Model Output Discussion - Into 2024

[Catacol]

Fascinating model watching ahead. Long term trends are good, becoming a medium range model stand off.

144h is where it begins to get really interesting. Taking the top 4 performing models in order:

ECM

Atlantic approach angled steeply SE, wave break forced up ahead, low pressure previously sat over Scotland has dropped over Europe as pressure rises over Iceland.

UKMO

Less amplified over the Atlantic, different orientation of the Euro low and softer profile over Scandy.

GEM

Similar Atlantic shape to the ECM but again a different take on the Euro low and developments over Scandy.

GFS 00z (taking from same data point)

Similar wave break profile to ECM and GEM but another different take on the Euro low and profile over Scandy.

 

In short - we have cross model agreement on the wave break (no surprise) but quite different outcomes to what occurs downstream of it and, indeed, the angle and composition of the momentum upstream causing it. Consequently anything beyond 144h is in Disneyland and we won’t know for a while yet just how much northerly traction the block will get nor the extent and angle of any undercut.

We don’t get many of these knife edge, high potential scenarios in our part of the winter world so here’s hoping folk can enjoy the ride rather than play the doomsayer “told you so” card that often gets trotted out if a run shows less snow/cold than the previous one. There is a fine line between realism and pessimism, so let’s get it said now: yes…cold options in the U.K. are rare and often downgrade rather than upgrade. There is no wisdom or kudos for pointing this out ad infinitum. But when there is a chance - and there is a chance over the medium term - then let’s keep it optimistic. If it stays dry or westerlies win out then snowhunters can commiserate together (hopefully without the doomsayers playing that predictable card once again) but fingers crossed for some luck, some favourable alignment and some snow by the middle of the month. Remember Scotland has seen some good falls already, and the South got lucky in parts in early December. This has already been a better winter than many so fingers crossed it can continue. Broad scale drivers are favourable.

[phil nw.]

Still some details to iron out within the operational runs but  the ensembles are starting to clear the uncertainties for the end of this week.The combined 850 ensemble graph for Warwickshire showing the average forecasts from the GEFS/ECM/MOgreps .Good agreement that cold air  is in by day 7 .

So the  suggestion is that the high will build just far enough north west to usher in the first cold wave from the east over next weekend.

Eps T168

I take that as the first hurdle overcome,get the cold in and then accept further forward remains uncertain on how the pattern develops.In the worst case under a UK high we retain quite cold air but  looking a few days further on the eps and gefs we  have another go at reamplifying the Atlantic pattern.

This looks much better with an extension of a European trough underneath so based on this an extension of the cold looks quite possible beyond the initial high.Likely we will get better snow chances from that setup.

The most unlikely scenario is any early return of the westerlies so plenty to be optimistic about going into January for cold seekers.

[Met4Cast]

There are a few genuine deep cold ensembles being modelled now, something that has generally been lacking up until now & something I flagged as a possible concern a while back, this is a good step forward. 

[phil nw.]

Just a little request to folk who are doubtful over telecommunications ie background signals please show a little respect  for the members who spend time and have gained knowledge to enlighten the rest of us on this accepted form of meteorology.

It all adds to enrich the forum and it would be a shame if unfriendly posts put these folk off from posting.

I myself have gained much more understanding of what causes certain patterns to develop and i am 75years old but you can never stop learning about this great hobby if you keep an open mind.

[tight isobar]

Everything trending colder by wide margins now! All sent voicenote colder conditions incoming.. what’s going to be intriguing is the notions of sync to perhaps just how cold …. Finally winter steps forward .. gfs/ gem/ ecmwf.. London ones ..

[Kasim Awan]

1 hour ago, Met4Cast said:

One thing of note; 

Any snow that does fall & accumulate from back edge snowfall of the cold front around the 6th or wintriness from the E/NE before the high builds in could be on the ground for upwards of 10+ days. 

Details of course but worth mentioning. Likely a case of a cold high & cold pooling deepening in situ, when weather fronts return that could be very interesting (assuming we don’t see the currently unlikely solution of a sinking high)

Too early to give an indication of how long snow will last, however if GFS/GEM solution happens the snow will melt before it turns cold. On top of that in the next 10 days the snow looks very limited but early days.

Edited December 31, 2023 by Kasim Awan

[swfc]

11 minutes ago, northwestsnow said:

Obviously we are all entitled to our opinions but I'm personally a firm believer in telecommunications- 9 times out of 10 from my POV,if telecommunications are not supportive of a UK cold spell it  won't happen.

I freely admit a lot goes over my head but the above I believe to be true.

Me also esp the over the head bit. Ive picked up and learnt a lot over the years but via various health problems my memory isnt what it was. My main go to now is the ukmo and various control and mean outputs. The ops obviously cause much more interest but a broadscale look at things is better for me. The actual telecommunications are of interest but you need a long term understand imo, like guys on here

[MJB]

I appreciate it isn't the top model but all signs positive help .................don't they 

 

The JMA seasonal round up for Jan Feb and March is truly stunning. 

