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

[Robbie Garrett]

Backtrack in the models? Meeh! NCEP Ensemble mean Anomaly indicative of a fairly blocked Greenland, Arctic and Pacific with lower heights over Scandinavia 2 weeks from now...

Edited January 6, 2013 by Robbie Garrett

[weather eater]

Nick actually Ian needs to expand on why he thinks we have had previous failures...Sorry Ian but show me a consistancy of failure and ill say ok but i suspect every failure was different in meteo terms.....

I think what he means is that when we have had failures in the past we have seen cross model agreement that shows just how that failure came about, this evening all the models agree with failing to raise heights where we need them but all for different reasons. For me that lack of agreement is why we should remain wary of the post 120hr output whatever it shows, I suspect we will continue to see several more days of volatile output and a lack of cross model agreement.

Just to add to this CV I may be wrong but I think you may be trying to read too much into his comment.

Edited January 6, 2013 by weather eater

[Radiating Dendrite]

Can somebody help me? i am looking for the model output thread but seem to have stumbled into the steve murr model reaction thread - members responses. I respect steve, but can you lot not give the guy a break and stop micro analysing everything he is saying - it's like the met office long range thread in here!

Poor models tonight for near time snow, but I am sure the pub run will cheer us up and then the 00z will depress us agin, before we all bin the following 6z run.

[Jason M]

For example, the late November episode, where the shortwave development off Southern Greenland was first picked by the ECM and then cottoned on to by the rest of the NWP. No North Easterly.

Then, the easterly failure, the GFS toyed with and then eventually, developed the Norwegian shotwave that would scupper the block that could have delivered the easterly. All the rest of the NWP quickly backed his and the subsequent strong jet streak that brought the Atlantic back.

Here, we don't have a scupperer because we don't what is going to happen. There is nothing concrete to go wrong because the models are such a mess. That's my point. Steve M says the 'models never go back' and he is right when a DEFINITE scupperer is picked up.

Post of the night for me. Nobody has a clue what the charts will look like come next weekend, if the 18z picks up a screaming easterly it will certainly be poetic justice. Of course if it does, that could still be wrong and probably will be in the current set up.

[Long haul to mild]

I don't see the likelihood of the failed E'ly next weekend as particularly worrying, especially when compared to the December non-event. When the December E'ly failed, the only likely outcome was mid Atlantic LP and zonality with a strong PV and jet, so a lot depended on it.

This time it's merely a potential bonus item thrown in as a tease at the last minute by the models. The real cooling down and possible cold spell is still to come later in January in my view, once the SSW has fully affected the weather. The extended output does not show zonality this time (except sometimes in GFS FI, which defaults to this with monotonous regularity), and I think we will see some really good runs in the coming days.

Patience (and we need a lot of that living in the UK) is the key here.......

[Ian Brown]

Accepted the December failure was something HIGHER UP or a shortwave who knows...However this period has NOT failed yet so lets have an un blinkered view, could go very cold...will go colder...accepted?...Snow who knows?

As for previous disapointments....Again im interested why you think they happened and if there was one consistent theme....

My point is that the positive to take from tonight's runs is there is so much uncertainty. If we were looking at a northerly, then all of a sudden the NWP picks up on a shortwave that will mean a brief toppler is all we get - once the models have got hold off that then it's a quick descent to game over. Similarly for an easterly, shortwaves, block unable to develop in the right place..once you can see it going instinctively you know it has gone.

Here, we have no FI candy, no definite suggestion where the blocking might be other than 2 ECM runs and the huge (right or wrong) hyberbole of the Strat thread. For me there are no upgrades or downgrades because nothing shown has been remotely backable as a solution.

[Chris K]

Yes its been a disappointing winter for many with regards to snow.

Yes like many here id like to see a blast of snow across the UK. (But still sparing a thought for those where snow is a hinderence)

Yes it can be frustrating to see `downgrades`...but be careful and explain in what context!

