Exactly Brian. It's the same model, the same software run on the same hardware. The only difference being the starting conditions are updated with each run. So there really isn't any way that a certain type of pattern or bias can appear on the 06Z versus the other runs.

The old story about the 06Z and 18Z getting out of date radiosonde data is a myth that was debunked by the NCEP on the US weather forums a couple of years ago :

We look at these models so much that we start projecting personalities into them I think.

http://www.wetterzentrale.de/pics/archive/ra/1963/Rrea00119630131.gif

A very warm welcome (or should I say mild). I think someone has already described how the 6hr interval models don't suffer from irregularities in dropsonde data as it's 'virtualised' from previous sets - in other words, even the interpolated data is as good as the actual readings when required. Add to that the fact that dropsonde parameters are only a percentage of the cohort that gets input and I tend to go along with the theory that model 'bias' is a myth and very subjective.

There are of course situations when chucks of data are missing or sections of the algorithm have not performed to well, but these are reported in statements and can (and often are) used as excuses when the models don't show what you're expecting them to show. For example, a classic flip from cold to mild on Boxing Day will be put down to the lack of transatlantic flights and data missing from lighthouses where the keepers have had one to many sherries

12z GFS op and GFSP both follow the 6z with the Atlantic smashing through quite easily.

Yes, welcome to the forum Gorgo, just in time for the dramatic season 

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=204&code=code&mode=0&mode3h=0&runpara=0&carte=1

Try running that lot through (192 to 384) hours... there are so many circulations going on that it can be a bit nauseating!

What's happening is the polar vortex losing the ability to bundle the energy up across Canada and Greenland, with areas of cold Arctic air flying around all over the place, along with remnants of the polar vortex, one of which pays the UK a fair old visit - but not in the right place for a snowfest I'm afraid.

That remnant remains quite well consolidated for much of lower-res, and only in the final stages of the run do we see the low heights dividing as the jet dives all the way down to Africa. High pressure can then develop to the north of the UK but really this run makes a hard job of things as far as getting some proper cold to the UK is concerned.

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=204&code=code&mode=0&mode3h=0&runpara=1&carte=1&runpara=1

The parallel version has a lot of similarities, but works out a bit better in terms of the outlook beyond day 16, thanks to less in the way of low heights making it from the Pacific to Canada.

Despite this, we could really do with the jet being weaker and tracking further south.

Some relief, then, that if there's one thing both GFS and GFSP tend to do, it's overcook the Atlantic jet. I've reached this conclusion regarding GFSP after making a note of what it showed for the coming week back on 14th November; a raging jet with countless storms blasting through the UK bringing strong winds and many spells of rain.

Instead, we have this:

Facepalm for GFSP, fist pump for those seeking a colder setup for the first week or so of December! 

The last week (7 days to be precise - ugh... Almost). We have El Niño Pattern Reload, Wave 2 ahem.

The jet stream splits with Cold air arriving to Europe Central and East side, Low dives South across W then SW Europe briefly give a few days Azores to Europe High link up UK get SE then East winds, as shown on UKMO, GFS thereafter following next Sunday relaxed weather, has North Atlantic Low move NE to Norwegian Sea to North NE Europe corner, some of this Low Pressure in week after This weekend should affect UK on its SW flanks, but always we look often seeing High Preesure from the SE or SW with NW flow followed by SW and then Calm settled spells, but at times UK is looking Windy and wet with both sectors of mild and also colder showery NW intrusions.

The UKMO 120 and 144 and the 96 hrs chart show some very cold airmass for Central E Europe, with North Atlantic and Norwegian Sea Low on a more northerly track with moves from West  to NE, over much of Europe in general, SW Europe and NW Africa inc. S of Bay of Biscay is Low Pressure shown to bring a lot of chilly cool and wet or showery and thundery weather there.

That includes Morocco and Tunisa west.

The pattern is based on a less cold set up with Cyclonic fast moving Northern Low Pressure areas, with large Blocking High's affecting Areas to their South SW and SE, so they keep stagnating in sync with mobile North Atlantic NE Europe and Arctic Norwegian Sea Low Pressure systems, west to NE in general.

