Model Output Discussion

[SussexmarkyMark]

can you please post the charts that make it less likely than yesterday morning because I think it still hangs in the balanace, it seems dependant upon the track of the two low pressures that either head north or south, until this is decided which is in FI then I am not too sure

Sorry, I don't have time to post charts as I'm at work, but as we have moved on another 24 hours and still none of the main models are showing an easterly for next week, I think the likelyhood of it happening is reducing. It's all a matter of looking at trends and the trend is towards the Atlantic and not an easterly.

As I said in my earlier post (which I repeated from yesterday) the most likely outcome is a fairly chilly SEasterly for SE parts of the UK mid next week and more of an Atlantic influence further NW in the UK, with the Atlantic influence spreading to post parts of the Uk later next week.

[Terminal Moraine]

i don't wish to make direct comparisons between this year and 1962/3 but I know from reading up about it that a high pressure with an centre of above 1050mb collapsed just before Christmas which then led to the developments that led to such an outstanding winter.

Of course no guarantee would come with the collapse of the current high pressure system in terms of what cold weather it might bring, but since it dominates a lot of the thinking on here, could I ask a few questions...

1) how common is it for such systems to collapse within a day or two as I believe happened in 1962?

2) are the models in place complex enough to forecast such collapses and, if so, do any of them forecast the collapse of the current Siberian one?

Many thanks

It wasn't so much that the high pressure to the east collapsed around christmas 1962, more that it gradually formed a link with the Greenland high and eventually established itself there immediately after christmas. It then went on to develop further and form a broad band of high pressure stretching from Greenland to Scandinvia, this forced the jet a long way south of its usual position.

The major difference between then and now is that, currently, the Siberian high is further east than was the high pressure in 1962 and is unable to drift westward due to the increasing power of the jet which is running directly at it rather than under it.

If the current Siberian high was to collapse the jet would have an unrestricted flow right into western Russia and we would be back in a situation similar to the horrors of recent winters.

Although the current models are favouring a return to less cold weather, as long as the high to the east retains its strength and position, I'd say there was a good chance of the cold weather returning in about two weeks time, the brief return to colder conditions and the battleground situation in the middle of next week will be an added bonus.

[weather eater]

Considering the way the models have been back and forward with regard to a

continental feed next week and we are still talking about the t144 range then nothing

is settled yet and I think it is a bit premature to say it is.

Next week certainly does not look mild, not in the east anyway.

Morning CC, I think your post sums up, exactly why we get days like yesterday, full of people getting the nark with one another. The models have really not been back and forth with anything; in fact I would suggest that they have been very consistent with the general pattern. Yes a few runs have tried to establish a meaningful easterly, but the general trend has been for an initial Atlantic incursion, followed by a brief period of influence by the Siberian high and then a return to a normal UK westerly based regime. I would say about an 80/20 split in favour of that evolution, I do often wonder if some members are looking at model runs in an alternative universe from the one I live in.

TEITS is right to suggest that this evolution is not set in stone, we have, after all, seen rock solid looking projections fall over at short range before. However, I doubt that if he turns out to be wrong, that those who have suggested that the Atlantic will most likely win out, will receive quite so many sycophantic posts suggesting that they are in fact forecasting geniuses, in the way that Dave has done. Don't get me wrong I’m not knocking TEITS he’s a great bloke and he has a good handle on the models, explains why he thinks the models will play out in a certain way. What has been nauseating over the last couple of days is the copious all praise to TEITS the weather forecasting guru posts. Its always nice to have a post commented on in a positive way, but there are many on NW who are just as good at analysing the models, but who get little praise just because they are less partisan about cold and easterlies. While I don't see any need for members commenting on the models to always be completely objective, I do think objective comments on those posts are a far better read, than an endless sea of posts praising XXXX while making no observations of their own.

The second paragraph is not a comment on any of your posts CC its just something I feel needs saying.

[KTtom]

I thought I had read somewhere that GP thought feb was going to be very mild with high pressure to the south and lows tracking between iceland and scotland, hope I misread it.

