The 00z ECM ensemble for London shows that there’s a growing cluster returning us to cold conditions again from 9th, after a short-lived milder interlude.

Some excellent analysis in the thread, but I think it'd benefit from some more input from 'seasoned expert campaigners' like Retron.

Yes it would appear that both ECM and GFS are favouring the Scandi Low/Aluetian Low longer-term as PV response,  with some mid Atlantic ridging, which would favour a PM NW/NNW feed. Ties in with the ECM 30 from Monday.

That's how it seems to me, too.

Yes; I was thinking several days ago that a period of ‘cold zonality’ was looking likely but GFS has oscillated between that and normal zonality.  

I’d be content with a seasonal spell, just not a mild dull south-westerly Bartlett-type - which appears a low risk, fortunately.

Does anyone know why the GFS operational run sometimes is different to the other 18 ensemble member runs at a short timerange (such as 6 to 18 hours) ??  I'm specifically talking about the charts showing the 850hpa temperature and precipitation. The OP run sometimes is higher or lower than the remaining 18 runs even though the 18 runs all agree on the temperature/precipitation!!

Someone just  asked this queston on a ski forum but I can't remember the reason!!

Thanks

And here I am Saint   . Certainly a +ve NAO set-up developing, perhaps we can achieve a toppler or two as early December progresses. GFS continues with it's zonality election day fest.

As December 12th has only moved into range in the last day I’m not sure ‘continues’ is right, is it?  Given it’s still 15 days away it will almost certainly look different by then.

Thats great , thank you Gandalf!!

But often it is the operational run that is out of kilter with ALL the other runs by a significant amount in one direction, so that can't be the reason, if the other runs have the starting conditions randomly tweaked. I've noticed the same thing and have no idea why. Maybe a resolution issue?

I liked it when it was widely referred to as 'FFS'

Yes, but we have to remember that there are far more data points in the models than there are data to populate them. That means even the operational model is starting with an estimate of the state of the atmosphere.  As the ensemble suite is essentially about asking "what if our opening position is slightly awry?" multiple times I don't see any logical reason why the op must always result in the most likely outcome.

Where, I trust, 'F' is for fantasy....

Not quite!  

When the models were teasing a much more amplified outlook with NE winds  and the cold spell lasting longer ,you were the one saying they were wrong and zonal would win out.

So well done to you this time,👋let's hope we get one frigid spell this winter 🏂⛷️🧚

I think that is right. The new GFS model seems quite different to the old one even though verification stats overall are quite similar. 

A stopped clock, and all that...  (only, with this island's crappy climate, repeating 'zonal rubbish' ad nauseum will be correct the majority of the time)

That AH is a real pest. In 2010, it went on holiday to the American half of the Atlantic

From the NOAA website:

FV3 is the first step. It was developed in NOAA Research’s Geophysical Fluid Dynamics Laboratory initially to power climate models and was then adapted for detailed global weather prediction. The NWS chose FV3 as the new GFS’s dynamical core in part because it uses less computer resources than other options. FV3 brings unprecedented accuracy to forecasts in three important ways:

• Computer Usage — FV3 is designed to efficiently scale to the available resources on any supercomputer for faster, higher resolution images. The current GFS, developed before the age of high speed computers, is not able to provide such highly detailed informations. Even if it ran on a computer with more processing power, it would not work faster.

• Vertical Equations — FV3 uses vertical equations to limitlessly zoom down to local scales and provide images of up-down air fluctuations, allowing us to resolve thunderstorms and their updraft winds. Older models assume the atmosphere experiences equal forces from above and below. This assumption can provide accurate prediction over large areas, but is unable to see the small-scale fluctuating winds that can lead to severe weather.
   


• Representation — FV3 represents weather through points in connected grid cells, so it can resolve weather that comes in irregular shapes. The current GFS represents all weather as waves. It’s been successful in large-scale modelling, but weather phenomena do not always follow wave patterns on the local level. For example, thunderstorms and cold fronts have sharp edges that a wave shape can not fully capture.

it still is in some households Saint 😂