Model Output Discussion - Into 2024

[Scott Ingham]

5 minutes ago, Cambrian said:

Looking at the ensemble means is always very valuable. Identifying the similarities and assessing the differences between the leading models allows the establishment of a baseline of expectation based on a more centred range of the wider ensemble envelope, which can’t be a bad thing to take into account, irrespective of any divergence in the longer term. 

The later divergence is also of interest for the same reasons. The models will inevitably diverge over the longer timeframes, but again there will be commonalities in their evolutions, which are worth noting. 

There are also of course the changes that occur between runs of the same model, which are useful to observe for the purpose of identifying trends. 

In addition, over time, with experience, we develop an understanding of the leanings and biases of particular models in certain situations.

 

This is a great example of why it’s very worthwhile keeping an eye on the ensemble means. 

12z GEFS yesterday for day 13 vs 12z GEFS today for day 12. 

 

Yesterday’s loss of Canadian Arctic heights and merged PV - dropped in favour of today’s maintenance of heights, Greenland ridge and well-separated lobes of the PV, and as a result, downstream a deeper Northern European trough, its core low heights held back further west. 

A very different perspective may be derived for the potential longevity of the forthcoming cold spell. 

Over the next few days, keeping an eye on the development of these aspects will inform our expectations for the Northern Hemisphere profile that will underpin our setup for week 2. It doesn’t matter even if the means for later in week 2 are indeed way off the mark right now. 

Studying the way that they gradually converge towards a consensus first with each other and then with the operational runs is valuable not only for the enjoyment of it, but also both as a learning exercise and to hone our interpretation skills, particularly for this specific type of scenario, and of course, precisely because the models are struggling with it in the longer timeframes. 

Couldn’t agree more

[Scott Ingham]

4 minutes ago, KTtom said:

Sorry, I think you misunderstand. You said M4cast didnt say the eps were poor...my quote is what M4cast said this morning, its not my opinion its what he said.

That’s all very well but it also has to be said in context. He doesn’t mean poor as in it’s an end to the cold spell and a return to above average temperatures he means it’s poorer than a previous set with more runs trending milder. M4cast is an experienced member I’m sure he wouldn’t look at those ensembles and means and denote them being “poor” for cold weather as it’s the opposite. I think for newbies this is important. Thanks

Edited January 7 by Paul
Removed comment

[kold weather]

Absolutely fascinating 12z ECM, synoptically at the end is just fascinating, because you've got an upper low driving SW near Iceland (and will probably form a surface low near Iceland further beyond) but the arctic high and the small upper high over SW Greenland influence each other and are actually rotating around a central point near the center of Greenland, which will mean even if a surface low does form near Iceland its all going to be ejected SE towards the UK anyways. Depending on how much development there was of the low, could evolve into a very snowy pattern...but if it overforms, a pretty rainy one before it moves away.

Anyways, it probably won't look anything like that so not sure why I'm overanalysing it!

[WYorksWeather]

Not going to start commenting on this evening's run until a bit later on when we have the ECM ensembles out. For those in the south, I thought it was worth taking a look at tomorrow's snow risk, with UKV and Arpege.

A fair few flurries in the south tomorrow on UKV, but not much accumulation as a result.

  

Not as much showing on Arpege (no accumulation chart available on TWO, but probably less than UKV).

 

This will probably turn into a bit of a nowcasting event, it is known that coastal precipitation can be underestimated, so some areas may see a few cm that doesn't show up on these charts.

I'll come back a bit later and take a look at the medium term on the ensembles. Back to work tomorrow, so I won't be staying up with the 18z crew.

[That ECM]

7 minutes ago, Scott Ingham said:

That’s all very well but it also has to be said in context. He doesn’t mean poor as in it’s an end to the cold spell and a return to above average temperatures he means it’s poorer than a previous set with more runs trending milder. M4cast is an experienced member I’m sure he wouldn’t look at those ensembles and means and denote them being “poor” for cold weather as it’s the opposite. I think for newbies this is important. Thanks

You guys could just ask him?

