Winter Model Discussion - Cold Hunting -12Z 06/01/13

[Panayiotis]

The models are good enough! Of course things won't stay that way forever but for those claiming it woud be mild throughout the winter they will now have more of a challenge calling an end to this cold period, but we all already know things will get mild in spring anyway!

Yes the models are superb but can they maintain this/upgrade? I love the cold (you have probably noticed that already) but we all know that getting cold/snow to our island has its complications. Edited January 6, 2013 by Panayiotis

[Costa Del Fal]

Well a pretty big set of 12zs coming up. I expect the GFS to remain messy for the end of the week but maintains it's consistency with regard to the Greenland area. I would expect the ECM to follow in lowering heights in that region from days 7-10.

WHY?

I want reasons to back things up here. Why should the 12z completely back previous runs where strong heights have been shown. C'mon Ian, dont hide your reasons. Without them, I have nothing to believe you.

Edited January 6, 2013 by Blizzards

[snowking]

I know somebody posted about the new Indian model, its certainly our friend on the 0z:

http://www.meteociel.fr/modeles/ncmrwfe_cartes.php?ech=6&code=0&carte=1&mode=0&archive=0

Worth taking a look through the whole run. Very ECM esque.

On the other hand, the Chinese model:

http://www.meteociel.fr/modeles/cmae_cartes.php?ech=24&code=0&carte=1&mode=1&archive=0

Easterly only really affects the southern half of the UK, we then get a temporary northerly before too much energy piles over the mid atlantic ridge.

I always said that the Indians were better meteorologists than the Chinese anyway

SK

[bradymk]

I know somebody posted about the new Indian model, its certainly our friend on the 0z:

http://www.meteociel...ode=0&archive=0

Worth taking a look through the whole run. Very ECM esque.

On the other hand, the Chinese model:

http://www.meteociel...ode=1&archive=0

Easterly only really affects the southern half of the UK, we then get a temporary northerly before too much energy piles over the mid atlantic ridge.

I always said that the Indians were better meteorologists than the Chinese anyway

SK

haha yes, never seen these two on meteociel before. Regarding the Chinese one, have a look at yesterdays 12z.

[weatherobsuk]

We'd be now into week 4 of a SSW event had the pesky scandi-shortwave troughs decided to hang around, going to be interesting to see what happens during the viable period of winter when residual/urban heating makes less of an impact and nocturnal temps create their own micro-climates especially in areas like Woodford where oddly it's a few degree's higher up across the moorland of the Pennines.

I'm attending a Pennine fell-race next weekend in the midst of all this cold-pooling so have a interest to see what comes out the coming 48hr model runs, the countryfile forecast no doubt should make for some good viewing.

[Catacol]

Catcol - careful using the meteociel strat temp charts. They do not show where the heights are situated. Dont assume coldest area = lowest heights.

Aso, i keep reading that the models dont have the strat warming in the starting data as yet so are not taking account of it. Not true, the models are creatng the forecast of the ssw in the same 3D atmospheric simulation which generates the trop run we look at.

Agreed, but:

1. The strat charts show the underlying forcing... ie if one assumes friction acts across the layers of the stratosphere, then if the warmings signal areas where the stratospheric wind slows and looks to reverse then it shows where the troposphere will most likely feel those effects. Of course it does not mean an exact match - hence why I await the cpc anomaly charts tomorrow.

2. The models, as far as I am aware, do not have vertical resolution right through to the top layers of the atmosphere. Actually I am a bit hazy on this - it would be good to see some sort of tabular analysis on it as I think I read the other day that the op run uses greater vertical resolution than other ensemble members... but certainly all runs do not go to 1Hpa for sure. Bearing in mind the large wave 1 warming forecast to break in from the top of the atmosphere this is especially relevant at the moment. Some of the model/ensemble runs wont be seeing it at all.

[lorenzo]

Inter run it may be the case that the 12z ECM throws out a slightly less bullish Greenland ridge, that is if you want to use that run and herald it as the absolute guaranteed solution that is certain to verify, something I would not be keen to do on day 1 of an atmospheric U turn.

The trend toward a Greenland high cannot be excluded when the Ens are considered. So perhaps Ian will see a flatter ECM... for now. Will this be a disaster - no, the trend is good.

India, China, Korea.. what next !! Don't forget the Brazilian, everyone loves a Brazilian..

[Panayiotis]

Shame to a small extent the models have backed away from dropping the PV from the Arctic into Scandinavia but fortunately the cold air does still make us given the any easterly flow will be strong enough.

It nearly does, look at the chart below (from the 06z) part of the PV is there but is blocked by the high pressure which is over Scandi. If the PV can get round the HP (which is unlikely though) it will be heading right for us, but that is more of hopecast than a forecast.

Edited January 6, 2013 by Panayiotis

[ukpaul]

We'd be now into week 4 of a SSW event had the pesky scandi-shortwave troughs decided to hang around, going to be interesting to see what happens during the viable period of winter when residual/urban heating makes less of an impact and nocturnal temps create their own micro-climates especially in areas like Woodford where oddly it's a few degree's higher up across the moorland of the Pennines.

I'm attending a Pennine fell-race next weekend in the midst of all this cold-pooling so have a interest to see what comes out the coming 48hr model runs, the countryfile forecast no doubt should make for some good viewing.

A SSW has only just started, there was none earlier.

