Catacol

Not sure whether this has been posted today or not - I've had to skim the thread a bit due to shortage of time so apologies if it has. Wow - just wow. Not sure I've seen many better of these. John Holmes put out a great post earlier today that ties in with it. Let's make the most of this - it could be 5+ years again before we see anything quite like it. Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4998624

Not sure whether this has been posted today or not - I've had to skim the thread a bit due to shortage of time so apologies if it has. Wow - just wow. Not sure I've seen many better of these. John Holmes put out a great post earlier today that ties in with it. Let's make the most of this - it could be 5+ years again before we see anything quite like it.

NWP playing the Hokey Cokey, but all roads leading the same way. Wave break is imminent, vortex right now is stressed and about to split, momentum set to be maintained for another week or so. When default westerlies are de powered modelling always struggles to get the small things “right” so just go with the flow and let the pattern unwind. Cold air is coming from the NE and will set up shop and we have a strong block that is going to be in play. And the AO is turning negative…all of which means cold for the foreseeable. Calmest I’ve felt all winter and I’m just enjoying the model ride. A moment to look further ahead. I mentioned before the belief that we will get enough from this pattern phase to keep the westerlies at bay once the less favourable MJO phases work their way through alongside the -AAM impacts that must inevitably follow a period of sharp amplification. Well - it’s good news tonight looking at these momentum patterns. First of all we can see that AAM is now climbing once again - earlier than I expected. Whether we end up with a bit of wobble in this gradient we will wait to see - I wouldn’t be surprised… but the fact we are back on the way up is great news and note that the dip we have just gone through is far less deep than the one that toasted our early December cold. This means the potential for a reignition of the amplification signal earlier than I expected, helped by a high orbit MJO that has stalled in phase 3, generally good news as 3 is better than 4 Overall this means wind flows have held on to a Nino imprint and from here I think we will be looking at finding a higher orbit again, especially if we get that +EAMT mid month. The plain language conclusion here is that it won’t be long before our block - which will inevitably begin to weaken in around 10 days’ time - will get reamplfiied soon enough to prevent a flat pattern reestablishing as happened in December. The MetO has alluded to as much today, providing the dual scenario of heavy snow and heavy rain hand in hand - code for that wonderful knife edge scenario stuff where some get big dumpings… and given the shape of the current pattern I think we can hold on to a decent amount of confidence that most of the U.K. will be on the cold side of any intrusions as we hit the final third of the month. From there, stronger block again. I’d go with our Greeny block subsiding towards Iceland, wedges deflecting weak Atlantic intrusions, movement towards Scandy and then amplified retrogression back to Greenland early Feb. It could all go wrong - of course it could - and if so I’ll flag it. But right now all remains on course. Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4998558

NWP playing the Hokey Cokey, but all roads leading the same way. Wave break is imminent, vortex right now is stressed and about to split, momentum set to be maintained for another week or so. When default westerlies are de powered modelling always struggles to get the small things “right” so just go with the flow and let the pattern unwind. Cold air is coming from the NE and will set up shop and we have a strong block that is going to be in play. And the AO is turning negative…all of which means cold for the foreseeable. Calmest I’ve felt all winter and I’m just enjoying the model ride. A moment to look further ahead. I mentioned before the belief that we will get enough from this pattern phase to keep the westerlies at bay once the less favourable MJO phases work their way through alongside the -AAM impacts that must inevitably follow a period of sharp amplification. Well - it’s good news tonight looking at these momentum patterns. First of all we can see that AAM is now climbing once again - earlier than I expected. Whether we end up with a bit of wobble in this gradient we will wait to see - I wouldn’t be surprised… but the fact we are back on the way up is great news and note that the dip we have just gone through is far less deep than the one that toasted our early December cold. This means the potential for a reignition of the amplification signal earlier than I expected, helped by a high orbit MJO that has stalled in phase 3, generally good news as 3 is better than 4 Overall this means wind flows have held on to a Nino imprint and from here I think we will be looking at finding a higher orbit again, especially if we get that +EAMT mid month. The plain language conclusion here is that it won’t be long before our block - which will inevitably begin to weaken in around 10 days’ time - will get reamplfiied soon enough to prevent a flat pattern reestablishing as happened in December. The MetO has alluded to as much today, providing the dual scenario of heavy snow and heavy rain hand in hand - code for that wonderful knife edge scenario stuff where some get big dumpings… and given the shape of the current pattern I think we can hold on to a decent amount of confidence that most of the U.K. will be on the cold side of any intrusions as we hit the final third of the month. From there, stronger block again. I’d go with our Greeny block subsiding towards Iceland, wedges deflecting weak Atlantic intrusions, movement towards Scandy and then amplified retrogression back to Greenland early Feb. It could all go wrong - of course it could - and if so I’ll flag it. But right now all remains on course.

