Model output discussion - Winter has arrived

[dragan]

2 minutes ago, Scott Ingham said:

Its a well known bias mate yeah especially so with the GFS. Its why it's frustrating to read people believing a 168 hour chart. Steve Murr has spoken about this for years and we still see people getting downbeat at the Atlantic breaking through a huge Russian block that is almost certainly being under estimated 

worth remembering tho, as we get the vast majority of weather from the west......this would still be the most likely outcome.

 

[chionomaniac]

Differences in the angulation and strength of incoming trough already in evidence at T+90 on 18z gfs

[Scott Ingham]

1 minute ago, dragan said:

worth remembering tho, as we get the vast majority of weather from the west......this would still be the most likely outcome.

 

Based on what scientific evidence/model/anything?? 

[Allseasons-Si]

3 minutes ago, Scott Ingham said:

Its a well known bias mate yeah especially so with the GFS. Its why it's frustrating to read people believing a 168 hour chart. Steve Murr has spoken about this for years and we still see people getting downbeat at the Atlantic breaking through a huge Russian block that is almost certainly being under estimated 

Not to mention the 384 hrs gfs charts that show winter narnia and hope that they will come off when the model can't even get it right out to days 4-5.

[Scott Ingham]

Just now, Allseasons-si said:

Not to mention the 384 hrs gfs charts that show winter narnia and hope that they will come off when the model can't even get it right out to days 4-5.

Hahahaha yes pal that as well!! I would say though the ensembles long range are sometimes good at picking up a trend or pattern change (sometimes )

[Mike Poole]

GFS pub run T108 (left) compared to T114 on 12z:

Looks like it’s getting the slider!  

Edited December 6, 2020 by Mike Poole

[Geordiesnow]

54 minutes ago, damianslaw said:

Good view, those of  cold persuasion may be advised to tune out and tune back in a week's time, as I fully expect some model outputs to run rampant with either a raging jet, or the bartlett high scenario, conversely expect rogue Greenland highs as well, there will be lots of flip flopping beyond reliable timeframe, making everyone scratch there heads where will things go for the latter third of the month, but as you say, the azores high building and ridging through the uK northwards ia a strong possibility, and some of our best cold spells have come courtesy of such a development, short term mild pain longer term gain.

It's always easy to read into the output too much regardless what it shows but as far as I can see, there is a definate trend for the Atlantic returning. Whether the lows splits and send some energy towards the med or stay more bowling ball shape, it's not going to turn all that cold and temperatures will be near average. The trend after that is more unclear but there's been a few ECM runs which suggests the weather could turn significantly milder eventually via a Euro high. 

Do like the trend for an Arctic high to develop but unless the Arctic high is on our side of the Arctic then the likely hood it affects our weather is much reduced.

[Allseasons-Si]

1 minute ago, Scott Ingham said:

Hahahaha yes pal that as well!! I would say though the ensembles long range are sometimes good at picking up a trend or pattern change (sometimes )

I am glad that you added sometimes although i do think that it picked up on the 2010 cold spell quite well.

[dragan]

6 minutes ago, Scott Ingham said:

Based on what scientific evidence/model/anything?? 

eh, based on hundreds (if not thousands) of years of Britain receiving the vast majority of weather from the west/atlantic 

Edited December 6, 2020 by dragan
bad word

[Catacol]

5 minutes ago, chionomaniac said:

Differences in the angulation and strength of incoming trough already in evidence at T+90 on 18z gfs

Surface heights to the north stronger too. Hell's teeth - how am I going to get any work and stuff done this week....  - I'm supposed to be moving house in 11 days and changing jobs. You just KNOW what is going to happen on my moving date don't you........ 

[Scott Ingham]

Just now, Allseasons-si said:

I am glad that you added sometimes although i do think that it picked up on the 2010 cold spell quite well.

GFS is better with Greenland Highs. Ecm better with Scandi highs and split flows

[Scott Ingham]

1 minute ago, dragan said:

eh, based on hundreds (if not thousands) of years of Britain receiving the vast majority of weather from the west/atlantic 

Im not even going to get into this as you clearly have no idea what your on about entertaining though.. 

[Daniel*]

4 minutes ago, dragan said:

worth remembering tho, as we get the vast majority of weather from the west......this would still be the most likely outcome.

 

A suggestion a general suggestion in fact, try put meat on the bones? Why do you think that is the case? If it’s not grounded to the now, the contribution is of no use to anyone. I see it as a lazy approach to say it will be mild because that is default, and provide no evidence when current situation isn’t particularly ordinary. I don’t think this thread is for personal opinions you can give opinions based on evidence that’s fine. You have to ask, what do people learn from your posts? 

[Matt H]

Already huge differences between the GFS 12z/18z at the crucial t138/t144 time period. How some people can claim that this is the model to be following at the moment is beyond me. 12z first.

[STRiZZY]

Just now, Scott Ingham said:

Im not even going to get into this as you clearly have no idea what your on about entertaining though.. 

Are you honestly suggesting that at the mid latitudes in the northern hemisphere that there isn’t predominantly west to east flow? 

