Model Output Discussion - cold spell to end Autumn

[Summer Sun]

7 minutes ago, Summer Sun said:

A quick look at the short ens for the 06z shows the Op going a fair bit below the mean around the 6th

We need to await the full ens to see if it is a rouge run or not

06Z is indeed way colder than the mean

[northwestsnow]

number 5 looks a beauty!!

[johnholmes]

24 minutes ago, claret047 said:

Good Morning everyone,

As a lot less knowledgeable on here than a number of other posters I find it very puzzling how the models can be so very different from one run to the next.

I would like to ask a question as to how these model outputs are produced. Mods if I have posted this in the incorrect thread then please move it to a more appropriate one.

Does for example the 0Z one then have computer feedback from readings onto the previous 0z one to perpetuate any bias, or is each run completely independent  of the previous OZ  run. I am afraid that I have not worded it very well, but I trust you know what I mean.

Kind regards

Dave

Have a look in the Net Wx Guide area, I am sure there is something in there about this issue.

In brief each run does tend to have slightly different base data input in. For instance more aviation reports, or radio sondes than another run, I forget which ones. But this can and does make a difference, have a look on the Met O site and read their pages on how the models are created. Hope that helps a bit.

[frosty ground]

3 minutes ago, Summer Sun said:

06Z is indeed way colder than the mean

But not unsupported 

Edited November 28, 2017 by frosty ground

[Weathizard]

7 minutes ago, Summer Sun said:

A quick look at the short ens for the 06z shows the Op going a fair bit below the mean around the 6th

We need to await the full ens to see if it is a rouge run or not

Theres no clear trend, had a quick glance through them and it does appear to be one of the coldest 2/3 members but not a rogue run persay.

 

2 minutes ago, bluearmy said:

We had this debate the other day - how is the ens mean any different to having a solution verify that is a blend between two differing op solutions - this seems to happen a lot of the time. 

I’m not someone who think means are a waste of time.

I don't normally but looking at the 144-168 timeframe there's a relatively big divergence there, there's quite a few ECM like solutions and some GFS/UKM like options, there's not really a middle ground between these two options hence why i think the mean is not very useful in this situation.

[ukpaul]

2 minutes ago, Summer Sun said:

06Z is indeed way colder than the mean

Op and control similar, but with slightly different timings, at the latter stages of high resolution, which is a useful pointer.

[Daniel*]

48 minutes ago, carinthian said:

Ends with blighty almost covered in snow .  Great stuff. The dream lives on for you snow lovers.

C

Got to love a channel low, they’re not so good for my blood pressure then again it’s low so that’s not such an issue. March 2013 was quite a disappointment while the Channel Islands had their most memorable snows in decades, still memorable and significant falls of snow for southern coastal counties. I never got a flake, AJP asked when will folk will learn the answer is quite simple never, some will nonetheless so take some from solace from that.

 

[Chesil View]

Crikey I log out on page 17 with wailing and despair filling the air then check back and we're on page 21. I'm assuming the 06z must be a snowfest..lol

[karlos1983]

Just now, Daniel* said:

Got to love a channel low, they’re not so good for my blood pressure then again it’s low so that’s not such an issue March 201.3 was quite a disappointment while the Channel Islands had their most memorable snows in decades, still memorable and significant falls of snow for southern coastal counties. I never got a flake, AJP asked when will folk will learn the answer is quite simple never, some will nonetheless so take some from solace from that.

 

Let us never speak of said event again.. AMEN 

[feb1991blizzard]

6 minutes ago, johnholmes said:

An interesting observation that, I might even be tempted to add that idea into my own look at different models, ensembles etc, thank you.

Is there sometimes a difference looking at ensembles for different places in the UK or am I talking rubbish?

I click on an area around here or near Manchester, tbf the parameters were mainly used on Easterlies but I doubt theres much difference on Northerlies, its a little unscientific because depending on the setup, I click a little further away from my location sometimes, hoping for a little more leeway! but we are talking uppers here so doubt it makes a great deal of differences.

 

The latest GEFS btw is critical now, I would give it 24 hours now, around 6th Dec, theres about 6 members between -5c and -10c, if by tomorrow on the 5th Dec, there isn't a few more dropping to that level, I doubt a potent cold outbreak is likely, certainly if there is only 3 or 4 then I would almost say its a negligible chance, of course that doesn't rule out some sort of cold spell in terms of surface temps but for a potent Northerly then its looking very bad.

[bluearmy]

Btw, many ens members are now showing heightened w Pacific TD activity through week 2 - if one of these systems recurves into the n Pacific then that interacting with the deep troughing over there would excite an already amplified background pattern. 

Keep an eye on it - was a few years ago that this very evolution was the final catalyst for a hugely neg AO phase 

[karyo]

22 minutes ago, Mike Poole said:

Who needs model output?

Dr. Cohen’s latest AO blog is hilarious.  In it he presents the winter forecasts from various models (NMME, CFS, ECMWF and UKMO), which are all screaming mild – junks the lot and in his AER forecast goes for cold right across Eurasia, to quote: ‘multiple weeks of severe winter weather across the NH’.

It’s quite a call – either he’s wrong or the models are.

Well worth a read after the rather mixed model output this morning:

http://www.aer.com/science-research/climate-weather/arctic-oscillation 

 

Interestingly, the below average temperatures start from about Germany and continue eastwards. The UK is in average territory.

