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

[The Northern Ramper]

I wonder if on future runs we can get that Bartlett high slightly less displaced and further east?

[Panayiotis]

-10's into Cornwall still in high resolution ..... oh please don't be an outlier

-10 uppers to the west of Ireland on that chart. Do you mean -5 as this is covering the majority of the country... Edited December 19, 2012 by Panayiotis

[Dampdorset82]

this just doesn't look right!! has somebody been on the sauce

Due to the high sea surface temperatures +2-3.5c higher then average north of iceland makes the air flow very unstable and would produce some potent LP's dropping off. Completly plausable at this stage.

[Mark Parsons]

-10's into Cornwall still in high resolution ..... oh please don't be an outlier

Highly unlikely to happen but if it did there would be a lot of snow potential into the west with the old convection off the sea.

[snowmadchrisuk]

The tilt of the Jet is perfect even the big Atlantic Lows get forced SE, maintaining heights to our north , it would be Snow heaven .

[PubliusEnigma]

I wouldn't call this a Bartlett-type setup by any means, clearly an Azores high is present but heights are low for most of continental Europe too.

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.

[Rocheydub]

-10's into Cornwall still in high resolution ..... oh please don't be an outlier

Eh? Surprised a chap like you got that wrong!!!

[snowmackem]

What exactly is a 'displaced' Bartlett?

Same as a displaced troll only spelt differently. Edited December 19, 2012 by snowmackem

[Panayiotis]

Yesterday I talked about the 18z being sober and it had stopped showing the usual drool over charts we are used to, seems it has listened to me and its got back on the vodka!

[Bristawl Si]

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

[The Eagle]

No complaints from me on this run. Very good even if it breaks down in FI.

[Bristawl Si]

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.

Cherry picking charts well into FI. How about commenting on 27th to 31st

[-uksnow-]

-10's into Cornwall still in high resolution ..... oh please don't be an outlier

-5's are just scraping the southern cornwall coast actually...

[bradymk]

What an earth is a displaced bartlett high? Am i being stupid here? GFS 18z shows pattern still too far east but does deliver colder weather, mainly for north and the west however. GEFS 12z definately trended colder also between xmas and new year. The block we were all loving a few weeks ago we now really need it to move and not buid back west. Interesting post Phill about NOAA guidance, did i sense a ramp at the end there

Edited December 19, 2012 by bradythemole

[PubliusEnigma]

The tilt of the Jet is perfect even the big Atlantic Lows get forced SE, maintaining heights to our north , it would be Snow heaven .

There would be a dividing line IF there was snow on the leading edge. The front would potentially identify are marked

transition from cold to much milder air. And we all know what problems that brings. The areas in the rain, are the very

places that wont need it, and could see copious amounts. The snow, again would tend to be over the Scottish mountains

and you are right, you could see very high snowfall totals build up on the piste.

[Robbie Garrett]

Any further east and South and the MetOffice are f****ed come end of next week. 192 which is what, end of the high resolution is not doing too bad.

There forecast is way out, if the GFS is to be believed.

[damianslaw]

Not sure why some are dismissing the 18Z output shown for this time next week tonight - in my eyes a very plausible evolution, indeed the ECM and GFS on Sunday were suggesting this type of set up for the 25th only to move away from the idea in the last couple of days, whilst the GFS this eve isn't showing a potent northerly it is showing a very unstable blast of cold polar air - for it to verify much will depend on the track of the azores high and the position of the jet - a bit more amplification of the flow would enable better retrogression of azores heights and bingo the jet is forced south meaning we would definately be looking to the NW for our weather.

[Cumulonimbus Tower]

The GFS excites me from an IMBY POV. Not often the west sees potential like this...

I agree. I must admit that I didn't really see anything to get excited about for the last couple of weeks but all of a sudden my ears have pricked up a little looking at the 12z from today. If things were to pan out like they might it could be quite a good week next week for being half way up a hill in the North West of the BI. There is always the danger that shortwave armageddon could spoin the party a little but hopefully the cold uppers will be spilling south that they swams any little systems coming over us and also squeeze down between the systems to give a right good old fashioned wintery week - from the north west.

[snowmadchrisuk]

Eh? Surprised a chap like you got that wrong!!!

I just worded it wrong , I meant to say heading towards Cornwall , Either way that setup would likely provide a lot of Snow ... We need to watch them heights between +96 and +120 , they have to delay the Atlantic SW to stand a chance of this happening , there were signs on the 12z and the 18z has the heights even stronger and further East

[Panayiotis]

Even in the far reaches of Fi the 18z nearly shows a split vortex, with a negative AO and NAO. http://cdn.nwstatic....384/npsh500.png

Again IMO the story of the 18z cold after Christmas, starts from the Bering Sea where a ridge 'breaks away' leaving a part of the high pressure to be pulled up by the PV into the pole, from there it migrates to the west of Greenland, and its now a growing signal for this to occur (been showing this for many days now)... The chart above showing high pressure in the Arctic started off again in the Bering Sea as a ridge..

Edited December 19, 2012 by Panayiotis

[Ruzzi]

http://www.wetterzen...s/Rtavn2401.png

It appears in FI that the displaced Bartlett is too far west of Greenland...

I'd be happy to see this set-up approaching the more reliable timeframes, Displaced Bartletts are volatile creatures and there's still plenty of opportunity for an eastward correction. Much better outlook than if a displaced Arctic high were to set up over central and southern europe.

[Ice Day]

Looking good for the Westerners; particularly NW England, N Ireland and North Wales. Only 8 days away so it may happen!

Edited December 19, 2012 by Ice Day

[swfc]

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

[LomondSnowstorm]

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.

I certainly agree with the last sentence, there's no sign of anything anticyclonic at all on the horizon. However, it's not exactly unusual to have high pressure around the Azores-Iberia region:

And at points it starts to ridge northwards before it goes into the low res, which, while probably not all that likely to lead to a proper block within the 8-10 day range, is a fairly typical evolution to a Greenland high:

[snowmadchrisuk]

Looking good for the Westerners; particularly NW England, N Ireland and North Wales. Only 8 days away so it may happen!

Something is likely to change very soon , and give or take a few SW locations , the 18z solution would make a lot of sense to me .