model discussion Model output discussion 11th July onwards

[damianslaw]

9 minutes ago, SLEETY said:

Signs now of very much colder weather arriving,little too far out at the moment ,so hope to see some consistency in the runs in the next few days.

Signs have been there for days but far beyond reliable timeframe . Now creeping into semi-reliable. The rest if the month forecast unsettled mild or very mild to start trending cooler by next weekend. A lot more rain for northern and western parts. Very typical late October fayre.. but no storms or gales indicative of a rather weak Atlantic overall. Into November look to the north and north west for where weather will be coming.

[carinthian]

On 21/10/2021 at 17:46, carinthian said:

Good news from the GFS model. Continuing to show a transformation to colder conditions from the North heading towards NW Europe for the beginning of November. Yes, and the snow models now picking up an area of snow between Iceland and Norway.. Lets hope this trend continues into the more reliable time span but looking better going forward.

C

The trend still there for a gradual transition to colder conditions during the first week of November. The overview picture from the latest GFS op run has the colder air . looking at the thickness values moving into NW Europe generally. An area of snow moving into Northern Scotland. The snow models still picking this up , although the % value still low that far out, but encouraging still showing. In the Alpine region we need to see this picture develop also to produce some much needed snow as some of the resorts are due to open  on 27th November. Enjoy your warmth for the rest of the month as a change is a coming !

C

[Cambrian]

That’s a better route to getting the trough, firstly over us, and then to the east of the UK on the last couple of ECM operational runs, and support from the UKMO extended too. Indeed the UKMO is slightly firmer, with a slightly deeper low.

0z operational runs ECM / UKMO EU for 168h, getting us under the trough.

  

The arrival of the somewhat colder air over us at 240h is again pleasingly coincident with the WAA pushing from Eastern Canada to Greenland, shown here on the ECM T850 and anomaly charts, which looks like a setup that could last for a fair few days with high pressure building in the North Atlantic. 
 

The 0z GFS with the same broad pattern, but with the advection into Greenland on a more southerly path, as a result pushing the colder air more quickly down to the Alps and bringing us under the influence of a succession of low pressure systems moving down  from Greenland in the NW-SE oriented jet stream.

 

This NW-SE orientation of the jet stream was indicated last weekend for the same period, which was at that time towards the end of the run, around days 13-16, the day 16 chart to 2 November shown here, although it was further south and stronger

GFS op 0z today / last Sunday

 

So even though it’s still a bit of a way off, a good deal of confidence in the general setup for repeated incursions of colder air from the northwest from about 7 to 8 days time appears very justified. 

[Methuselah]

Oh, Mr Bartlett, what shall I do?      

[Methuselah]

Aaaaand, the GFS 06Z is here!

    

    

    

Plenty of cold air, oop norf; but that LP near Iberia (should it ever exist) has some worrying potential. Especially if that European HP should rebuild?

[Eagle Eye]

I agreed to look back in a week at my previous forecast and update you on it and that's what I will do. 

I would just like to quickly mention my post yesterday in reply to @Kirkcaldy Weather question in the run up to Winter thread.

The question as such

'I will start a seperate thread for the atmospheric River event and not sure if there is a link to colder winters or if it's just a coincidence but interesting to see those 2 years noted' 

 

I had a quick look at the 1962 Winter and found a slight link

'I wouldn't be surprised if there is a sort of link if you could say that. 

This would indicate in my veiw a more stronger PV than usual such as I think the case was in those years. 

Charts from 1962 December look eerily similar to now. 

Then look what happened  

A strong Arctic plunge 

Hopefully this is a sign for this Winter. '

What I noticed was the fact that not only was there a low located in almost in the exact same position as this low is now. There was also a link on which the PV outbalanced the Atlantic high which usually has such a profound effect on Autumn' s which we seem to be having now. As was said earlier this week a split PV looks possible and I don't pretend to be an expert but it seems to me like that could be a force this Winter for the good if you are a snow lover. 

Right now there are particular links between these charts and those if 1962. Whether you call it a wave pattern or something else, you cannot sent that there is a particular pattern setting up. This imo makes it a little bit easier in the long run cutting down the number of different possibilities as to what could happen. 

As we continue looking at the 0Z here's more delving into the run

A couple things that I said last week about this certain type of setup 

'In my opinion this could become a fantastic Winter with a bit of luck, this depends on the movement of that Greenland low at around 168 hours, the movement of the Atlantic High at that time as well. A weakening high means a good winter and I'd give it a good chance of giving snow to a lot of people, without that weakening we could be stuck In this system for a while of in and outs of lows and highs. 

So to summarise my predictions on just two of these stages we have 

I predict that this Winter will be very good but only if a couple things are true

1)There will be a strong Greenland low coinciding with the Atlantic wave

2)When that happens the low moves its position towards the UK

3)As timing is everything on this run, this happens just as the Atlantic is about to impact Britian

4)When that happens the low pushes it out of the way'

Well we're now at the 168 hours mark right now and the low over Greenland has in fact strengthened but so has the Atlantic high. It really is getting to crunch time now for my predictions. The evolution over the next week will be interesting to watch, I'll have my eyes firmly focused on the Atlantic, we're now pretty likely to see a small splitting PV in my honest opinion. 