January Cold and blocked, HP over us and slightly NW of the UK

Feb looks absolutely primed for a snowy and cold month blocking pushed further North and West towards Greenland.

March signal is weaker and mixed.

[Bullseye]

2 minutes ago, MJB said:

I appreciate it isn't the top model but all signs positive help .................don't they 

 

The JMA seasonal round up for Jan Feb and March is truly stunning. 

January Cold and blocked, HP over us and slightly NW of the UK

Feb looks absolutely primed for a snowy and cold month blocking pushed further North and West towards Greenland.

March signal is weaker and mixed.

Hello, would you be able to link latest JMA for JFM? Many thanks 

[MJB]

1 minute ago, Bullseye said:

Hello, would you be able to link latest JMA for JFM? Many thanks 

Go to Gavs weather vids, he explains it very well 

3 minutes ago, Bullseye said:

Hello, would you be able to link latest JMA for JFM? Many thanks 

 

[bluearmy]

45 minutes ago, Nick2373 said:

Yes that keeps getting pushed back abate the cold, the teleconnections in my opinion aren’t the best in predicting cold nirvana runs, they are good in pushing them back through 

The period post 7th has been signposted as being cold.  Longer range modelling will always undercook that because of the general noise of the members that differ from the main cluster.  When we’re speaking about surface cold then at this time of year that can come via high slp or cold uppers.  But this period was also signposted with colder than normal 850’s.  Now whether we get a few days of cold followed by a pull back and a second bite remains uncertain. It could yet stay sig below average for 7/10 days.  But what was originally 10/15 days away is now a week. This isn’t being pushed back on the models. Those using telecons cannot specify dates with confidence - that’s not how telecons work.  But whilst gfs ops and some ens suites were dithering somewhat, the fact that the telecons were supportive leant weight to those ens suites that were fairly solid in their consistency. 

I see no reason to doubt the trend to cold and hopefully that will be notable with some snowfall for all 

[Ali1977]

19 minutes ago, Kasim Awan said:

Too early to give an indication of how long snow will last, however if GFS/GEM solution happens the snow will melt before it turns cold. On top of that in the next 10 days the snow looks very limited but early days.

I think his point was that if any snow falls (the ECM suggests possible) then with the sun at its lowest, very cold nights and days only just into plus temps - it won’t melt.  With temps very cold, snow is quite possible for some - weather that’s showers, a little trough or more prolonged events from whichever direction. The cold weather is coming - just how cold and snowy to be decided. 
 

As ever my cup is half full, and will be till early April

Edited December 31, 2023 by Ali1977

[Metwatch]

Thank goodness it's looking drier from later next week as that high builds in around or just west of the UK!

[Kasim Awan]

5 minutes ago, Ali1977 said:

I think his point was that if any snow falls (the ECM suggests possible) then with the sun at its lowest, very cold nights and days only just into plus temps - it won’t melt.  With temps very cold, snow is quite possible for some - weather that’s showers, a little trough or more prolonged events from whichever direction. The cold weather is coming - just how cold and snowy to be decided. 
 

As ever my cup is half full, and will be till early April

It will probably melt if it's only 1-2cm.

[Ali1977]

1 minute ago, Kasim Awan said:

It will probably melt if it's only 1-2cm.

It’ll be a nice predicament to be in, I guess some -3 to -6c nights before would help 

[MATTWOLVES 3]

I needed to jump out of semi retirement for this post..hope the mods don't mind.

When I joined this forum nearly 5 years ago I was sceptical of back ground drivers as I didn't really understand them..so I just played ignorant to it all....but I never disrespected any of the posters who shared this knowledge! As the years have rolled by the likes of Tamara..catacol...met4cast...chio..matt H.. eagle eye...(I could go on with this list as there's more of you) have completely changed my attitude to such a wonderful science,and the amount of work that goes into this subject with there posts is unreal! Do keep in mind many of the above are not professional! Yes you would think they were...they are that good at it,they simply have a gr8 passion for the subject and spend a hell of a lot of time studying,and then they pass this information on to us giving us the chance to learn something new!

I for one know for a fact some of them in the past have come close to stopping posting due to non stop criticism...and I've actually talked one of them out of it privately on more than one occasion!

Where do you think the Met get there long range forecasts from! A clairvoyant!! The tea leafs! It's all based on drivers around the globe and much of it is inputted into those monthly text updates.. yet when they're talking up cold and snow,everyone loves em! When they get it wrong they're useless! Get my point here!

Let's all dismiss those drivers and base our forecasts on 4 gfs runs a day! One run shows Greenland blocking...the next a bartlett high! Exactly!!! Its not quite that simple.

