Model Output Discussion

[snowray]

UKMO at t120 and t144 very different to the GFS at these time frames, with much better

heights over Scandinavia due to the vortex being pushed away east.

I must admit the t144 UKMO chart looks very strange though with the low filling out and

becoming very flabby.

I would have thought the cold would undercut this and that the t144 is actually a cold

outcome for the UK.

Definately a colder run from UKMO, the colder air getting much further South by T72. :lol:

[Snowyowl9]

UKMO at t120 and t144 very different to the GFS at these time frames, with much better

heights over Scandinavia due to the vortex being pushed away east.

I must admit the t144 UKMO chart looks very strange though with the low filling out and

becoming very flabby.

I would have thought the cold would undercut this and that the t144 is actually a cold

outcome for the UK.

UKMO T144 looking more like ECM 0z these just look like the same charts we had at christmas.

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

[Guest North Sea Snow Convection]

UKMO at t120 and t144 very different to the GFS at these time frames, with much better

heights over Scandinavia due to the vortex being pushed away east.

I must admit the t144 UKMO chart looks very strange though with the low filling out and

becoming very flabby.

I would have thought the cold would undercut this and that the t144 is actually a cold

outcome for the UK.

Yes I think we are on the way to a second half of February freeze. All the ingredients are in place for air originating from the Urals that is already signposted as have bitingly cold uppers with dessicatingly low dewpoints to track SW 'erds - the last week or so of Feb could be quite a climax to 'official' winter' and leading to a bonechilling fanfair entrance for March too .

[Cheese Rice]

UKMO T144 looking more like ECM 0z these just look like the same charts we had at christmas.

http://www.wzkarten....cs/Recm1441.gif

Perhaps a North Easterly blast at the end of Feb, seems very plausible with the current synoptics.

[johnholmes]

You are certainly right John in these situations being a challenge,I wonder in all your years forecasting how many times such winter synoptics came up?

fortunately my memory 'ain't that good so I'm not sure. I do remember loads of times-before models arrived, when trying to get the right sort of precip predicted 12 hours ahead was just as difficult as it is now.

In that sense forecasting has not changed. So in spite of the huge model ability to number crunch the nitty gritty at T+24 and 12 is, it seems, just as difficult as 30 or so years ago.

[TEITS]

A fasinating UKMO run which is going to prove to be a real headache. Look at the temps and the precip charts.

The front at +72 is likely to stall over E Anglia/SE like I suggested earlier before even possibly moving back further W before weakening. At this stage difficult to say what will fall but there is a risk at the moment across E Anglia that if this does fall as snow it could be very prolonged falls. I would say the risk is N of London at the moment.

At +144 and the UKMO goes with the ECM. If a +168 chart existed the main LP would be across S France with this pulling colder NE,lys across the UK. Alot would depend on the track of this LP how cold the UK becomes. The further S this LP tracks the better.

[cooling climate]

I expect things will change a fair bit by t144 though CC. hoping that ecm continues its recent trend though i'd like to see that energy not go mid atlantic this run as it cuts off the cold uppers advecting into the north at an earlier stage. just have a feeling that north midlands/northern england could see a big snowfall week after this one.

Yes quite agree, and I think the trend will be for much colder continental feed with

the low trending further south.

Also a stronger block over Scandinavia.

[kold weather]

Your going to struggle to get any NE blast with this set-up I feel, not impossible but it requires something of a whole scale change to what is progged within our neck of the woods. Still this is a very complex evolution where we get a cut off low try and form whilst at the same time the other upper low tries to dominate, what one becomes stronger is going to make a decent amount of difference.

I suspect what we will see happen is we do indeed get into a flabby LP solution, but with these sorts of set-ups small changes make big changes in terms of actual weather, and in this flow whilst the upper flow is quite easy to call, the surface pattern being so flabby can cause serious synoptic changes.

Worth noting Monday does look interesting, for most a wintry mix but clearly in heavier bursts and on higher ground it could well be snowy!

[Guest North Sea Snow Convection]

The GFS in particular is overcooking and prolonging the strength of the low near the UK. The euros, thus far, are nearer the mark - but there is more yet i think to come in terms of the pattern developing. The signal for the arctic high ridge into Svalbard/Scandinavia should factor more into the modelling with pressure rising from the north over the top of the low as it phases with the lows forming down south along the very suppressed jet stream.