Right now we have the intense low pushing further into the Atlantic than I anticipated which brings me to think if that can bring down the splitting PV then surely the Canadian high which troubled the runs this whole week then surely that will help weaken it and if that happens then we will not have to rely on that Greenland low, this wave pattern could in fact help us much further and temporarily get us out of this mixed weather.

So right now the Greenland low will indirectly affect our future by weakening the Atlantic, it'll most likely go through once but as it does it COULD bring down part of the PV as I alluded to in my former post.

The high doesn't exactly weaken but as we can see it is pushed lower and lower as the low movement and the Jet Stream coincide perfectly for Winter lovers like me. This is what we need for the stars to align for a good November with snow perhaps further south than Scotland, aprroaching the Midlands if we get lucky and these things often end up in a cycle lasting often a couple months so hopefully this doesn't effect mid-Winter in a bad way which I don't think it will even if it does come off. 

Next up is to look at the anomalies as these help making these decisions 

Temporarily the colder area seems to take away a lot of the warmer areas possibility for impact, as we get further into this week we will have to see what happens with that red hot area over Canada which pushes south in this run but looking at the anomalies it still has an impact even when it looks like it won't have any impact at all. 

This is all looking far out and that is why I'm not too worried right now, like I said last week 168 hours is probably the furthest you could look at for anything really close to reality, it's around the last area where the agreement and outcome are both above 50% on average. 

This seems pretty conclusive to me that we will have a battle between high and low but how are we supposed to know which will win here. For the cold to win we will have to have the strengthening low over Greenland. Should that happen then the high could split and weaken therfore allowing the PV to win this battle however on the other hand we could also see the split stop this happening altogether. Where the split is most likely to happen is whay will ultimately decide our fate as I look into it further. 

This is where I will first look at the 6Z

Far out in the 6Z it seems that the original split will be further out than I thought it would be which takes me back to looking further into what it could be. 

Let's look at the 6Z at 168 hours

The 6Z continues the battle and it doesn't look like we're going to get a conclusion soon, I think it's best if I look further into this later on this week. 

Here's what I think at the moment 

Right now there is a lot riding on the battle across the Atlantic, should the low backing behind Greenland nip the Canadian high that always seems to be theree in Autumn stopping Winter on the bus then we could see that happen. There is a lot more riding in this, this year than there has been for many years. This time however it is not a fantasy looking at this and hoping, there is a decent chance well above the usual that a split PV could mean that there is a collapse which would stop the Atlantic interfering finally. I did not go into this much depth last week as I felt it was a lot simpler but I didn't notice the Canadian high or I dissmised it. Last week I did not go into things as I should have but there is a lot that has remained the same and that is why I am still going to look at this and not dismiss it. The battle has a pretty hgih cjancew of being won by the low and I'm not kidding myself here. Having researched a bit more on this the fact that it was so similar to 1962 surprised me, not only that but what was alluded to in that tweet about now also having happened in 2009, we all know what happened early 2010.

This post may not be conclusive but we can never be conclusive this early before Winter so this is about as conclusive as I can get when writing a post about the next few months, a lot of id's and but's but I see an opportunity for the low to win over the high and it only needs 1 slight change then we could see a decent early Winter. I have proof read it but  there may still be a lot of spelling errors and it may be confusing but this is as Un-confusing, if that's a word, as I could make it

Xander 

[Cambrian]

You’re right to pick up on the wave pattern, @Eagle Eye, a good few of the 500hPa anomaly charts that you selected are showing a 4 wave NH pattern to my eye. I imagine @Mike Poole will be pleased to see these as he was talking about this progression several weeks ago and these are the clearest to date at such close range. This one, for 1 November, was my favourite for showing a 4 wave pattern. 

On the 500hPa charts you showed, the cold trough remains over us for a good week, so these are still evidently slow moving patterns at the beginning of November.

The later stages of the 6z GFS op run followed a rather different script though, so roll on our view of the next few runs.

[Dorsetbred]

@Eagle Eye a good synopsis of where we are at today and what might happen, may I say "brave" in one way as fluid dynamics is something that takes a lot of time and study, so credit due, you are prepared to put you ideas down, now let's see how this plays out..

[topo]

[I remember Atlantic 252]

Northern members look cool, rest of us eeeww yuk

[Dancerwithwings]

6 minutes ago, I remember Atlantic 252 said:

Northern members look cool, rest of us eeeww yuk

That’s  07/11...it’s expected, December would be differs

[Cambrian]

12z GFS operational run is great viewing.

It gets the trough over most of the UK and all of Ireland by next weekend, 168h.

 

Into a good looking northerly by day 10.