Edited January 7 by Cambrian
Consistency of edits to quoted post

[Met4Cast]

10 minutes ago, Scott Ingham said:

That’s all very well but it also has to be said in context. He doesn’t mean poor as in it’s an end to the cold spell and a return to above average temperatures he means it’s poorer than a previous set with more runs trending milder. M4cast is an experienced member I’m sure he wouldn’t look at those ensembles and means and denote them being “poor” for cold weather as it’s the opposite. I think for newbies this is important. Thanks

haha bloody hell. 

yeah exactly this,  they were poor in terms of the lack of deeper cold runs compared with previous outputs, the mean however was still broadly good which was a little odd. I don't think this is resolved yet despite this evenings outputs and we do need to begin discussing the uptick towards the 20th across all modelling, even though it could potentially be pushed back (GFS 12z Det a good example of how that's possible).

Edited January 7 by Cambrian
Consistency of edits to quoted post

[bluearmy]

That Ec 12z ops must be v close to a displacement reversal at 10 hpa by day 10 

that’s the timescale where gfs has been sniffing too 

the ec is even further south than the gfs 12z op at T228 off the west Norwegian coast  

 

[Scott Ingham]

Just now, Met4Cast said:

haha bloody hell. 

yeah exactly this,  they were poor in terms of the lack of deeper cold runs compared with previous outputs, the mean however was still broadly good which was a little odd. I don't think this is resolved yet despite this evenings outputs and we do need to begin discussing the uptick towards the 20th across all modelling, even though it could potentially be pushed back (GFS 12z Det a good example of how that's possible).

I thought as much mate that’s why I didn’t even seem fit to ask you as your in top echelons of ability to read some charts! Yeah I have noticed that around the 20th but atm I’m not overly worried as I believe this will be a battleground period of which traditionally very low 850s wouldn’t be an ingredient anyway

[northwestsnow]

3 minutes ago, kold weather said:

Absolutely fascinating 12z ECM, synoptically at the end is just fascinating, because you've got an upper low driving SW near Iceland (and will probably form a surface low near Iceland further beyond) but the arctic high and the small upper high over SW Greenland influence each other and are actually rotating around a central point near the center of Greenland, which will mean even if a surface low does form near Iceland its all going to be ejected SE towards the UK anyways. Depending on how much development there was of the low, could evolve into a very snowy pattern...but if it overforms, a pretty rainy one before it moves away.

Anyways, it probably won't look anything like that so not sure why I'm overanalysing it!

EC 12z is a big upgrade in the reliable timeframe from my POV..

still waiting to see how the pieces fall...

[bluearmy]

Better MAR on the eps day 9

 

[northwestsnow]

Just now, bluearmy said:

Better MAR on the eps day 9

 

Upgrade....

Great news..

Fingers crossed things are moving in the right direction..

 

 

[Big Gally]

3 minutes ago, Met4Cast said:

haha bloody hell. 

yeah exactly this,  they were poor in terms of the lack of deeper cold runs compared with previous outputs, the mean however was still broadly good which was a little odd. I don't think this is resolved yet despite this evenings outputs and we do need to begin discussing the uptick towards the 20th across all modelling, even though it could potentially be pushed back (GFS 12z Det a good example of how that's possible).

I enjoy your posts. I’m still trying to learn as I go lol. I have been listening to another experienced person talking about it turning milder from the 20th. This is because of the mjo going back into phases 5/6? Is that right? Then turning colder again around start of February? Thanks.

[TSNWK]

1 minute ago, bluearmy said:

Better MAR on the eps day 9

 

Hello. Was ecm op and ctrl aligned at day 10? If so how did ctrl end at day 15

[feb1991blizzard]

1 minute ago, bluearmy said:

Better MAR on the eps day 9

 

How good compared to 12z yesterday?

[Bricriu]

26 minutes ago, Mark wheeler said:

Exciting times Yes and do you know  what!  since the introduction of the Kma I have really grown fond of it  

A prolonged cold spell? Does anyone know how this model verifies compares to the big three in the verification stakes? I would really love if the answer is it's neck and neck with them:)

[Met4Cast]

Just now, Big Gally said:

I enjoy your posts. I’m still trying to learn as I go lol. I have been listening to another experienced person talking about it turning milder from the 20th. This is because of the mjo going back into phases 5/6? Is that right? Then turning colder again around start of February? Thanks.

