Model Output Discussion

[Frosty.]

I'm talking within the context of a reload of another countrywide cold spell such as we have seen in the last month or so. Yes undoubtably there is potential for some snow in a few parts of the country over the coming days, but overall there is no reliable sign of a return to the significant upper cold conditions that have dominated the first half of winter. More importantly, in my opinion, the chances of the UK being influenced by any further upper cold surge are less than they have been

It's very hard to get a country wide cold spell though isn't it Tamara, so it will probably be just the northern half of the uk and especially the hills in the northeast which has a chance of some more wintry spells during the next few weeks with the south and west somewhat less cold / milder. Let's see what the meto think later.

[Cheshire Freeze]

Signs are there in FI, deffinately. The 6z run is also showing some promise- now coming into the 192-240 timeframe.

Aaron

[MR EXTREMES]

I'm talking within the context of a reload of another countrywide cold spell such as we have seen in the last month or so. Yes undoubtably there is potential for some snow in a few parts of the country over the coming days, but overall there is no reliable sign of a return to the significant upper cold conditions that have dominated the first half of winter. More importantly, in my opinion, the chances of the UK being influenced by any further upper cold surge are less than they have been

i cant agree more signals are not there but i dont think its going to be blowtorch either not even in feb with arctic snaps and pm snaps.

all the more experienced posters including joe b are suggesting not much chance of return to cold.

and as ive said so many times there is no need to be dissapointed because winter has been fantastic.

i think chances of snow and cold flip to the west and north west side of england and scotland its only fair they has some of the action aswell.

so over all foreget fi that will change.

alantic will win.

but never blowtorch.

cold snaps for the north and west.

rest of winter average or slightly below im happy with that.:unsure:

[lorenzo]

Living near the east coast of Scotland the ECM provides a shiver this morning for mid-week and limited potential.

The ensembles evidence 850 temps in the area of just cold enough, LS spotted on the t96 fax from MO the 528 dam line appears just off the E coast. Also ensembles show another dip in temps from 27th.

SST for the North sea are also heading in the right direction - so definately potential for snow dependent on ppn.

Not looked North West yet and not experienced enough to know what a cold low heading SE over the country would bring..

[TEITS]

Personally I feel its a case of wait and see what happens next. Lets remember during Xmas there was little suggestion of another cold spell and members were making similiar comments. Look what happened our cold spell appeared out of nowhere at +168!

The combination of the GEFS ensembles and the large differences between the 0Z/06Z means anything is possible. However the models have backed away from endless mild SW,lys as I thought tbey would do.

Based on the model output especially the 06Z the Teleconnections look wrong at the moment. Some were suggesting the PV will drop in Scandinavia but like I said yesterday this won't be the case. Also the GFS is suggesting LP to our S rather than HP!

I feel the best of our winter is yet to come and this could begin in the last week of Jan into the start of Feb.

[Methuselah]

I'm talking within the context of a reload of another countrywide cold spell such as we have seen in the last month or so. Yes undoubtably there is potential for some snow in a few parts of the country over the coming days, but overall there is no reliable sign of a return to the significant upper cold conditions that have dominated the first half of winter. More importantly, in my opinion, the chances of the UK being influenced by any further upper cold surge are less than they have been

Good morning,T.

I think that your last two posts sum-up the situation pretty well: there doesn't seem to be a re-load situation coming soon. But, as you say, things look like staying cold enough for outbreaks of wintry weather to come from other directions from time-to-time...And, I'm definitely not going to attempt to predict any detail!

[Ben_Cambs]

Personally I feel its a case of wait and see what happens next. Lets remember during Xmas there was little suggestion of another cold spell and members were making similiar comments. Look what happened our cold spell appeared out of nowhere at +168!

The combination of the GEFS ensembles and the large differences between the 0Z/06Z means anything is possible. However the models have backed away from endless mild SW,lys as I thought tbey would do.

Based on the model output especially the 06Z the Teleconnections look wrong at the moment. Some were suggesting the PV will drop in Scandinavia but like I said yesterday this won't be the case. Also the GFS is suggesting LP to our S rather than HP!

I feel the best of our winter is yet to come and this could begin in the last week of Jan into the start of Feb.

I totally agree, Feb has always been our best month for blocking etc,

[Bobby]

There's little sign of the Atlantic properly taking control and establishing itself on the models. It's certainly there but there's a lot of interesting things happening too. Hints now emerging on today's charts I think of another potential cold spell towards the end of the month. I expect we will see something interesting emerging over the next few days as we get closer.