Agreed though, this is different to what all the long range models show.

[Islander]

11 minutes ago, karlos1983 said:

Let us never speak of said event again.. AMEN 

Errr you can mention it as many times as you like, was a truly awesome experience!! 

[Geordiesnow]

Think the frustration with the outputs at the moment is the fact that the trend is for high pressure to remain just to the west of us, does not look like it will head NW'wards but it barely moves eastwards or on top of us for at least a few days so we are in a run of cool NW'lies which is likely to bring a lot of cloud and frost is likely to be quite limited so after this northerly flow then the trend is for the weather to turn quite boring really. I would not rule out a Northerly just yet as the output and details of each run will vary but the signal for a northerly flow is weakening somewhat.

In all honesty, I would not mind things to take a turn to a less blocked outlook and allow a positive AO to form because I have never seen our side of the Northern Hemisphere looking so 'warm' at higher latitudes, this northerly shot proves it, end of Novemeber, a northerly which lasts for around 3 days and we are struggling too get uppers of -8 to enter the UK so that just tells you we are feeding on scraps in terms of what cold air is avaliable to us.

 

[nick sussex]

The doctors have detected a pulse! 

Typical just as the priest was called the GFS 06 hrs revives hopes! This occurs because of a slight change over Artic Canada with a more amplified pattern which stops the shortwave appearing to the nw which is now becoming the make or break of the current long winded saga.

You must maintain a clear flow from the UK ridge back towards ne Canada. If you don’t as the upstream amplification works east it amplifies the pattern to the west of the UK which takes shortwave energy to the nw.

In terms of meangate I agree with Weathizard, the mean is not very useful in this set up because the evolution with or without spoiler shortwave is completely different.

 

Edited November 28, 2017 by nick sussex

[Frosty.]

2 minutes ago, nick sussex said:

The doctors have detected a pulse! 

Typical just as the priest was called the GFS 06 hrs revives hopes! This occurs because of a slight change over Artic Canada with a more amplified pattern which stops the shortwave appearing to the nw which is now becoming the make or break of the current long winded saga.

You just maintain a clear flow from the UK ridge back towards ne Canada. If you don’t as the upstream amplification works east it amplifies the pattern to the west of the UK which takes shortwave energy to the nw.

In terms of meangate I agree with Weathizard, the mean is not very useful in this set up because the evolution with or without spoiler shortwave is completely different.

 

Please can we go on white alert after that 6z nick

Edited November 28, 2017 by Frosty.

[feb1991blizzard]

34 minutes ago, Broadmayne blizzard said:

Crikey I log out on page 17 with wailing and despair filling the air then check back and we're on page 21. I'm assuming the 06z must be a snowfest..lol

Yes, its an absolute right old dumping.

[Methuselah]

Thanks for the reminder, Nick...Dr Snow (I kid you not!) will be on LBC tonight...

So, let's all hope, pray, cross our fingers & toes and perform our communal snow-dance...

And, praise be to the GFS.

Seriously though, isn't it about time us coldies had a wee bit of luck? Let's hope the models have got it right, this time?

[Polar Maritime]

Can we please use the banter/moan/ramp thread for anything other than model output discussion.

Thanks 

Edited November 28, 2017 by Polar Maritime

[Gavin Hannah]

1 minute ago, Ed Stone said:

 

Seriously though, isn't it about time us coldies had a wee bit of luck? Let's hope the models have got it right, this time?

Doesn't everyone know that the weather gods hate our tiny island.???

Anyway, I would be surprised if the 12z is as good as the 06z.  Usual route is for a downgrade followed by a halfway house compromise.

 

[memories of 63]

 

Whisper it, theOp is a cold outlier 

[Seasonality]

So in terms of the London ensembles I think we can safely say bottom of the spread but not an absurd outlier either. And just for fun, check out the member that shows the 2m temp dipping to around -13!

[Frosty.]

Just now, memories of 63 said:

 

Whisper it, theOp is a cold outlier 

I thought it was a mild outlier..

[karlos1983]

15 minutes ago, nick sussex said:

The doctors have detected a pulse! 

Typical just as the priest was called the GFS 06 hrs revives hopes! This occurs because of a slight change over Artic Canada with a more amplified pattern which stops the shortwave appearing to the nw which is now becoming the make or break of the current long winded saga.

You must maintain a clear flow from the UK ridge back towards ne Canada. If you don’t as the upstream amplification works east it amplifies the pattern to the west of the UK which takes shortwave energy to the nw.

In terms of meangate I agree with Weathizard, the mean is not very useful in this set up because the evolution with or without spoiler shortwave is completely different.

 

Stateside Forecast discussions are amusing this morning Nick, more blending of the models than a Nutribullet 

They probably watched the 06z roll out, switched the lights off and went home. 

[knocker]

10 minutes ago, Ed Stone said:

Thanks for the reminder, Nick...Dr Snow (I kid you not!) will be on LBC tonight...

So, let's all hope, pray, cross our fingers & toes and perform our communal snow-dance...

And, praise be to the GFS.

Seriously though, isn't it about time us coldies had a wee bit of luck? Let's hope the models have got it right, this time?

Good Lord Pete, I never had you down as one of the unhinged