WInter Model Output Discussion 12z- 28/01/2013

[surrey slush]

Instead of cold we may want to concern ourselves with the 977 Low thats over Kent on Saturday.

http://www.meteociel...F1-96.GIF?29-12

Storm force winds & flooding likely.

S

How likely is that beast to verify I wonder, should I be oiling the chainsaws?

[WhiteFox]

BFTP as you can see you have just done the biggest contradiction in the universe can I ask why ?!!

Im disappointed this morning also , but 10 hours ago and all year in fact you have gone on about this feb been the month , and now you say this will be dominated by southwesterlies ?!

Is there reasons behind this or just feeling a bit emotional this morning like others ?!

Sarcasm alert!

Anyway, a very tenuous straw to clutch: the pressure anomalies have trickled ever so slowly north over the past few days:

26th Jan:

28th Jan:

If only it would push further north! Of course, this is all due to the PV over Canada, but IF we were to see a weakening as we often do in February then the Azores High really wants to push north.

It's a very thin straw, but it's all we have for sustained cold!

[Summer Sun]

Looking at the ensembles this morning the only clear pattern emerging is a drier first half to February which will be welcomed by many I'm sure

Matt Hugo has Issued his latest blog looking at what the final 28 days of winter may have in store - http://matthugo.word...whats-in-store/

Edited January 29, 2013 by Gavin.

[Severe Siberian icy blast]

Just a couple of points of order here Shaun.

Firstly for me, (with the knowledge that SSW's are hit and miss affairs) the SSW has more than delivered for me this winter - even if we don't get anything more from further downwelling. The whole tropospheric pattern is still being influenced to a more or less extent by the SSW (as well as other telecomnnections) - so to say that the topplers have nothing to do with the SSW is incorrect. it may be that some just don't like their influence on our shores.

You are correct in your assertion that we still have a lot to learn about stratospheric tropospheric interactions and feedback - but progress is being made. With the upper strat PV slowly reforming we will see some changes with, I suspect, the waning of the troublesome Canadian segment. There are still no signs that we will see anything other than topplers in the first week of Feb - but to me this pattern is still being dictated by events north of Greenland and towards the Pacific sector.

While I appreciate your response , I don't see how the Azores high ridging north from its southern most depths have anything to do with the SSW , to me it's the MJO moving through its phases that's helping this amplification ?

The SWW has along with wave activity split the vortex , agreed.

But the Canadian vortex has spoilt the fun this year , spilling too much energy into the Atlantic .

But baring in mind the SSW promotes high lat blocking , when looking at the Azores you can hardly call it that can you?

It's a mid Atlantic high , the NAO isn't cut off , the high ridges for a short time , then gets sunk by the low pressure riding over the top.

I love the strat side of things and have been nothing other than fascinated by your and GP's work , but you know that this downwelling hasn't had the effects we ALL thought .

Unless like I said a flip takes place in the mods .

[TEITS]

Mixed feelings on the model output this morning.

Everyone keeps mentioning the PV and a GH but if you look at the ECM ensemble mean you can clearly see the PV weaken.

However at the moment im not seeing a great deal of consistency in the output around this region and you can clearly see this on the Iceland SLP mean as this is going up and down like a yoyo.

At the moment im still going for the same outlook i.e progressively colder with the NW,lys eventually veering N then NE,ly. I would prefer to see a stronger signal in the GEFS ensembles but for the moment im not convinced they are right.

[winterof79]

I think that we will see a return to very mild SW'lies to dominate February and that winter 2012/3 has been ok but is over now. I hope you enjoyed.

Might as well say it, that's all I'm reading at the moment.

BFTP

Have to laugh at everyone taking the above seriously.Did nobody think to read the last bit

[SMU]

The pacific jet will always teleconnect to greenland- being that if its strong & the upper vortex is in close proximity to the canadian maritimes then a grenland high has almost no chance. That vortex has been in place for most of the winter....

It doesnt totally negate UK cold, but with a fast jet & low amplitude waves usually the best you can get is a pebble shaped scandi high..

I notice Matt in his blog has moved away from Any greenland high this winter & his assessment is basically what I said night - transient cold shots from the NW with a low probability of deep cold, but a probability we cannot totally rule out- Especially later in the month.

S

Edited January 29, 2013 by Steve Murr

[Methuselah]

Hope u have your tin hat on BFTP

Now, now, peeps...Unless Fred has suddenly taken-up 'modelling' trench-warfare costumes, I think that we are in imminent danger of wandering off-topic!

[Hotspur62]

Only been watching models for last 4 months and have picked up alot of knowledge reading and interpreting the experts on here,but feel there is a bit of negativity on here this morning(don't know if it is a reverse pschology thing?).The ECM looks fairly positive for cold and no one was expecting very cold air until about 10th Feb anyway were they?Models seem to be struggling with what impact SSW will have(if any),the vortex over Canada seems fairly strong but could weaken which might help us in UK,the Azores high is moving slowly Northwards but if it could move a bit more Westwards as well, it would help.The point i am trying to make is in the real scale of things it wouldn't take very much at all for the UK to have a very potent cold spell at all which would make the cold spell we have just had look insignificant.Conversley,if the AH stayed where it is projected to be or even move a little more Eastwards the cold would just ridge over us and put Central Europe in the freezer again.Margains are very fine for the UK but for those wanting cold and snow all is not lost.

As many have said before it is hard enough to look at T96-120 so everyone lets all see what the models produce in next 48hrs or so when things will slowly become clearer.

[Timmytour]

Here's the not impressive 0z GFS for next tuesday

And here's the more impressive 18z for the same time...

