Model Output Discussion - mid Autumn

[Cambrian]

Yeah, silly old us, clearly nothing doing, all just a coincidence (again).

12z GFS ensemble mean at day 11; 12z GEM ensemble mean at day 11

  

12z GFS control at day 12; 12z GEM control at day 14; mere variations on a fortuitous theme…

 

But we fall for it every time. 
 

12z ECM control at day 13 looking very different indeed to recent runs…

…so maybe the beginning of the end for our amazing run of “coincidences”, though extremely interesting in a completely different way. 

Well, in any case, whatever comes our way, I must admit I’ve thoroughly enjoyed studying the models the last few days. Have a lovely end to your day. 

Edited November 14, 2023 by Cambrian
added ECM chart and comment

[LRD]

EC46 looks Atlantic ridge-y for next week

Anomalies - so can be misleading but make of it what you will

Going into December it looks pretty westerly. Won't post a bunch of charts but here is the link

ECMWF - Charts.url

ECMWF | Charts

CHARTS.ECMWF.INT

 

Edited November 14, 2023 by LRD

[TSNWK]

4 minutes ago, Cambrian said:

Yeah, silly old us, clearly nothing doing, all just a coincidence (again).

12z GFS ensemble mean at day 11; 12z GEM ensemble mean at day 11

  

12z GFS control at day 12; 12z GEM control at day 14; mere variations on a fortuitous theme…

 

But we fall for it every time. 

We do.. so long as we remain polite and take it all with a pinch of salt its all good sport and a nice little distinction and theatre:)

[johncam]

ECM disappointing again , getting watered down with each run 

[northwestsnow]

EC 46 looks an improvement for coldies..

 

[Jeremy Shockey]

GFS 12z ensembles

 

Well lets hope that the GFS 12z Op is on to something.  We could all do with a few days of a relatively blocked Atlantic . I'd take a 48 hour Northerly or Northwesterly to be honest.  

[booferking]

Ec clusters won't look to bad later still quite a few going for the block.

[damianslaw]

Mmm big differences between ECM and GFS this eve longer range, outside the reliable, to be expected. GFS sharpens the scandi trough, no shortwave energy near Iceland, and then builds very steong heights over Greenland.

ECM after playing around with similiar fair, shows a much less clean amplified ridge/trough pattern, hence the mid atlantic heights collspse somewhat and we maintain a mostly westerly airstream, though there is much room for things to evolve as per GFS.

As said this is all beyond the reliable, the outcome could all be different. Just interesting to see different fayre to the Autumn pattern as a whole, a season do far devoid of any real northerly or even north westerly flow.

Edited November 14, 2023 by damianslaw

[January Snowstorm]

You would wonder really what if any use there is in analysing day 10 charts. The ECM proves this time and time again. For the more experienced on here, we know that a pattern change picked up around day 7 is the one to look out for!! They do happen and the counting down is a shorter timeframe.

For me right now the outlook looks rather non descript. Nothing to be despondent about just typical Autumn fayre. The ground temps are still quite high so a few hard ground frosts would be welcome

[TSNWK]

Blooming heck gfs.. on the pop! On a school night… tut tut,,

[Mike Poole]

ECM clusters T192-T240, I’ve been keeping a close eye on these last couple of days, and the picture really hasn’t changed much in 3 runs now:

The big Atlantic ridge scenario is still here, in clusters 3 and 4, combined 21 members.  So I’m not quite sure why this seems to have been called as ‘GAME OVER’, other than maybe because it is still at day 9/10.

Edited November 14, 2023 by Mike Poole

[Tim Bland]

Anyone know where to book cheap flights to Sweden

[Don]

3 hours ago, blizzard81 said:

Oooh! Ecm you naughty boy. You didn't even attempt to let us down gently . We shouldn't be surprised. This happens just about every year - the end of November tease. It's almost as if it's programmed into the models lol. The big give away this time around was how lowly placed those juicy ecm ops were in the clusters. Must try harder next time ecm when trying to tease. 

