WInter Model Output Discussion 12z- 28/01/2013

[Tim Bland]

Awful 06gfs,flat as can be upstream.

It's not all bad. A very unsettled end with low heights surrounding us, however if you look closer you will see the air is sourced from the arctic and with uppers between -4c and -6c there would be snow opportunities. Fair enough not sub zero days and drifting powder but IMO we are in the uk and perhaps need to lower our expectations a little

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=288&mode=1

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=300&mode=1

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=348&code=code&mode=0&mode3h=0&runpara=0&carte=1

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=336&mode=2

Edited February 1, 2013 by Tim Bland

[bluearmy]

not a happy bunny from a coldie perspective this morning. the ecm ens and gem operational the main culprits. the door hasnt closed yet but the main message appears to be that yes, we will get a height rise to the ne and yes, we will get an undercutting jet but it all looks to be too far east - likely thanks to the canadian vortex just not being prepared to give up and the jet being too strong over the north atalntic. the consistency of the gfs operational to flatten the pattern is the final piece of the jigsaw from my perspective this morning. it is too early to call time on another possible decent cold period but imo the pendulum has swung too far to less amplified to be able to get back to where it needs to be to deliver a good cold spell. there is clearly a chance that things will re amplify again as we approach mid month but hoping that next weeks cold will deepen and sustain thorugh till mid month and beyond seems to be unlikely now.

[nick sussex]

Perhaps we can ask the Americans for a drone attack on that Canadian limpet PV!

It's just flatly refused to relent for any length of time. I do think we're left now hoping that the ECM can pull this out of the bag in terms of overall pattern with an adjustment westwards.

In terms of ice days and deep cold we don't have weeks to play with, so either that high to the ne shown on the ECM becomes the main player or we just lower expectations.

This isn't a winter is over post but a deep cold and ice days chances maybe over if we don't get that blasted PV to set up further to the nw.

Edited February 1, 2013 by nick sussex

[Frosty.]

I'm really not concerned what the gfs 06z shows, i'm more interested in what the next meto update shows because I have a feeling it will be more on the side of the ecm 00z than either the gfs default to flat zonal tosh.

[bluearmy]

I'm really not concerned what the gfs 06z shows, i'm more interested in what the next meto update shows because I have a feeling it will be more on the side of the ecm 00z than either the gfs default to flat zonal tosh.

and what of the ecm ens karl ? i dont take gfs op too seriously beyond day 6/7 but when the op and control throw out a flatter solution, run after run and then the ecm ens begin to shift that way, where do you think we might be going after the northerly ?

[chris55]

GFS versus ECM at 192 and you can see how easily the pattern could be flattened out, we need some energy heading south east from the mother Low between Greenland and Iceland like the ECM. If the energy pushes directly east then it's westerlies for us, if we get the energy heading south east this allows heights to rise to the north east and we are in a great position,

GFS, energy pushes directly east

ECM, energy heads south east with a split flow just west of Iceland

Resulting in a proper undercut and a "snowy slider", would be better if the pattern was backed west a little though.

Overall a delicate situation, the fattening of the pattern would be the most likely route given our luck, but the GFS 6z often is to fast with the pattern. Will be very interesting to see where we go in the next few days.

[Cecil Hogmanay Melchett]

Im with BA,tbh i never really bought the ecm ops from the last day or so,way to much energy to our NW and i think that will be how the winter will be remembered,terrible profile to the North west,dont care what anyone says,once you get to mid feb onwards you need a deep cold pool in place to negate the effects of the higher/stronger sun,so far my assesment of the winter would be poor and im seeing nothing in the outputs to suggest anything other than standard fare for Feb,or at least the 1st half of it!

[TEITS]

A real mess on the 06Z ensembles with some showing E,lys or W,lys.

I think we have to be realistic here that we're not going to see a prolonged, deep cold spell. However im not convinced we're going to see the mild W,lys after the N,ly. What is still possible is a cold E,ly lasting around 3 or 4 days but due to that damn PV I doubt a cold E,ly will be sustained.

