Model Output Discussion - Winter arrives

[frosty ground]

1 minute ago, That ECM said:

If two models are showing this then it needs watching. 

This is not a one of run and there is a chance of a strong storm developing an running across the British isles.

lower the pressure further south it will go thou

[fromey]

7 minutes ago, That ECM said:

If two models are showing this then it needs watching.  955 on gfs. At t120.

You posted the same charts. At different times of the day 

Edited December 2, 2021 by fromey

[Uncertainty]

Remarkably coherent signal at 360 from the big 3 ensembles

GEPS

 

GEFS

 

EPS would doubtless be similar

 

MJO phase 6 Nina composite

 

 

Forecast

Interesting where the 46 takes the Urals high towards xmas…

 

[knocker]

First some wave breaking and then next week's low deepens near the left exit of the jet

[sheikhy]

Arpege dont develop the storm at all!!leaves us in a much colder slack conditions!

[Updated_Weather]

On 02/12/2021 at 16:37, sheikhy said:

Arpege dont develop the storm at all!!leaves us in a much colder slack conditions!

Why doesn’t that surprise me

[Frosty.]

9 hours ago, Scandinavian High. said:

Could there still be a chance of a flip back to cold or as ship sunk.

There’s always a chance that the models could flip back but in the meantime…there’s an iceberg right ahead!  

[sheikhy]

1 minute ago, Updated_Weather said:

Why doesn’t that surprise me

The storm actually looks unreal to me!!!meaning it so deep i still dont believe its gona actually happen!

[Blessed Weather]

3 hours ago, Ruzzi said:

(Snipped)

With regards to the CFS, it's a complete waste of time looking at it as is looking at any one model that tries to tell you what the weather will be like months in advance! 

There's a reason that human input is put into the MetO fax charts and that's only at a couple of days out, so an automated forecast from a model months in advance is utterly pointless. Whatever time you are spending viewing the CFS, instead dive into the depths of each different teleconnection and how they can impact our weather and winters etc and watch your perception change. There's stacks to be learned, loads of helpful threads on here too with great explanations. It'll dismantle any creedance you hold for a 3-4 month in advance nonsense automated weather model like CFS. 

Poor old CFS keeps getting a bashing. So in its defence, here's the thoughts of Dr. Simon Lee of Reading University, on his excellent website. Worth a read.

CFSv2 ain’t that bad: tips on using long-range forecasts
Now, every time I mention CFSv2 forecasts, someone invariably replies with “but it’s garbage beyond week 3” or “the model changes day-to-day, just guesswork”. If this is true, why have I bothered putting effort into making CFSv2 charts? The answer is that CFSv2 isn’t actually as bad as some people find it to be. Part of my PhD involves looking at the longer-range forecasts from multiple modelling centres around the world – including CFSv2 – and in what I’ve seen (some of which is in a few upcoming papers), CFSv2 doesn’t stick out as being rubbish. Far from it, in fact. That doesn’t mean it’s the best — it isn’t — but it’s worthwhile to look at (especially as we all have access to it), and it does quite well considering it is 9 years old.
https://simonleewx.com/2020/05/31/cfsv2-aint-that-bad-tips-on-using-long-range-forecasts/

[blizzard81]

I always remember as kid back in the 80's fronts from the atlantic would try to cross the UK but the blocks to the east would cause them to stall. These events could dump quite a bit of snow where the front stalled which was usually down the spine of the country. The front then started to move back westwards. You hardly ever see this phenomenon these days. I think there might just be a small possibility of this happening on Monday. 

[Battleground Snow]

3 minutes ago, sheikhy said:

The storm actually looks unreal to me!!!meaning it so deep i still dont believe its gona actually happen!

Gem doesn't develop it either, interesting differenceces at just 114

[Blessed Weather]

3 hours ago, Battleground Snow said:

It's not really nonsense is it?

It's a statistically proven phenomenon that has direct evidence of affecting the UK's climate in winter.

Granted, it's not sole influence, and not at a very high amplitude, but it can't be discounted either.

 

What is the Madden-Julian Oscillation?

WWW.METOFFICE.GOV.UK

---

The Madden-Julian Oscillation is characterised by an eastward spread of large regions of enhanced and suppressed tropical rainfall, mainly observed over the Indian and Pacific...

 

And just to add if I may, the ECMWF extended range forecasting output (including the EC46) extensively uses MJO input data. This from the ECMWF themselves:

"An important source of predictability on the monthly time scale is the Madden-Julian Oscillation (MJO), characterized by an eastward propagation of convection in the tropics, typically initiated over the Indian Ocean. We have specific products to monitor and forecast MJO activity."

