Model Output Discussion 12z 07/11/2012

[johnholmes]

The anomaly charts, ECMWF-GFS, NOAA, NAEFS all continue to show a trough as the dominant player in the areas over and around the UK.That is in the time frame 6-15 days or so. Heights are certainly held fairly high out to T+240 on all of them to the east and rather more variably well west. The only model going beyond T+240 is NAEFS and it shows the eastern ridge waning and the one well west building and moving east a bit while the long lasting trough in and around the UK also tends to decline.This has been a feature of this model for several days.

I still favour some kind of ridging initially, in the 6 day plus time frame, from a western direction rather than an eastern one but the weather is very good at making most of us look pretty foolish at times so we will have to wait. By the end of November it will all have become clear!

people getting excited about a cold shot in fi not a chance of it happening and even it does come off it will be downgraded loads of times as all models are useless at that range fact

welcome to the site blackdog, a rather dogmatic post for a new arrival perhaps but you are of course quite entitled to that view. Have you got any charts to back up your view?

May I ask that you put your nearest town in your avatar please?-thanks

[cyclonic happiness]

My main concern with this set up is that, with southeastern Russia being so warm atm, there's no cold to tap into with a direct easterly.

The 528 DAM line is around 1500 to the east.

That means that we'd have to have an easterly pumping winds from that directions for up to a week before the 528 even gets here.

[Alan Medlock Valley]

Well I did say last night that there would be a flip around to something less cold and again it has happened, people getting all excited last night for it to be dashed this morning, in reality it really is difficult to get proper cold weather in the UK, we have lots of reasons against it. There is still time though - that is the one thing we have for now anyway.

No doubt tonight the models will tease again and show something colder ha ha. But as of this morning this shows a milder end to the month NOT cold: http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png

Edited November 12, 2012 by Alan Medlock Valley

[jethro]

people getting excited about a cold shot in fi not a chance of it happening and even it does come off it will be downgraded loads of times as all models are useless at that range fact

I'm a model numpty, utterly useless at reading and predicting anything from the models, but even I can see that they give clues for future trends. Admittedly they can't accurately predict the weather to the point of being able to say there will be 6 inches of snow in my back garden on the 3rd of December - I wouldn't expect them to be able to either. That said, their accuracy at that range is probably greater than your statement of fact above. Why and how can you be so certain that there's no chance of a cold shot in the future?

[bluearmy]

alan - the models are just fine for a blocked end to november this morning and follow on from yesterdays 12z's pretty well as expected. its impossible to get to the correct solution immediately and there will be a fair amount of chopping and changing before we see where the blocking is going to establish and then if it will hold in situ or migrate elsewhere. and cc, dont worry about russia not being cold, in time, a trough would drop into the block and introduce some colder uppers.

[Alan Medlock Valley]

alan - the models are just fine for a blocked end to november this morning and follow on from yesterdays 12z's pretty well as expected. its impossible to get to the correct solution immediately and there will be a fair amount of chopping and changing before we see where the blocking is going to establish and then if it will hold in situ or migrate elsewhere. and cc, dont worry about russia not being cold, in time, a trough would drop into the block and introduce some colder uppers.

As of this mornng the mean shows above average temperatures for the end of the month. Some very mild runs there too. It can't be ignored.

[Adam lufc]

Agreed jethro. Very interesting ecm once again today...... But each year this happens until we're let down. But u have to start from somewhere.

[snowking]

As of this mornng the mean shows above average temperatures for the end of the month. Some very mild runs there too. It can't be ignored.

True - only just it should be added

But that's not the end of the story. The reason we see the mean just above average is its placing itself between two rather distinctive groupings of ensembles split roughly 50/50 between something above or below average - and the above average solution is more above average than the cold solution is below average (if that makes sense), hence the mean coming out slightly above the 30 year average.

But simply saying they're showing 'above average' does not paint the full picture. We always see this sort of split in ensemble modelling around times of potential blocking from the east due to the complexity of the potential undercutting situation (given the delicate energy budget in the situation involved)

Kind Regards

SK

Edited November 12, 2012 by snowking

[Alan Medlock Valley]

Let's see what the 12z and 18z bring later on, hopefully there will be more consistency again with bringing the cold in let's hope so anyway.

But again as of this morning most runs (at the moment) are not going for a cold end to the month comparable to 2 years ago, but there was certainly more hope of that around 10pm last night. All I am saying is what I am seeing. I like cold weather but I never use a cold bias and pretend the mild runs don't exist or that they are irrelevant. It wouldn't be fair on the new visitors to the site This next chart looks promising on the GFS but as always it is deep FI and not likely to verify as shown http://www.wetterzentrale.de/pics/Rtavn3841.png

It really is all hope at the moment, nothing more.