[blizzard81]

Just to add to some of the latest posts from fellow coldies. Latest gfs for 12pm next Friday compared to yesterday's 18z run for the same time. Much more ridging into north west scandi from the Russian high and the atlantic low doing the much loved limbo dance (negative tilt) that its been doing for the last 6 weeks or so. 

[dragan]

1 minute ago, Daniel* said:

A suggestion a general suggestion in fact, try put meat on the bones? Why do you think that is the case? If it’s not grounded to the now, the contribution is of no use to anyone. I see it as a lazy approach to say it will be mild because that is default, and provide no evidence when current situation isn’t particularly ordinary. I don’t think this thread is for personal opinions you can give opinions based on evidence that’s fine. You have to ask, what do people learn from your posts? 

yeh, my evidence is what the current models are showing lol, coupled with the fact it is also the default setting indeed. If the models were showing cold then yes, i would need to explain past what models are showing, but i don’t need to. I could pick or just about any of the charts and give my evidence. have a look at the last god knows how many runs 

[Scott Ingham]

1 minute ago, STRiZZY said:

Are you honestly suggesting that at the mid latitudes in the northern hemisphere that there isn’t predominantly west to east flow? 

Im suggesting that within this west to east flow we have things in meteorology called blocks that stop this flow and send this south keeping us on the cold side of a jet. Im suggesting that when we have formidable blocking in place models always underestimate the strength of said block and blow it away until we get within 4 days time. Im suggesting the GFS has the greatest bias with this and id suggest you compare the 150hr chart on the 12z to the 144hour chart on the 18z you'll see this bias in all its glory

[Jason M]

12 minutes ago, Scott Ingham said:

Its a well known bias mate yeah especially so with the GFS. Its why it's frustrating to read people believing a 168 hour chart. Steve Murr has spoken about this for years and we still see people getting downbeat at the Atlantic breaking through a huge Russian block that is almost certainly being under estimated 

Correct, but this cuts both ways. The very people who criticize tonight for people giving credence to a 168 GFS chart showing a mild outcome will be the first to post a freezing easterly on the ECM despite us knowing it also has its bias. This is usually followed by a whole load of abuse for anyone that dares point out that another model is showing a Spanish plume at the same timescale.  Lets all just be more tolerant this year!! Its been calm on here recently so lets keep it that way.

[Geordiesnow]

2 minutes ago, Frosty Winter said:

Already huge differences between the GFS 12z/18z at the crucial t138/t144 time period. How some people can claim that this is the model to be following at the moment is beyond me. 12z first.

Differences are not that huge really. Only difference is more energy is heading through the UK so any blocking is further eastwards. We got to accept there will be variations from run to run in the medium range. 

Either way another run which trends to a less cold set up, even the UKMO shows it turning less cold in western areas. 

 

[Mike Poole]

Pub run T144, and now GFS has got itself in a mess, which is usually a half way house to sheepishly coming in line with UKMO and ECM, the collection of lows in the Atlantic looks wrong, but at least it isn’t blowing up a big low anymore, jet stream plot as well:

As it seems the block is putting up a fight as expected, but the air is not that cold (cold air harder to shift) - but it seems the weakness of the Atlantic balances this out, this is a weak jet stream for this time of year, related to the lack of coherence of the trop vortex.  

But as i don’t believe the GFS is right at T144 in the Atlantic sector, the rest of the run is for the bin...

Edited December 6, 2020 by Mike Poole

[feb1991blizzard]

5 minutes ago, Catacol said:

Surface heights to the north stronger too. Hell's teeth - how am I going to get any work and stuff done this week....  - I'm supposed to be moving house in 11 days and changing jobs. You just KNOW what is going to happen on my moving date don't you........ 

Yes, in 11 days time in Somerset i do - well i don't actually know what will happen but in all probability i know what won't and i think you do as well deep down.

It would take a big turnaround.

[bluearmy]

7 minutes ago, Catacol said:

Surface heights to the north stronger too. Hell's teeth - how am I going to get any work and stuff done this week....  - I'm supposed to be moving house in 11 days and changing jobs. You just KNOW what is going to happen on my moving date don't you........ 

Can’t see it by day 11 ..... can’t see anything proper wintry (snow widely at low levels this side of  the 20th tbh)  .....

[blizzard81]

2 minutes ago, bluearmy said:

Can’t see it by day 11 ..... can’t see anything proper wintry (snow widely at low levels this side of  the 20th tbh)  .....

What about post 20th?

[Scott Ingham]

17 minutes ago, Jason M said:

Correct, but this cuts both ways. The very people who criticize tonight for people giving credence to a 168 GFS chart showing a mild outcome will be the first to post a freezing easterly on the ECM despite us knowing it also has its bias. This is usually followed by a whole load of abuse for anyone that dares point out that another model is showing a Spanish plume at the same timescale.  Lets all just be more tolerant this year!! Its been calm on here recently so lets keep it that way.

Ive never given certainty to any chart at that range. Only give something a higher chance of being correct based on whether it matches background signals and fits into any model bias at that time. This for me has nothing to so with cold or mild bias. I have spent two days saying I expect a mid lat high over the UK Christmas week. Why turn this into a two camps thing? Criticism is there because its warranted and I strongly believe the Atlantic won't win out for all the reasons I've spent all day saying 

Edited December 6, 2020 by Scott Ingham