Indeed, but he also thought the second half of January would bring the coldest spell of the winter, his recent silence is deafening...no-ones infallable

[nick sussex]

The cut off low is causing a real headache with some models edging this east under the advancing ridge whilst the gfs pulls this nw into the main Atlantic trough, this difference then effects everything afterwards in terms of whether a cold surface flow moves into the UK which then effects any possible snow in relation to the advancing fronts from the west. So IMO until this is resolved then everything afterwards is liable to a high degree of variability.

[cooling climate]

Morning CC, I think your post sums up, exactly why we get days like yesterday, full of people getting the nark with one another. The models have really not been back and forth with anything; in fact I would suggest that they have been very consistent with the general pattern. Yes a few runs have tried to establish a meaningful easterly,

Maybe you have missed a few of the model runs then, or was simply not paying attention to

what the models were showing.

Given what the 06z GFS run is showing I still would not like to say for certain what will happen next week.

[nick sussex]

Morning CC, I think your post sums up, exactly why we get days like yesterday, full of people getting the nark with one another. The models have really not been back and forth with anything; in fact I would suggest that they have been very consistent with the general pattern. Yes a few runs have tried to establish a meaningful easterly,

Maybe you have missed a few of the model runs then, or was simply not paying attention to

what the models were showing.

Given what the 06z GFS run is showing I still would not like to say for certain what will happen next week.

I agree, as i just mentioned the models dont even agree on where the cut off low goes at T-72hrs which has a big effect later on so why then are people assuming that output into FI will verify.

Edited January 15, 2010 by nick sussex

[chionomaniac]

What we are seeing presently is a completely different PV profile than we have become accustomed to this winter. We have already seen a couple of vortex splits leading to two segments, one over Canada and one over central Siberia which have been very favourable in producing northern blocking and leading to the last month of cold weather.

What we see forecast now is a displacement of the PV in totally the opposite way stretching the heart of the PV over Pacific Siberia with an arm from this stretching right out to Greenland. It is this arm that is responsible for the troughing seen to our NW. Furthermore the energy in the PV is being invigorated by an increase in mean zonal winds that are working themselves down from the stratosphere as a result of cooling there over the last month. This is likely to continue before the effects of any MMW will be felt at lower levels.

After reading GP's latest update and looking at the composites for the MJO phases 6 and 7 in January and phase 8 in February we should see a eastward slow migration of the Greeenland based vortex arm over the coming weeks. This could leave the door open for NW height rises and northerly winds as a result. Longer term in February it is difficult to say whether the MMW will propagate effectively to the troposphere as displacement type MMWs do not normally propagate as well as split type MMWs. There are thoughts on Eastern that we will have another strongly negative AO period in February as a result of the MMW but that remains to be seen. Remember the last MMW where La Nina conditions almost completely overrode any blocking pattern. Well this year we have an El Nino but with a strong La Nina undertone so will February follow last years pattern?

Edit: I will add that any battleground situation is still possible in the coming week before the trough to the west slowly migrates to the east but I think that ultimately the Siberian High will lose - the 100 hPa forecasts also suggest this.

Edited January 15, 2010 by chionomaniac

[karyo]

The cut off low is causing a real headache with some models edging this east under the advancing ridge whilst the gfs pulls this nw into the main Atlantic trough, this difference then effects everything afterwards in terms of whether a cold surface flow moves into the UK which then effects any possible snow in relation to the advancing fronts from the west. So IMO until this is resolved then everything afterwards is liable to a high degree of variability.

This looks even worse for the UK as it makes it less likely to pull a continental flow. I', afraid we're moving further away from a cold outlook.

Regarding the stratosphering warming, there are some interesting posts in the Stratospheric discussion thread, but GP hasn't mentioned it at all. Reading between the lines, he expects the la nina state that the atmosphere has entered to overide the stratospheric warming - similar to what happened last year!

Edit: I see Chiono has just posted a better explanation...

Karyo

Edited January 15, 2010 by karyo

[weather eater]

Morning CC, I think your post sums up, exactly why we get days like yesterday, full of people getting the nark with one another. The models have really not been back and forth with anything; in fact I would suggest that they have been very consistent with the general pattern. Yes a few runs have tried to establish a meaningful easterly,

Maybe you have missed a few of the model runs then, or was simply not paying attention to

what the models were showing.