 

Another low in from the northwest by day 13 - bonfire night

 

This low brings some proper cold air in its wake by day 15, with lower than -5 uppers  for almost all of the UK and Ireland.

[Mapantz]

On 23/10/2021 at 12:37, Eagle Eye said:

In my opinion this could become a fantastic Winter with a bit of luck, this depends on the movement of that Greenland low at around 168 hours, the movement of the Atlantic High at that time as well. A weakening high means a good winter and I'd give it a good chance of giving snow to a lot of people, without that weakening we could be stuck In this system for a while of in and outs of lows and highs. 

A good post in its entirety. However, I think a little realism is also needed.. The movement of an LP around Greenland & Atlantic HP at a timeframe of 168 hours will not dictate our weather in winter.

[damianslaw]

25 minutes ago, I remember Atlantic 252 said:

Northern members look cool, rest of us eeeww yuk

Ties in with Met Office thoughts as we progress through November. Mid Atlantic high, showery troughs for the north and east under a chilly NW airstream drier further south and west with fog and fog. 

[swfc]

6 minutes ago, damianslaw said:

Ties in with Met Office thoughts as we progress through November. Mid Atlantic high, showery troughs for the north and east under a chilly NW airstream drier further south and west with fog and fog. 

Yes the gfs 12z imo is a good run and has you say ties in with there thinking. Usual caveats but anyone disappointed "if it transpires" with that set up in November are going to have a long slog the coming winter

[damianslaw]

Just now, swfc said:

Yes the gfs 12z imo is a good run and has you say ties in with there thinking. Usual caveats but anyone disappointed "if it transpires" with that set up in November are going to have a long slog the coming winter

Should have said fog and frost.

[Mike Poole]

Just taking a look at the 12z models that go to T240:

There’s some variability there, but a consensus might be that the vortex is shunted to the Russian side not the usual Canadian location - which is what coldies want.  And there is nothing driving the Atlantic.  The question now is how this translates to the upcoming weather and of course to winter…I will give an update in the upcoming winter thread in a couple of days, but for now….I’d hold the line, it is looking OK.

[swfc]

Ec looking similar to gfs 12z. Good looking charts be it over 7 days

[Eagle Eye]

On 23/10/2021 at 18:38, Mapantz said:

A good post in its entirety. However, I think a little realism is also needed.. The movement of an LP around Greenland & Atlantic HP at a timeframe of 168 hours will not dictate our weather in winter.

Sure, I didn't mean to say that it'd dictate the whole of our Winter after all it is such a small proportion that I'm looking at there. What I meant by my post was in rather brief terms, the movement of one low when you take it down a lot of levels could have repercussions which could be good for snow lovers that would last further than the normal amount you would expect. 

[Methuselah]

31 minutes ago, Eagle Eye said:

Sure, I didn't mean to say that it'd dictate the whole of our Winter after all it is such a small proportion that I'm looking at there. What I meant by my post was in rather brief terms, the movement of one low when you take it down a lot of levels could have repercussions which could be good for snow lovers that would last further than the normal amount you would expect. 

Hey, nae bother, Eagle Eye, you'd nae be the first, or the last, person on here to think that a broad similarity to 1962 (in any month from September to December) means that this year will be THE ONE! 

Edited October 23, 2021 by Ed Stone
I'm pished!

[snefnug]

On 23/10/2021 at 16:18, Cambrian said:

You’re right to pick up on the wave pattern, @Eagle Eye, a good few of the 500hPa anomaly charts that you selected are showing a 4 wave NH pattern to my eye. I imagine @Mike Poole will be pleased to see these as he was talking about this progression several weeks ago and these are the clearest to date at such close range. This one, for 1 November, was my favourite for showing a 4 wave pattern. 

On the 500hPa charts you showed, the cold trough remains over us for a good week, so these are still evidently slow moving patterns at the beginning of November.

The later stages of the 6z GFS op run followed a rather different script though, so roll on our view of the next few runs.

This is what I like to see, discussion about weather. Our young eagle is a keen and fast learner and there are many on here who can actively engage in adult conversation and provide good leads/advice that in the whole interaction allows a middle aged weather novice like me a chance to learn.  Keep it up.

Edited October 23, 2021 by snefnug

[swfc]

Gfs 18z continues a theme witn no sign of a west to east flow ie Atlantics traditional movement. Very blocky to the west and even off the esb which bodes well in keeping a North to sse flow, out to a 10 day max etc. Interesting times

Edited October 23, 2021 by swfc

[Ali1977]

Big swing to cold by bonfire night, looking at the mean a Northerly around this point is looking even more promising  and the Op setting up an easterly too.

Edited October 24, 2021 by Ali1977

[Anthony Burden]

Morning all Gefs ensembles heading steadily down from beginning of November temperature wise,

could be a quick culture shock to the system after such a long mild spell.

[Methuselah]

All change, on today's GFS 00Z. Although, not a very appealing change, unless you like cold drizzle:

    

    

    

Too soon for snow but soon enough to be a nuisance!