Its descended into many unnecessary posts tonight (yes i`m not helping).

Treat it as eye candy and trend spotting (whilst remembering its extremely likely to change) nothing more...until it becomes almost certain to happen. Model uncertainties have been stressed time and time again!!! People must be fed up of this being said but some reactions tonight make it look like it needs reminding...

So lets just continue now and see how the outputs progress and HOPEFULLY our patience gets rewarded.

[A.J]

I've directed my browser to this thread to view the model output discussion, but instead find myself viewing a soap opera about the various merits and stresses of moving house....All very interesting I'm sure, but hardly on topic......with that in mind can we please get back to discussing the models and leave other comments to other more relevant threads.....ta!

[Stu_London]

Can somebody help me? i am looking for the model output thread but seem to have stumbled into the steve murr model reaction thread - members responses. I respect steve, but can you lot not give the guy a break and stop micro analysing everything he is saying - it's like the met office long range thread in here!

Poor models tonight for near time snow, but I am sure the pub run will cheer us up and then the 00z will depress us agin, before we all bin the following 6z run.

Which you have just contributed to

[Cheshire Freeze]

Which you have just contributed to

and you.......ooopsss and now me. Tut.

This is how the thread descends.

Edited January 6, 2013 by CreweCold

[492]

Really not sure where this thread is going. ! Looks to me we will see a dramatic cool down by the weekend...Let nature do the rest!!!

Quite agree. The cooling down later this coming week in unlikely to be connected to the stratospheric warming which is not forecast to split the vortex for another 3 days. The coming week is likely to be just a normal part of winter. It is the following weeks that all hell may break loose as the unusual events in the stratosphere start to have an influence. It is not known if we will get a few days of colder conditions, a Bartlett or a 1947 style block setting up.

[johnholmes]

I very rarely post in here because I refused to get sucked in to all the false ramping or doom mungering but I do follow to try and learn from more experienced users, But there seems to be very little acknowledgement to the fact our whole weather system has dramatically changed over the last 20 years & this is why the computers are finding it nearly impossible to read anything past 48hrs so my point is why do so many people get in to arguments over something that is so inaccurate that you may as well toss a coin as to when or if? cold weather will get here or not.

The change in weather patterns, assuming it is correct and I am not arguing that point, has no effect on any model. All the models use basically a similar set of thermodynamic equations that are run on the actual data at that time. Thus the fact that the earth has temperatures in general higher than 10, 20, 50 years ago will not affect how the models deal with the prediction out to

t+ whatever.

[ChartViewer]

My point is that the positive to take from tonight's runs is there is so much uncertainty. If we were looking at a northerly, then all of a sudden the NWP picks up on a shortwave that will mean a brief toppler is all we get - once the models have got hold off that then it's a quick descent to game over. Similarly for an easterly, shortwaves, block unable to develop in the right place..once you can see it going instinctively you know it has gone.

Here, we have no FI candy, no definite suggestion where the blocking might be other than 2 ECM runs and the huge (right or wrong) hyberbole of the Strat thread. For me there are no upgrades or downgrades because nothing shown has been remotely backable as a solution.

Ian,

I think thats what people want to see, clear explained plausible reasons why you think this might not work...Me however will go with the dynamics, strat signals and suspect we are in for a sustained cold spell.....We will see in the next few days some fantastic charts for cold...thanks for your responses

Kind regards

Edited January 6, 2013 by ChartViewer

[bobbydog]

Please can we get our heads around this ssw data thing. Of course, real tme data is better than forecast data but thats the same for any variable fed into the model. The model was forecasting the sudden rise in temp so it carrys on from the point when the temps rises as it has done for the past umpteen days modelling.Just because the rise in temps was in the simulated run and now its fed in as starting data shouldnt make any difference.