The MJO may actually mill around in phase 3 for a while longer looking at latest modelling which wouldn't be a bad thing at all!

Worth noting the MJO is just 1 variable within the broader windflow (GSDM) budget so shouldn't be taken in complete isolation. I flagged the 20-25th on Twitter as a period where the jet may begin to edge northwards as blocking wanes, this suggests to me the potential for high impact snow events as weather systems hit the colder air across the UK (Indeed, Tamara echoed this in her earlier post here). 

With Atlantic weather systems comes the potential for milder air depending on exactly how/where they track and something that wont be resolved for at least another 7-10 days. A waxing and waning of blocking seems likely but plenty to suggest renewed blocking into February as per @Catacol's (I believe?)  post earlier today.

[kold weather]

6 minutes ago, northwestsnow said:

EC 12z is a big upgrade in the reliable timeframe from my POV..

still waiting to see how the pieces fall...

Absolutely an upgrade from 00z ECM, I don't think there is much of a question there.

Anyways we have tomorrow first to keep an eye on, think there maybe quite alot of snow showers around tomorrow, even if relatively little actually accumulates.

 

[WYorksWeather]

1 minute ago, Met4Cast said:

haha bloody hell. 

yeah exactly this,  they were poor in terms of the lack of deeper cold runs compared with previous outputs, the mean however was still broadly good which was a little odd. I don't think this is resolved yet despite this evenings outputs and we do need to begin discussing the uptick towards the 20th across all modelling, even though it could potentially be pushed back (GFS 12z Det a good example of how that's possible).

I'm not an expert on teleconnections / MJO etc (still trying to learn!), but isn't the suggestion that the MJO may progress into phases 4/5 later in the month, which per this page are generally associated with reduced prospects for blocking, and higher temperatures for the UK?

I don't know what the typical lag is on the MJO though, and whether I'm interpreting this correctly.

Almost all the model runs here seem to be suggesting an MJO in phases 4/5 around the 15th. Would that be soon enough to be responsible for a breakdown in the blocking and a return to milder conditions around 20th-22nd?

Happy to be corrected by far better experts on the teleconnections if I'm completely making a mess of this .

[Bricriu]

5 minutes ago, Big Gally said:

I enjoy your posts. I’m still trying to learn as I go lol. I have been listening to another experienced person talking about it turning milder from the 20th. This is because of the mjo going back into phases 5/6? Is that right? Then turning colder again around start of February? Thanks.

Milder could be a battleground scenario if the deep cold is entrenched before any Atlantic attack. Places further  north and east would be favoured in that scenario, we'd probably  be wet rather than white though.

Edited January 7 by Bricriu

[Met4Cast]

1 minute ago, WYorksWeather said:

I'm not an expert on teleconnections / MJO etc (still trying to learn!), but isn't the suggestion that the MJO may progress into phases 4/5 later in the month, which per this page are generally associated with reduced prospects for blocking, and higher temperatures for the UK?

I don't know what the typical lag is on the MJO though, and whether I'm interpreting this correctly.

Almost all the model runs here seem to be suggesting an MJO in phases 4/5 around the 15th. Would that be soon enough to be responsible for a breakdown in the blocking and a return to milder conditions around 20th-22nd?

Happy to be corrected by far better experts on the teleconnections if I'm completely making a mess of this .

See my above post answering exactly that!

[bluearmy]

7 minutes ago, TSNWK said:

Hello. Was ecm op and ctrl aligned at day 10? If so how did ctrl end at day 15

Pretty much 

too early to say (but likely v decent )

7 minutes ago, feb1991blizzard said:

How good compared to 12z yesterday?

Better 

Edited January 7 by bluearmy

[damianslaw]

A busy old day in here.. no surprise with it being a Sunday, Sundays in January when there are prospects of cold and snow on the way, tend to see this thread at its most active, and difficult to keep up with!...