[bluearmy]

teh evolution of the 06z, whilst looking odd is not, is not implausibe. the retrogressive signal is strong in a week or so.

[Guest North Sea Snow Convection]

From what I can see of the stratospheric charts a MMW is still a real possibility but as I said in a

post yesterday its not the b all and end all as I think some are now over fixated with this

Atmospheric response.

In my opinion it is more important to look at the mjo and possible rosby wave dispersal into the

Arctic, afterall this is what led to the tanked AO that we have seen so far this winter.

Plus lets not forget the increased ozone in the lower stratosphere which aided in blocking over the

Arctic.

I really can not see this suddenly switching off and fully expect a cold pattern to return as the models

are starting to trend to in FI.

Not an over fixation at all - it is just that the overall background of factors are not as conduisive as they were for a return to the conditions we have previously seen. It is in that sense that any potential MMW is important to offest those factors. Remember it was the upwelling phases in the lower stratosphere that played a major part in ushering us into the very cold weather of recently - that is now over and we have a backlog of positive zonal winds to deal with. This is going to make it harder for blocking to back the cold south and west enough once again to us

Edited January 17, 2010 by North Sea Snow Convection

[weather eater]

We often talk about trends on these pages, well the GFS certainly has one and its not Bartlett's. Although it gets there by slightly different routes, its a mid Atlantic ridge that keeps appearing, that's now shown its hand about four times over the last five or six runs worth watching if the ECM also starts to pick this idea up.

[Duane S.]

In this sort of setup a cold spell could spring up and be upon us very quickly. It would hardly be 'out of nowhere', when there is a block of that size to our East it simply cannot be dismissed no matter what else is going on. But I think the cigars are going to have to go back in the box for the time being at least.

Personally I still think that we are looking at a negative NAO and low pressure over Scandi in about two weeks time, I think we are looking at a potential Northerly regime come then. Before then though and if (and I hope I'm wrong) the block doesn't assert any meaningful influence upon us as I suspect it won't, we will really need to look out to the west to see what that building low pressure has in store for us, I think it could be quite spectacular for many towards the end of the month.

One thought I had reference TEITS' seagulls. I think they are picking up on the high pressure sprawling out of Siberia. All the gulls know is that very cold weather is heading towards them from the east, they cannot possibly know that the block has an adversary to the west at least equal to it. They may normally get it right but I think (despite a farly cold incursion midweek) they have got this one wrong.

[Shiny_Bottom_1]

Before people start jumping down Richards throat, what perhaps we need to watch is, no matter the name (Bartlet, Azores, Euro), is that High Pressure is sitting to our south.

We are presuming that high pressure will be more dominant from the east, because...well...the jet etc are forecast as such. But the jet and pressure forecast are linked, no matter how many times I mention it, it is still used as a reason why there can't be a different outcome.

Teleconnections, and influences outside of what the models show, such as the thoughts of GP/CM/BFTP/RJS, use this and for me, show a far less biased view on the outcome.

Some teleconnections favour a colder scenario, but some do favour a milder scenario. But, the longevity of both, is not being stated, but there is an assumption on a milder scenario, people assume that it would be a south HP for months. Never assume!

But back to the high pressure situation. People are talking about there being nothing mild in the charts, but in the same breath, there is nothing cold similar to what we have experienced either (or cold to the same scale as what people rant their worries on when someone mentions mild/milder).

My issue is, why can't somebody discuss a mild potential, especially when there is a pressure in a position to potentially deliver this (and this is all thats been pointed out...the potential), yet anybody can discuss a cold potential (again, potential).

I understand its winter, and I would much prefer cold to mild (and average), but we need to inject some realism.

This is a thread to discuss the models, but, and i'm glad, we discuss our personal opinions (or instinct if you want to call it that). But there is too much emphasis on jumping on peoples backs when they note their opinions, when it isn't about what others want to show.

Again, the points made about the high pressure to our south, is about the potential, not the deliverance (the same as people are discussing the potential of the high to our east, not the deliverance). This is why it gets on my wick, because there are quite often too many double standards (in this is much more emphasised in winter).

I could go on for ages about my own annoyances on how people both perceive their own opinions, and how they criticise others, but the crux is, for these reasons, I hardly post in this thread anymore. Its not worth it, when you give a balanced (mild or cold) view, if you don't have a clique of followers. Because if you says the word 'mild' or 'milder', you're perceived as being a 'mildie' or 'wind up merchant'. It bores me, and I find at times some of the posts on here childish and 'band-wagon' style.

