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Ed Stone

General Model Output Discussion Thursday December 24Th:

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A new thread, in time for the 06Z rampede analysis... :cold:

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this will need to be 'stickied'

interesting to see the GEFS mean bring a blocking high over us. hopefully will be worth watching the ensembles catch up with the ops rather than the other way around.

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this will need to be 'stickied'

interesting to see the GEFS mean bring a blocking high over us. hopefully will be worth watching the ensembles catch up with the ops rather than the other way around.

if not we will lose it plus the models are stunning up to the new year

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I think I've 'pinned' it?? :cold:

But, I agree, the recent outputs have been stunning...Where are the 'dowgrades' some folks were talking about? :oops::cold:

There's not much sign anything particularly mild, as far as I can see...

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Morning all and a Merry Xmas Eve to you all,

Some early Xmas presents from the models this morning but we need to be patient and wait until New Years Eve to unwrap them in the south but a day or so earlier in the north!

Of course too early to discuss fine detail but the general signal is there for more height rises over Greenland and trough digging south through Scandinavia.

Possible classic battleground scenario developing by early/middle of next week.

http://www.wetterzentrale.de/pics/Rtavn1441.png

http://www.wetterzentrale.de/pics/Rgem1441.gif

http://www.wetterzentrale.de/pics/Recm1441.gif

http://www.wetterzentrale.de/pics/Rukm1441.gif

Impossible to say where battleground will develop yet but at the moment I would say N.England favoured with the cold air gradually undercutting ppn further south by New Years eve.

The models that produce forecasts further ahead then showing high pressure developing towards Greenland/Iceland.

The ECM produces an absolute peach of a run late on but way too early to get excited about that yet.

Finally, those younger members who've heard us oldies banging on about Greenland highs, will now realise the importance of height rises in that area, you do need a trough east of the meridian as well though to get cold air through the whole of the UK.

As this cold spell wanes in the south, high pressure over Greenland has ensured that we've had, for the bulk of the UK, the most wintry spell of pre-Xmas weather since 1981.

Lets hope the models continue to show that a similar scenario is about to occur by this time next week.

Regards,

Tom

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Retrogression features strongly on both the gfs & ecm 00z this morning, the ecm 00z has pulled out all the stops with an amazing run, the gfs is also sensational and the ukmo, we will probably run out of superlatives in the coming days if these extraordinary charts continue. Next week looks like becoming very wintry in scotland early on and then pushing south by midweek onwards with potential reloads galore.

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Excellent post there by Tom and Happy Xmas Eve to you too :) . Yes it's looking very interesting but as yet no way of knowing exactly where the battleground may set up. This is however bringing back some memories of 78/79, was still a kid then and was flying back with the family from Cyprus on New Years Eve, wonderful views of the Alps from the plane, then thinking wouldn't it be nice to see some snow for the New Year, arrived to chaos at Heathrow with a baggage strike, then on the way to my aunties heavy snow started falling on the North Circular road which caused mayhem!

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May be I am misunderstanding something but the temperatures predicted by GFS don't look that excitingly low - certainly mild in the first part of next week in the south and then just below freezing.

R

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I think I've 'pinned' it?? :)

But, I agree, the recent outputs have been stunning...Where are the 'dowgrades' some folks were talking about? :):)

There's not much sign anything particularly mild, as far as I can see...

No Pete, not much mild there. The UKMO brings the colder air flow south again on Sunday and Monday. Thereafter, a battle royal starts in the run up to New Year. Looks like a classic battle of mild verses polar very cold air mass. This winter so far, looks like the mild will be repelled for you in the Britsh Isles !!

Greatposts on this thread. The reports are second to none. They do not have the same enthusiasm as you Brits in Euroland.

C

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its very interesting looking at the models, this cold pool over us never really gets moved away to far if at all in places keeping very cold overnight minimums, most of the snow form this period of cold has passed but not without surprise for many of us.

plus bone chilling temps, especially scotland -16c reached again in aviemore this time right now.

prospects of another lengthy cold spell and agreement with models, which is looking quite messy for the end of the year into the new year, with cold arctic air possibly undercutting a low pressure over the uk, and no doubt it would bring blizzard conditions to the north.

hoping the heights to our north continue to build, but a week away and alot can change, but hats off to the models which picked the trend on this cold spell as it turned to be memorable for many, maybe we should have more confidence in them, or maybe thats just wishful thinking the weather will do what the weather wants!!!

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Wow some fantastic model output this morning for pretty much the whole of the country.

Some excellent agreement from the models that around +144 (30th Dec) we are going to see HP being centred just SW of Iceland with LP tracking somewhere along the S of the UK or N France. Beyond +144 and we see bitterly cold NE,lys as the LP tracks E and we develop what can only be called a super block! So what does this all mean for the UK?

At +144 a battle ground situation will occur with mild air to the S and cold air to the N. Where this battle ground takes place very much depends on the track of the LP system. At the moment I would say N England probably somewhere in Yorkshire. What would then happen is the snow in N England would very slowly move further S as the LP moves E.

