Winter Model Discussion - The Hunt For Cold -12z 14/12/12

[mulzy]

Disappointing runs this morning I feel, ensembles look a lot worse compared to the 18z. The Iberian high is going to be a nuisance, how often do we see it in winter and we have good charts at around 216-240 with the Azores high dominant and then suddenly we are in a cold spell, think we need to be in this for the long haul but I am worried that the Azores high seems to be rearing its ugly head again

Agreed. People talk about Greenland highs and Scandi highs, but the high we should all focus on is the Azores high - it is the winter killer...

[Tom Montalbano]

Exactly and thats why members shouldn't be making bold statements about the rest of this year. The ball gets rolling at +240.

http://modeles.meteo...snh-0-240.png?6

Shows what a challenging task the likes of GP, CH have in trying to predict our weather.

Yes Dave, yet again this run shows that IF we get a break re. fragments of the PV staying clear of Greenland, the atmosphere seems primed for some amplification of the flow, out in the Atlantic. Anyone writing off the next few weeks just yet, maybe a little premature in their assumption!

Regards,

Tom.

[Tim Bland]

A white new years eve for many on this run.

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=348&code=0&mode=2

[Duane S.]

Of course it will be, it's 2 weeks away!!!!

Thanks for pointing that out. Maybe I should have written a bit more. My point being those talking about Azores high domination for the next 2+ weeks could be way off the mark.

Edited December 17, 2012 by s4lancia

[VillagePlank]

GEFS, 00z,

Very interesting set of ensembles; the variance chart looks quite unusual with uncertainty half way through threw the roof, and then settling back down again. These charts have, would you believe it, two start dates for FI - but I suppose one can remove the first one because those two cold bits at R+24 look to be clear outlier - main FI starts at T+148!

Edited December 17, 2012 by Boar Wrinklestorm

[bluearmy]

with so much energy russhign around the polar region in week 2, i think the models will struggle to resolve in a consistent fashion. what i would re iterate is that in my experience over the years looking at the nwp, if any chunks of vortex are close to greenland (inc n greenland) then the atlantic jet gets a kick. the 06z fi is notable as it ejects the chunk of vortex back round the pole which allows heights to rise.

[legritter]

I have always said that anyone making a forecast well into the period past two weeks is treading on very shaky ground .we have plenty of tools to give us guidence but even with modern computers ,sattelites past weather records ,etc etc we MAY get the pattern right but SLIPPIMG it into the right place is always the biggest obstacle .at the moment there are plenty of options in the modells with big changes ,my hunch at the moment watching arctic predictions is that the vortex could come crashing south but the escape route still open to modelling . a possible is scandy or further into finland nw /russia area . i think we will have a very dire spell of weather from late wed onwards going by charts and i wouldnt be surprised if future runs show height rises across east of greenland and some potent lows mid atlantic ,but that is my look for now ,it could all fall into place with all modells singing together but a different Tune to the present .and it could happen at the drop of a hat ,whilst wer;e all asleep .roll on tonights ECM .

[The Eagle]

All I will say is this is at 120 hrs

A relatively small correction south and a lot of folks are in.

Again 144hrs - small correction south...it's not as bad or far away as some are making out I don't think.

[Frosty.]

All I will say is this is at 120 hrs

A relatively small correction south and a lot of folks are in.

Again 144hrs - small correction south...it's not as bad or far away as some are making out I don't think.

It's fangtastic for northern scotland with cold Easterly winds and some wintry precipitation, if it happens.

[VillagePlank]

GEFS,06z,

The period between R+18 .. R+30 now looks highly unpredictable with more runs opting for the colder evolution. The skew suggests colder towards R+18, and warmer towards R+30. The warmest run for the period, going for 14C, is a clear outlier. If you trace the colder runs then they eventually warm up, so it seems to me, not to be a case of warm vs cold, but rather when a temporary "cold" blip subsequently warms up.

Overall trend, as has been the case so far this winter, is for 850hPa mean/median to moderate at around 0C.

FI seriously stuck at T+72, now.

Edited December 17, 2012 by Boar Wrinklestorm

[AGAL]

A white new years eve for many on this run.

http://www.meteociel...8&code=0&mode=2

DO NOT TRUST THE GFS AT THAT RANGE. Like the mythical sirens it will lure us all onto the rocks of despair.

Maybe one shouldn't trust one's own subjective judgement: but it seems to me that the GFS being the model to extend the furthest, when picking up a SW theme at the extent of its range; that it's prediction picked up over two weeks earlier always seems to come to pass. Yet when picking up a northerly or easterly the so-called trend the model seems to have spotted,it always turns out to be false.

