Model Output Discussion - Into Winter

[Anthony Burden]

Morning all,sorry pressed wrong button ,well just to return to the up and coming high pressure and it’s possible position and orientation as Nick just mentioned the Azores high looks likely to ridge over the UK which could depending on it’s orientation give milder temperatures to the North while the south could be in a Faux situation keeping lower temperatures,all very speculative at present.The good thing with a pressure rise over the UK at this time of the year is the possibility of seasonal weather can develop quickly all be it dry and white.

 

[MattStoke]

13 minutes ago, Anthony Burden said:

Evening all, GFS GEM looking keen to bring a pressure rise from the Atlantic along with the chance of dry weather with frost etc that goes with high pressure hopefully with out cloud cover.looks to kick of around the 13 th December temperature wise once again will depend on position and orientation,hopefully a positive sign for more seasonal weather.

Evening already? Wow. I'd best leave work. Not sure why my boss is giving me a funny look.

[PiscesStar]

9 hours ago, Scandinavian High. said:

I really want something from east this time if we do get another cold spell northerly don’t really cut it for me manly dry and sunny.

Snap. We didn't see a flake of snow from the last one 

[ITSY]

35 minutes ago, Bricriu said:

The EC46 seems to change alot, but hopefully  this time it's a case of the models will quickly  change  to a more favourable outlook  to reflect what the EC46 is showing.

I can't respond in detail to this but the models are already beginning to show similar outcomes. What the EC46 is showing is essentially ridges of HP moving gradually away from the UK and into the Mid-North Atlantic towards Greenland and, at the same time, lobes of vortex moving gradually away from Svalbard and towards N and NW Europe. It's a little more fine than that but that's the jist of it. 

Now if you look at some of the recent GFS OP runs, here's what they show. 

None of them are immediate nor nirvana. And we should always, always, take what deep FI is saying with a pinch of salt. But, as of now, the very far reaches of FI are beginning to show something that resembles, at the right timeframe, the latest EC46. And if we look at the latest GEFS 850 trend line, you can see this reflected in the downward clustering in the runup to the festive period - again in line with both the UKMO online wording and the EC46. 

Nothing is banked or close. Indeed, there's a lot to get through and if it can go wrong it will go wrong. But the chase is certainly on and there is some early indications of Euro/American model alignment on the type of pattern evolution we could soon see. It's boring I know but for now the best we can do is look into the crystal ball of FI and see whether it resembles what the long term computers, and some pros, are seeing. I would say they are beginning to do so...

 

 

 

[That ECM]

A little more ne on this run. It’s a start.

[Met4Cast]

The changes we’re seeing on extended NWP modelling & the EC46 is consistent with the background drivers a few of us have been highlighting. 

A recent +EAMT event has reversed to -ve but only briefly, as a large ridge over Siberia moves south into the Tibetan Plateau we’ll see a fairly large +EAMT event spike, driving up +AAM tendency again. 

 

We need to watch the ECM & GFS MJO forecasts, they both continue to suggest a less amplified cycle than you’d expect, the recent BOM update continues to suggest good amplification. 

[rwtwm]

42 minutes ago, johncam said:

The ECM control run isn't great right to the end. I take it the MJO in  7/8 doesn't always guarantee a cold dpell for us?

No, it doesn't. But it's worth noting that ECM doesn't foresee a high amplitude MJO through phase 7/8, so I wouldn't expect the consequences to be reflected either.

This is yesterday's ECM.

There has been discussion up the thread of amplitude decay being a known bias of MJO forecasts. 

Well luckily it seems that the ECM page from which I've drawn the above has a recent history.

ECMWF | Charts

CHARTS.ECMWF.INT

 

Below is the same chart from Nov 28th and Dec 2nd:

 

 

Note the change of the amplitude in phase 5 (in particular) as we move from 1 week ago to today. Bear in mind of course that previous performance is no guarantee of future success. In the same way that if the first 3 lows miss us to the south, doesn't mean the next will.

The BOM has been posted a few times, but for quick reference, here it is again...

