold air towards Scandinavia and ultimately northern Europe and the UK. Once this cold is established it becomes much more difficult for the Atlantic to make inroads into the UK and shortwaves are inclined to run southeastwards into France and into the European trough.

I agree, I believe with this persistant Arctic high pulling down colder heights, its just going to become harder to budge in the long term. Will also act as something we could easily tap into to gain some cold conditions. I believe this is what will eventually happen this time next week.

SM

[fujita5]

Another thing that has to be taken into consideration is that the Artctic high which is already in position is currently driving very cold air towards Scandinavia and ultimately northern Europe and the UK. Once this cold is established it becomes much more difficult for the Atlantic to make inroads into the UK and shortwaves are inclined to run southeastwards into France and into the European trough.

Correct me if I'm wrong, but once these systems have moved over land, they will drop a fair bit of snow over the European mainland, increasing the size and depth of the cold pool available when winds are steered in from an easterly quarter.