Beyond +144 and very cold NE,lys would spread snow across many regions especially in the E. However many other locations wouldn't miss out and if the ECM +240 verified a number of troughs would move S in the N,ly flow.

Looking at the charts beyond +144 and you have to ask yourself is this possible? Well the answer is yes although in previous years I would of been dubious. The difference between now and recent years is the state of the AO and also the behaviour of the Polar Vortex so far this winter. Remember if the AO is positive then this indicates lower pressure than normal around the pole which increases strong SW,ly flow and a series of deep LP systems that normally track N of the UK. However if the AO is trending towards being negative then this increases the chances of HP at N,ly lattitudes. Also the PV has been rather pathetic this winter and has failed to become strong or organised. The ECM shows a split PV with part of this being in Scandinavia. Remember in recent years we have seen a strong PV centred over Greenland.

Although obviously another cold spell isn't guaranteed. The chances of further N blocking with cold/very cold N/NE,lys is definately the current trend in the models. Hopefully this will continue over xmas but I must warn you that last Xmas day/Boxing day the model output was very strange indeed. I still maintain the lack of data was the cause of this.

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I think I've 'pinned' it?? unsure.gif

But, I agree, the recent outputs have been stunning...Where are the 'dowgrades' some folks were talking about? cold.gifcc_confused.gif

There's not much sign anything particularly mild, as far as I can see...

A bit of a 'downgrade' for the south of the UK. Only a couple of days ago GFS was showing 3 or 4 c for early next week, now into double figures!

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It's simply to do with how far North the mild air gets before being pushed back South, subsequent runs will chop and change this boundary line; I think the double figure numbers will not extend as far North as the GFS 0z shows - either way the mild air won't be winning.

That wasn't really the point I was making. I was responding to a post that was commenting that they couldn't see any mild, so I was just showing him where it was. Certainly the trend over recent days has to increase the temperatures over the South early next week and delay the return of the cold.

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It seems to me this morning looking at the models that cold wintry weather will soon be making a comeback

across the country regardless of what operational run is correct.

All models seem to have the emphasis on another cold or very cold pattern to set up shop over Europe and

the UK.

The ECM t 240 chart is just as good as it can get for cold and snow especially down the eastern side of the

UK.

These charts and weather that we are seeing prove that to see sustained blocking and established

cold across the UK we really do need the -AO and blocking to the north rather than a high throwing a flimsy

ridge north that soon gets toppled before the cold has a chance to sink south.

All I think we need to see is for the ridge in the Atlantic to link with the -AO block and hey presto another

long and potent very cold spell (aka ECM t240) is on the cards.

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That wasn't really the point I was making. I was responding to a post that was commenting that they couldn't see any mild, so I was just showing him where it was. Certainly the trend over recent days has to increase the temperatures over the South early next week and delay the return of the cold.

I think you're missing the point of the thread which is about the models. The model outputs most certainly have NOT downgraded. In fact at about T120 onwards they become some of the best charts one could see. The fact that there's a battleground which the operational places 200m further north for 24hrs than the other members and the ECM is, in terms of 'downgrade' an irrelevance at best, a wind-up at worst.

Let's be decent and straight about this: these model outputs are not a downgrade.

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Following on from Daves post regarding the model data issues around Xmas/Boxing Day i agree with him, flight data that would normally come from many airlines will be much reduced, this is especially important regarding northern blocking as the much higher latitudes suffer from a lack of data anyway, really much depends on how robust the pattern is, if it was very complex this could make a large difference, the projected set up is not as complicated as some we've seen so hopefully there won't be too much model drama over the next few days!

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A new thread, in time for the 06Z rampede analysis... :D

HI Pete,

A polite request - could you add the link to the new thread when you close the previous one - saves trawling through looking for it.

Thanks

Stewart

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That wasn't really the point I was making. I was responding to a post that was commenting that they couldn't see any mild, so I was just showing him where it was. Certainly the trend over recent days has to increase the temperatures over the South early next week and delay the return of the cold.

Yes its mild mild for the foreseeable future in the south with that mild heading north around sunday

Anything else is F1 im afraid although its fun to look at year end charts

We need things to get into T96 before we talk with any confidence, as we have seen in the last few weeks T144 or T168 is often miles out to what happens

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I can't really add to the excellent posts above; a strong possibility that we will be seeing height rises over the Atlantic/Greenland with low pressure over the Azores.

Could winter 09/10 be the new 78/79 ?!

It's simply to do with how far North the mild air gets before being pushed back South, subsequent runs will chop and change this boundary line; I think the double figure numbers will not extend as far North as the GFS 0z shows - either way the mild air won't be winning.

Im sorry but that from you IB has made my christmas...thank you. Not having a dig at you mate but you were the instigator of the MW theory and to see you post that...... :D

I would just like to add that i have really enjoyed following this thread over the past 2 months but i must say that there have been the odd few that have tried at every oppertunity to find a reason to say that it wont happen or just down right depressive when in fact what the models gave us a few weeks back has more or less played out.