[Fred Sykes]

It looks like being mild for the next week or so. Some models showing the usual eye candy in FI, but that's about it. Will this turn out to be another miserable winter

[TobyT]

alan - the models are just fine for a blocked end to november this morning and follow on from yesterdays 12z's pretty well as expected. its impossible to get to the correct solution immediately and there will be a fair amount of chopping and changing before we see where the blocking is going to establish and then if it will hold in situ or migrate elsewhere. and cc, dont worry about russia not being cold, in time, a trough would drop into the block and introduce some colder uppers.

Plus 1 from me! patients is required.. cold does not just appear from nowhere but a trend in the models is clearly there..hopfully as we progress through the month the synomics will be in place for our first real taste of winter..if not we have plenty of time as we are not even halfway through Nov yet!

Edited November 12, 2012 by TobyT

[bluearmy]

It looks like being mild for the next week or so. Some models showing the usual eye candy in FI, but that's about it. Will this turn out to be another miserable winter

Thats not the greatest post fred. its short and to the point but not completley accurate. the second half of the week could feel quite cool under a slack feed and seeing as we are not half waythrough autumn, your second question belongs in another thread altogether.

the ecm ens for london from yesterday

http://www.meteo24.fr/fr/home/meteo-france-et-europe/passion-meteo/ensemble-de-previsions.html?eps=london

also, the extended ecm control in the freezer again this morning for de bilt

[Glacier Point]

GEFS and ECM mean height anomalies at day 10 are in very good agreement w/r/t the longwave pattern across the NH, depicting three anomalous ridges extending into the Arctic.

The key message is that the AO is trending negative as we head into the final week of the month. It's a bit of a race at the moment to see whether the ridge to our NE extends over the top or the ridge over Canada migrates eastwards, or even of we get the Atlantic trough disrupting and setting up a ridge over Iceland, but the final evolution here looks to be southern Greenland and Iceland area for the block to lock (in line with upstream ridge placement).

Edited November 12, 2012 by Glacier Point

[TobyT]

alan - the models are just fine for a blocked end to november this morning and follow on from yesterdays 12z's pretty well as expected. its impossible to get to the correct solution immediately and there will be a fair amount of chopping and changing before we see where the blocking is going to establish and then if it will hold in situ or migrate elsewhere. and cc, dont worry about russia not being cold, in time, a trough would drop into the block and introduce some colder uppers.

Totally agree with you bluearmy...as has been said many times on here patience is required..the models are on to somthing and are consistanly showing some form of blocking..lets hope the synomics come right for us to get our first tast of winter around the latter stages Nov but if we dont there will be further chances further down the line..we are still in Nov..so how anyone can write off winter with any degree of certainty at this stage is beyond me??

Edited November 12, 2012 by TobyT

[Radiating Dendrite]

GEFS and ECM mean height anomalies at day 10 are in very good agreement w/r/t the longwave pattern across the NH, depicting three anomalous ridges extending into the Arctic.

The key message is that the AO is trending negative as we head into the final week of the month. It's a bit of a race at the moment to see whether the ridge to our NE extends over the top or the ridge over Canada migrates eastwards, or even of we get the Atlantic trough disrupting and setting up a ridge over Iceland, but the final evolution here looks to be southern Greenland and Iceland area for the block to lock (in line with upstream ridge placement).

Hi GP,

When will this begin to show in the operational models?

All we seem to have in FI from them at the moment (especially the GFS) is over deepened troughs out west.

[Met4Cast]

people getting excited about a cold shot in fi not a chance of it happening and even it does come off it will be downgraded loads of times as all models are useless at that range fact

Whilst that would usually be true, we're not really chasing FI charts this time around. Sure it's out in FI but upstream teleconnective patterns are supportive of some type of Scandi/Atlantic ridge developing at the end of the month, we're not just seeing one isolated chart out in FI and deciding it's going to happen. There's support and good reason to believe the trend towards that scenario will continue.

Welcome to the forum though, I look forward to more of your expert analysis

[BLAST FROM THE PAST]

UKMO analysis of 00z runs considers more blocked scenario into trend period as low probability scenario: rationale as follows:

" 4. Trend for Days 10-15 : Most probably scenario is for a continuation of the conditions described above, but with an ongoing low prob alternative (around 25%) of generally drier, colder conditions developing.

5. Discussion : Following the development at the start of this period (described in the 4-5 day guidance) the main broadscale themes apparent in the ensembles are for W’ly mobility across the Atlantic making some progress into the UK next week, but also for downstream ridge amplification across central Europe and Scandinavia limiting any further progression. This implies that largest amounts of rainfall are likely to affect western parts with a reduced risk further east. However, it should be noted that the last two runs of EC deterministic, along with its control run and a small (but growing with time) cluster of its EPS, extend a more marked longwave trough southwards in the W Atlantic. This allows a downstream build of GPH across the UK and a retrogression in the pattern, resulting in something more blocked by the trend period (similar to the trend in EC monthly output for week 3) and should be mentioned as a low prob for now..." (abstracted)

Always nice see the bit in bold, this keeps the door open for potential retrogression. Thanks for updates as usual Ian

BFTP

Edited November 12, 2012 by BLAST FROM THE PAST

[Frosty.]

