Model Output Discussion 23/11/2012 18Z onwards

[Geordiesnow]

The only negative on this run on the face of it that the ECM is still insisting on sending the trough into Scandi, I think it would be better if we can keep the cold across Scandi therefore any Northerly that does follow will be more potent than the ECM is showing.

So we got GFS/ECM insisting on sending the trough further Northwards into Scandi, whereas the UKMO still has it further South so it will be interesting which model is right on that.

Regarding the shortwave, although it is sort of playing with fire having it coming into play, it can have a couple of positive factors, if the air is cold enough, then the leading edge of the PPN from the shortwave may fall as snow and the second one will be because of the forcing from the jet stream, it will head southwards anyways into Europe. The shortwave that can form in the Norwegian Sea as per the GFS run is more risky as that can affect blocking and stop cold air heading southwards and westwards. We must also bear in mind the UKMO shows the same shortwave.

If the Northerly for Tuesday is perfect, then some places may see some wintry(snow even) as early as then which if you like, could be a taster for what to come if everything falls perfectly.

No doubt alot of twists and turns to come yet but I don't see too much sign yet of any heights weakening nor do I see much sign of the Atlantic coming back in.

Edit: when I say the UKMO is showing the same shortwave, its the one from the Atlantic I mean, not the one that forms in the Norwegian Sea.

Edited November 24, 2012 by Geordiesnow

[SMU]

http://www.meteociel.fr/modeles/ecmwf/runs/2012112412/ECH1-216.GIF?24-0

Slider alert!!!

Snow for many & very cold at day 10-

The ECM ensembles will be very cold tonight,

S

[Buriedundersnow]

For an interesting glance at the GFS, ECM and the BOM from today and their projections from 4 days ago:

should have made one of these for 7days ago but that would have been silly wouldn't it ?

i'd like to see the 7 day ones looks like the gfs was worst didnt pick up the hieghts in the pole as well

[The Eagle]

A very cold ECM run overall.

[Catacol]

I'll tell you what:

1. These are some of the best ensemble charts in the semi reliable frame that we have had for snow in a long time, comparable with Dec '10.

2. The current longer range teleconnections for winter are possibly the best we have had since internet weather watching came into being. When GP starts talking of a distressed vortex into January, with "interesting" consequences, we should all know that something is afoot.

3. The MetO longer range forecast mentions "cold" and "snow" - and they choose their words very carefully. This now takes us out to Xmas Eve.

4. For those who had to endure the winters of the late 90s and early 00s everything at the moment is eye candy of the best sort.

5. Today is November 24th. The fact that 611 people are on this thread as I type - and winter hasnt even started yet - is extraordinary and exciting. 14 weeks of full on winter is still in the near future!

Conclusion? Chill out. Take the wise advice and stop jumping on top of every operational run and look at ensemble mean charts and read the wise words of wise old heads. Cold is coming; some people will get snow. We will all get frost... and the outlook is excellent. When GP finally releases his full winter forecast (and if you are new to this then trust in the fact that he has a very very good trend record for winter forecasting) then hopefully we can all get even more excited. Most of us know that in pattern change scenarios where blocking is on the cards the models have a poor record, and cant be trusted beyond 120h - maybe even past 72h - so keep some perspective.

However I must admit I am more excited at the overall prospects for this winter than I have been since joining the weather community over at TWO many years ago. Flooding down here is awful at the moment, but even that fills me with winter excitement because with the jet so frequently south these days it increases the chances of the battleground scenario snow that is best for many of us away from the east coast or the highlands. The ensemble means are screaming of battleground snow potential for the first week of December at least.

Fantastic.

[ICETAB]

The pattern looks like its reloading at T240 on the ECM!!

[Weathizard]

A very good ECM all round, still room for improvement but a big step in the right direction, UKMO very good, GFS 12z ensembles good, ECM good.

A few tweaks here and there on this run and it could be something really special, looks to be more heights ridging towards Greenland at 240hrs, can anyone explain why the Highs are ridging up too Greenland more than usual? Assume its because low pressure to the east and no vortex centred on Greenland?

[cold snap]

http://www.meteociel.fr/modeles/ecmwf.php?ech=240&mode=1&map=1&archive=0

At end with that at 240

Wow it's an epic run and the Atlantic is all forgotten about

[I remember Atlantic 252]

Reminds me a bit of Fri 03 Dec 2010, the 216-240 charts, 3-4 Dec, that day snow moved from the NW a shortwave, remained cold on 4th, but there was a very slight thaw

[london-snow]

Best ecm run we have seen over the past two days in my view.

[Bobby]

1. These are some of the best ensemble charts in the semi reliable frame that we have had for snow in a long time, comparable with Dec '10.

I noticed that looking through the ensembles, much more promising with more Northern blocking showing with signs of a Scanindavian high and plenty of reload potential. ECM at +240 showing a reload possibility too. Also that shortwave diving down around +120 could cause a snow event for some it all goes well, similar to the GEM.