Anyway, i've said before, and i'll say again. Watch the High Pressure to our south. Do not presume i'm talking about heat waves, or particularly hugely above average temps, but watch it. I do not see it going anywhere fast, just as much as (at the moment) I do not see the high pressure to our East particularly making it over all of the UK or for a long period of time.

The pressure to our south, may, in the long run, be to our benefit. In the mean time, low pressure from our west looks the most predominant feature.

Edited January 17, 2010 by Shiny_Bottom_1

[chionomaniac]

A lot of pointing towards FI this morning in terms of another cold spell possibility. Nothing especially mild is suggested, but other than the proximity of some surface cold initially in the east then temps wise things look fairly average.

I may be wrong, but I do think that the coldest weather of the winter has passed us by and although there is plenty of time for further cold weather with signs of pressure build over the arctic it could be the case that some are over assuming that we in the UK are going to automatically reload into another very cold spell towards the end of the month. Whilst the possibility is there, I do think the overall signals are fading in terms of whether the UK is going to see any renewed surge.

The falling angular momentum and the rather diminished prospects for an MMW are not going to help. Also there is a rise of pressure over Iberia also progged in FI that could easily also keep the cold air to our NE. That could easily be a first step towards the Feb scenario that GP has repeatedly pointed to.

Understandable hopes being expressed within the context of the remarkable first half of the winter - but expectations about the second half of the winter might be rather too high imo. I am less convinced now than previously about a further very cold spell.

Morning T. I believe that the wobble seen from the models yesterday regarding an MMW has been replaced with further indications that this is likely to occur now with significant negative mean zonal winds between 70-90ºN. As I have just posted in the strat thread I feel that the positioning and strength of any residual energy left from the vortex displacement in the Greenland branch will be critical in whether any further significant cold spell will develop. It is too early to rule one out for the end of the month but equally it is to early to rule one in. I would far rather see a longitudinal stretching/splitting of the PV similar to the one we saw earlier in the winter rather than the present forecast, however, we will have to take what we can get.

[High Altitude]

Personally I feel its a case of wait and see what happens next. Lets remember during Xmas there was little suggestion of another cold spell and members were making similiar comments. Look what happened our cold spell appeared out of nowhere at +168!

I feel the best of our winter is yet to come and this could begin in the last week of Jan into the start of Feb.

Absolutely agree with that. By this time next week (if not before) it'll be another cold spell that we're talking about. The signals might not be there at the moment but they can change at the drop of a hat and with so many variables its not worth worrying about. Even in 78/79 there was a period of average temps, followed by a thaw and flooding that lasted for about 15 days before the next cold spell set in at the end of Jan.

In my eyes we've still got over 2 months of proper winter left and with Feb traditionally a more blocked winter month all is still to play for. There is a lot of bottled up cold to our North and East which wouldn't take much to tap into. This is just my opinion but i think the Siberian High will be more of an influence than the models let on. This dense pool of cold air will not be easily pushed aside.

Edited January 17, 2010 by High Altitude

[lorenzo]

Lancia you mention the low pressure being spectacular towards the end of the month - being new to this and looking through the winter set ups from the guides area this synoptic is not illustrated. Correct me if I am wrong it appears unusual compared to what I have been looking at over the last 3 weeks.

Would this create a platform for the Greenland High to re-establish itself first week in February?

Are there any past winters where a low moving with this amount of cold has slammed NW Scotland?

[TEITS]

Watch the High Pressure to our south. Do not presume i'm talking about heat waves, or particularly hugely above average temps, but watch it. I do not see it going anywhere fast, just as much as (at the moment) I do not see the high pressure to our East particularly making it over all of the UK or for a long period of time.

The pressure to our south, may, in the long run, be to our benefit. In the mean time, low pressure from our west looks the most predominant feature.

I do not see any of the above on the link below i.e HP to the S, LP being dominant.

http://www.wetterzentrale.de/pics/Rtavn1681.png

Like I said last night next weekend looks rather benign. What I mean by this is we're not influenced by the HP to our E neither the LP to our W. What happens beyond next weekend is very uncertain at the moment.

[chionomaniac]

From what I can see of the stratospheric charts a MMW is still a real possibility but as I said in a

post yesterday its not the b all and end all as I think some are now over fixated with this

Atmospheric response.

