Winter Model Discussion 18Z 3/2/13 onwards.

[Tamara]

But without the actual outcome of the weather being known currently (as it is a future forecast), how can we be certain that GFS is 'shocking' or the others 'good' Steve? It makes it sound like they are not showing a certain preferred scenario yet and so must be good or bad (or indifferent), surely we need to wait until the outcome has passed to judge their quality?

Well, the most 'preferred' scenario is under scrutiny for sure. I was looking to see if the UKMO edged further towards the ECM on the 12z, but it didn't, and fwiw as I see it, it was not quite as good as this morning suggested, with the trough disruption further west on the overnight output. So I for one am very slighly less optimistic of the coldest scenario (pending the ECM) But it's only the weather, and fun watching how it turns out

Phil above - very similar thoughts really

Edited February 4, 2013 by Tamara Road

[weather eater]

The reason is for calling the ECM the assumed solution is because the GFS was total Woeful last time, the GFS has an easerly bias & the GFS cannot deal with trough disruption-

So we should always assume the GFS is a lower varifying model with less chance of being correct. especially with the known bias.As said though we cannot 100% discount it .

S

Last time, if we mean January both the GFS and ECM played catch up with the UKMO, although to be fair the GFS was poorer than the ECM, the fact that the GFS was wrong last time is irrelevant, lord alone knows how many easterly’s in the past the ECM has projected that have fallen over, back tracking toward the GFS and I would suggest that in fact the ECM may well have a westerly bias when it comes down to Scandi blocks. Remembering also it was the GFS not the ECM that picked up the pattern in 2010 first, the ECM spent days floundering like a wet fish. I seriously hope you are right this time but I have to say you sound less sure today than yesterday.

[Weather-history]

Not quite as flat and progressive as the GFS but we are talking fine margins here and any eastward shift is not good in order to have a chance of an easterly.

Isn't the easterly, a low probability to begin with anyway? To me, the debate with the models should be about how long can the cold stay, even the much vaunted ECM doesn't really go for an easterly or not an easterly in the classic sense or one of sustained length.

[Ice BIast]

Meanwhile the NOGAPS and the GEM both on board and back the ECM!

http://www.meteociel...&mode=0&carte=0

http://www.meteociel...&mode=0&carte=0

Indeed. One thing that I would like to say though is that everyone should remember that shortwaves always end up interfering with easterlies, one can be seen on the GEM for example north of Scandi at T144, so just something to keep in mind.

Edited February 4, 2013 by lce Blast

[Bobby]

Yep, fair point. I personally marginally favour ECM / Steve Murr, but every GFS run that says no increases the doubts. Ensembles running out at present and within next 10 minutes will be out to day 5. Will be interesting to see and of course ECM still to come.

Jason

I don't have confidence in any model being able to accurately predict what this 'slider low' is going to do at the range we're talking about, +144 or so, that's a long way out ATM isn't it. There's not much margin for error, we want just the right angle of attack and I don't think it will be resolved until its at +96 or even less , so maybe another day or so before a resolution. And I think the higher res of the OP runs will be more important than the ensembles in determining what this tricky low is going to do.

It's all up in the air ATM and I won't be getting excited yet for sure.

Edited February 4, 2013 by Bobby

[snow mad]

Last time, if we mean January both the GFS and ECM played catch up with the UKMO, although to be fair the GFS was poorer than the ECM, the fact that the GFS was wrong last time is irrelevant, lord alone knows how many easterly’s in the past the ECM has projected that have fallen over, back tracking toward the GFS and I would suggest that in fact the ECM may well have a westerly bias when it comes down to Scandi blocks. Remembering also it was the GFS not the ECM that picked up the pattern in 2010 first, the ECM spent days floundering like a wet fish. I seriously hope you are right this time but I have to say you sound less sure today than yesterday.

I can understand if Steve is less sure today as the models this year have all been crap at some point so anybody who's willing to second guess what the models will show next have my respect... Keep it up exciting viewing tonight

[johnholmes]

Some of you really need a chill pill it seems.

Why oh why get so worked up about one run.

Take time to compare the last two runs, 06 and 12z, although no doubt someone will say never believe the 06z!

Up to T+120 GFS shows an almost identical pattern, upper air and thus the surface. After that its a bit like chalk and cheese. Why folk refer to short waves with centres over pretty low values is always beyond me, another mis use of a technical term but no matter.