After yesterday's very variable op fayre, the latest 12z from GFS, ECM and UKMO appear to be in sync, i.e. heights advecting to the NW, with very cold air ready to plunge SW through the UK. ECM yet again though is in no hurry to pull in the cold uppers, not until day 9.. At day 10 it shows sub 522 dam air through Scotland and is setting the scene for a very snowy slack airstream..

Alas such a change is still comfortably beyond the reliable, it will probably be Wednesday before we can begin to comment more comfortably on how cold and for how long things may become in week 3. As for snow, always a near timescale / now timescale conversation.

In general comment, I'd say week 3 of Jan is prime mid winter, when snowy cold weather feels right and can pack its greatest punch..  but its been a long time such a period delivered any notable cold or snow. Last year brought a cold week with some snow but not severe, 2021 also to an extent. 2018 was cold. Have to go back to 2013... which was quite snowy for some, even in 2010 by the third week the cold relented. Indeed I'm struggling to think when the 3rd week of Jan was last consistently very cold and snowy... 

Edited January 7 by damianslaw

[Scott Ingham]

1 minute ago, WYorksWeather said:

I'm not an expert on teleconnections / MJO etc (still trying to learn!), but isn't the suggestion that the MJO may progress into phases 4/5 later in the month, which per this page are generally associated with reduced prospects for blocking, and higher temperatures for the UK?

I don't know what the typical lag is on the MJO though, and whether I'm interpreting this correctly.

Almost all the model runs here seem to be suggesting an MJO in phases 4/5 around the 15th. Would that be soon enough to be responsible for a breakdown in the blocking and a return to milder conditions around 20th-22nd?

Happy to be corrected by far better experts on the teleconnections if I'm completely making a mess of this .

It would suggest a rise in the jet stream north but as Met4 cast says it’s only 1 aspect of a momentum budget and this budget currently on forecast hasn’t dropped all that low and is forecast to rise again suggesting a possible battleground snow event period followed by what I believe and Tamara and Caracol and I think M4cast to be a rise then in pressure over scandi before another rise middle of Feb in Greenland. 

Anothher option is a complete relaxation of the pattern followed by another cold period in February.

All in all not bad at all to see out winter!

We also have a ssw potentially occurring at the end of this month which adds even more interest or complication going forward

[Derecho]

3 hours ago, Derecho said:

Just a point of clarification I saw recently. The MJO phase 4 composite is still cold, so it will be interesting to see how this verifies....

Battleground cyclonic it looks like to me. Clearly we won't have a Greenland High that lasts forever but if we get a good blast of cold air from the north mid-month it wouldn't surprise me if we got an interesting battleground scenario to follow as heights to our NW wane (or move back to Scandi?)

Phase 5 isn't favourable but I expect that to come into play later in the month (post January 25th)

 

 

2 minutes ago, WYorksWeather said:

I'm not an expert on teleconnections / MJO etc (still trying to learn!), but isn't the suggestion that the MJO may progress into phases 4/5 later in the month, which per this page are generally associated with reduced prospects for blocking, and higher temperatures for the UK?

I don't know what the typical lag is on the MJO though, and whether I'm interpreting this correctly.

Almost all the model runs here seem to be suggesting an MJO in phases 4/5 around the 15th. Would that be soon enough to be responsible for a breakdown in the blocking and a return to milder conditions around 20th-22nd?

Happy to be corrected by far better experts on the teleconnections if I'm completely making a mess of this .

 

Phase 4 is quite blocked and cold, see the above.

Phase 5 however is mild but may lead to a battleground scenario if we are lucky and still have cold air in place.

I reckon things will stay blocked until around the 25th as @Met4Cast says. How that will look in terms of cold prospects is uncertain but if the MJO moves as expected, things will probably become less favourable for blocking at the end of the month.

Of course there are other factors besides the MJO and it may have other ideas. Right now we are in a good place though with a prolonged Phase 3 likely.

[MOF]

Woke up this morning, checked the forum and doom and gloom. Back on this eve and we're back in the game. Over the years watching the models, it's always seemed to me that the 0z start with a fresh set of data which evolves through the day till pub run, then starts again. Today is another perfect example. There is loads of good advise and input from a whole host of guys on here, but the best bit of advise is just to compare the same set of runs to each day to get a better picture of how the situation is evolving.