Im with BA,tbh i never really bought the ecm ops from the last day or so,way to much energy to our NW and i think that will be how the winter will be remembered,terrible profile to the North west,dont care what anyone says,once you get to mid feb onwards you need a deep cold pool in place to negate the effects of the higher/stronger sun,so far my assesment of the winter would be poor and im seeing nothing in the outputs to suggest anything other than standard fare for Feb,or at least the 1st half of it!

You know its strange because this winter and last winter I witnessed more snowfall then the Dec 2010 cold spell. However I do agree with your point that when it comes to synoptically speaking this winter has been crap. I count myself rather lucky to have seen the snowfalls this winter in what we're relatively weak cold winter synoptics.

Edited February 1, 2013 by THE EYE IN THE SKY

[Cecil Hogmanay Melchett]

A real mess on the 06Z ensembles with some showing E,lys or W,lys.

I think we have to be realistic here that we're not going to see a prolonged, deep cold spell. However im not convinced we're going to see the mild W,lys after the N,ly. What is still possible is a cold E,ly lasting around 3 or 4 days but due to that damn PV I doubt a cold E,ly will be sustained.

I agree Teits not looking like a deep freeze is anywhere near the horizon! You just know all those dreadful blues and purples to the North west willbe replaced by oranges and tellows come march april.

[Frosty.]

and what of the ecm ens karl ? i dont take gfs op too seriously beyond day 6/7 but when the op and control throw out a flatter solution, run after run and then the ecm ens begin to shift that way, where do you think we might be going after the northerly ?

I took onboard what you said earlier about the blocking probably being too far east etc..but i'm in the same camp as chio who said the gfs ensembles should be looked at just for fun. I realise even the ecm 00z looks finely balanced once the northerly has blown itself out and we are left in a no mans land, albeit a cold and frosty one, but it all now depends on the strength of the cold block versus the atlantic, chio gave some reasons why we failed to tap into the coldest air to the east in January but I got the impression that we will have more success this time.

[Severe Siberian icy blast]

So the question is .

What has been the reason for this Canadian PV all winter been relentless and strong?

If we can answer that and understand why then we can learn from this ,considering there was very strong signals for a cold winter this year and Greenland heights inparticular , then we must find the reason why , because its taught us that the weather really in general is in its very early stages from a scientific point of view , because there is factors that this year has completely over ridden all other signals.

Saying this , I also don't think anyone can say that we will not see a prolonged cold spell , judging by the gfs and the ECM ens , because they change every few hours and they can flip as quickly one way as they do another. It was only yesterday many was very positive on a prolonged cold spell , so that doesn't disappear over night.

The vortex is reforming slowly ok , but yet through feb it weakens somewhat naturally anyway so I think it's unlikely we will see a rampant PV during the second half of feb.

[Tamara]

Far too soon imhlo to draw conclusions I'm not aware of any signal for the momentum for the pattern to step down from a more heightened amplified state, and whilst this remains the case, and whilst there are still warm upper anomalies in the stratosphere being downwelled to the surface, then there is no reason for some kind of favourable blocked programme to hold for a period though February and at least give the energy profile to the NW something to have to chew on, before the recent colder trended upper stratosphere starts to take effect. I'm not sure that the ECM ensemble mean gives us a true picture of what might happen - the individual members from a week away don't look overly progressive to me with the jet stream amplified well enough in such a way that height rises to the NE can come into play. As far as the GFS is concerned, we have seen often enough how this tries to be progressive with the pattern and relents/adjusts within 4/5 days. At the very least, an east/west Europe/Atlantic battleground is conceivable. We would need to see any eastward progression of the jet stream come within t144 to t168 (after the northerly)before we can start to call it with any certainty. As I see it anyway - and whatever happens, its only the weather afterall

[nick sussex]

Im with BA,tbh i never really bought the ecm ops from the last day or so,way to much energy to our NW and i think that will be how the winter will be remembered,terrible profile to the North west,dont care what anyone says,once you get to mid feb onwards you need a deep cold pool in place to negate the effects of the higher/stronger sun,so far my assesment of the winter would be poor and im seeing nothing in the outputs to suggest anything other than standard fare for Feb,or at least the 1st half of it!

At least HD you're in a good location for that nw flow next week so that should deliver some snowfall.

In terms of February cold I've seen some great spells towards the end of the month but they've normally come about either with a Greenland high or strong Scandi high.

