model discussion Model output discussion 11th July onwards

[Frosty.]

Tonight’s ECMWF 12z ensemble mean, unlike the op indicates a brief northerly between day 6 and 7, as you can see, it does become colder from the north for a time later next week…actually, it plays out very similar to the GEFS 12z mean with a northerly which is quickly cut off by a brief ridge and then followed by a return to unsettled / Atlantic conditions.

 

[Mike Poole]

My take on the ECM mean, here T144:

Nothing from the west at this point.  Quite astonishing that most of the blue is east of the UK, Greenland and further south! again (the other side of the NH is what I mean).  

Moving to T240, I would love to know what is causing that big high over the USA.  Chart looks like a Pac-Man!

Edited October 15, 2021 by Mike Poole

[damianslaw]

2 hours ago, jon snow said:

Well there’s no northerly on the ECM 12z operational, but it’s only mid October so I don’t care!… …actually I do care and if it was winter I would really care but it’s the same old story, just when the pros start talking about below average temps and hill snow..it gets warmer! …actually, this run isn’t even particularly unsettled, indeed it’s half decent at times further s / se!…..next..  …. 

Just one run, its a major flip from yesterday's and would not be surprised to see a northerlt appear again. I tend to rate GFS better when it comes to northerlies and developments to the NW. All too often ECM seems progressive on northerlies.. GFS less so.. looks like a colder polar airstream will replace the tropical maritime airstream early next week, just as happened today.. flip flops between the two airstreams. All very normal for the time of year.

[Ali1977]

Northerly back on for T120 on ECM, then now showing another T240

[Methuselah]

Now, that's more like it! GFS 00Z:

    

    

    

    

Changeable!

   

[Neil Harris]

Matt Hugo suggesting over 100m of rain for western areas this week.

 

Do the models support this?

[northwestsnow]

Certainly a horrible week for Western Britain.

Just subtle signs in the unreliable of pressure falling across Europe...

Which of course means little ,in the way of snow and severe cold .

But it may allow any collapsing Azores high to get far enough North to cater for a colder high ,as opposed to one centred to our south ,yuk.

In November that would mean a quicker cool down for Europe.

[damianslaw]

54 minutes ago, Ali1977 said:

Northerly back on for T120 on ECM, then now showing another T240

.. and just as per my last comment, ECM is showing the northerly again!

[damianslaw]

50 minutes ago, Ed Stone said:

Now, that's more like it! GFS 00Z:

    

    

    

    

Changeable!

   

Whilst in the realms of fantasy land that last chart above 31 October, is very interesting, the diving trough - something I look for in the height of autumn as an indicator all is not perhaps normal service in the northern hemisphere, such synoptics and features can be a harbinger for the winter - i.e. an upcoming season that doesn't imprint the typical traditional atlantic base state - 2021 as a whole has been quite abnormal in this respect.

[damianslaw]

45 minutes ago, Neil Harris said:

Matt Hugo suggesting over 100m of rain for western areas this week.

 

Do the models support this?

The detestable long fetch SW airflow in all its full glory - equals copious rainfall here, and has been the reason for most if not all of our flooding incidents.. the rain never relents, the added warmth results in heavier precipitation. Go away soon please - you are not welcome for long periods! Sorry but I despise it.

[Cambrian]

The main pinch point for the rain early next week is for the 24 hours from Tuesday morning through to 10am Wednesday, according to the 0z ECM. 60-70mm in 24 hours for spots in North Wales, Dumfries and Galloway, and just outside Glasgow, 40mm+ in wider areas of Southwest Scotland, Cumbria, Wales and parts of County Cork. 

Met Office fax charts from yesterday show the culprit, a deceivingly innocuous feature well to our southwest midday Tuesday hauls up a whole load of moisture and deepens on its way in, to form a low pressure system, situated over the Irish midlands at midday Wednesday, already having delivered all that rain from its advancing fronts. 

 

Edited October 16, 2021 by Cambrian

[MP-R]

On 16/10/2021 at 09:27, damianslaw said:

The detestable long fetch SW airflow in all its full glory - equals copious rainfall here, and has been the reason for most if not all of our flooding incidents.. the rain never relents, the added warmth results in heavier precipitation. Go away soon please - you are not welcome for long periods! Sorry but I despise it.

More likely in the coming month or so than any other time of the year. Unfortunately just gotta bear it. Hopefully not another November 2009 scenario for you up there.

Should push through by Thursday though with much fresher conditions behind. I can see further such episodes thereafter though if we have repeating pressure builds underneath.