Given what the 06z GFS run is showing I still would not like to say for certain what will happen next week.

Nope I've seen them all, of course there are differences in detail, and yes these could change things, but the overall pattern especially in regards the Siberian High, is for it not to be a real influence on us or at best a fleeting visit. If we are making comment on recent model outputs a really fail to see how anybody can see it differently.

Edited January 15, 2010 by weather eater

[bluearmy]

the ebbing and flowing re the siberian block v the atlantic is next weeks story. the strong signals from the extended ens means is that the trough will head in our direction and ecm and gfs are both showing this on their 00z output. there is also, currently, a strong indication of a northerly/north easterly type flow around the 25/27th of the month with associated drop in uppers and a shortwave running w - e at the southern end of this flow. keep looking for a channel low type evolution around this time period. ecm T240 shows this scenario quite well.

[weather eater]

Indeed, but he also thought the second half of January would bring the coldest spell of the winter, his recent silence is deafening...no-ones infallable

I think you will find that he made a long post yesterday evening on the technical thread, he does seem less inclined to post in the general model thread, can't say I'm surprised.

Edited January 15, 2010 by weather eater

[nick sussex]

This looks even worse for the UK as it makes it less likely to pull a continental flow. I', afraid we're moving further away from a cold outlook.

Regarding the stratosphering warming, there are some interesting posts in the Stratospheric discussion thread, but GP hasn't mentioned it at all. Reading between the lines, he expects the la nina state that the atmosphere has entered to overide the stratospheric warming - similar to what happened last year!

Edit: I see Chiono has just posted a better explanation...

Karyo

Yes well the Siberian high might eventually lose the battle but there could still be some fun and games next week beforehand. The gfs wasn't used today by NOAA as they see it as an outlier solution by phasing energy over the eastern USA. We'll have to see what the models do first with the cut off low before having a better idea of whats to happen next week.

[len]

i don't wish to make direct comparisons between this year and 1962/3 but I know from reading up about it that a high pressure with an centre of above 1050mb collapsed just before Christmas which then led to the developments that led to such an outstanding winter.

Of course no guarantee would come with the collapse of the current high pressure system in terms of what cold weather it might bring, but since it dominates a lot of the thinking on here, could I ask a few questions...

1) how common is it for such systems to collapse within a day or two as I believe happened in 1962?

2) are the models in place complex enough to forecast such collapses and, if so, do any of them forecast the collapse of the current Siberian one?

Many thanks

I've looked at this many times

http://www.wetterzentrale.de/topkarten/fsreaeur.html

Between the 20th Dec & Boxing Day 1962. There was a very deep vortex over Baffin which split and sent a centre over to NW Russia. This allowed the rapidly developing East-Euro High to duck under the Eastward travelling vortex and transfer quickly to Greenland, they passed like two slippery blobs.It makes interesting watching.

While this kind of this is possible, that does not mean it will, or even can, happen on any occasion. I rely on GP, Brickfielder, Chionomaniac et al to tell me if it could or should happen. Presumably in the final days of 62 there were compelling physical forces and/or teleconnections that made it happen

[Timmytour]

It wasn't so much that the high pressure to the east collapsed around christmas 1962, more that it gradually formed a link with the Greenland high and eventually established itself there immediately after christmas. It then went on to develop further and form a broad band of high pressure stretching from Greenland to Scandinvia, this forced the jet a long way south of its usual position.

The major difference between then and now is that, currently, the Siberian high is further east than was the high pressure in 1962 and is unable to drift westward due to the increasing power of the jet which is running directly at it rather than under it.

If the current Siberian high was to collapse the jet would have an unrestricted flow right into western Russia and we would be back in a situation similar to the horrors of recent winters.

Although the current models are favouring a return to less cold weather, as long as the high to the east retains its strength and position, I'd say there was a good chance of the cold weather returning in about two weeks time, the brief return to colder conditions and the battleground situation in the middle of next week will be an added bonus.

Many thanks for the explanation TM. I must admit that the sweep of Atlantic weather all the way into Siberia was what i was thinking if the High did indeed collapse....which is not an unusual sight based on the past few winters! Your explanation of the high linking up with one over Greenland makes sense and sounds like it created the conditions that gave us 1947 as well.