The former is looking very unlikely at the moment and the latter has only a small chance given where the PV is determined to set up.

If we look at the outputs and general pattern upto ten days that takes us to around the 11th, if the high to the ne of the ECM gets pushed too far east then by the time any reset could take place we'd be looking at around the 18th, that still just about gives us time but again we're chasing the deeper cold uppers.

For that reason I think its now or never ie the high to the ne on the ECM 240hrs either gets a shunt westwards and the PV sets up further to the nw or we lower expectations to perhaps still colder interludes but without those ice days and longer lasting snow cover.

Of course the weather is full of surprises and we might see some outlandish synoptics towards the end of the month and I have recorded an ice day even down here at the beginning of March so you never know but at the moment I do think we need to see a retrogression in the pattern ASAP!

[EML Network]

Well, I'm still not seeing anything in the models that is exciting me, with the ECM we're chasing shadows, always looking at a 240 chart to deliver a decent shot at a snow event.

All I am seeing in the charts is cold, but dry and not exceptionally cold either, pretty standard February weather if you ask me.

Hopefully this is just a prelude to something much more interesting mid month

[Severe Siberian icy blast]

I took onboard what you said earlier about the blocking probably being too far east etc..but i'm in the same camp as chio who said the gfs ensembles should be looked at just for fun. I realise even the ecm 00z looks finely balanced once the northerly has blown itself out and we are left in a no mans land, albeit a cold and frosty one, but it all now depends on the strength of the cold block versus the atlantic, chio gave some reasons why we failed to tap into the coldest air to the east in January but I got the impression that we will have more success this time.

I agree,

So as chiono said it was the third warming that basicly through a spanner in the works , but what happened to the downwelling of the SSW ? The quick response wasn't the downwelling . So where has it gone? I recognise that the SSW doesn't guarantee cold and snow , and blocks can set up in the wrong places which can leave us in the wrong side. But the last week we have seen no evidence at all of this downwelling having an effect anywhere . Ok next week the ECM is looking at a scandi high by the 10th feb , but thats 35 days or so after the initial SSW , some 15 days or so after the SSW is meant to propergate down to effect us . So not convinced the scandi high is a result of the SSW .

[SnowBallz]

The UKMO has been updgraded to a higher vertical resolution to incorperate more of the stratosphere-

Also the seasonal model has been updated as well but I cant remember its bloo*dy name-

S

Steve,

That would be the GloSea4 model.

If any members would like to get a better understanding of GloSea4, this is a very good presentation:

http://www.ecmwf.int/newsevents/meetings/workshops/2011/MOS13/presentations/Hewson.pdf

SB

[Frosty.]

Although the Gfs 06z does flatten the pattern and the weather becomes briefly milder after the Northerly, we soon see a return to a more amplified pattern with the jet tilting nw/se once again, the 6z returns to the cold and unsettled pattern it shows for next week although the Northerly next week is cut short compared to the ecm and ukmo, the angle of the trough to the northeast is crucial, the 6z shows a flow to the north of the uk just west of north whereas the ecm is more tilted east of north, those fine margins then create the gulf that opens up between the gfs and ecm soon after, the gfs looks too progressive.

Edited February 1, 2013 by Frosty039

[nick sussex]

I agree,

So as chiono said it was the third warming that basicly through a spanner in the works , but what happened to the downwelling of the SSW ? The quick response wasn't the downwelling . So where has it gone? I recognise that the SSW doesn't guarantee cold and snow , and blocks can set up in the wrong places which can leave us in the wrong side. But the last week we have seen no evidence at all of this downwelling having an effect anywhere . Ok next week the ECM is looking at a scandi high by the 10th feb , but thats 35 days or so after the initial SSW , some 15 days or so after the SSW is meant to propergate down to effect us . So not convinced the scandi high is a result of the SSW .

I read a paper suggesting the initial state of the AO at the onset of the warming is correlated with whether you get a statistically significant tropospheric response.

The suggestion being that if the AO was neutral or positive you saw a clear tropospheric response, if it was negative then you didn't.

Perhaps that might be one factor in the puzzle. If thats not the case here then even if any HLB doesn't effect Europe you would generally expect to see this in evidence somewhere in the NH.

