Model Output Discussion - Autumn arrives

[LRD]

5 minutes ago, Don said:

A pity these charts are not two months down the line and seeing those patterns around mid December but hey ho!!

Patterns have been repeating for months (even years) now. So you never know

ECM is a cold run but is only briefly an outlier

The Met are talking about uncertainty now. I don't see an Atlantic onslaught but high pressure could develop in a place that could bring cold (for the time of year) for the UK. Ed Stone's Oct fog index might get tested this year. Early days but something to keep an eye on in one of the more tepid times of year for our weather/climate

[Scorcher]

10 hours ago, LRD said:

Patterns have been repeating for months (even years) now. So you never know

ECM is a cold run but is only briefly an outlier

The Met are talking about uncertainty now. I don't see an Atlantic onslaught but high pressure could develop in a place that could bring cold (for the time of year) for the UK. Ed Stone's Oct fog index might get tested this year. Early days but something to keep an eye on in one of the more tepid times of year for our weather/climate

Massive understatement about the ECM last night- it was bottom of the pack for a time and colder than the mean for virtually all of the run.

This morning's ECM looks much warmer. Cool nights are always likely under HP as we move into October but I can't really see how the high could set up in a cold position? The Atlantic is looking too active for that to happen at the moment.

[sheikhy]

Very dry ecm after this fridays rain!!!similar with gfs!!!!!bring it on!!!

[BlueHedgehog074]

Autumn looks like it’ll be rocking around throughout much of this week. Some further showers to come on a chilly North-Westerly to Northerly wind, especially over Northern, Northern-Eastern and North-Western spots. Troughing over North-Western Europe just to our East:

 

Likely a bit of a break on Friday with A little ridge shifting East over the UK before the Atlantic Low from the West with its disturbance brings in a spell of rain.

The North-Westerly winds come back for another fight over the weekend, though showers are likely to decrease in number later in the weekend, especially across the South-West, as another (somewhat more wider) ridge of High Pressure from the South-West starts shifting towards the UK:

The 6 to 10 day 500mb anomaly chart from the NOAA does show an appetite for the weather to settle down into next week for the UK (certainly become less unsettled and it doesn’t look wet) as upper heights look to increase. Highest towards South-West of the UK. 

Operational models, such as the latest ECMWF, does show some fairly good support for the weather to start settling down next week. (Well, to be fair, it has the ridge building over the UK into early next week, then gets pushed further South-East clinging over that part of the UK. Never leaves completely. But later into next week, the ridge comes back and puts up a stronger fight over the whole UK).

 

Perhaps a real possibility, depending how the outlook continues to shape up and the particular placement of High Pressure, for Summer to give Autumn one last punch in the face before next year. It’s however possible too for some chilly nights with a possible chance of frost in this sort of setup. But does again depend exactly where High Pressure sets up and the clearness of the nights. 

One other thing, should the Polar Vortex cause trouble for both the mild and cold weather enthusiasts this Winter, am gonna ink it to death with one of the guns from Splatoon 3.

Edited September 27, 2022 by DiagonalRedLine
(attaching anomaly chart/typos)

[carinthian]

GFS latest comes up with a rather chilly chart next week  for Central and Eastern Europe and what looks like a dry less chilly flow into the British Isles. Our own model forecasts quite low temps from Tuesday next week in the Eastern Alps. So will last weeks snow continue to survive ? I have put an update this morning on the Austrian thread for those interested.

C

[LRD]

10 hours ago, Scorcher said:

Massive understatement about the ECM last night- it was bottom of the pack for a time and colder than the mean for virtually all of the run.

This morning's ECM looks much warmer. Cool nights are always likely under HP as we move into October but I can't really see how the high could set up in a cold position? The Atlantic is looking too active for that to happen at the moment.

Well, I did say it was a cold run. And I meant compared to the pack. Might not have made that clear but that's what I meant

As for a high not setting up in a cold (relative to Oct) position (and I only said it 'could' not it 'will') how about this:

Yes, I've cherry-picked one image and from FI but it must be possible otherwise the models wouldn't, er, model it! And this scenario has been advertised a few times over the last few days. It's not the favourite option by any stretch but I don't see an 'active' Atlantic at all - at least not in the "succession of lows"/zonal/strong +NAO sense of that phrase. Not seen that for about 18-20 months - well, not for any length of time anyway

Edited September 27, 2022 by LRD

[Rain All Night]

As a fan of warmth who has been looking out for any sign of a final burst (really missing the late September warm spells of late '20 and '21!) I am pleased to see agreement on a warmer air mass being pulled up above us around Tuesday - but would this be enough to produce anything appreciable at the surface?

[Kirkcaldy Weather]

Following on from my post yesterday, further fascinating output         

[Dan B]

1 hour ago, RainAllNight said:

As a fan of warmth who has been looking out for any sign of a final burst (really missing the late September warm spells of late '20 and '21!) I am pleased to see agreement on a warmer air mass being pulled up above us around Tuesday - but would this be enough to produce anything appreciable at the surface?

 

Are allowed to boo &  heckle at all?

[Rain All Night]

3 minutes ago, Dan B said:

 

Are allowed to boo &  heckle at all?

You can if I'm still making posts like that in November... until then let me dream my dream

[stodge]

Evening all

GFS OP continues to weave its non-autumnal magic. Tonight sees northern blocking in extremis - charts that do a post-SSW April proud. I'm told this is manifest of the MJO moving which is a change from waht seems a long period of COD.

Tonight's gem (not GEM) is from T+276 on the GFS 12Z OP - blocking to the north west, blocking to the north east and the poor old cut off LP has nowhere else to go but the British Isles. 