As for what lies ahead...well the models don't make optimistic reading I guess, but I'll remain optimistic nonetheless, but not for any scientific or model analysis reasons! I just think that so much can change in such a short time. Only a couple of weeks ago I was reading that the models were giving us unbelieveable sights of a prolonged, bitter, snowy winter. As fast as they have recoiled from that, they can surely revert to something near it again.

And while I have the utmost respect for GP, his analysis of what's happening is only commensurate with the data he is receiving. This can change as well. I recall during the cold snap early last February that he was advising that things could get even colder going into the second half of the month when it actual fact it turned almost springlike.

Nobody can say with 100% success rate what's going to happen, but certainly at the moment the head is going with a wet and mild outlook while trying to rebuff the cold excursions offered up by the heart!

[Rollo]

Re the battleground situation betwixt the Siberian high and the atlantic. Making comparisons is dangerous but nevertheless I hark back to the mid-end Jan 1956,the old memory seems to recall that for days during that period the weather forecasts threatened a cold blast from the east and it just did not happen so the MO stopped refering to it and when it came it was virtually unannounced. I think therein lies the problem,the charts are in a state of flux and if and its a big if we are to get a return of cold we will not get a great deal of warning,

[Methuselah]

Looking at today's models, I fear another '1982' is about to happen: one of the deepest/coldest blocks in years was blown-away in a matter of days, leaving the rest of the winter pretty nondescript...Having said that, I cannot possibly know what'll transpire over the coming three months???

Blocks come, go and come again. And, at the end of the day, they usually take us all by surprise!

[Glacier Point]

Indeed, but he also thought the second half of January would bring the coldest spell of the winter, his recent silence is deafening...no-ones infallable

Oooh, you are a tough cookie to please ! Although the return to milder conditions during the next few days cannot derail the below average forecast for January.

The updates on the in-depth model analysis thread show where I think we are heading. There is still a window around the last week or so of the month as the longwave trough migrates eastward across the UK dropping into Scandinavia. The warming (not technically a MMW yet) of the stratosphere may have some more immediate impact at this time and some of the model output has being playing around with a height rise towards Svalbard around month's end with a negatively tilted jet. Any potential impacts of this warming look more likely being a factor in March than February.

Two weeks ago I was favouring mild for February and I still am. I see Joe B has also flagged up the atmosphere starting to turn on this Nino and there is a definate Nina-like tendency developing which will I think trend for a mean trough solution into Scandinavia for the first week Feb (this will be very noticeable as a contrast to the pattern now) thereafter becoming something of a Euro High type solution so quite contrasting weather patterns for NW Europe in prospect.

Edited January 15, 2010 by Glacier Point

[markg]

Looking at today's models, I fear another '1982' is about to happen: one of the deepest/coldest blocks in years was blown-away in a matter of days, leaving the rest of the winter pretty nondescript...Having said that, I cannot possibly know what'll transpire over the coming three months???

Blocks come, go and come again. And, at the end of the day, they usually take us all by surprise!

Well said Pete , we have too much data and info these days, much of which is all FI after 144hrs and generally only trends are spotted after this in low resolution , if we only had up to 144 hrs if would be a lot more fun , and as you say a small change in the short term makes a hugh change in the eventual evolution ,bring on the next one its still only the middle of january 28 days with snow on the ground here is just the best winter ever in my memory

Edited January 15, 2010 by markg

[cooling climate]

Well after reviewing the models and reading the latest discussions from NOAA I am of the view

that at least the eastern half of the country will be under a continental cold feed during the middle

of next week (Wednesday, Thursday time) whether the Siberian high can then keep the Atlantic at

bay further into the week and weekend is still open to question.

[D KARLSON]

Yes well the Siberian high might eventually lose the battle but there could still be some fun and games next week beforehand. The gfs wasn't used today by NOAA as they see it as an outlier solution by phasing energy over the eastern USA. We'll have to see what the models do first with the cut off low before having a better idea of whats to happen next week.