The Ecm 00z ens mean is looking quite progressive with low pressure centred just to the west of iceland becoming the dominant feature in FI but the op run shows the block much closer to the east and low pressure has a big fight on it's hands to push east, a real battle there and I would bet the cold block to the east would win but the ens mean shows there is currently more support for a cool zonal further outlook, likewise with the gfs mean, progressive with the trough near iceland in control later. Coming back to this week, tomorrow will be the mildest day of the week with 13c widespread and in the south, perhaps 15c in prolonged sunshine so a very mild day tomorrow but then we begin to see colder continental air begin to filter into the southeast and push in a northwesterly direction, so temps begin to slide and with light winds, mist and fog begin to feature more and more and with increasing frost risk at night, that takes us through to friday, the far nw of the uk probably unsettled and windier all week and then through the weekend the unsettled weather begins to push southeast but there is now a lot of uncertainty about how far it gets, the colder anticyclonic block may persist to the south and east and may emerge as the winner next week but it need to gather more support for that to happen.

[snowking]

or even of we get the Atlantic trough disrupting and setting up a ridge over Iceland, but the final evolution here looks to be southern Greenland and Iceland area for the block to lock (in line with upstream ridge placement).

And thats exactly what the 0z ECM control run in the extended range shows. Around +216 we see pressure rise between iceland and svalbard, preventing the energy from riding over the top of the sceuro HP, so we get an undercut, sceuro HP heads NW towards the icelandic ridge and the pattern gets locked in. It should be noted that whilst it would be cold at the surface, it takes a while for a cold upper pool to develop. This develops courtesy of the mean trough dropping into eastern europe (as discussed earlier on this thread) and then goes on to develop a fairly substantial pool of sub -10c uppers right across scandinavia, down in towards germany, poland and the netherlands, all heading WSW.

Also worth pointing out pressure remains fairly high across the UK through the run post +216, though even at this range light precipitation shown right across the eastern side of the UK, most notably the further south you head (where pressure is lower)

SK

Edited November 12, 2012 by snowking

[nick sussex]

Interesting control run from the ECM:

http://www.weerplaza.nl/15daagseverwachting/?type=eps_pluim

If you look at the rainfall totals its looking likely that any low pressure won't make much inroads into continental Europe.

Todays ECM operational run gets to the same end point as yesterdays 12hrs, so the ECM at least wants to keep putting energy into the southern arm of the jet.

This really is key because if it keeps doing this you will eventualy see an undercut,

[chris55]

UKMO analysis of 00z runs considers more blocked scenario into trend period as low probability scenario: rationale as follows:

" 4. Trend for Days 10-15 : Most probably scenario is for a continuation of the conditions described above, but with an ongoing low prob alternative (around 25%) of generally drier, colder conditions developing.

5. Discussion : Following the development at the start of this period (described in the 4-5 day guidance) the main broadscale themes apparent in the ensembles are for W’ly mobility across the Atlantic making some progress into the UK next week, but also for downstream ridge amplification across central Europe and Scandinavia limiting any further progression. This implies that largest amounts of rainfall are likely to affect western parts with a reduced risk further east. However, it should be noted that the last two runs of EC deterministic, along with its control run and a small (but growing with time) cluster of its EPS, extend a more marked longwave trough southwards in the W Atlantic. This allows a downstream build of GPH across the UK and a retrogression in the pattern, resulting in something more blocked by the trend period (similar to the trend in EC monthly output for week 3) and should be mentioned as a low prob for now..." (abstracted)

Hi Ian thanks for the analysis. Great to have my local (and very good) weatherman posting on the forum!

Out of interest when does the UKMO seasonal model update?

This one,

http://www.metoffice.../glob-seas-prob

Edited November 12, 2012 by chris55

[legritter]

Interesting control run from the ECM:

http://www.weerplaza...?type=eps_pluim

If you look at the rainfall totals its looking likely that any low pressure won't make much inroads into continental Europe.

Todays ECM operational run gets to the same end point as yesterdays 12hrs, so the ECM at least wants to keep putting energy into the southern arm of the jet.

This really is key because if it keeps doing this you will eventualy see an undercut,

this is certainly the area to watch ,and keep an eye on continental temperatures .before i discovered computer modells on the computer i just studied fax charts from met office etc ,and sort of read between the lines . its when these fronts grind to a halt they start to tell a story ,but of course no guarantee . certainly interesting times a coming but a couple of possible outcomes past this weekend .

[liam79]

Hi Ian thanks for the analysis. Great to have my local (and very good) weatherman posting on the forum!

Out of interest when does the UKMO seasonal model update?

This one,

http://www.metoffice.../glob-seas-prob

Its updated it says Issued November?? still going for a higher prob of below average temps??

[liam79]

Its updated it says Issued November?? still going for a higher prob of below average temps??

Though not as good as the previous update

[Adam lufc]

Please will some people stop being so downbeat and negative all the time.