I've been sympathetic to the thought that highlighting the BOM feels a bit like 'cherry picking'. But I have to concede it's been consistent with this. I can't find a BOM 240 chart for our part of the world to compare (do they exist?) but that's where if be looking to test the impact of phase 7/8 on our weather, that's where I'd look.

[That ECM]

The last chase was fascinating. This one is also. The pv profile is interesting to say the least.

 

we have had many seasons where it has offered little in terms of cold for coldies.

[minus10]

Yes interesting to see the Gfs, Ecm and Gem 0z all showing the same basic pattern upto the festive period for 850s..

...so, as others have said, perhaps confidence growing  that after this wet period the strongly signalled high will dry things up but also warm things up for a while...but then...still with less confidence at this range there is a signalled cool down towards Christmas as the high moves to a position letting in cooler/colder air...from which direction still to be decided...one to watch..

Edited December 7, 2023 by minus10

[Mike Poole]

It seems to me that the models (in FI) are just looking for the opportunity to swing the high to the northwest.  When and whether an opportunity presents itself will be different on every run (and indeed the ‘run’ that matters, the actual weather!).  We’ve reached such a point at T330 on the GFS 6z:

[BartyHater]

06GFS....BANK!! I've already passed the point where a week of dry weather is now my preferred option, if we get some cold out of it and then a genuine cold pattern sets up in the run down to Christmas then bonus... but for now dry will do just nicely. 

[MJB]

3 minutes ago, Mike Poole said:

It seems to me that the models (in FI) are just looking for the opportunity to swing the high to the northwest.  When and whether an opportunity presents itself will be different on every run (and indeed the ‘run’ that matters, the actual weather!).  We’ve reached such a point at T330 on the GFS 6z:

Moves NWards as you say, just one outcome as we approach the big day 

[feb1991blizzard]

GFS 6z is a corker albeit way outside anything resembling the reliable timeframe.

[mountain shadow]

Christmas week again looking promising. 

[Polar Maritime]

Looking at how the models are evolving atm, We could very well end up with a chilly N/W - N/N/W flow over the Christmas period. 

Edited December 7, 2023 by Polar Maritime

[MattStoke]

Settled, chilly mid month under high pressure. On the GFS 6z, even orientates in such a way that we get a chilly easterly.

Potential for a cold spell to develop thereafter, maybe in time for Chrimbo.

[Methuselah]

A pretty dire GFS 06Z IMO. . . Dull, coldish and incredibly boring: 

    

But it is, of course, only one run!

[BartyHater]

3 minutes ago, Methuselah said:

A pretty dire GFS 06Z IMO. . . Dull, coldish and incredibly boring: 

    

But it is, of course, only one run!

Rather be bored than drowned....which given the way this rain is coming down in S Cornwall right now, is a genuine possibility!

Edited December 7, 2023 by BartyHater

[joggs]

Definitely picking up the trend of the background drivers in the very outer limits........

Interesting.

[Neilsouth]

Just now, MattStoke said:

Settled, chilly mid month under high pressure. On the GFS 6z, even orientates in such a way that we get a chilly easterly.

Potential for a cold spell to develop thereafter, maybe in time for Chrimbo.

If I remember correctly, back in the 90's before the great Easterly, there was a lot of high pressure and dense FOG. Something most winters have been lacking. So just maybe a settled high would be a good thing?

[Scandinavian High.]

If we do get a greeny high at some point this winter is it possible it could transfer to Scandinavia later on.

Edited December 7, 2023 by Scandinavian High.

[NewEra21]

You’d genuinely take either GFS run today, 00z or 06z.

Both singing very much from the same hymn sheet, opening up the possibility of real cold just in time for Christmas.

Such a long, long way to go though. Purely fantasy right now, but good to see the option seems to be on the table.

[Northwest NI]

As another chase begins, you can’t help but reflect on the contortions we need to go through, to get cold to our part of the world. Basically it does not want to come here and it takes a veritable jigsaw puzzle to be completed. The inevitable happens and the forum goes back to 2 posts an hour.

On the other hand, any mild, wet, windy weather programmed comes sweeping through the doors saying ‘hi, it’s me’ like some very unwelcome in law on Christmas morning.

But here I am, reporting for duty, on the next chase!

 

 

 

[MJB]

Belter 

[minus10]

There are no words...