Winter Model Discussion Thread 12Z onwards 5/1/13

[SMU]

In the long run yes, but like you say, other models pointing more favourable outcomes. In the short term, our regions have snow potential by +126/132 on the 06Z as the Ely begins.

yes despite the 06z being the worst run of the day at least its significantly better at 138 & 144 with the -10c line approaching fast..

http://modeles.meteo...snh-0-144.png?6

If we can get just a little bit more sustainability & depth out of the scandi high then its close to a strike from the east like 1991, but initially still could be as good as feb 2009 easterly IIRC-

http://modeles.meteo...009-2-2-0-0.png

S

Edited January 6, 2013 by Steve Murr

[chris55]

GFS 06z messy and the broader pattern is not as good compared to the EC but still cold!

EC ensemble mean at day 10 is pretty impressive today,

[Ian Brown]

And conversely we see the ECM with inter run consistency showing a Greenland block 2 in a row. Ian if it was the other way around and we had the gfs showing showing the GL block and the ECM showing more of an Atlantic influence I bet your post would have been almost similar (swapping gfs for ECM ) to fit in with your winter theory at least that's how it looks IMHO. For me and someone posted earlier why wouldn't we trust the worlds best model at varifiyingl from d5 onwards. If the ECM had similar Synoptics to gfs at d6 onwards then I would be inclined to think its a none starter but its not and therefore from a cold perspective we certainly have more hope to colder conditions than what was shown a week ago.

Paul

Paul, if it was the other way around I would still be advising extreme caution; as those who have been around a long time will know - if the big models don't agree then the one that shows the worst outcome for cold fans, will nearly always be the one that comes closest to verifying.

[ITSY]

yes despite the 06z being the worst run of the day at least its significantly better at 138 7 144 with the -10c line approaching fast..

http://modeles.meteo...snh-0-144.png?6

If we can get just a little bit more sustainability & depth out of the scandi high then its close to a strike from the east like 1991, but initially still could be as good as feb 2009 easterly IIRC-

http://modeles.meteo...009-2-2-0-0.png

S

Someone is happier today! I'd take either thank you!

My only concern, which I am sure is shared by you, is the lowering of heights around southern Greenland which could prevent (again) a Greenland block. Worth watching.

Having said that, lets not get too hung up just yet. By +168 almost all area are expected to see snow with a significant band moving south reinforcing the Ely as it does and adding to snowfall totals in the South. Lots going on, even without Greenland. But write it off at your peril, we need it for the long term!

Edited January 6, 2013 by ITSY

[Panayiotis]

Question to anyone who is bothered to answer to it: Would any low from Canada/Greenland just follow that jet down, making it a possibility of a polar low?

Edited January 6, 2013 by Panayiotis

[TEITS]

Certainly no expert in these sorts of charts but to me the 06Z shows a far more favourable split of the PV compared to the 0Z.

[weather eater]

06z developing quite differently to the 00z and the GFS, indicative IMO of how much there is still to resolve.

Paul, if it was the other way around I would still be advising extreme caution; as those who have been around a long time will know - if the big models don't agree then the one that shows the worst outcome for cold fans, will nearly always be the one that comes closest to verifying.

Unfortunately that’s usually the way of it, however given the background signals we might just be seeing different ways to get to the same place, if we are lucky.

Edited January 6, 2013 by weather eater

[snowking]

The small backtrack that started on the 0z in terms of the modelling of the PV lobes continues on the 6z at 168:

Also, the amplification differences in the trough that the fantastic post by Lorenzo highlighted are obvious at an even earlier timeframe between GFS and ECMWF:

SK

[SMU]

Question to anyone who is bothered to answer to it: Would any low from Canada/Greenland just follow that jet down, making it a possibility of a polar low?

no- A polar low will only develop between Greenland & Norway- we dont want a low tracking through greenland as it will flatten off the pattern....

S

[Southender]

Question to anyone who is bothered to answer to it: Would any low from Canada/Greenland just follow that jet down, making it a possibility of a polar low?

Wrong area for a PL mate.

You need to be looking towards Svalbard for those.