The only relevant point is that the propogation and dynamics in the strat following the warming are very complex and the models have less layers in the strat than the trop. Therefore, the closer we get to ssw and then beyond, we would hope the models will handle any propogation better. The changes seen in the modelling of heights over the pole in the past 36 hours should be enough evidence of the possible short term changes in nuance we may see.

I expect the 12z ecm will sit either in a group of less cold members or in the upper reaches of the general grouping. Its not so strange for a whole run to be skewed to the op solution. The undercut at the end of the week is far from clear re track and strength. The behaviour of the scandi ridge and movement of the trough around it are also unclear. The only consistent thing from todays runs is inconsistency.

i take it from that, that the anwer to my earlier question-

that may be the case, but isnt it true that the effect on the troposphere is extremely variable and relatively hard to model, especially at longer range? if that is the case (and i could well be wrong- i'm no expert) would we not be looking at a very dynamic and evolving situation even at short range?

was 'yes'

[Grimsby Snow Lover]

Latest countryfile forecast highlighted high degree of uncertainty towards end of next week and stress possibility of cold air affecting us from the east from next weekend, That will do for now for me.

Edited January 6, 2013 by Grimsby Snow Lover

[Richie V]

Im, fearful,

Far from convinced on the much colder outcome.

I'll see what the 00z and 06z throws out before making analysis.

On android at the moment so am limited in posting charts.

My 20 plus years of atlantic wrath experience tell me a whole different story right now. Will update soon, it aint pleasent

Tho.

I aint trolling mods, I promise, just the bad reality of the pest from the west!

[Thundery wintry showers]

The change in weather patterns, assuming it is correct and I am not arguing that point, has no effect on any model. All the models use basically a similar set of thermodynamic equations that are run on the actual data at that time. Thus the fact that the earth has temperatures in general higher than 10, 20, 50 years ago will not affect how the models deal with the prediction out to

t+ whatever.

I can potentially see an argument that if the global climate system shifts significantly, the thermodynamic equations that work up to a point today may become less effective in the "new" climate- but I haven't seen any evidence of this happening yet, as the model verification stats have consistently shown a gradual upward trend in accuracy. I feel that the sudden stratospheric warming is probably the main factor that is causing so much variability in the outputs.

Edited January 6, 2013 by Thundery wintry showers

[Bristawl Si]

Latest countryfile forecast highlighted high degree of uncertainty towards end of next week and stress possibility of cold air affecting us from the east from next weekend, That will do for now for me.

And that's the one thing that's remained certain over the last couple of days for next weekend and beyond - "a high degree of uncertainty"!

Nothing's really changed from what i can see.

[karlos1983]

Taken from a tweet from Matt Hugo. Things certainly don't look mild for northern Britain if this graph is proved accurate.

http://176.31.229.228/modeles/gens/graphe_ens4.php?temp=1&x=250&y=40&ext=1&run=12&runpara=0

Some nice precip spikes as well

[weather eater]

Can somebody help me? i am looking for the model output thread but seem to have stumbled into the steve murr model reaction thread - members responses.

Its evolved it was the Ian Brown model reaction thread at lunch time,

[SMU]

A definite scupperer....

i will remember that one.

Eyes down for the 18z...

One thing to watch for.

As it stood on the 12z GFS the tilt and orientation of that high to the NE still allowed just enough cold air tap available that with a shortwave to the sw of the uk we could still enough cold air to produce some frontal snow, however the trending of the high today means that there is little room for manoever as the resovoir of cold is thinning by the run.

So any more correction east and there will be a sharp cut off from cold to a mild westerly flow again, such is the tight rope of cold from the east.

The most frustrating part of the 12s is the real lack of any ao negative blocking, whilst the pv isnt as organised as before the residual energy is enough to mute any blocking signal.

If the ukmo or ecm varifies that despite some comments from a poster earlier the snow chance would be near zero and the temps would recover to normalised values.

Fingers crossed for a decent pub run..