Source: https://www.ecmwf.int/en/forecasts/documentation-and-support/extended-range-forecasts

[Updated_Weather]

Well that two models GEM and APERGE that doesn’t develop this storm at all… interesting or …..

[booferking]

So there you have it pick your bones out of the following storm or no storm let's see what ecm and jma have to say.

[sheikhy]

If ecm doesnt develop the storm then i think the depth of this low is gona downgrade with each run!but thats a BIG if!!

[frosty ground]

On 02/12/2021 at 17:06, sheikhy said:

If ecm doesnt develop the storm then i think the depth of this low is gona downgrade with each run!but thats a BIG if!!

Not sure you could upgrade it to be fair

[sheikhy]

1 minute ago, frosty ground said:

Not sure you could upgrade it to be fair

Yeh pretty scary how it blows up out of no where!!seen these kinda lows over the years!!!

[Updated_Weather]

I would be suprised if ECM does the same aperge and gem but whose to know - we find out in 50 mins +!!

[knocker]

1 minute ago, frosty ground said:

Not sure you could upgrade it to be fair

I am not sure it is that big a mystery. If some models don't engage it with the jet then there is no rapid cyclogenesis. So we await the ecm

[Mike Poole]

13 minutes ago, booferking said:

So there you have it pick your bones out of the following storm or no storm let's see what ecm and jma have to say.

That’s quite astonishing.  You would expect some differences between the models at T120, but not the total presence or absence of a feature like that!  The heights to the NE look stronger on the two that don’t develop it.  

Edited December 2, 2021 by Mike Poole

[SLEETY]

Met keeping close eye on this low could be some wild weather next week, then what? 

Don't think anyone is sure! 

[Ruzzi]

25 minutes ago, Blessed Weather said:

Poor old CFS keeps getting a bashing. So in its defence, here's the thoughts of Dr. Simon Lee of Reading University, on his excellent website. Worth a read.

CFSv2 ain’t that bad: tips on using long-range forecasts
Now, every time I mention CFSv2 forecasts, someone invariably replies with “but it’s garbage beyond week 3” or “the model changes day-to-day, just guesswork”. If this is true, why have I bothered putting effort into making CFSv2 charts? The answer is that CFSv2 isn’t actually as bad as some people find it to be. Part of my PhD involves looking at the longer-range forecasts from multiple modelling centres around the world – including CFSv2 – and in what I’ve seen (some of which is in a few upcoming papers), CFSv2 doesn’t stick out as being rubbish. Far from it, in fact. That doesn’t mean it’s the best — it isn’t — but it’s worthwhile to look at (especially as we all have access to it), and it does quite well considering it is 9 years old.
https://simonleewx.com/2020/05/31/cfsv2-aint-that-bad-tips-on-using-long-range-forecasts/

Its an interesting read for sure however as he states himself, it has huge model bias towards a weak polar vortex as the forecast time period increases. 

Any model with model bias will always present its issues, such as the GFS having a bias to blow up low pressure systems etc but if you have a model bias of something as significant as lowering the strength of the polar vortex as time increases, then I can't fathom how a model forecasting a time period so far in advance, on its face value, could ever be taken seriously. 

What his article explains is potentially how it could be used as something more useful, but on its face value, that far in advance, its almost useless.... I say almost, because even a broken clock is right twice a day

[minus10]

Prior to the maybe storm it is frustrating how this shortwave to the north of Scotland appears to prevent deep cold from moving closer to uk on GFS 12z

Edited December 2, 2021 by minus10

[Froze were the Days]

9 minutes ago, minus10 said:

Prior to the maybe storm it is frustrating how this shortwave to the north of Scotland appears to prevent deep cold from moving closer to uk on GFS 12z

This seems to be a regular occurrence on the Norwegian coast...difference between a relatively warm sea and airmass from the cold land/continent I presume? happened last winter on the odd occasion.

Edited December 2, 2021 by Froze were the Days

[shunthebartlett92]

20 minutes ago, SLEETY said:

Met keeping close eye on this low could be some wild weather next week, then what? 

Don't think anyone is sure! 

It's certainly got the potential to be a gamechanger! Here's hoping it heads for the continent and stays to our south and the scandinavian high can come over and say hi. It's been too long, dont be a stranger . The worry is of course it stays on the traditional jet trajectory and heads to our northeast and the azores high dominates us once again (Sigh).