It’s a slightly daft tweet because it is referencing 850s. Without doubt models are useless at getting 850s right at anything like medium range. You’ll never see me mention them. Synoptic shape is all important, but I’ve seen near identical synoptics upgrade a flow predicted to be 0 at 120h to something colder than -4 by 48 hours. Given the fine lines required for snow I don’t see the point worrying about 850s until we get to the 48hour point. The only EPS that matters is this one….and it is rock solid still out to 240h.

Yes. He has tweeted that EPS are trending milder.

Ha - you being distracted by Brian’s gloomy tweet? Keep the faith. Either we commit to the general shape of a GWO-sourced forecast in the context of a stressed and weakened vortex or we don’t. ECM op overnight struck me as struggling in the extreme with the unusually disrupted pattern.

Best in years - certainly since 2018. Technical SSW is perhaps something we get a bit hung up on. We know a downwelling reversal has the most significant impacts, but a speed reduction and split such as is occurring now will also have impacts, even if less severe. The key is we do not have a tight, well formed and above average strat vortex preventing tropospheric drivers from controlling the pattern. Let’s hope we get to make the most of it!

All roads continue to lead in that direction, though the most recent ECM run was quite bizarre in its evolution. GFS ECM GEM And if the UKMO went that far out I think we have a decent idea what it would be showing!

Seriously @Scott Ingham - stop it!

And away from ECM, GEM continues the theme as broadly so does the GFS No change in the EC weekly for the core landing zone All good. The models will continue to have difficulty modelling with precision the wave break, and factoring in also the impacts of what increasingly looks like a vortex split that will run through the trop and lower strat, and perhaps UKMO at 144 this morning shows this rather well. An unusual chart to be sure, more like a hopscotch setup than a standard synoptic pattern! But models finding it tough at the moment is all part of the fun because the signals remain solid. If anything the EC weekly cold signal has upgraded a bit on the most recent run for week 4, first week of February. 22-29 Jan continues to look the most brokendown... Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4995953

Completely agree. I wonder really why some of these folk are on this forum. In winter the momentum is always around the hope and search for rare winter synoptics and that should mean that the forum population are used to let down but optimistic by definition. Instead we have posters who see a single run that has slipped to a less cold picture - often at significant range - and who seem unwilling to contemplate the reality of the drivers that several of us try hard to explain and represent as accurately as we can. Of course the UK experiences let downs. We are an island on the eastern edge of a warm ocean no matter our latitude. But there is nothing happening at the moment that should do anything other than raise optimism. For my part I have not deviated from my confident sense that we are in a cold pattern for the extended. That was a bold thing to say yesterday, and partly driven I know by a desire to see cold, but I also try and keep my focus on what the data and the patterns and the likely predictions are putting out there (and I listen carefully to those who know a good deal more than me) and I dont see wet, windy and mild atlantic westerlies returning for a good wee while. I probably ought to qualify what I said by emphasising I am not expecting ice days for 28 days in a row nor am I expecting that all precipitation will be snow rather than rain. I'm not daft! But a cold pattern for an extended period is all I can see, with 22-29 Jan possibly the least cold part of that period, and unless something comes out of left field to skew the signals I think all will remain good for cold hunters.

