Winter Model Discussion - The Hunt For Cold -18z 17/12/12

[karlos1983]

On this run looks like that "pesky" Ruskie high has decided to retreat, opening the door for greater potential from the North.

Yep, I've been guilty over recent day's/weeks of urging it back west, I now can't wait to see the back of it. I remember Nick Sussex stating almost immediately after the disappointment of the failed BFTE, "it's had it chance, now it needs to push off ASAP",or something along those lines.

[TEITS]

Looking at the 12Z ensembles and to be honest the 18Z isn't surprising.

Mean nearly -5 for Aberdeenshire.

http://cdn.nwstatic.co.uk/ensimages/ens.20121219/12/t850Aberdeenshire.png

Nowhere near as cold for London.

http://cdn.nwstatic.co.uk/ensimages/ens.20121219/12/t850London.png

Which is my earlier point about commenting on all of the UK.

BOM also brings in a cold N,ly on Boxing day.

[SnowBallz]

not sure whether its my laptop but there seems to be a black hole on the nh chart at 384 hrs!!!!!pub run eh

Oh that?

That's where the North Pole has displaced itself over to Australia.

Don't worry, it'll be back soon.

[NorthernRab]

The snow, again would tend to be over the Scottish mountains

Is there any chance that we can stop referring to Scotland as the "Scottish Mountains"? It's becoming increasing inane and misleading.

This sort of chart can and does lead to fairly widespread snow at low-levels.

Edited December 19, 2012 by NorthernRab

[peterf]

i just want 1 flake lol.

[Zakos]

Its more of a displaced Bartlett. It's not in its orthodox location. But its stubbornly there for most of the 18z run.

And the heights seem to get stronger the deeper into FI one goes. If the charts hold true, the volume of rain into the new

year country wide could be a real problem.

this "displaced bartlett" you refer to is called the Azores high. you know... being centred over the Azores kinda gives it away.

It is, by definition, a semi-permanent area of high pressure, explaining why it is there the entire run...

perhaps... but the undeniable trend is for the Azores high to have less of an influence, hence the recent upgrades

[Duane S.]

What an earth is a displaced bartlett high? Am i being stupid here?

No. It is however the most amusing new 'forum weather term' I've heard for a while though. What I have come to realise though is those wonderful retrogression episodes in the winters of 2009 and 2010 were in fact the work of a 'displaced Bartlett'!

[phil nw.]

Phil the mystery behind the canonical negative AO maybe here, I've just skimmed it but its excellent for many other things, one of the best articles I've seen on the MJO etc, I'm not sure if GP has this but its really interesting.

http://iprc.soest.ha...ed_withFigs.pdf

Phil you need to look at page 42, cluster 4.

Thanks Nick-a few pages in that i wondered why it took a while for the link to fully open!

So cluster 4 is what they were intimating then -that looks quite promising for the UK.

Yes the MJO stuff is very detailed and is a long read in itself but useful to anyone who wants to find out about it and it`s influence on our weather patterns.

Cheers Nick.

[Panayiotis]

I think we should stop talking about a 'displaced bartlett' as a bartlett is actually a displaced AZORES high, its called an azores high as that's where it usually is!

Rant over!

Edited December 19, 2012 by Panayiotis

[cold snap]

Where are you steve or nick ?

Not a bad run that infact some people will be best please .

Russian high disappears and look what happens and that Azores high doesn't really get going

[Jason M]

i just want 1 flake lol.

I wish I was better at posting images :-)

Call it a hunch, but I feel confident your wish will be granted by someone here within the next 10 minutes or so :-)

Jason

[LomondSnowstorm]

Is there any chance that we can stop referring to Scotland as the "Scottish Mountains"? It's becoming increasing inane and misleading.

This sort of chart can and does lead to fairly widespread snow at low-levels.

Yes, anything around or below -5C can usually deliver the goods in terms of being cold enough for lowland snowfall, precipitation is another issue but that chart would certainly bring something along the lines of 2-3C maxima for inland Scotland and northern England.

[lorenzo]

Great find Nick, a good read and particularly topical with respect to ENSO, the Cassou paper cited throughout and in references is also excellent, would post it here but have temporarily displaced it.

[TEITS]

this "displaced bartlett" you refer to is called the Azores high. you know... being centred over the Azores kinda gives it away.

It is, by definition, a semi-permanent area of high pressure, explaining why it is there the entire run...

perhaps... but the undeniable trend is for the Azores high to have less of an influence, hence the recent upgrades

Also a Bartlett HP is accompanied by a positive AO with the jet running to the N of the UK.

Back to the models and what is interesting is until today the models have been shifting the pattern W. However when you look at the +96 to +144 the models are far more eager to push the LP further E. This trend needs to continues although again whether the extent of the cold N,lys can push all the way to the S is another question.

The 18Z GEFS mean at +138 is a massive upgrade compared to the 12Z.

[Chess01]

Maybe stoke can get some snow for christmas through the cheshire gap effect. It has a smell of the christmas 2004 that was caught out of suprise

[cold snap]

Also a Bartlett HP is accompanied by a positive AO with the jet running to the N of the UK.

Back to the models and what is interesting is until today the models have been shifting the pattern W. However when you look at the +96 to +144 the models are far more eager to push the LP further E. This trend needs to continues although again whether the extent of the cold N,lys can push all the way to the S is another question.

The 18Z GEFS mean at +138 is a massive upgrade compared to the 12Z.

Don't forget the ukmo. At 144 tonight barking along a similar tree

[Downburst]

Great find Nick, a good read and particularly topical with respect to ENSO, the Cassou paper cited throughout and in references is also excellent, would post it here but have temporarily displaced it.

Why the post so?

[peterf]

I wish I was better at posting images :-)

Call it a hunch, but I feel confident your wish will be granted by someone here within the next 10 minutes or so :-)

Jason

2010 was easy,last year i never even bothered.this year has my nerves shredded.not to worry 50% goes to the Great North Air Ambulance.

[snowblues]

Looking at the n/h in the mid frames from some of the outputs,the p/v is just sliced in half from N Canada.Is it still to early for any signs of Strat warming.Not meaning a spilt.

Edited December 19, 2012 by snowblues

[Ice Day]

Also a Bartlett HP is accompanied by a positive AO with the jet running to the N of the UK.

Back to the models and what is interesting is until today the models have been shifting the pattern W. However when you look at the +96 to +144 the models are far more eager to push the LP further E. This trend needs to continues although again whether the extent of the cold N,lys can push all the way to the S is another question.

The 18Z GEFS mean at +138 is a massive upgrade compared to the 12Z.

http://modeles.meteo...21-1-138.png?18

Oooh, drag that low 300 miles SE, then things could be quite interesting!!!

[karlos1983]

here you go Peterf

[bradymk]

No. It is however the most amusing new 'forum weather term' I've heard for a while though. What I have come to realise though is those wonderful retrogression episodes in the winters of 2009 and 2010 were in fact the work of a 'displaced Bartlett'!

phew, have come on to find this new term. Wouldnt you say it was a displaced azores high rather than a "displaced bartlett" though.

[JCP]

What an earth is a displaced bartlett high? Am i being stupid here?

No, but the person who coined the phrase might be!

[LomondSnowstorm]

A very tasty ensemble mean for Boxing Day:

[lorenzo]

Why the post so?

The reason I wrote the above post was to thank Nick for locating a good paper on the MJO and to recommend the paper cited in the bibliography by Cassou.