 

Oh balls, are we looking at the first let down of winter 2023/24 (well, not quite winter I know!)?!  If so, will it be one of many or will we have more success during winter proper?!  

4 minutes ago, Tim Bland said:

Anyone know where to book cheap flights to Sweden

A postive that Scandinavia remains colder and snowier than average, which could help us down the line?!

[near northampton]

For potential cold weather Strange times, outside of NWP Matt Hugo not very interested backed up by Tamara, Exeter don't seem interested, has anyone ever considered all the models are wrong?  

[Lincs Observation]

The fact that despite the timescale issue at this time, the models seem to be throwing up various journeys to a cold pattern change must indicate the start of a trend. A bit like focusing in to an object with out of focus binoculars eventually you will get a pin sharp image sooner or later. As someone said yesterday you can’t ignore the trend it’s your friend

the noise over a cold spell is getting louder on various social media outlets so I say despite the uncertainty something is afoot

[Beanz]

3 minutes ago, Lincs Observation said:

As someone said yesterday you can’t ignore the trend it’s your friend

I used to believe this, but now I’m not so sure.  If you follow a trend, eventually it will change and you’ll be stuck wearing the wrong t-shirt. 

[WYorksWeather]

Not had chance to post much lately in here as I've been busy either in RL or on other threads. Typical that I miss an interesting cold weather chase!

Anyway, I'll see where we're at with the GFS 18z vs ECM 12z comparison. We don't have the GFS 18z ensemble and others have posted the 12z, so here's the ECM 12z high resolution ensemble run for temperatures. For London, temperatures probably net out slightly above average to day 7, and then beyond that the uncertainty magnifies to the point that the chart is fairly meaningless. This can be seen most strongly around day 12, which shows a 25C variation in the 850hPa temperature possibilities, from an ensemble that would probably break the 850hPa record at nearly +15C, all the way down to -10C. Mean flattens everything out as is usual, but it still shows that the ECM is struggling to pick out the way ahead.

As usual when I do 18z vs 12z, I'm lagging the 18z GFS by 6 hours so we are looking at the same valid date and time - e.g. T+66 for GFS and T+72 for ECM.

At T+66/72, there seems to be good agreement that an area of high pressure will build in from the Azores, settling the weather down and leading to a couple of days with temperatures possibly into the mid-teens in places. A strong Greenland high on the GFS, less so on ECM as has been seen for weeks now, and low pressure systems to our west and east.

 

At T+114/120, we see that the ridge is unable to hold back the Atlantic, and we see another area of low pressure aimed towards Scotland and northern England. Nothing particularly notable, but more wet and windy weather as a result. Southern areas probably avoid the worst of it. In the broader scale, we see the beginning of some sort of Scandinavian high setup appearing, and the Greenland high weakens. There is also a mid-Atlantic ridge, which could be strong enough to finally hold back the Atlantic for a considerable period.

 

At T+162/168, we see both GFS and ECM massively amplify this ridge! A huge area of high pressure sets up in the mid-Atlantic but ridging across into the UK and Scandinavia, with a low around Greenland. It isn't quite enough for snow to low levels most likely, but not too far off especially in more northern regions, so it wouldn't surprise me if we start to see snow down to 250m or so. In any case, clear spells with those 850hPa temperatures will give widespread hard frosts.

 

 

Stepping through more slowly, at T+186/192 we see a quick change. The position of the high changes ever so slightly on the GFS, with a slight rotation and less influence across Scandinavia, which quickly allows milder air to return from the southwest. Blocking gets set up over Greenland once again. ECM goes for a radically different scenario, with the high being reshaped more towards central and eastern Europe, with low pressure east of Greenland. Not as mild as the GFS, with temperatures probably close to average.