So I say to all of those that spend so much time bringing us these amazing insights with the teleconnections to please keep at it...most of us on this Forum want to keep learning from it.

Keep the peace folks...no point in dismissing something you either don't understand,or are simply not willing to try and understand.

[MJB]

1 minute ago, MATTWOLVES 3 said:

I needed to jump out of semi retirement for this post..hope the mods don't mind.

When I joined this forum nearly 5 years ago I was sceptical of back ground drivers as I didn't really understand them..so I just played ignorant to it all....but I never disrespected any of the posters who shared this knowledge! As the years have rolled by the likes of Tamara..catacol...met4cast...chio..matt H.. eagle eye...(I could go on with this list as there's more of you) have completely changed my attitude to such a wonderful science,and the amount of work that goes into this subject with there posts is unreal! Do keep in mind many of the above are not professional! Yes you would think they were...they are that good at it,they simply have a gr8 passion for the subject and spend a hell of a lot of time studying,and then they pass this information on to us giving us the chance to learn something new!

I for one know for a fact some of them in the past have come close to stopping posting due to non stop criticism...and I've actually talked one of them out of it privately on more than one occasion!

Where do you think the Met get there long range forecasts from! A clairvoyant!! The tea leafs! It's all based on drivers around the globe and much of it is inputted into those monthly text updates.. yet when they're talking up cold and snow,everyone loves em! When they get it wrong they're useless! Get my point here!

Let's all dismiss those drivers and base our forecasts on 4 gfs runs a day! One run shows Greenland blocking...the next a bartlett high! Exactly!!! Its not quite that simple.

So I say to all of those that spend so much time bringing us these amazing insights with the teleconnections to please keep at it...most of us on this Forum want to keep learning from it.

Keep the peace folks...no point in dismissing something you either don't understand,or are simply not willing to try and understand.

Post of the year

Well said Matty boy

 

[jcw]

1 minute ago, MATTWOLVES 3 said:

"I needed to jump out of semi retirement for this post..hope the mods don't mind.

........So I say to all of those that spend so much time bringing us these amazing insights with the teleconnections to please keep at it...most of us on this Forum want to keep learning from it.

Keep the peace folks...no point in dismissing something you either don't understand,or are simply not willing to try and understand."

Well said. Evidence will build, one way or the other, as this science continues to be studied. It's too easy, and too early, to dismiss it out of hand. 

J.

[Metwatch]

3 minutes ago, MATTWOLVES 3 said:

I needed to jump out of semi retirement for this post..hope the mods don't mind.

When I joined this forum nearly 5 years ago I was sceptical of back ground drivers as I didn't really understand them..so I just played ignorant to it all....but I never disrespected any of the posters who shared this knowledge! As the years have rolled by the likes of Tamara..catacol...met4cast...chio..matt H.. eagle eye...(I could go on with this list as there's more of you) have completely changed my attitude to such a wonderful science,and the amount of work that goes into this subject with there posts is unreal! Do keep in mind many of the above are not professional! Yes you would think they were...they are that good at it,they simply have a gr8 passion for the subject and spend a hell of a lot of time studying,and then they pass this information on to us giving us the chance to learn something new!

I for one know for a fact some of them in the past have come close to stopping posting due to non stop criticism...and I've actually talked one of them out of it privately on more than one occasion!

Where do you think the Met get there long range forecasts from! A clairvoyant!! The tea leafs! It's all based on drivers around the globe and much of it is inputted into those monthly text updates.. yet when they're talking up cold and snow,everyone loves em! When they get it wrong they're useless! Get my point here!

Let's all dismiss those drivers and base our forecasts on 4 gfs runs a day! One run shows Greenland blocking...the next a bartlett high! Exactly!!! Its not quite that simple.

So I say to all of those that spend so much time bringing us these amazing insights with the teleconnections to please keep at it...most of us on this Forum want to keep learning from it.

Keep the peace folks...no point in dismissing something you either don't understand,or are simply not willing to try and understand.

In short, never stop being curious

[Catacol]

2 hours ago, The Enforcer said:

I am sure GSDM is a useful forecasting tool, but there hasn't been a cold period yet.

I’d describe it as a diagnostic tool probably more than a forecasting tool. The fact the MetO don’t use it illustrates its one weakness, namely that the GSDM approach is itself the product of other forecasts. So…if pressure patterns don’t develop to allow a mountain torque spike, or if the pacific wave is derailed or lowered in amplitude then GSDM forecasts, like any other, can bust. The ENSO profile can suggest the likely direction of the GWO orbit, but - as we have seen in recent years - the atmosphere can fall into a pattern that disconnects from this forcing and perhaps most significantly the GSDM approach produces a shape of wind flows to the hemisphere and this doesn’t factor in locally relevant features that can overtake it on a local level.