Look at the area south of Newfoundland at T+144, one has surface pressure of 992 mb the other 1032mb. So which is more likely to be right. No one line answers please-a proper explanation then folk can better understand why you take the position you do.

Maybe a look at UK Met 1-3, then 6 day outlooks to what those who have a great deal more data available and also a great deal more understanding than most of us on here might suggest which model is nearer the mark and on which run.

Yes its the model discussion area but there are some pretty knee jerk posts in here almost every time after every run-think about it please?

[weather eater]

Meanwhile the NOGAPS and the GEM both on board and back the ECM / UKMO!

http://www.meteociel...&mode=0&carte=0

http://www.meteociel...&mode=0&carte=0

Indeed good to see, I'm not suggesting that the GFS is going to be right, only that being bullish about the ECM being on the money is not always wise, best verifying model or not it backs down to the GFS on a regular basis.

[chris55]

Indeed. One thing that I would like to say though is that everyone should remember that shortwaves always end up interfering with easterlies, one can be seen on the GEM for example north of Scandi at T144, so just something to keep in mind.

Initially we are not looking for a big link up with the Russian high to get the slider, just the wedge to our north east so shortwaves should be less problematic . .

GEM is great tonight, finally on board with the ECM, if anything the slider is to far WEST for frontal snowfall in most places!! Just goes to show how finely balanced things can be for our little patch.

[offerman]

Hi John , Well said.

Everyone including you, myself and many more on here don`t have a clue whats going to happen. The professionals struggle sometimes even at short notice so what hope do we have. Relax and let it unwind and wait to 48 hrs out for a better idea but don`t even bank that as 48 can change such is the frivolity of Birtains weather.

[bluearmy]

There is no real easterly on the table. not in a biting strong flow sense which lasts for more than a day. we are just after a flow east of north/south which has low enough uppers to bring some convection off the north sea and crucially, means the atlantic is held back. alternatively a very cold cyclonic trough is ok if it comes in from the east..

[Man With Beard]

I think cold lovers need to hope that this shortwave is subject to the southerly corrections that so often happen between T72 and T144. UKMO at T144 looks like going to far north but it's extremely close and any southerly corrections at all bring the cold (and snow).

[SnowObsessor90]

We had this before back in Jan when some Models such as the GFS underestimated the blocking but then there's no garruntees the same this so as others have said the fence is probably wisest place to be for the time being.

[offerman]

I haven`t seen a proper Easterly since way back in the early 90`s. That was bitingly cold in the south but not much in the way os snow then. However i remember the 80`s easterlies bringing a fair dumping of the white stuff.

[swilliam]

I suspect a few will be watching the ECM roll out from behind the sofa or between their fingers. Expect a backdown and then anything else is a bonus IMO. I was shot down in flames for suggesting the UKMO will be more on the money and show us the halfway house between the ECM & GFS. To my eyes it is just that

You told us several times yesterday to expect a backdown (no reason given) and it didn't (12z or 0Z) - why do you think it should this time?

[SE Blizzards]

Indeed good to see, I'm not suggesting that the GFS is going to be right, only that being bullish about the ECM being on the money is not always wise, best verifying model or not it backs down to the GFS on a regular basis.

And i'm pretty sure that the GFS backs down to the ECM on a regular basis too. It's all swings and roundabouts really. Am pleased that the GEM has come on board though. It's not everyone's favourite model but it did do rather well in last months cold spell of weather (that's not to say it will get this one correct though).

Anyway, D-day is fast approaching, so we'll all find out in the next day or 2 which of the models are correct and which one's have got this very wrong.

[Ice BIast]

Initially we are not looking for a big link up with the Russian high to get the slider, just the wedge to our north east so shortwaves should be less problematic . .

GEM is great tonight, finally on board with the ECM, if anything the slider is to far WEST for frontal snowfall in most places!! Just goes to show how finely balanced things can be for our little patch.

I guess I'm just looking for convection. A slider would be nice though, and the recent runs are quite good for it IMO.

[phil nw.]

Isn't the easterly, a low probability to begin with anyway? To me, the debate with the models should be about how long can the cold stay, even the much vaunted ECM doesn't really go for an easterly or not an easterly in the classic sense or one of sustained length.