Very rare but can crop up in strong Northerly flows. Look for a comma like signature.

[Wivenswold]

Looking at +174hrs on GFS, I'd put good money on that mid-Atlantic low steaming West once we get to Low-res output. But I don't think anyone should panic about it.

[That ECM]

Freezer or bin GFS you have been warned!!!

[Weathizard]

6z looks far better than 0z for sustainability but still messy compared to the ECM.

Look at that lobe of the vortex near northern Scandinavia? If the greenland block comes,that's a good sign.

)

Edited January 6, 2013 by Weathizard

[TEITS]

Difference in the 06Z GFS compared to the 0Z is so stark its a waste of time even looking at FI whatever it shows.

[ITSY]

That low coming out of Canada did hurt us in the end, with the pattern flattened as heights fail to build into Greenland as a result. The run did give 2 snow events (for SE and NW) before then (in high res) so can't sniff at that, but the long term cold will fail if heights don't build north of our latitude. The ens will give us a greater idea. Got to go now, travelling back to Leeds, so hope for some interesting possibilities when I return here this evening!

Edited January 6, 2013 by ITSY

[Panayiotis]

Second go at it?

[Ian Brown]

Difference in the 06Z GFS compared to the 0Z is so stark its a waste of time even looking at FI whatever it shows.

http://modeles.meteo...snh-0-288.png?6

But another run that shows full reorganisation of the PV to the NW in FI even if the synoptics over Europe are different.

[Panayiotis]

At 336hrs so should be ignored but wow!

[Weathizard]

Wow didn't expect this run to end up like this! Was all going wrong and suddenly boom the cold uppers flood back! Bizzare looking charts in FI!

Edited January 6, 2013 by Weathizard

[East Herts Snow]

Snow is one of the main reasons why a lot of people contribute to these forums in the winter and in the medium term this run brings good snow potential for many Western and Northern areas between +162 and +186 hours.

Not such a good run in the longer term as good old GFS reverts back to its usual default zonal pattern, but does produce several 'battleground situations' between rain and snow. However it regularly does this in its low resolution output, so I only view them to try to spot a new trend.

[IDO]

The GFS does not want to go towards a GH initially (unlike ECM). This run the Scandi high is pushed east as the UK gets cold uppers from the NW as well as the NE. The PV piece over W Greenland remains dominant.

Very messy but it sort of looks right. Forces coming from opposing directions interacting, battleground scenarios, swings and fro's of energy. Scandi high is its favourite on this run. The ECM just looks to clean, like out of a textbook.

I think which ever way we go, it looks like the trend is for a wintry period of weather:

At the end of FI the Scandi high retrogresses towards Greenland. Classic:

Anything can happen after D5/6 (according to GFS).

Edited January 6, 2013 by i'm dreaming of...

[That ECM]

But another run that shows full reorganisation of the PV to the NW in FI even if the synoptics over Europe are different.

True but is that the way you think this would play out considering all that is going on to the PV currently and forecast to be kicked again? I would suggest this will not be the case.

[weather eater]

I agree with TEITS here FI not worth bothering with much; still the 06z is going to end much better than the 00z another indicator of the models trying to resolve the stratospheric signals.

Just to add to that personally despite the hiccup in the middle i would bank this run if we got the whole lot.

Edited January 6, 2013 by weather eater

[TEITS]

But another run that shows full reorganisation of the PV to the NW in FI even if the synoptics over Europe are different.

What are you on about Ian.

I know very little about the PV but even I could see a big difference in the 06Z compared to the 0Z. Also the lobe of PV over Greenland actually backs W. I don't see a reorganisation of the PV,, what I do see is a split PV with one lobe over Siberia and the other W of Greenland which eventually backs W.

[snowking]

But another run that shows full reorganisation of the PV to the NW in FI even if the synoptics over Europe are different.

Yes Ian....but from where?

There is no support from other modelling at this present time, not from the stratosphere above it, not from the projected MJO phasing, and not even (in terms of the 0z) from its own ensembles!

Completely understand that taking the models at face value its not impressive, but you have to ask where such a solution is coming from

SK