[swfc]

So ecm gives the gfs another kick in the what nots and delivers a good run.So see what the pub run brings which just happens to be where im off too

[Liam J]

Very cold ECM tonight with many snow chances.... Final chart is superb to finish the run, bye bye Atlantic

-4 to -8c over parts of Scotland and N England.

Edited November 24, 2012 by Liam J

[snow drift]

Kept my powder dry for 12 hours. Not saying that others should wait this long but please try and wait five mins into a run!

So theme continues and as I said this morning lets get the blocking in place and then the uppers will drop. From 24 hours out we can hunt for what most want. Snow. Great post Catacol_Highlander.

[london-snow]

Very cold ECM tonight with many snow chances.... Final chart is superb to finish the run, bye bye Atlantic

In my opinion the atlantic is long gone by 192 Liam -

http://www.meteociel...H1-192.GIF?24-0

Change cry with smile lool...

Edited November 24, 2012 by london-snow

[Liam J]

In my opinion the atlantic is long gone by 192 Liam -

http://www.meteociel...H1-192.GIF?24-0

Yes, just highlighting the fact even on the last frame the Atlantic is dead... Kind of a dig to the GFS.

[crimsonp]

G.P. must be feeling a whole bunch of pressure riding on his shoulders at the moment hahaha! would be cool to know what his thoughts are with these runs we've been getting?

i'm learning all the time about the charts but one thing i don't quite get is how can you tell if it's gonna rain/snow just from a few wavey lines? i get the the way LP and HP circulate but how can one tell? if i knew then i would be sitting on a gold mine!! please someone enlighten me without sending me to the "learning center", i've been there and it scares me so!

thanks team

[Buriedundersnow]

would it be better or worse if at 144 that atlantic high slipped up through to greenland

[Zenarcher]

Comparing the ECM, UKMO and GFS side by side and lets see what's wrong with the GFS,

72 hours ECM and UKMO are very similar here while the GFS appears more messy with shortwaves,

96 hours ECM and UKMO continue to agree while the GFS wanders off on its own, shortwaves still cause problems for the GFS. The Atlantic ridge is slightly more West and North on the ECM and UKMO while the GFS has it the opposite slightly flatter and more East,

120 hours you can't see it on my images below but the heights to our far North on the ECM and UKMO are much better and more important similar to each other, GFS does have them but is shy in bringing it in like the others. The low pressure system just to the South of Iceland causes a problem on the GFS with our ridging it stops it getting into place. The ECM and UKMO don't show this because they position it in a more favorable position,

144 hours once again the ECM and UKMO here are pretty much the same both showing excellent charts but why does the GFS not agree? The low I mentioned at 120 hours still causes problems here I've highlighted where it is now on the 144 hours charts. The shortwaves and everything make it messy.

Looking back through the post there are a lot of things at each point that leave the GFS on it's own meanwhile the ECM and UKMO continue to agree on most things. I've heard people asking on here today about the BOM model it's resolution is not as high as the main weather models but every year I like to do a weather model experiment this year the BOM done pretty good so yes I would say it's okay to use it but remember like all the models especially at times like this is not to get too caught up with it's long range but to look for trends there. I would look at BOM for trends and see if it gives any of the main models support.

Edited November 24, 2012 by weathermaster

[bluearmy]

G.P. must be feeling a whole bunch of pressure riding on his shoulders at the moment hahaha! would be cool to know what his thoughts are with these runs we've been getting?

He said forget about the ops and watch the ens mean and anomolys post day 6/7

[cold snap]

I think it's safe to say tonight it's every model v gfs

[Snowy Easterlies]

BOM is poor tonight past T168

[ITSY]

trends are important. BOM, JMA and UKMO all sustain an Easterly + inevitably snow for some. ECM gives us a more NEly and snow for virtually all at some point. GFS is the sticking point; looks as though the balance has shifted towards the UKMO today (if it weren't there already), although the GFS ensemble mean for London is still around -5 uppers for the first week of December, it's just really the Op that is having a bad time of it. Come Tuesday, we should have a clearer idea of what will happen, that's my guess anyway.

[phil nw.]

The operational outputs are now starting to "get it" as we get closer to the changeover in the NH pattern next week.

They are very much closer to the forecasted mean 500hPa height anomalies and CPC days 8-14 outlooks

Still some niggles to be ironed out with those shortwaves around T96-120hrs and the consequent placing of the euro/scandi core of low heights.

Overall though all the runs introduce a cold setup later next week.

The GFS ens graph

Notice the much tighter grouping of members tonight with the mean running close to -5C !

I would think the ECM ens.would be worth a look later too.

[Frosty.]

We have taken another significant step towards a very cold outlook, the block holds by T+240, unlike the ecm 00z when atlantic lows were breaking through, peachy ukmo at T+144 and we look like picking up some snow showers off the north sea, frosts also becoming widespread and moderate to severe, let's not forget windchill, the source of the air is bitter so it will be numbing in the strong winds.