So therefore the northerly shown for boxing day now tlike left over Christmas dinner gets rehased for the New Year. Now it may come to pass but it won't be due to GFS model predictions, if it does happen then the GFS just got lucky.

Actually maybe the GFS system could be sold to Las Vegas.

Edited December 17, 2012 by AGAL

[nick sussex]

I've been saying for a few days its crunch time for the possible ne/e flow and yet I'm not convinced the models can be trusted at 96hrs.

So here we are and at least for northern and ne areas it could still get more interesting.

The ECM ensembles seem to be all over the place, this mornings are better than last nights with more colder solutions,indeed it looked like the writing was on the wall last night but up pops another variable this morning, this being the shortwave forming on the southern flank of the main troughing to the west.

This has now thrown a curveball into proceedings because depending on the track and how much it deepens it could help pull that troughing further nw.

It actually cuts off and delays the ne movement of the Azores high which is really needed if you want the colder solutions to verify. At the moment it looks like any wintriness will just be reserved for more n/ne areas and the odds still favour milder conditions for Xmas but more delicately balanced the further north you are.

I've just looked through yesterdays ECM postage stamps and this mornings and its really down to that shortwave.This really must verify to have any chance of at least something interesting for parts of the UK.

Edited December 17, 2012 by nick sussex

[Frosty.]

At least the models have a sense of humour, the uk flooded in greens which will match the grass this xmas day and christmas week.

[nick sussex]

In a true sense of irony it could turn out that a shortwave unexpectedly forming could indeed be the game changer! How many times have one of these scuppered a cold outcome!

Here we have to see it verify!

[Frosty.]

I would say the easterly being shown across scotland at the end of this week on the ecm 00z is hanging by a thread according to the gfs 06z, and then later in FI the gfs finds a way of bringing a pitiful end to a cold spell later on christmas week towards new year.

[MisfitDog3]

Excellent stuff at the moment! If you don't like what you're seeing outside 96 hours....don't worry! All you have to do is wait for 12 hours and you're presented with a radically different solution. If you don't like that one...well don't worry...because there's another one coming along very soon! From my own angle, the Atlantic looks like it's going to take some serious stopping before early Jan! There may be a colder interlude but I just don't see the framework for anything sustained to hang around on the cold front. Any Low heading in from the Atlantic is going to have its wicked way for the time being.....

[Frosty.]

It looks like being a mild christmas according to the latest models and the meto update today, mild weather spreading to all areas by xmas eve (much sooner across central and southern britain) and then continuing mild and green through xmas day, boxing day etc etc.. I noticed the meto update is suggesting something like the ecm 00z at the end of this week with cold and unsettled weather across northern scotland by friday and into the weekend with snow rather than rain for the far north and ne, most of the uk looks milder in the same period or at least closer to average with rain at times. As for beyond boxing day, maybe colder in the north with an increasing risk of hill snow but nearer average for southern britain with rain and showers, this type of split could continue out to mid january, with northern uk colder at times with a mix of rain, sleet and snow but milder in the south with rain more likely.

Edited December 17, 2012 by Frosty039

[Bonjangle]

Still no call on the Xmas prospects this morning, and although a cold outcome remains possible it’s still not the most likely one. Before Christmas we’ve got some heavy rain on the way as weather fronts push in from the Atlantic and grind to a halt as they hit the block of cold air which remains just to the east of Britain. This needs watching because it’s possible some of the cold air will back far enough west to affect north eastern parts of Britain for a time later this week. If that happens it could bring a wintry flavour to the weather in Scotland and possibly the north east of England, with rain turning to sleet or snow, especially over higher ground. The ECM chart shows this happening, with -5C 850hPa covering much of Scotland and fringing into north east England on Saturday. The later stages of the same model run show the cold retreating east by Monday, so if there is a cold incursion into the north east it probably wouldn’t last too long, and the main concern for most of the country is the potential for very heavy rain.

Edited December 17, 2012 by Aquastarmist

[Carl46Wrexham]

Still no call on the Xmas prospects this morning, and although a cold outcome remains possible it’s still not the most likely one. Before Christmas we’ve got some heavy rain on the way as weather fronts push in from the Atlantic and grind to a halt as they hit the block of cold air which remains just to the east of Britain. This needs watching because it’s possible some of the cold air will back far enough west to affect north eastern parts of Britain for a time later this week. If that happens it could bring a wintry flavour to the weather in Scotland and possibly the north east of England, with rain turning to sleet or snow, especially over higher ground. The ECM chart shows this happening, with -5C 850hPa covering much of Scotland and fringing into north east England on Saturday. The later stages of the same model run show the cold retreating east by Monday, so if there is a cold incursion into the north east it probably wouldn’t last too long, and the main concern for most of the country is the potential for very heavy rain.