The stratosphere forecasts/developments fully support such an evolution in terms of the positioning of the residual energies and where the ridging should take place. This in turn gives good credence to a very cold easterly developing thereafter. I wouldn't be surprised to see the GFS wake up to this and we see a big turnaround in the ensembles with some of them dropping off the bottom of the page. An ice age GFS special operational could come out of nowhere in the next few days. The ECM members have already shown an isolated few members dropping very low (sub - 15 uppers).

[TEITS]

The GFS in particular is overcooking and prolonging the strength of the low near the UK. The euros, thus far, are nearer the mark - but there is more yet i think to come in terms of the pattern developing. The signal for the arctic high ridge into Svalbard/Scandinavia should factor more into the modelling with pressure rising from the north over the top of the low as it phases with the lows forming down south along the very suppressed jet stream.

The stratosphere forecasts/developments fully support such an evolution in terms of the positioning of the residual energies and where the ridging should take place. This in turn gives good credence to a ery cold easterly developing thereafter.

Absolutely 100% spot on with that post Tamara.

I know our current pattern is different to the recent farce with the models suggesting mild SW,lys but in some respects the modelling is similiar. I don't know why but these models do seem to have a bias of pushing everything too far N and being reluctant to push the pattern S. As we know the mild SW,lys never occured for the simple reason that the models wanted to push the Atlantic trough NE rather than SE. I feel the same is happening again, especially with the GFS because in my opinion the Arctic HP will be further S and so will the LP system.

I have no idea how these models are programmed. However our normal weather pattern is low heights across Greenland with LP systems tracking NE. The model output at the moment is pretty much the complete reverse of this and this I feel is causing the difficulties. Seems to be once outside +72 the models want to return our pattern back to default and I feel this is due to how the models have been programmed especially the GFS.

[Guest North Sea Snow Convection]

Absolutely 100% spot on with that post Tamara.

I know our current pattern is different to the recent farce with the models suggesting mild SW,lys but in some respects the modelling is similiar. I don't know why but these models do seem to have a bias of pushing everything too far N and being reluctant to push the pattern S. As we know the mild SW,lys never occured for the simple reason that the models wanted to push the Atlantic trough NE rather than SE. I feel the same is happening again, especially with the GFS because in my opinion the Arctic HP will be further S and so will the LP system.

I have no idea how these models are programmed. However our normal weather pattern is low heights across Greenland with LP systems tracking NE. The model output at the moment is pretty much the complete reverse of this and this I feel is causing the difficulties. Seems to be once outside +72 the models want to return our pattern back to default and I feel this is due to how the models have been programmed especially the GFS.

Hello Dave - can only agree wholeheartedly with all that.

We know that the modelling towards such a promising evolution is not going to be straightforward and may not be immediately apparent at face value, but I think the coming days model viewing is going to certainly raise the interest stakes higher

[kold weather]

The GFS in particular is overcooking and prolonging the strength of the low near the UK. The euros, thus far, are nearer the mark - but there is more yet i think to come in terms of the pattern developing. The signal for the arctic high ridge into Svalbard/Scandinavia should factor more into the modelling with pressure rising from the north over the top of the low as it phases with the lows forming down south along the very suppressed jet stream.

The stratosphere forecasts/developments fully support such an evolution in terms of the positioning of the residual energies and where the ridging should take place. This in turn gives good credence to a very cold easterly developing thereafter. I wouldn't be surprised to see the GFS wake up to this and we see a big turnaround in the ensembles with some of them dropping off the bottom of the page. An ice age GFS special operational could come out of nowhere in the next few days. The ECM members have already shown an isolated few members dropping very low (sub - 15 uppers).

It's such a tough call because quite honestly its such a messy set-up, the thing is we don't want it to become too flabby either...

In this evolution it has to be said its just as likely that the upper low sits over the UK and doesn't move away very quickly at all as it is to possibly sink. Both the UKMO and the GFS hold the upper low to our north and somewhat elongate it westwards.

Rather then a cold spell, I think we need to be more watchful for a surprise snow event to crop up, maybe somewhat like Feb 07...

[TEITS]

Looks like the ECM wants to keep the LP centred over the UK at +144. However this isn't a mild chart with upper temps around -6/-7C.

[ANYWEATHER]

Looks like the ECM wants to keep the LP centred over the UK at +144. However this isn't a mild chart with upper temps around -6/-7C.

Yep...even in the lowland south any precip would be Wintry,certainly very Wintry and unsettled charts and lots of surprizes coming up...but a forecasters nightmare!