In my opinion it is more important to look at the mjo and possible rosby wave dispersal into the

Arctic, afterall this is what led to the tanked AO that we have seen so far this winter.

Plus lets not forget the increased ozone in the lower stratosphere which aided in blocking over the

Arctic.

I really can not see this suddenly switching off and fully expect a cold pattern to return as the models

are starting to trend to in FI.

I don't think there is an over fixation however there are certain fundamentals that need to be considered when looking at the position of the tropospheric vortex. Whether we are going to get atmospheric blocking or even a MMW the current displacement of the PV through all layers of atmosphere will be heavily influencing the model projections over the coming weeks. Whether the MJO reaches phases 7/8 and can counter this remains to be seen.

[cooling climate]

Now I am not saying that the 06z GFS is right although a trend could well be emerging but again

we see heights over central and western America(northeast Pacific ) extending up into the Arctic

once again and these then helping a mid Atlantic ridge to build north just like the last two cold and

blocked spells of weather we have seen this winter.

The GFS could be slightly progressive with this, we shall see in subsequent runs.

[cold snap]

I do not see any of the above on the link below i.e HP to the S, LP being dominant.

http://www.wetterzen...s/Rtavn1681.png

Like I said last night next weekend looks rather benign. What I mean by this is we're not influenced by the HP to our E neither the LP to our W. What happens beyond next weekend is very uncertain at the moment.

Think they call this no mans land.

Just seams to me at the moment are weather is not being influenced by west or east.both have potetinal to be in control,but nobody wants to take full control.GFS shows this this morning.

We could be siting in a not a cold not a mild air mass for sometime.however F1 in both GFS and ECM they both go about there buisness in different ways so what happens after the stand off is anybodys guess.

But as the moment thats what it is a standoff.between east and west and knowbody wants to pull the first punch

Edited January 17, 2010 by cold snap

[blitzen]

Lancia you mention the low pressure being spectacular towards the end of the month - being new to this and looking through the winter set ups from the guides area this synoptic is not illustrated. Correct me if I am wrong it appears unusual compared to what I have been looking at over the last 3 weeks.

Would this create a platform for the Greenland High to re-establish itself first week in February?

Are there any past winters where a low moving with this amount of cold has slammed NW Scotland?

The one time that always sticks in my mind is January, 1984. At least for Scotland it was a N/NW dominated month with huge snowfalls. Have a look at the archives.

[lorenzo]

The one time that always sticks in my mind is January, 1984. At least for Scotland it was a N/NW dominated month with huge snowfalls. Have a look at the archives.

Thank you Blitzen. Found this which I have also seen on the runs today.. looks familiar..

[weather eater]

I can't see us being influenced by the Siberian high at least not in the way that many on here think, in other words an easterly, our next meaningful cold outbreak will come from the N/NW west initially, this then may tap into the cold to our east. I think there is a fair degree of operational support for something of this kind, least wise there are more pointers towards this than anything else is, unfortunately all very FI at this stage.

[Duane S.]

Lancia you mention the low pressure being spectacular towards the end of the month - being new to this and looking through the winter set ups from the guides area this synoptic is not illustrated. Correct me if I am wrong it appears unusual compared to what I have been looking at over the last 3 weeks.

Would this create a platform for the Greenland High to re-establish itself first week in February?

Are there any past winters where a low moving with this amount of cold has slammed NW Scotland?

Hi Lorenzo, I certainly think this could be a severe spell in terms of snow but probably only for Scotland. Once it's allowed, I can see the energy smashing through the Meridian on quite an unusual track bringing very strong winds to most of the country. After that, yes, there would be a window where HP could build over Greenland.

[nick sussex]

Well all i can say is what a mess with the models trying to pull some plausible synoptics out of conflicting teleconnections.The things that stand out though are the block to the east unlikely to sink as this will be held north as the AO goes into negative territory, the formation of cut off lows in the Atlantic and the suggestion that the main Atlantic trough wll be stuck to the west, depending on how far negative the AO goes theres a decent chance that enough disruption will occur to the trough to see shortwaves heading se towards the UK with a build of pressure to the NE.

The Azores high is likely to displace further westwards and may yet again as before Xmas aid the development of further cold weather.I think however we need to get away from trying to find another cold spell as good as the last one, these things are rare but we should be pleased that at least the outlook isn't a typical reset to mild mush that has so often occured in past recent winters.

Edited January 17, 2010 by nick sussex