Just what we need!...Never mind green Christmas...brown, muddy and waterlogged Christmas more like for us in the West and South West. I've stopped looking for cold weather from the models....looking for badly needed dry weather...if it's mild with it, then so be it.

[The Eagle]

FI seriously stuck at T+72, now.

I think more 96hrs myself which has been more volatile than normal for some time now. This is not done and dusted yet.

[Frosty.]

Still no call on the Xmas prospects this morning, and although a cold outcome remains possible it’s still not the most likely one.

It's still a week away but there is overwhelming model support for a mild christmas, mild air arriving later this week and then continuing well into next week is the form horse, that is showing on the main models and today's meto so anyone saying different is in denial of the output shown. The easterly later this week for the far north is on very shaky ground as to whether there will be enough undercut to pull cold air from the east across the far north, but even if it does, it will only last a few days before milder air from the rest of the uk pushes north to all areas. I will be happy if this situation changes to any degree but we have to face the probability we will have a green christmas week.

Edited December 17, 2012 by Frosty039

[Buzz]

It looks like being a mild christmas according to the latest models and the meto update today, mild weather spreading to all areas by xmas eve (much sooner across central and southern britain) and then continuing mild and green through xmas day, boxing day etc etc.. I noticed the meto update is suggesting something like the ecm 00z at the end of this week with cold and unsettled weather across northern scotland by friday and into the weekend with snow rather than rain for the far north and ne, most of the uk looks milder in the same period or at least closer to average with rain at times. As for beyond boxing day, maybe colder in the north with an increasing risk of hill snow but nearer average for southern britain with rain and showers, this type of split could continue out to mid january, with northern uk colder at times with a mix of rain, sleet and snow but milder in the south with rain more likely.

Do you really think that's it's wise to make any kind of prediction for more than 72 hours in the future? Given the ongoing severe fluctuations in the model outputs only a fool would try and predict the weather for Christmas Day and beyond (it's still 8 days away you know).

[SnowObsessor90]

It's still a week away but there is overwhelming model support for a mild christmas, mild air arriving later this week and then continuing well into next week is the form horse, that is showing on the main models and today's meto so anyone saying different is in denial of the output shown. The easterly later this week for the far north is on very shaky ground as to whether there will be enough undercut to pull cold air from the east across the far north, but even if it does, it will only last a few days before milder air from the rest of the uk pushes north to all areas. I will be happy if this situation changes to any degree but we have to face the probability we will have a green christmas week.

This may be be a little of topic Frosty but what your currents for the overall winter? starting to get feelings of deja vu?

[LomondSnowstorm]

It's still a week away but there is overwhelming model support for a mild christmas, mild air arriving later this week and then continuing well into next week is the form horse, that is showing on the main models and today's meto so anyone saying different is in denial of the output shown. The easterly later this week is on very shaky ground as to whether there will be enough undercut to pull cold air from the east across the far north, but even if it does, it will only last a few days before milder air from the rest of the uk pushes north to all areas. I will be happy if this situation changes to any degree but we have to face the probability we will have a green christmas week.

Hopefully the other models don't follow the GFS 6Z in downgrading the easterly, it looks like it may be potent enough to deliver fairly widespread snow to even lowland eastern Scotland going by the ECM 00Z at least.

Also, looking for a straw to clutch for Christmas would lead us to the BOM:

This would deliver a white Christmas to many parts of the country and would certainly be cold enough for snow almost anywhere:

Anyway, just one run and not all that well supported but if the energy goes east rather than northeast and the PV stays off Greenland then who knows what could happen, it is still at +192 so no outcome is set in stone at this stage (although this is clearly not the favored option at present).

[Frosty.]

Do you really think that's it's wise to make any kind of prediction for more than 72 hours in the future? Given the ongoing severe fluctuations in the model outputs only a fool would try and predict the weather for Christmas Day and beyond (it's still 8 days away you know).

Yes I do, i'm not going to say it's looking cold because it's clearly not. I'm only saying what the models are showing and i'm not expecting anyone to like what i'm saying for obvious reasons but unless there is a major change, we are on course for a milder spell from later this week and well into next week.