Now the later run is obviously not what we want, and indeed it goes on to virtually remove any cold uppers to our east whereas the 18z develops quite a pool.

But I'd say there's not really any more reason for the latter run to verify. What's appealing to me is the inconsistency of the runs which to my mind will provide us, not with a promise, but with opportunities for things to develop our way. For the moment I'm telling the fat lady she can put away the microphone cos Shannon Entrophy is still on the stage.

And i like the 18z....i know it gets called the pub run but I do think it's occasionally a trendsetter...sometimes good as here, sometimes it's the first the point in the direction of titsup!

looking forward to the 6z with interest......here we go

Edited January 29, 2013 by Timmytour

[TEITS]

Another thing I want to add is some of the comments saying "Time is running out".

Sorry but this is wrong. If you notice +384 only takes us to the 14th Feb. Now its quiet possible to have upper temps below -15C with max surface temps well below freezing even into the 3rd week of Feb.

The only time I would agree with this statement is from mid March onwards and even then snowfalls can occur. The only difference between cold spells in early Dec & late Feb is the strength of the sun which for obvious reasons would thaw lying snow despite very cold temps. However this does not bother me because in recent winters including this one I have seen many days of lying snow. Im not looking at the model output for endless days of lying snow but snowfall events whether this is frontal of convective.

Lets suppose another cold spell arrives this month and I see 3 snowfalls and 5 days of lying snow which is quiet possible. This would mean that during this winter I would of seen 8 snowfalls and 13 days of lying snow. Now I don't mean to be funny but that for me would be a damn good winter.

[tinybill]

Have to laugh at everyone taking the above seriously.Did nobody think to read the last bit

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=6

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

well all i say things could get very tasty from feb1 on onwards

[Weathizard]

ECM has proven itself within 96 over the GFS once again, nasty low pressure in about 4 days now on GFS 6z also.

[Timmytour]

The 6z seems to have that low over the North of Scotland for tomorrow as more intense.... I'm beginning to wonder if Murcie Boy's been predicting anything lately!

[Frosty.]

I think that we will see a return to very mild SW'lies to dominate February and that winter 2012/3 has been ok but is over now. I hope you enjoyed.

Might as well say it, that's all I'm reading at the moment.

BFTP

I like your reverse psychology Fred, i'm going to assume your post was a joke otherwise.

If there was going to be a change to prolonged mild swlies, they won't be here until after mid feb

[SomeLikeItHot]

Amazing difference between the GFS 0Z and 6Z at 90hrs with that low being non existent on one and intense on the other.

[Blizzardof82]

ECM has proven itself within 96 over the GFS once again, nasty low pressure in about 4 days now on GFS 6z also.

I thought the GFS was first to pick up that channel low?

[Bobby]

The GFS has picked up on that nasty low now, the GEM has it too. Strong winds...

[Joe Levy]

Amazing difference between the GFS 0Z and 6Z at 90hrs with that low being non existent on one and intense on the other.

New poster on this thread here. I think this clearly highlights how we need to be careful about taking individual runs as the truth - if they can't manage to agree on what will happen in 90 hours time, how can they possibly be expected to give a conclusive answer on the chances of cold in 10 days time?

[Nick F]

ECM has proven itself within 96 over the GFS once again, nasty low pressure in about 4 days now on GFS 6z also.

Yes, GFS had the same deep low wandering SE down to the Pyrenees on yesterday's 06z run! EPS yesterday were in support of ECM op of taking it east along Channel/S England.

Aswell as the GFS, ECM suggests snow across N England Friday PM, could be nasty conditions combined with the gales up there:

[Timmytour]

Amazing difference between the GFS 0Z and 6Z at 90hrs with that low being non existent on one and intense on the other.

And yet a day later there's not much discernible difference from the previous run!

[bluearmy]

New poster on this thread here. I think this clearly highlights how we need to be careful about taking individual runs as the truth - if they can't manage to agree on what will happen in 90 hours time, how can they possibly be expected to give a conclusive answer on the chances of cold in 10 days time?

the low at the weekend is a small scale feature within a general agreed overall background pattern joe. the models can disagree with the particular feature but they have the same background longwave pattern in place. where you have a point is that with a sceuro trough and atlantic ridge we could easily get shortwaves running across our locale far enough west to be slider features which deliver snowfall. these samll scale features will not be showing at such a long timescale.

i am noticing the ecm day 10 mean with the canadian vortex linking to the siberian segment in the alaskan area. that would take a lot of energy away from the atlantic thereafter.

[Weathizard]

Interesting at 156, looks slightly different low out of the eastern seaboard looks to be advecting heights between two lobes of the PV.

[Joe Levy]

the low at the weekend is a small scale feature within a general agreed overall background pattern joe. the models can disagree with the particular feature but they have the same background longwave pattern in place. where you have a point is that with a sceuro trough and atlantic ridge we could easily get shortwaves running across our locale far enough west to be slider features which deliver snowfall. these samll scale features will not be showing at such a long timescale.

i am noticing the ecm day 10 mean with the canadian vortex linking to the siberian segment in the alaskan area. that would take a lot of energy away from the atlantic thereafter.

Yes you do make a very good point about the low at the weekend. However, I would say that given that the strength of any low pressure systems has an effect on the formation of high pressure (I think it's called WAA or something like that?) small features can make a big difference. On the 6z all low pressure systems seem to be much stronger in my eyes at least and consequently the high in south-western Greenland is at 1025mb at 156hrs as opposed to 1015mb from the previous run.

Edited January 29, 2013 by Joe Levy

[Timmytour]

T165 come on Scandi low....start falling down the North Sea!