It's a mystery and just shows perhaps with so many different variables going on in the background how do you ever get a clear a+b=c sort of outcome.

Edited February 1, 2013 by nick sussex

[snowmadchrisuk]

There is still quite a few of the GFS Ensembles going for the NE'ly option - One of the best is below , but at least 5-6 give us -10 850's at +240 .. I know it's quite far in advance , but these are the ensemble members that don't reset the pattern

[snowmadchrisuk]

UK Outlook for Saturday 16 Feb 2013 to Saturday 2 Mar 2013:

There are large uncertainties at this forecast range. Conditions will most likely start with temperatures close to or a little below average, with fairly typical winter weather across much of the UK. There are signs that a slightly colder spell may then prevail throughout much of the rest of the period, with more widespread overnight frosts.

Yesterdays 15-day Tending to turn colder and rather unsettled across the UK throughout much of this period. There will be a mixture of sunny spells and blustery showers, which will turn increasingly wintry, though probably falling as rain or sleet in the south at first. There is the potential for some accumulations of snow in places exposed to the north and northwest. It will be windy across the UK, with severe gales possible in the northwest. The best of the sunshine will be towards the east and southeast of the UK. Generally rather cold, with overnight frost in inland shelter at first, becoming more widespread throughout next week. Towards the end of the period, there is a good deal of uncertainty, but perhaps becoming drier and less cold for a time.

Today's: Slow Climb down maybe ??

Conditions tending to remain a little colder than average for much of the period. A fair amount of dry and bright weather across the UK at first, but always the potential for some rain or showers, the showers especially affecting eastern coastal areas, where they could be heavy and thundery with hail and snow. A few wintry showers elsewhere too, particularly Irish Sea coasts and parts of the Midlands at first, but tending to become confined to eastern coasts towards the end of next week. Windy at first, with gales in exposed western areas. Widespread overnight frosts with some icy patches. From the middle of the period, conditions look likely to become a little more unsettled, with temperatures returning to nearer normal, though still perhaps a touch below in places.

Edited February 1, 2013 by snowmadchrisuk

[Severe Siberian icy blast]

I read a paper suggesting the initial state of the AO at the onset of the warming is correlated with whether you get a statistically significant tropospheric response.

The suggestion being that if the AO was neutral or positive you saw a clear tropospheric response, if it was negative then you didn't.

Perhaps that might be one factor in the puzzle. If thats not the case here then even if any HLB doesn't effect Europe you would generally expect to see this in evidence somewhere in the NH.

It's a mystery and just shows perhaps with so many different variables going on in the background how do you ever get a clear a+b=c sort of outcome.

Yes that sounds logical , so ideally we would prefers the AO to be in a rampant like state when the SSW occurs , obviously there's so much more involved hear , but that would perhaps explain why we didn't see such a tropospheric response, if it isn't the case, then like you say I'm completely baffled as to why we have seen no response to the downwelling anywhere in the northern hemisphere .

Disappointing to be honest as the winter had so much promise. But then if we can get a good February with another significant snow event or 2 then this winter would have been a good one , the last spell certainly was very snowy for my part of the world , and even more so for ppl toward b'ham such as my brother.

I'm hoping that ECM operational is onto something with the night rises to our north, just has me wondering if there can be a late response for some reason which is what the ECM has picked upon ? Would there be a scientific reason that can delay a response , rather then mute it?

[Tom Quintavalle]

Far too soon imhlo to draw conclusions I'm not aware of any signal for the momentum for the pattern to step down from a more heightened amplified state, and whilst this remains the case, and whilst there are still warm upper anomalies in the stratosphere being downwelled to the surface, then there is no reason for some kind of favourable blocked programme to hold for a period though February and at least give the energy profile to the NW something to have to chew on, before the recent colder trended upper stratosphere starts to take effect. I'm not sure that the ECM ensemble mean gives us a true picture of what might happen - the individual members from a week away don't look overly progressive to me with the jet stream amplified well enough in such a way that height rises to the NE can come into play. As far as the GFS is concerned, we have seen often enough how this tries to be progressive with the pattern and relents/adjusts within 4/5 days. At the very least, an east/west Europe/Atlantic battleground is conceivable. We would need to see any eastward progression of the jet stream come within t144 to t168 (after the northerly)before we can start to call it with any certainty. As I see it anyway - and whatever happens, its only the weather afterall

Just a quick post from work.