Im with you on that one ,there are many details to be resolved as the atlantic tries to push in and of course still the outside chance that the cold high could push back in albeit temporarily.

What perhaps looks like the more probable long term outcome ,would be the lows shunting up against the high to our east and forming a north south trough over britain which would preclude any really mild spell and then perhaps bringing a cool northwesterly although this is pure conjecture at this time.

I think the problems with the synoptics currently forecast is how the atmosphere is going to interact with the very cold surface temps over europe , this will be very difficult to factor into the models as high prssure will always want to reform over this very cold landmass ,certainly wil l be amusing to see what happens !!!!!

[Duane S.]

Re the battleground situation betwixt the Siberian high and the atlantic. Making comparisons is dangerous but nevertheless I hark back to the mid-end Jan 1956,the old memory seems to recall that for days during that period the weather forecasts threatened a cold blast from the east and it just did not happen so the MO stopped refering to it and when it came it was virtually unannounced. I think therein lies the problem,the charts are in a state of flux and if and its a big if we are to get a return of cold we will not get a great deal of warning,

I very much agree with that last sentence. The charts are struggling at the moment and reading through the past 4-5 pages of posts I find it incredible how so many people simply 'know' what's going to happen

We've been here before, many times and we all know which side normally wins BUT that hardly makes it the formality so many are referring to. However, the energy around Greenland is quite obviously the problem here and I suspect that it will indeed become the over-riding factor in the end as the lag effect from Stratospheric cooling now starts to show its hand.

What gives me some hope, medium and long term, is that the AO is, possibly, set to plummet again. Although the Arctic Oscillation only has an indirect effect on us in the UK, we will need help from elsewhere but its a start.

The NAO shows no sign of going strongly positive, all members are there or thereabouts neutral.

The MJO looks set to move on round to move favourable phases which may encourage blocking to our NE and later NW.

and Strat warming, to some degree, is still looking possible which would (possibly) help break up the PV later on.

Edited January 15, 2010 by s4lancia

[Methuselah]

Well said Pete , we have too much data and info these days, much of which is all FI after 144hrs and generally only trends are spotted after this in low resolution , if we only had up to 144 hrs if would be a lot more fun , and as you say a small change in the short term makes a hugh change in the eventual evolution ,bring on the next one its still only the middle of january 28 days with snow on the ground here is just the best winter ever in my memory

Thank you, Mark!

IMO, we may have to wait a few weeks before we see any 'deep cold' return? But, either way, lying snow for twenty-seven days, is not to be sneered at??

[Frosty.]

I'm reading a lot of posts talking about a battleground, I can't see there being a battle, more a skirmish which the mild will win although tomorrow there could be some rain turning to snow in the east before turning back to rain again with next week less cold / milder everywhere.

Edited January 15, 2010 by Frosty039

[nick sussex]

Im with you on that one ,there are many details to be resolved as the atlantic tries to push in and of course still the outside chance that the cold high could push back in albeit temporarily.

What perhaps looks like the more probable long term outcome ,would be the lows shunting up against the high to our east and forming a north south trough over britain which would preclude any really mild spell and then perhaps bringing a cool northwesterly although this is pure conjecture at this time.

I think the problems with the synoptics currently forecast is how the atmosphere is going to interact with the very cold surface temps over europe , this will be very difficult to factor into the models as high prssure will always want to reform over this very cold landmass ,certainly wil l be amusing to see what happens !!!!!

I think it's a case of trying to squeeze out as much fun from the Siberian high before the Atlantic throws the kitchen sink at it! Given the model output the ukmo further outlook looks like a west/east split with cold air never too far away from the east. Tonight my attention will be on the cut off low as that helps to advect some colder surface air westwards as it helps the ridge, also theres the shortwave that dives se further into europe, this is a fly in the ointment as it delays the ridge backing west, it's likely to verify so here the further west it is the better as that brings the ridge further west with it. These two variables are within the 96hrs timeframe and have a large effect on the outlook.

However it's hard to make a case for a proper easterly unless the models have called the upstream pattern wrong,so we're looking more at trying to get enough cold air in to give a chance of some snow as fronts try and push eastwards. The really cold upper air looks to stay tantalisingly close but for the moment unable to push far enough west.