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

[Weathizard]

Bloody Iberian high, nick can I borrow a nuke? Or maybe even a steam roller?

[Ian Brown]

Crazy difference between the 06/12Z.

http://modeles.meteo...fs-0-114.png?12

Someone go and squash that bloody Iberian HP!

Beat me to it Dave !

[OldMetMan]

So am I, but the metoffice with all the extra forecasting tools at their disposal are gunning for a mild or very mild spell for most of the uk apart from maybe the far north of scotland before and during christmas and unfortunately, the gfs 6z and ecm 00z concur, anything cold is in FI as usual. If the models do a massive turnaround I will be as happy as everyone else on here but I think straight talking and being realistic is better than hopecasting and missleading anyone.

Hi Frosty, It is certainly the case that I have described a number of different possible cold scenarios in recent days because we have quite an unusual synoptic pattern at present with which, as I said, the models seem to be struggling. Yesterday, I did suggest that this warm/cold struggle could go on for a while and that would seem to be the case. Historically, some notable cold spells, indeed cold winters, have been preceded by unusual mildness - 1981/1982 springs to mind or 1978/79 - but I remain convinced that the pattern of a low latitude jet and blocking european high are, to my mind, clear signals for cold, if not immediately, then in the not-to-distant future. It will be fascinating to watch the pattern shifts as time goes on.

[Southender]

Great run for NE Scotland thus far. With -8's encroaching by the weekend.

[492]

Well this is rather different, the shortwave is ejected more SE, and HP is trying desperately to extend Westward from Scandinavia. But we still have that Iberian High preventing a better outcome.

Yes, a much better shape at T+120 than the 06Z

[TEITS]

Im sure the members in Scotland are loving this run.

http://www.wetterzentrale.de/pics/Rtavn1201.png

[LomondSnowstorm]

Im sure the members in Scotland are loving this run.

http://www.wetterzen...s/Rtavn1201.png

Could do with a 150 mile nudge southwards so we don't have to worry about coastal marginality but I've certainly seen worse runs

[lorenzo]

Away from the Europe view early 12z really assaults the vortex on the other side of the NH , jet attempting some kind of meridional action, that NPacific low in place and briefly a mid US trough.

Where would you put FI on this run??? 72 hrs

[bluearmy]

over the polar field, we are getting close to the point on the 12z gfs where the low siberian heights wont be able to get across to greenland at all as the build of heights to our north approaches those ejected from the aeutian ridge. now that would be very interesting

[The Eagle]

We have high pressure stretched out to the north at 144hrs. Undercut from atlantic depression?

Chalk and cheese compared to 6z.

[LomondSnowstorm]

Even better from the UKMO:

[TEITS]

UKMO at +96!

I wonder if we're about to see a massive shift in the output with regards to the Iberian HP and LP now taking a more S,ly track under the UK rather than NE bringing mild SW,lys.

[Cal]

Wouldn't take much of a southwestward shift to leave the majority of teh UK in a cold continental feed, fascinating model watching atm.

[-uksnow-]

Even better from the UKMO:

Is it feasable for a low to zip across the atlantic like that in 24hours though?

[OldMetMan]

Very interesting that the Atlantic LP by T144 on the GFS has not made nearly as much northward progress into the cold air as previous runs. Jet configuration looks a bit different too, not so much of a northerly component.

[LomondSnowstorm]

Is it feasable for a low to zip across the atlantic like that in 24hours though?

I think that's just the shortwave developing, the trough itself has just filled a bit:

[BLAST FROM THE PAST]

Can't post charts at work but UKMO heading same way......could we see a reversal on the scale of the let down??? Think dramatic music!!! This modelling is simply absurd but truly fascinating

BFTP

[nick sussex]

After all this long winded drama from the models they had better get to a final result that is cold!

I'd not drawing too many conclusions from the output so far as it will probably change again by tomorrow. Its interesting and a better trend but answers on a postcard as to what the correct outcome might be.

[bluearmy]

shame we didnt see this evolution when we embedded cold last week. ne'er mind. i wouldnt look much further than T144 with any detail on the 12z GFS - basically, the point at which the block begins to give ground without any obvious reason to do so although it may be that the low heights from the ne are responsible. ukmo and gfs are quite diff to the north btw with a shortwave out of the arctic at days 5 and 6.

[Zenarcher]

GFS 12z looks more similar to the ECM,

06z 23rd 1am

12z 23rd 1am

And the 00z ECM for the same time,

[TEITS]

Very interesting that the Atlantic LP by T144 on the GFS has not made nearly as much northward progress into the cold air as previous runs. Jet configuration looks a bit different too, not so much of a northerly component.

Starting to make more sense the way this is going synoptically speaking as we suggested last night.

I never did buy the idea of extremely mild SW,lys via the LP moving N. What we are now seeing is this LP taking a more E,ly track rather than a N,ly. The outlook for xmas could become very different over the next few days.

[Zakos]

Right at the last minute, the models undergo a large backtrack. The chance of cold winning the battle has just massively increased

The difference in pressure over Iceland is farcilce. The low is so much further south.

everything about this run is just so much better. Uncertainty for the Xmas period is still very high. I would not want to be one of those who have bet heavily on a white Christmas. We would usually have a good idea of the picture by now. But the setup is very uncertain, and could still go either way

Edited December 17, 2012 by Zakos

[nick sussex]

The UKMO phases a bit of the PV with the low which isn't good at 144hrs but what a surprise the GFS does something different!

I'd say FI starts at 72hrs so we wait to see what different solution the ECM might come up with! Anyone got some tea leaves handy or do they now a reliable psychic!

[The Eagle]

Crucial thing is we are seeing gradually things pushed further south (at near timeframes too) and slightly higher pressure to the north. Hopefully the trend continues. GFS has potential out to 144hrs and the UKMO to 120hrs for upgrades. If we could see the darn high pressure over Iberia weaken further we would be in.

Edited December 17, 2012 by The Eagle

[UV-RAY]

I can't take any model output seriously at this moment in time, all of them have been truly woeful over the last few weeks with huge differences starting at +72 on most days of model viewing. In the last thirty years we really have got nowhere in modelling HP to our East.