In fact that's the reason that people should be less concerned about sudden changes this time; with the continued disintegration of the PV for a couple of weeks then any missed opportunities in the next week are likely to be followed by other possibilties. Nothing written in stone for this part of the globe of course but the condition of the strat was not supportive of December's event, unlike now.

[Met4Cast]

Heights are a little stronger across Greenland thus far at T72..

Edited January 6, 2013 by Daniel Smith

[Catacol]

Well a pretty big set of 12zs coming up. I expect the GFS to remain messy for the end of the week but maintains it's consistency with regard to the Greenland area. I would expect the ECM to follow in lowering heights in that region from days 7-10.

Day 10 10hpa chart from 06z is this:

If low pressure winds up substantially in the Greenland area then I will be surprised. It also bucks the latest MJO analysis. I guess we are chicken and egg a bit here - can tropospheric patterns buck the stratoshere? (back in December GP believed so, and argued for blocking due to low tropospheric mean wind speeds despite the strat profile which was still quite strong.) However in December you were proved correct perhaps BECAUSE the strat signal eventually overrode a tropospheric pattern which the models initially believed was going to lead to reversal and blocking.

So which signal is the stronger? I'm of the mind at present that the strat is the egg that gives birth to the chicken - no egg, no chicken. I am hoping I learned a lot on December - perhaps we all did - and this time we are sat very favourably in this comparative analysis.

However all things are possible. I havent looked at the atlantic SST proflle for a while - how is it set?

[bluearmy]

Catcol, the ecm op goes to the top of the strat, as does the gfs op. the ecm ens go to 5hpa. I cannot find details re the top of the gefs.

You can see the heights from the strat part of the gfs run here:

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2013010606&var=TMP&lev=10mb&hour=360

As for the brazilian, i'm expecting a 'close shave' from that model !

Edited January 6, 2013 by bluearmy

[Continental Climate]

I think slightly stronger heights to our north http://www.wetterzentrale.de/pics/Rtavn841.png!! can only be a good thing i suppose

[Kentish Snowman in Yorks]

I think Ian is a closet coldie but just relies on the law of the sod for his predictions. I.E. whichever output is the mildest will be the likeliest to verify!

Unfortunately that is often correct although we are in a completely different ball park to previous predicted cold weather failures such as December 2012 due to developments in the stratosphere, so I for one am quietly confident of a decent cold spell incoming.

GFS is rolling...

Edited January 6, 2013 by Kentish Snowman

[Catacol]

Catcol, the ecm op goes to the top of the strat, as does the gfs op. the ecm ens go to 5hpa. I cannot find details re the top of the gefs.

As for the brazilian, i'm expecting a 'close shave' from that model !

Thanks - very useful information. If I get the chance sometime this week perhaps I will try and research and produce something that tells us how much vertical resolution the different models have. Not always relevant of course, because sometimes the tropospheric signals at medium range are so strong that I guess what is happening up at 1hpa is pretty irrelevant, but at other times like this where the stratosphere is suddenly experiencing such a dramatic change it becomes very important.

Amazing looking at the models for the coming week. A few days ago they were all showing a Euro/Azores high and lots of warm air. Now the whole picture is changing. I too would still like to see a section of vortex drop down through Scandy... GP was pretty bullish about it a few days ago.

[bluearmy]

Enough differences at day 4 to make a commentary very speculative!

[chris55]

Up stream pattern could be much better this run, more akin to EC.

[Continental Climate]

Enough differences at day 4 to make a commentary very speculative!

Hmmm i agree big changes in the orientation of the high pressure, everything from 108 onwards is fi

[weatherobsuk]

A SSW has only just started, there was none earlier.

In fact that's the reason that people should be less concerned about sudden changes this time; with the continued disintegration of the PV for a couple of weeks then any missed opportunities in the next week are likely to be followed by other possibilties. Nothing written in stone for this part of the globe of course but the condition of the strat was not supportive of December's event, unlike now.

There was a brief SSW event a week or two before the December's "beast from the east" failed to materialise, Easterly winds which eventually became blocked into Europe giving the eastern continent some exceptional low temps and snowfall cover. If it hasn't been for the scandi-shortwave blocking this pooling then we too would have endured a similar fate.

We would now be into week 4 of that event if it wasn't for the scandi-shortwaves breaking down any scandi-high that otherwise would have formed in its usual place. As we all know from 09/10 the implications of that is with exceptional cold eastwards.

[Catacol]

Pattern noticeably further west at 102. Signs that actually the 12z might begin to side with ECM. Should this happen then I smell forum combustion tonight, :-)

[on the coast]

Enough differences at day 4 to make a commentary very speculative!

Mmmn. All change again as you say.

[snowking]

Enough differences at day 4 to make a commentary very speculative!

My thoughts precisely

The thing I wanted to see in the shorter term though is it continuing to back the Greenland PV lobe west (as per its previous output and as per ECMWF) and it has indeed continued that backtrack. That separation of energy I was talking about to our north happens much sooner on this run.

SK

[chris55]

Overall the 12 is very very similar to EC from this morning,

[bradymk]

There was a brief SSW event a week or two before the December's "beast from the east" failed to materialise,

There was no SSW event in December, there was a slight warming prior to it but not a SSW which is complete reversal of zonal winds.

[TAFKAP]

Pattern noticeably further west at 102. Signs that actually the 12z might begin to side with ECM. Should this happen then I smell forum combustion tonight, :-)

Indeed, early indications that the model forum may go nuclear!