[Frosty.]

Just a quickie, the GEFS 6z mean shows a cold Northerly later next week..I’m happy, that’s all… Arrivederci!  

 

 

 

Edited October 16, 2021 by jon snow

[Eagle Eye]

Well here if is I have finally found the time to write this post. 

Stage 1 will most likely continue further southeast allowing stage 2 to strengthen, this isn't what I'm focusing on in the long term of this run. 

Stage 2 will once again close down as of my forecasts from before. Stage 6 is the Immidiate worry here as stage 1 clears this could potentially block/delay an early Winter. Stage 4 is indirectly affecting our weather as we will see more clearly later. 

I seem to have swapped stage 1 and 2 not that it matters. Stage 1 will clear, we know that but what happens with stage 6 and 3, the next battlefield. I am not writing my in depth predictions yet so I'm going to say that 4 and 5 could be the big factor affecting 3.

Stage 6 is worrying me I am definitly hoping that 3 will become strong enough to push out stage 6 and what trails behind it. 

And finally we have stage 6 slowly collapsing  and stage 5 and 3 look like slowly merging with cold beggining to invest in Europe as it were. 

So here's the basic outlook 

Stage 1 will most likely continue further southeast allowing stage 2 to strengthen, this isn't what I'm focusing on in the long term of this run. Stage 2 will once again close down as of my forecasts from before. Stage 6 is the Immidiate worry here as stage 1 clears this could potentially block/delay an early Winter. Stage 4 is indirectly affecting our weather as we will see more clearly later. I seem to have swapped stage 1 and 2 not that it matters. Stage 1 will clear, we know that but what happens with stage 6 and 3, the next battlefield. I am not writing my in depth predictions yet so I'm going to say that 4 and 5 could be the big factor affecting 3.Stage 6 is worrying me I am definitly hoping that 3 will become strong enough to push out stage 6 and what trails behind it. And finally we have stage 6 slowly collapsing  and stage 5 and 3 look like slowly merging with cold beggining to invest in Europe as it were. 

Finally we have my predictions with models. 

Originally we have the basic pattern with the weakening high moving to the south east and the weak low approaching us. From the Atlantic a minor high approaches, this is not what to focus on if you want snow soon, instead what follows it is incredibly important in the possibility of an early Winter. 

That mass in America makes a huge difference to our Winter normally but even more this year. Should when it enters the Atlantic, should the pattern weaken, then the Atlantic might become meaningless for those further North than me. The deeper into Winter that we go the better it could be in my opinion this year, I'm going for an early predicton of a cold January with a bit of luck now. 

Looking far ahead now, you can see on the anomaly quite clearly the cold approaching that's what I'm looking out for. 

The question remains how would we get to this? 

Well looking at the anomalies what it needs is for that high in the Atlantic to slide south towards Spain. What pushes this is the strong low from Greenland. This isn't just a peanut shell sweetly picked out of 30 different runs, this is the anomaly right now as predicted. If you remember the model agreement to outcome ratio you know that outcome is typically 6-10% less than model agreement which will definitly be a shambles at 300 hours in however this is after all a strong feature. As someone who loves Winter it does seem like I'm trying to big up this Winter even to myself. Alright so there is a lot going on here look at how much I've written contradicting myself, let's try and make sense of this. Alright so here's the furthest you should really go out on Winter.

Day 7

168 hours 

What we have here is a collapsable Arctic system, that Greenland low could at any point collapse all it needs is a small push. Once that happens then the Atlantic will become almost irrelevant for a month for those north of the M5, never before when I've been on here have I seen such a powerful low over Winter which to me signals a good sign for Winter. Other members have mentioned that this could be a good Winter, there was a lot more negativity about the Winter last year and it turned out alright for those wanting snow especially down south. If this is a strong snow season then this should be treasured because there seems to be a lot of reason for this to become less frequent which should this come off ( In my opinion way to early to say IT'S OCTOBER AFTER ALL) look at 2019 as an example I'm not too sure of elsewhere but there was barely a flake here. So there is a lot riding on the Atlantic Low, I haven't even delved that much into the Arctic yet which I shall do now. 

The Arctic of course will play such an important role on this Winter as usual. Greenland seems to be the initial flow which hasn't brought too much recently, except that should this come from Greenland I don't see much reason for the rest of much of the Arctic to be pulled slightly this way, we already see this in the forecasteed models right now although very far out. 

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

If this happens then I'm confidently saying that it's going to be a good Winter. 