[J10]

Yep...even in the lowland south any precip would be Wintry,certainly very Wintry and unsettled charts and lots of surprizes coming up...but a forecasters nightmare!

This chart does increases the chance of snow to low ground, but it is at T+144, so things can easily and probably will change.

[Eugene]

I think thats it for a wintry spell similar to early to mid January, just like in the summer you very rarely get hot spells to equal early to mid July ones after mid August, still looks rather cold though and mainly dry in the week ahead so very nice weather for getting out and about in the countryside like i have done the past few days

Nice chart here with slack low pressure nights would be nice and frosty

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

[kold weather]

Looks like the ECM wants to keep the LP centred over the UK at +144. However this isn't a mild chart with upper temps around -6/-7C.

Yeah the LP looks to be fairly cold, I'd imagine therefore in any showers you'd be getting snow down to lower levels with that chart, and its a very decent chart for those on higher ground.

[Guest North Sea Snow Convection]

The ECM is fairly cold but I don't think this is the right way forward. No consistency from the last two outputs and i don't think the trough over UK/Scandinavia is the right one. The models cannot model developments well over the polar field right now. This has flipped flopped back to the west based -NAO suggestion of a few days ago. Inconsistent.

[TEITS]

Looks like this might be a disappointing run and dare I say similiar to some of the GEFS members I have seen.

If the LP doesn't phase with the Iberian LP at +144 we then see a ridge of HP from the S. This then has the knock on effect of sending the next LP NE.

[cooling climate]

Absolutely 100% spot on with that post Tamara.

I know our current pattern is different to the recent farce with the models suggesting mild SW,lys but in some respects the modelling is similiar. I don't know why but these models do seem to have a bias of pushing everything too far N and being reluctant to push the pattern S. As we know the mild SW,lys never occured for the simple reason that the models wanted to push the Atlantic trough NE rather than SE. I feel the same is happening again, especially with the GFS because in my opinion the Arctic HP will be further S and so will the LP system.

I have no idea how these models are programmed. However our normal weather pattern is low heights across Greenland with LP systems tracking NE. The model output at the moment is pretty much the complete reverse of this and this I feel is causing the difficulties. Seems to be once outside +72 the models want to return our pattern back to default and I feel this is due to how the models have been programmed especially the GFS.

You could very well be right,it seems to me that because the jet is so far south the model (models) want to move

everything further north. initially the models want to bring the low south but then they can't find the jet so they let the

low just fill but like you, North Sea Snow Convection and a few others I am sure the models have this all wrong especially

as the models enter the medium time range(t120 plus).

This is of course all conjecture on my part and could be complete nonsense.

The ECM operational seems to have lost its way tonight as well.

[kold weather]

Yeah the 12z ECM is a good run upto 144hrs but as others have said the LP after this doesn't play ball, still even then the 216hrs chart shows why I think there could be a snow risk, obviously the low is way too strong on this run but weaken that low and for at least the northern part of the country that chart would be very interesting.

[Snowyowl9]

MMMM push this low further south and we have another repeat of this.

http://www.wetterzentrale.de/archive/ra/2009/Rrea00120091229.gif

http://wzkarten.de/pics/Recm2161.gif

[Duane S.]

Whilst undoubtedly it would bring snow to many including plenty of surprise falls next week it is not the way forward to a decent cold spell. This would open the door to an Atlantic attack which would have no problem coming in NE with this setup come about the end of next weekend.

Very frustrating with all the blocking and teleconnections in our favour ATM. I thought we would have seen some sort of cross-model agreement to sinking the LP by now (or at least move it to our East). Not so.

Still time left but not a lot now (I don't mean 'time' as in what's left for the winter but in in the context of this pattern).

[snowmadchrisuk]

Whilst undoubtedly it would bring snow to many including plenty of surprise falls next week it is not the way forward to a decent cold spell. This would open the door to an Atlantic attack which would have no problem coming in NE with this setup come about the end of next weekend.

Very frustrating with all the blocking and teleconnections in our favour ATM. I thought we would have seen some sort of cross-model agreement to sinking the LP by now (or at least move it to our East). Not so.

Still time left but not a lot now (I don't mean 'time' as in what's left for the winter but in in the context of this pattern).

Have to agree not very good 12's for Blocking with the Gem removing it totally. I feel something doesn't seem quite right in todays output. I often find this at weekends though and a way forwards should become clear on Monday.

[karyo]

I'll happilly take what the ECM shows up to 216 hours and worry about the 240 hours later. We'll cross that bridge when (if) we come to it!

Karyo