Re. the situation at t144/t168, looking at the N.Hemispheric charts, the catalyst for the differences between GFS/ECM is how they handle that shallow low off the E.Seaboard. GFS keeps it shallow out into the Atlantic and then it deepens and flattens the attempted ridge, whereas ECM deepens the low further west and then it moves further north and gets pulled towards the Canadian segment of PV this allows a more amplified scenario, with a ridge thrown up to the east of this low.

Must admit to being a bit concerned by the ECM mean, which suggests the Op was a bit of an outlier in that regard.

Gfs then goes on to suggest another attempted northerly in FI but with the clock ticking I really do hope that the ECM 00z is nearer the mark in its evolution, otherwise very little prospect of any prolonged cold before mid-month.

Regards,

Tom.

[phil nw.]

This is quite a cold setup with only brief milder incursions and with some snow around next week.However being realistic in this changeable pattern with less colder intervals any snow is not likely to lie for long at lower levels.That 2 day Northerly does look promising for the best chance of some lying snow at this stage though.

Looking into week 2 of the runs and at day 10 we can see the mean 500hPa charts from the last GFS and ECM runs show a Euro.trough to our east and that blessed Azores high nicely snuggled up at home.This would keeps us where we are now in a chilly North Westerly type pattern average uppers around -4C with colder air to our east.

The anomaly charts from the combined NAEF`s and ECM again show the UK under the influence of those nearby Euro low heights.

Looking at the ens and anomalies it`s likely to remain rather cold for much of the period but it`s hard to make a case now for an Easterly.

I notice that the models still have the vortex stretching more towards the Pacific side of the pole but too much energy still remains around Canada and W.Greenland to give us a window for blocking further north.

[Tamara]

Just a quick post from work.

Re. the situation at t144/t168, looking at the N.Hemispheric charts, the catalyst for the differences between GFS/ECM is how they handle that shallow low off the E.Seaboard. GFS keeps it shallow out into the Atlantic and then it deepens and flattens the attempted ridge, whereas ECM deepens the low further west and then it moves further north and gets pulled towards the Canadian segment of PV this allows a more amplified scenario, with a ridge thrown up to the east of this low.

Must admit to being a bit concerned by the ECM mean, which suggests the Op was a bit of an outlier in that regard.

Gfs then goes on to suggest another attempted northerly in FI but with the clock ticking I really do hope that the ECM 00z is nearer the mark in its evolution, otherwise very little prospect of any prolonged cold before mid-month.

Regards,

Tom.

Yes that is a good analysis of things, and puts another perspective on my rather glass half full post . And it highlights how the crossroads I mentioned earlier is a very tight one. The resilience of the Canadian portion of the vortex post the SSW split has certainly tempered prospects for an extension beyond the cold spell in January, as to how things might have been seen to evolve. Goes to show that whilst splits create opportunities for cold, forecasting the balance and movements of energy left over is much more difficult and might not always meet hopes and expectations for everyone in the NH, all the time. Still, the glass remains just maybe a sip less than half full..

[Frosty.]

I detected a little uncertainty in the latest metoffice update towards the end of the 6-15 day section, my interpritation of it was that residual cold could persist in parts of the north and east with a wintry mix, the less cold probably more towards the southwest and far west so if that's the case, it still looks as though the gfs is being way too progressive in shunting the cold air away eastwards later next week, so the cold looks like persisting for longer which means the block should become strong enough to slow down the atlantic breakdown, and the breakdown itself could bring a risk of snow as mild air tries to make inroads. As for most of next week, it looks like turning colder and showery with strong NWly winds veering Nly, heavy thundery snow showers especially to northern scotland and down eastern coastal counties, also some wintry showers down irish sea coasts down to north wales and down to sw england and s wales, inland looks cold and sunny but there could be some troughs swinging south in the cold unstable airflow, frosts become widespread and then turning more unsettled from the southwest by the end of next week or early the following week with rain, sleet and snow edging northeastwards but that is just how I understood the update.