S

[Cheshire Freeze]

Ian Brown with a starred 'popular' post, Steve Murr admitting defeat and a supposed GFS triumph over ECM; have I stumbled into an alternative parallel?

For what it's worth, Ian has rather succinctly summarised the situation this evening. There doesn't appear to be one major 'spoiler' which is common to all of the NWP output. This being said, I think the strings are well and truly being pulled by the modelling of that chunk of PV west of Greenland. It's been the scourge of this winter thus far and it looks like it's causing more problems now. Can we just have the strat warming dedicated to this feature please and erradicate it once and for all?! Ta muchly!

[john mac]

Here here steve

[Tony Beets]

And that's the one thing that's remained certain over the last couple of days for next weekend and beyond - "a high degree of uncertainty"!

Nothing's really changed from what i can see.

Exactly! Why can't people see that ? It's utter madness in here and we've got a ssw going on at the moment so the outcome is like the flip of a coin, could go anywhere yet!!

[Zenarcher]

Evening everyone overnight two models called CMA from China and NCMRWF from India have joined the party! So lets see where each model stands tonight and how much agreement each one holds.

First of all the next three days Monday to Wednesday - Monday will be cloudy and misty over the UK with heavy rain over Ireland and Scotland. Tuesday heavy rain over Scotland at first but clearing away elsewhere will remain cloudy and misty and England can expect a few showers as well. On Wednesday we finally see a change it will be clear and sunny over England and Wales but Ireland and Scotland will remain cloudy. Wind will be mainly calm but we can expect severe gales over Western and Northern Scotland on Tuesday and Wednesday.

96 Hours Thursday - The models seem very uncertain about the heights to our North how much we can expect to build up there and we have a low pressure system over Europe that also has large disagreement on it, the ECM, GFS and JMA all seem to have agreement in this area by having the heights in a similar position and the low over Europe at the same depth but this means they go against 5 other models they do mostly agree on the heights being the same strength and position but want to make the low over Europe a lot deeper. I don't really like the look of the GFS here when we look out to the West of the UK most models show very weak shortwaves here or none at all but the GFS is the only model two show two small weak lows.

What most models agree on at 96 hours,

120 Hours Friday - First of all the amount of disagreement between the models was higher than normal when I usually check them over and now at 120 hours there's bigger disagreements between them the only thing I can point out is similarities between them.

So what most models show is a weak low that seems to go under the heights,

About 5 of the 8 models show this so at the moment it may be a likely thing to happen.

Next the low entering the Atlantic is where the key to the problems really start we want it to head North like what the good ECM showed us yesterday. The image below shows the low on the ECM from yesterday it's placed further North than what most models suggest today,

Anyway onto today I've made this image to show where the models place the center of the low, and yes the image shown is today's ECM chart.

So most models show it to be placed further South than what the ECM is showing but it still shows the large differences we have because some models want high pressure to build up around the low meanwhile others don't.

144 hours Saturday - By this point the disagreement is huge so much higher than normal I can't remember a time where I've seen so much differences,

Something that the UKMO shows seems to have the best support heights to our North with some energy going under it at least another 3 models show something slightly similar to that.

New Models - I'm happy to see two new models to use, how useful they are will show over time but I say the more the better.

Current Stat Temp - I posted this up in the strat thread earlier today the temps up there are rising as forecast,

Models will have to get to grip with this over time.

Overall - We have decent agreement at 96 hours with the heights to our North but the low over Europe is where the models are uncertain. At 120 hours the models take different paths although some similar to others by showing a low trying to go under the heights to our North but there is huge disagreement between the models over the low in the Atlantic none of them show something the exact same as another they all sum up their own solutions. By 144 hours it's hard to make sense of whats going to happen here but the UKMO does gain a bit of support from some of the other models but even then I stress they can and could be all wrong here. So big uncertain picture painted up by the models tonight.

Edited January 6, 2013 by weathermaster