And away from ECM, GEM continues the theme as broadly so does the GFS No change in the EC weekly for the core landing zone All good. The models will continue to have difficulty modelling with precision the wave break, and factoring in also the impacts of what increasingly looks like a vortex split that will run through the trop and lower strat, and perhaps UKMO at 144 this morning shows this rather well. An unusual chart to be sure, more like a hopscotch setup than a standard synoptic pattern! But models finding it tough at the moment is all part of the fun because the signals remain solid. If anything the EC weekly cold signal has upgraded a bit on the most recent run for week 4, first week of February. 22-29 Jan continues to look the most brokendown...

15th Jan now sneaks into the range of ECM op. @Scott Ingham - you are a genius.

As we move closer to events to come and get closer to the 120h window a quick update on model performance. UKMO, ECM and GEM have opened up a decent gap on GFS at the moment.

Others have got in ahead of me but: Let me know if you want to learn how to interpret this. It is absolutely supportive of a sustained spell of cold weather.

Yep. There are some extremely half empty comments in here this evening. This is EC 240 Strong block, southerly displaced jet, shattered vortex with the main remnants over Asia, flow over the U.K. north of east following around a week of steadily falling temperatures. As an overall pattern what more do folk wish to see?

Unless we have a line into the comms between Exeter and central government we are blind to any such signals. And most certainly the Met are looking beyond 144h but, as stated already, they won’t say anything in their text until they are 110% sure of their ground. The point is that therefore we will never get forecasts of significant cold at medium range couched in anything other than the current probability terms, even if they are as certain as they can be at that range.

Pfft. This is getting ridiculous. Getting bored of all the constant north easterly charts and anti-zonal flow. I'm hankering after some good old fashioned +NAO and a mild south westerly feed. Someone please find me a chart that shows the Fine Folk of Good Ol' Blighty what the weather round here is really all about. This really sucks. Cross model consensus of continental cold and snow is just so 1980s. Not. Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4994909

This is not 2018, but 2018 is the only time since Dec 2010 that I looked at charts more than a week out and felt 100% confident that the cold was going to land. Things were so well aligned back then that really it couldn't happen any other way. For the landing zone around 15th January I am now feeling the same. How it develops over the period that follows will be up for grabs as a micro exercise, but I really can't see anything that will deviate this broad pattern now. This is why, I think, we are getting such consistent op runs for mid month. I need to lie down.....

Yeah. Yawn. 15th Jan once again. Almost didn't need to bother to look.... Ummm - is this about the best January chart I have ever seen? Might be.

Yes - good observational stuff. The jet has been generally more southerly most of the season so far and back into November too. This has left Scotland on the cold side quite a bit with a fair amount of wintry stuff up there already this year. And with this block about to turn the pattern upside down, and the jet forced underneath, we are all going to get in on the fun (we hope)..

They'll bloody struggle the way NWP has finally cottoned on to the momentum surge!

Pfft. This is getting ridiculous. Getting bored of all the constant north easterly charts and anti-zonal flow. I'm hankering after some good old fashioned +NAO and a mild south westerly feed. Someone please find me a chart that shows the Fine Folk of Good Ol' Blighty what the weather round here is really all about. This really sucks. Cross model consensus of continental cold and snow is just so 1980s. Not.

I don't think that will be the language next week. Looking at the strength and location of the block, and given the current mildness and inherent warmth present in water logged ground, we need next week to dry things out and cool things down. We are now guaranteed to get that - frost is going to feature, severe frost for some, and this then sets things up for the week that follows. I think at that point it is possible the language may change, but it assumes luck in getting snow to fall. Remember that last year we had a cold spell at the start of December, but the trough was slack and lacked the punch to develop much in the way of precipitation. It is too far out to guarantee yet that this time around the flow will be more solid and perhaps carry fronts within it, something we also lacked last year. But it has to be more than just possible that we get luckier with this current, much more potent looking setup. And then "concern" will follow. As a country we don't deal well with more than about 2cm of snow!