The ECM solution would deepen the cold in a slack easterly WH -i think that`s the hope rather than a full blown classic long fetch easterly.I haven"t seen anyone suggest that scenario.

[swfc]

I haven`t seen a proper Easterly since way back in the early 90`s. That was bitingly cold in the south but not much in the way os snow then. However i remember the 80`s easterlies bringing a fair dumping of the white stuff.

They do seem very elusive for some strange reason.Given the decent winters of late there still not there to be fair and i for one have no idea why?

[weather eater]

The ECM solution would deepen the cold in a slack easterly WH -i think that`s the hope rather than a full blown classic long fetch easterly.I haven"t seen anyone suggest that scenario.

Certainly the ECM a couple of days ago was projecting a much more potent easterly than it is doing now, for me this is yet again another example of problems with ECM easterly projections, they start well and fade over time, that seems to be theme.

Edited February 4, 2013 by weather eater

[snow mad]

Certainly the ECM a couple of days ago was projecting a much more potent easterly than it is doing now, for me this is yet again another example of problems with ECM easterly projections, they start well and fade over time, that seems to be theme.

I Assume they pick up the general theme without the shortwaves then as it gets closer it can gradually sniffs out the shortwave spoilers which obviously water down anything from the east unfortunately

[LomondSnowstorm]

Certainly the ECM a couple of days ago was projecting a much more potent easterly than it is doing now, for me this is yet again another example of problems with ECM easterly projections, they start well and fade over time, that seems to be theme.

I think generally speaking all models struggle towards the latter part of their runs and often the forecast solution is somewhat oversimplified, moreso with the ECM perhaps overdoing easterlies and the GFS certainly struggling to pick up on trough weakening and disruption and overdoing the jet. In this instance I tend to favour a solution not dissimilar to the outcome of the the two main undercut attempts in January, with most of the energy going under the block and a relatively cold but messy and potentially quite snowy solution for some.

[Tamara]

Certainly the ECM a couple of days ago was projecting a much more potent easterly than it is doing now, for me this is yet again another example of problems with ECM easterly projections, they start well and fade over time, that seems to be theme.

Another one of those interesting different perceptions As I've seen it, it has consistently suggested the type that Phil mentions with a slack cyclonic trough close by in Europe rather than any classic reverse zonality look about it and straight NE'erly tramlines of isobars. The issue once again is the close proximity of the Azores High as these potential continental flows set up - much as has been the story for much of the winter. We have had trough disruption into Europe, but no classic -NAO. I guess on that basis we have done relatively well out of modest synoptics when they have presented thmselves

[Mucka]

I think ECM will be closer to UKMO and it is beginning to look like a truly cold spell with a direct Easterly is unlikely, even ECM has moved away from really significant blocking for something much messier with the battleground over the UK. Looks like spells of rain for the West with the chance of some sleet and snow times but all rathier messy and transient.

GFS Op run today is a joke but the fact that it has gone into full reverse along with its ensembles showing zero support for ECM type solution means purely believing the ECM requires a leap of faith.

Would UKMO deliver? Very debatable. It looks as though the once the slider was through (which would bring mostly rain) the trough would set up too far west but a lot would depend on how amplified the pattern was behind. Blocking to the NE is weaker than this mornings ECM and there is more energy to the NW and the pattern is further East.

Given ECM barely held off the Atlantic later there is no reason to think UKMO would set up a better or as good a pattern with all those extra negatives by 144.

I would say GFS is wrong UKMO probably not that far off which would mean, given some wiggle room, the ECM could be right but will likely move things just a little further East. We really need the trigger low to dive down the Western flank of the UK rather than across NW/SE or further East and for the pattern to be less flat behind with another supporting ridge holding off the Atlantic while the block is reinforced. That means there is more room for things to go the way of the pear than toward a winter wonderland but it doesn't mean a cold spell proper won't happen.

Edited February 4, 2013 by Mucka

[Dexter29]

Certainly the ECM a couple of days ago was projecting a much more potent easterly than it is doing now, for me this is yet again another example of problems with ECM easterly projections, they start well and fade over time, that seems to be theme.

Absolutely, I remember a couple of days ago "BOOM" posts as the ECM churned out a good Easterly flow!!

Look how watered down it has become