However, what it does do is provide the context within which NWP forecasting sits. So….we can be pretty confident in a period of low momentum and coupled Nina season that amplification will be significantly less likely to occur than a higher momentum profile coupled to a Nino ENSO. We know that momentum spikes produce meridional responses and the phases of the MJO help give a clue as to where the peak/trough pattern will setup. So GSDM diagnostics help provide an understanding of higher or lower probabilities of events occurring.

Finally - to show its value the GSDM approach correctly “forecast” the cold at the end of Nov/early Dec. It also correctly forecast the flatter period through the middle of the month. It didn’t quite get the latter third of December because the MJO didn’t play ball…so 2 from 3 there. And now we have a period of blocking on the horizon that GSDM analysis diagnosed as likely a fair while ago. 3 from 4? Useful.

Edited December 31, 2023 by Catacol

[winterof79]

22 minutes ago, MATTWOLVES 3 said:

I needed to jump out of semi retirement for this post..hope the mods don't mind.

When I joined this forum nearly 5 years ago I was sceptical of back ground drivers as I didn't really understand them..so I just played ignorant to it all....but I never disrespected any of the posters who shared this knowledge! As the years have rolled by the likes of Tamara..catacol...met4cast...chio..matt H.. eagle eye...(I could go on with this list as there's more of you) have completely changed my attitude to such a wonderful science,and the amount of work that goes into this subject with there posts is unreal! Do keep in mind many of the above are not professional! Yes you would think they were...they are that good at it,they simply have a gr8 passion for the subject and spend a hell of a lot of time studying,and then they pass this information on to us giving us the chance to learn something new!

I for one know for a fact some of them in the past have come close to stopping posting due to non stop criticism...and I've actually talked one of them out of it privately on more than one occasion!

Where do you think the Met get there long range forecasts from! A clairvoyant!! The tea leafs! It's all based on drivers around the globe and much of it is inputted into those monthly text updates.. yet when they're talking up cold and snow,everyone loves em! When they get it wrong they're useless! Get my point here!

Let's all dismiss those drivers and base our forecasts on 4 gfs runs a day! One run shows Greenland blocking...the next a bartlett high! Exactly!!! Its not quite that simple.

So I say to all of those that spend so much time bringing us these amazing insights with the teleconnections to please keep at it...most of us on this Forum want to keep learning from it.

Keep the peace folks...no point in dismissing something you either don't understand,or are simply not willing to try and understand.

Top post Matt

Having read in detail Tamara's posts before summer she got it spot on in my view.

Hope she doesn't mind me reposting this from early June and she was one of the first to flag up the upcoming westerly influence that will be seen over Iberia after a very long period of static High pressure influence down there.

 

"Yes. The sub tropical jet stream continues to be the interest as summer wavelengths take stage c/o a Nino-esque split flow driving an increasingly amplified trough in the Atlantic and corresponding tendency to inflate downstream ridges and warm air advection. Worth watching for renewed heat build moving north from southern Europe interplaying with the Atlantic trough. Which translates to larger and larger plumes and thundery potential across much of Europe/UK.

Its been some time since this type of summer pattern has been seen. The broad scale trend should greatly please many rather than getting bogged down in the detail of each and every intra day output"

Edited December 31, 2023 by winterof79

[Scott Ingham]

5 hours ago, Mike Poole said:

Hi John, yes, not feeling it this morning, unfortunately.  I think the trend has been going in the wrong direction over the last day or two.  And I still think we lost a lot of impetus towards a really decent cold spell when the very favourable split in the vortex (which resulted notably in the SSW, but was showing at all vertical levels on the models) went belly up.  

I think we’re looking at the wrong week. Like I’ve probable said a million times it’s the 15th onwards for any change of snowy cold with the 8th -15th drier with the odd surprise thrown in. The cycling caused by the rise in AAM will have 3 or 4 bites to it before it subsides

[Scott Ingham]

4 hours ago, winterof79 said:

To be honest i never expected snow at that time scale nor the Met. We seem to dream up earlier snowy spells when they were never fully on the table.

A UK High or somewhere near in early Jan is fine to start with.

Finally! Someone who talks some sense on here! Pressure always looked too high 8th -15th as the met have said for 6 days in a row now. We aren’t even within 14 days of the deeper cold arriving as per met office

[Battleground Snow]

Probably some scattered snow showers as early as next Saturday according to the ecm control 

[markw2680]

It really wouldn’t surprise me in the slightest that the closer we get to the weekend (7th) the low in the southeast will be stronger than modelled at present and closer to the uk which will obviously enhance the cold coming from the east or north east and will bring snow to some, then as that pulls away we get some kind of cold high keeping most of the snow if any of course on the ground. Becoming very cold and frosty. That’s enough for me at this time