GFS does offer opportunities for some pulses from the NW Atlantic SE Greenland at times from the West sides of each UK tracking Low the GFS shows, but UKMO at 96,120 and 144 has us in High Pressure with either SE or easterly winds and that is meridian blocking/ Continental weather/ mild bringer!.

http://www.theweatheroutlook.com/charts/gefs/7_336_850tmp.png?cb=733

P7 delivers snowmageddon on the 6z GEFS

Yes not bad prefer P17 though snowmageddon again

http://www.meteociel.fr/modeles/gefs_cartes.php?code=17&ech=336&mode=0&carte=0

(raises an eyebrow)

Snowy GEM as well for the SE.

http://www.wetterzentrale.de/pics/Rgem2282.html

http://www.meteociel.fr/modeles/ecmwf/runs/2014112412/ECH1-192.GIF?24-0

This wont be mild at all

first week of december 1995 rings a bell that was very cold and snowy. these are cracking charts, too far out for me to get to excited, lets see what the next few days bring could be over cooked or evan a red herring,

Excellent JMA as well. Very good output it has to be said tonight.

http://www.wetterzentrale.de/pics/Rjma1921.html

Day 6 JMA

Day 8 JMA:

Quite a few signals supporting some kind of easterly outbreak by early December.  Interesting times, jet and synoptics are interesting particularly, as they are quite odd.

Coldest GFS ensembles of the winter so far some very wintry efforts there.

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Perhaps the means are more useful in a more realistic time scale with such uncertainty at the moment

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=144&code=21&mode=0&carte=1

http://www.meteociel.fr/modeles/cmc_cartes.php?code=21&ech=144&mode=0&carte=1

The encouraging thing is that some of the output now has the HP to the east further north.However  around 240 h the majority of GEFS  ENS are Atlantic flows.

It doesn't take a genius to spot the major short-term difference between GFS/GFSP and the rest of the models:

UKMO: large Iberian trough as a robust cut-off feature.                   ECM: large Iberian trough as a robust cut-off feature.

JMA: large Iberian/French trough as a robust cut-off feature.            GEM: large western Med. trough as a robust cut-off feature.

GFS and GFSP: smaller Iberian trough that struggles to separate from the Atlantic jet stream.

What gives?

Answer: the jet is stronger than the other models have it even at just 4 days range. The upstream Atlantic troughs push east too quickly for the Azores High to build a 'bridge' of higher pressure to the north of the low that's diving south of the UK.

So, given the agreement between the other models and that this includes the most reliable of them all in the 4 day range, it seems likely that this is a classic case of GFS overcooking the jet, and it's a shame to find this, but the upgraded version appears to have the same trait and in fact it could be concluded from the above that the tendency might be even more pronounced!

I have seen comments on other forums indicating that the GFSP has a few problems with it, which should be amended prior to it's full take-over from the current GFS. I'm hoping this overcooking of the jet is one of those that will be sorted!

Let's hope so, eh?   Which model has the best verification stats at that range currently?

If anyone has a link to the latest verification stats I would be most grateful 

A brief note on the longer term - ECM has backed off from the very fast movement of the Greenland lobe into the Atlantic that was present on the previous two op runs, and in that sense has brought the pace of events more in line with GFS/GFSP.

This leaves the blocking to east as once again the main source of uncertainty in the output for the first week of December. JMA makes by far the most of that, but this comes from the Atlantic troughs making less progress east as early as day 4 when compared to ECM and UKMO, and it would be quite something for that duo to have that modeled incorrectly at such short range when they are in agreement.

The stronger Iberian trough supports a stronger blocking high on the ECM run than what GFS and GFSP go for, and it's fair to assume that UKMO would head the same way, though perhaps the high wouldn't be quite so extensive.

GEM could have followed suit, but deepens the Atlantic storms more than the other models, resulting in a messy - though actually snowy for some - battleground scenario rather than the blocking high in full control.

The theme of recent months has been that blocking to the east holding on in the face of longer-range projections for it to fall, so I'm starting to settle on the theme of a blocking high to our east and a slowly disintegrating polar vortex lobe in the Atlantic - allowing lows to slide down to the Med. - as the favoured way forward.

Now just watch tomorrow's models change tracks completely 

North easterly winds~!! - I do believe that there are some interesting things that are starting to develop post 10 days.

Even if this turns out to be a milder winter - it won't be as wet as last year - looking at the models/gfs etc there is no real deepening low and relentless low pressure system after system - the models certainly are not showing this - it's all very vague and the Atlantic looks set to be quieter - at least for now.

Just worth a watch deep into FI: - perfect set up for an easterly before Xmas:

 http://modeles.meteociel.fr/modeles/cfs/runs/2014112312/run/cfs-0-684.png?12

I reckon it is December 2012 you are thinking of there WM. I could be wrong, but I have no clear recollection of the ECM, or any of the other models, showing an easterly of any sorts at any stage during last December. My recollection of last year is that in the early part of December, the models initially showed high pressure controlling the weather for much of the month although never really that cold, before the breakdown to atlantic dominance that went on to last until after mid-Feb was picked up.

December 2012 did have quite a few cold days here in the first half of that month, and during that time I do remember some pretty interesting model runs on a few occasions. The second half of that December was milder and wetter but that wasn't to set the tone for the rest of the winter; IIRC the model runs in the first few days of 2013 clearly indicated that a change in pattern was afoot.