By T+360, it's gone beyond a joke - doubtful it will ever get that far of course:

All together now, IF ONLY IT WERE JANUARY....

[Don]

2 hours ago, RainAllNight said:

You can if I'm still making posts like that in November... until then let me dream my dream

I remember that day well, went to the coast and there were plenty in the sea!  I would not grumble if we had a repeat for that date this year and I'm a coldie!!

[Don]

1 hour ago, stodge said:

All together now, IF ONLY IT WERE JANUARY....

I'm sort of hoping these charts don't come off as they will be totally wasted!!  Hopefully the models are being WAY too progressive and these charts will crop up and come off two months later.....

[damianslaw]

Not commenting much on the models at present, namely because it all looks very average and typical for the time of year, cooler wetter spells interspersed with milder calmer ones. Mind not been able to say very average much this year. 

[Eagle Eye]

Looking closely into the future and right now we have a pattern driven into the exact opposite of a vertically propagating wave pattern into the stratosphere that ends up with a negative NAM (Northern Annular Mode). That typically has an enhanced Scandinavian ridge and a Northern Pacific troughing. In a La Nina Winter, a Scandinavian ridge may be quite likely however troughing in the Pacific hasn't looked that evident over recent years and so the vertical wave propagations into the stratosphere won't have the right momentum to cause the negative NAM. This was a particular problem last year and caused us to rely on surface conditions and northerlies if I remember correctly. However, 2021 still had a SSW and it's not necessarily a problem that will last all of Winter, there could be forcing over Siberia that causes the cold air to plunge south over the North Pacific and trough as they propagate into the Stratosphere. If this problem does last through Winter, then we may have to rely on the northerlies that may end up being a feature if we're lucky, if not then a SSW or something similar may be possible.

[MAF]

thanks Eagle Eye.

pity i didn't understand a word of it 

[Eagle Eye]

16 minutes ago, MAF said:

thanks Eagle Eye.

pity i didn't understand a word of it 

Essentially, waves move up from the troposphere to the stratosphere, if we want to have a pattern in the Stratosphere that's good for us to have snow we want low pressure troughing over the North Pacific and high pressure building over Scandanavia because that would cause a certain momentum cycle of air that weakens the air speed in the stratosphere which causes cold air to displace itself from the poles to us and that could cause an SSW or even more simply a negative NAO.

That last part sort of explained by these images.

 

[MAF]

1 minute ago, Eagle Eye said:

Essentially, waves move up from the troposphere to the stratosphere, if we want to have a pattern in the Stratosphere that's good for us to have snow we want low pressure troughing over the North Pacific and high pressure building over Scandinavia because that would cause a certain momentum cycle of air that weakens the air speed in the stratosphere which causes cold air to displace itself from the poles to us and that could cause an SSW or even more simply a negative NAO

Thanks EE, i have been around here long enough to have learnt something by now..... you'd think   

[Frosty.]

I’ve just looked at the GEFS 6z mean and here is my assessment …for sure it looks predominantly changeable.. …but with a large slice of emphasis on a north / south to northwest / southeast split!…in other words, I see NO sign of a raging Atlantic affecting the u k, just something more meek / mild, especially further s / se…all very broad brush of course!   …and just my humble opinion… 

Edited September 28, 2022 by jon snow

[Frosty.]

The Gfs 12z operational kind of backs up what I was saying about the GEFS 6z mean in that high pressure is predominantly close to the s / se with the best of the drier & brighter / calmer / warmer spells whereas the NW / N bears the brunt of the occasionally more unsettled phases. For sure, we all see some rain from time to time during the run but the emphasis is on drier further s / se…to me, it’s NOT a typical fired up autumn Atlantic onslaught …anyone agree…or is it just me?…if it’s just me, I’ll get me coat!   …the end of the run looks more unsettled generally but it’s the Gfs being the Gfs innit!  

Edited September 28, 2022 by jon snow

[Frosty.]

For the most part, the Ecm 12z operational has high pressure / ridging influence, occasionally punctuated by more unsettled interludes but most of that is across the far NW / N…the S / SE doesn’t look bad at all for the majority of the time, especially later…most of the widely unsettled weather is early in the run! ️ 🌫  

[Frosty.]

Wowzers, no posts for 18 hours!?…hmmm..is the outlook bad?..nope, it’s essentially a n / s split from the GEFS 6z mean…the south / southeast does quite well compared to the n / nw..but, twas ever thus..etc! …eventually guys, we will have to accept summer is over, and autumn is just a prelude to the incredible winter to come..yeah yeah frosty, that’s too much.. nice try though!!!!  

[Downburst]

Still a lot of high pressure about. Next week a few fronts encroach but the week ends next week with more high pressure, ECMWF

Looking at the GFS and into the following week, that high pressure may well protect us from a potent ex tropical storm. Or will it? 

[Frosty.]

Wowzers, no posts for 18 minutes.. ..I mean 18 hours.. ..and then a veritable downburst of posts.. from .. erm..…downburst! …anyway, the longer term has some potential for fine weather fans from the GEFS 6z!!.. I salute you Christopher.. .. I mean.... P25!  🫡 

 

Edited September 29, 2022 by jon snow

[Rain All Night]

On 27/09/2022 at 19:22, RainAllNight said:

As a fan of warmth who has been looking out for any sign of a final burst (really missing the late September warm spells of late '20 and '21!) I am pleased to see agreement on a warmer air mass being pulled up above us around Tuesday - but would this be enough to produce anything appreciable at the surface?

My answer is apparently not, other than those up East possibly scraping 20c on what looks like it will be a cloudy day everywhere, oh well.