This is the eventual end of this post 

I may be well of here because I'm basing it off one model run and I'm trusting models 7 days out but I noticed that this might all be connected to just couple stages of the pattern for it to be a great Winter. 

Xander 

Edited October 16, 2021 by Eagle Eye

[Frosty.]

Awesome post Eagle Eye! ..I myself neither have the time nor inclination to post anything as comprehensive as you have above (and previously), hats off to you.. great job!  

[Eagle Eye]

On 16/10/2021 at 15:06, jon snow said:

Awesome post Eagle Eye! ..I myself neither have the time nor inclination to post anything as comprehensive as you have above (and previously), hats off to you.. great job!  

Thanks for those kind comments

I get bored a lot of the time and too cheer myself up I decide to look through the weather models for clues for Winter and write my thinking up here. 

[Dorsetbred]

On 16/10/2021 at 14:54, 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.

Xander 

A good synopsis, and interesting possible outcome. Do you propose to come back in 168hrs with an update?

[Eagle Eye]

On 16/10/2021 at 17:50, Dorsetbred said:

A good synopsis, and interesting possible outcome. Do you propose to come back in 168hrs with an update?

Thanks and yes I most likely will as it'll be a Saturday and i'll be on school break

[Mike Poole]

The ECM has for me the more likely evolution as to the T240 timescale, here with GFS:

It is quite a difference though, and these differences will only get accentuated the further we get towards winter I think.  Very difficult to predict the situation into winter on 1st December.  Some might try, some might try to accuse others of trying…but, we will see…

Edited October 16, 2021 by Mike Poole

[Cambrian]

I think I’ve found a 4 wave pattern - granted it is on the CFS op at 384h, but they all count surely. Is there a prize for this sort of thing?

 

While we’re at it though, it’s an interesting looking chart, and the accompanying 300 hPa wind chart shows the main action all coming off the Pacific, but it’s then meeting the US - Canadian heat pump (which has been prevalent for many weeks) and getting diverted around over Greenland, the same anomalously warm upper temperatures still effectively killing off the Atlantic jet. 

By contrast, the GFS op at 384h is still displaying a 5 or 6 wave pattern and in addition has lost the obstruction of the North American heat pumping into Greenland, allowing sufficient upper winds to run south over the Eastern Seaboard to begin to pep up the Atlantic jet, as we would indeed expect at this time of the year. 
 

It’s going to be extremely interesting to see how this all resolves over the next few weeks.

[Ali1977]

Last nights FI chart is crazy, not sure I’ve seen anything like this before!! Definitely not the standard autumnal zonel set up!

[Cheshire Freeze]

On 17/10/2021 at 05:49, Ali1977 said:

Last nights FI chart is crazy, not sure I’ve seen anything like this before!! Definitely not the standard autumnal zonel set up!

Trop response to a Canadian warming of sorts. You could see as the strat vortex was displaced over towards the Siberian side, the trop followed suit almost instantaneously.

Not ideal unless we can see further pressure on the strat after this initial warming (this one has come too early). For that we’ll want to see the Russian HP allied to a deep Aleutian low. 
 

There is hope that once disturbed, the trop vortex can dictate the way forward, but with this we’re on a timer until the strat organises and dictates proceedings.

Edited October 17, 2021 by CreweCold

[damianslaw]

Cursory glancing at the models this morning.. much of a much ness for the remainder of the month. Unsettled with bouts of wind and rain from off the Atlantic broken by shortlived ridges. Generally mild or very mild with SW or westerly winds. However, later in the coming week a polar airstream will pull down much cooler air and precipitation likely to be wintry on high ground in the north. As we move towards end of the month, GFS suggesting a more concerted movement if polar air as the azores high is pulled back westward..  the end result cold and wet with the trough over and slightly to the east of the UK. ECM moving in this direction but not before another blast of unseasonably mild air from the SW. Possibly most zonal outlook for a long time.. all very normal for the second half of October which typically is Atlantic driven, wet and more often mild. Roll on November...

Edited October 17, 2021 by damianslaw

[Methuselah]

Thankfully, there's nothing too anomalously nasty in this morning's woodshed: GFS 00Z:

    

    

    

Then again, I see nothing (in these charts} that gives me any reason for either over-optimism or downheartedness.

[SLEETY]

A brief 24hour Northerly ,then prologned mild sw winds,with brief colder interludes is what this mornings output is basically  showing,hope this isnt the sign of things to come for the winter ahead!

Edited October 17, 2021 by SLEETY