 

At T+234/240, we see GFS sticking with its Greenland blocking idea, and we're under a separate area of high pressure now centred just to the south west of Ireland. ECM moves the high further west and looks like it is trying to drag down colder air from the north, but at this point it is still a bit marginal, and the 850hPa temperatures don't show anything unusual for the time of year over the UK. Notably cold in Scandinavia and some parts of Central and Eastern Europe though.

 

The GFS extended shows one or two interesting cold incursions, likely enough for some snowfalls in Scotland. The position at T+384 looks like this. Generally a dry pattern, with high pressure largely in control.

 

 

[MATTWOLVES 3]

Can I just steady the ship a little here folks.

Firstly the EC46 drove everyone up the wall when it was only being issued 2 times a week,now its become daily its gonna serve to make a fair few heads fall off!

2ndly there seems to be far to much emphasis on the Exter updates by some and please remind yourselves how badly wrong they got the mid Summer period wrong and multiple other times they've been barking up the wrong tree! They are not messiahs with all the answers...they can only go on the global drivers with these long range forecasts and these drivers change on a very regular basis.

Look at this way last Winter started positive with cold conditions locked in place for early December...but look what come next! It all fell apart as we moved beyond Xmas.. this year looks more set up for colder conditions too become more probable beyond the Xmas period. So absolutely know point whatsoever in getting highly strung over conditions in mid November. And don't be thinking Exeter have all the answers all the time,because they clearly do not!

Take a deep breath and relax...NWP will throw up many scenarios in the coming weeks,and at times it will be miles out.

[Mucka]

All a bit convoluted and full of traps but GFS gets there

Not often you get a Greenland high from Arctic blocking moving into Greenland 

By the way, what is the record negative AO 

Edited November 15, 2023 by Mucka

[Cheshire Freeze]

GFS just a bit nuts this morning-

[Nick2373]

 

Not seeing much in terms of something dramatically cold, perhaps a Northey toppler, Temps look to be around the same as we seeing now with just a little over at times.  looks to be more of a flat zonal high where we see clear nights may get a touch of ground frost and fog in places, that's about it no 2010 repeat looks likely.  

Best keep the feet firmly on the ground and not get caught up in the hype.

 

Edited November 15, 2023 by Nick2373

[sheikhy]

Ecm flat later on once again!!for me if ecm doesnt show what we want i can put the gfs aside lol!!!thats just my opinion!!anyone noticed something typical over the last 3 or 4 days in regards to this potential cold northerly?!someone gimme the right answer i be waiting lol!!

[Premiere Neige]

6 minutes ago, sheikhy said:

Ecm flat later on once again!!for me if ecm doesnt show what we want i can put the gfs aside lol!!!thats just my opinion!!anyone noticed something typical over the last 3 or 4 days in regards to this potential cold northerly?!someone gimme the right answer i be waiting lol!!

It never gets closer than day 10 and if/when it does, it gets watered down? 

[TSNWK]

7 minutes ago, sheikhy said:

Ecm flat later on once again!!for me if ecm doesnt show what we want i can put the gfs aside lol!!!thats just my opinion!!anyone noticed something typical over the last 3 or 4 days in regards to this potential cold northerly?!someone gimme the right answer i be waiting lol!!

It keeps on being pushed back as part of the downgrade to nothing process 

[sheikhy]

6 minutes ago, Premier Neige said:

It never gets closer than day 10 and if/when it does, it gets watered down? 

BINGO!!!!!!!now what i find more interesting is the models tryin to find a bit more amp in the atlantic and the high arching around into scandi at days 5 and 6 more and more in the last few runs!!!we may not get snow out of it but could feel colder and frostier a lot sooner!!lets see if the 12zs keep it going at days 5 and 6!!!

9 minutes ago, TSNWK said:

It keeps on being pushed back as part of the downgrade to nothing process 

BINGO!!!!!!!now what i find more interesting is the models tryin to find a bit more amp in the atlantic and the high arching around into scandi at days 5 and 6 more and more in the last few runs!!!we may not get snow out of it but could feel colder and frostier a lot sooner!!lets see if the 12zs keep it going at days 5 and 6!!!