I wish to make a point though especially to thoswe who wish to continue rubishing model runs as not possible or unlikely. GP, CH and the others who at this time i cannot remember the names of who have been folowing the teleconnection side of this. Have been by far THE most consistant of any1. It was those people who said that this winter is going to be one to remember. It was GP who said that the next cold spell was comming and its those very same people who have told us time and time again what the trend for this winter will be. However it sems that every time they post its acknowledged and then a few posts later ignored.

I would have thought when there is a 50/50 situation it would be more prudent to take note of what they suggest, which a massive predisposition for COLD. It is those people who have told us that the signals are all there for somthing special this year. And we must give those people some credit.

Anyway im happy with what i got upto now. Its snowed in the NW region more or less everyday since the easterly and only today have i seen sleet. May the good time continue :D:D:drunk:

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That wasn't really the point I was making. I was responding to a post that was commenting that they couldn't see any mild, so I was just showing him where it was. Certainly the trend over recent days has to increase the temperatures over the South early next week and delay the return of the cold.

I think it's what I said: "There's not much sign [of] anything particularly mild, as far as I can see..." that's led to the confusion.

I was a little vague, I guess...I don't see any sign of any imminent return to generally mild synoptics, is maybe what I should have said? :D:D:D

HI Pete,

A polite request - could you add the link to the new thread when you close the previous one - saves trawling through looking for it.

Thanks

Stewart

Aye, I will do that in future... :D

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Yes its mild mild for the foreseeable future in the south with that mild heading north around sunday

Anything else is F1 im afraid although its fun to look at year end charts

We need things to get into T96 before we talk with any confidence, as we have seen in the last few weeks T144 or T168 is often miles out to what happens

I have to disagree here, perhaps theres been so much cold recently that average is the new mild. In terms of the foreseeable future its not mild, it would be with the a strong zonal set up with PV limpeted to Greenland and the models all keeping this pattern. All the major models agree on the general set up, battleground somewhere over the uk, with colder air digging south!

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It seems to me this morning looking at the models that cold wintry weather will soon be making a comeback

across the country regardless of what operational run is correct.

All models seem to have the emphasis on another cold or very cold pattern to set up shop over Europe and

the UK.

The ECM t 240 chart is just as good as it can get for cold and snow especially down the eastern side of the

UK.

These charts and weather that we are seeing prove that to see sustained blocking and established

cold across the UK we really do need the -AO and blocking to the north rather than a high throwing a flimsy

ridge north that soon gets toppled before the cold has a chance to sink south.

All I think we need to see is for the ridge in the Atlantic to link with the -AO block and hey presto another

long and potent very cold spell (aka ECM t240) is on the cards.

you also forgot the talk of a neg NAO that gp was talking about.

sure this would make it even more intresting?:D

its also intresting how joe b has been going on about battle ground since end of summer so hat off to him.

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Looking at the ECM ensembles there is good support for the OP and the control run goes off on one in deep in FI - maxes in Holland of -10 and min of -15

post-9179-12616470390413_thumb.png

BY the way there is now a link of the meteociel ECM page to the De Bilt ensembles - the link showing when they have been updated.

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Guest North Sea Snow Convection

The GEM gives good support to the continuing theme expressed so brilliantly by the ECM this morning - and as shown, the ECM ensembles are also supportive which is most encouraging still to see.

The UKMO at t120 to t144, although it doesn't orientate the low as favourably just to the SW, does also indicate proper height rises over souther Greenland, so ignoring the precise detail, which will always change at that range, then there is good agreement here also for the basic trend which continues to gain momentum. The GFS is good as well and it does look as though we could be closing 2009 and starting 2010 on a wintry notecold.gif

Just love that ECM though - it all starts to click in place from quite early onclap.gif

I very much agree that what should give more confidence about any ridge not toppling, but instead connecting up with heights over the arctic, is the state of the AO - which is gaining a momentum of its own that can only intensify and consolidate as we get into January in terms of its connective state with other indicators, including mirroring closely the NAO as well as the near inevitablity of an SSW and all that entails.

So it is important that the split disrupted vortex and negative zonal wind anomalies hold the pattern into the New Year. As long as these factors are in place then the sort of charts indicated especially by the ECM this morning are fully validated. When people are looking for things to go wrong, and of course they can, they should bear this in mind if they are being objective about the model outlook.

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The ECM and GFS are both consistent with ridging towards Greenland in around a weeks time and I believe that this will occur to a more or less extent. However, differences lie in the modeling of the polar vortex. The ECM has a far more favourable outcome with the main vortex being displaced before dropping into Scandinavia. Things are not quite as clear cut with the GFS with a more disorganised approach with the main vortex being situated near Baffin Island. These differences will be ironed out as New Year approaches but could vitally be the difference between a cold pattern or very cold pattern emerging. Lets see what the GFS 6Z shows.

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