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Catacol

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Catacol last won the day on January 1

Catacol had the most liked content!

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    Male
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    Wellington, Somerset
  • Interests
    History, Rugby, Cricket... and snow. World of Tanks ain't bad either.
  • Weather Preferences
    Frost and snow. A quiet autumn day is also good.

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  1. Agree 100%. Only Jan 20th and half of winter still to go. Very disrupted hemispheric pattern, strat reversal still ongoing and downwelling, and MJO coming back towards favourable phases. Much uncertainty on specifics, but overall pattern of Euro trough very much still the feature of the ensembles. Waiting a day or two while the atlantic blows itself out thanks to the storm over in the US wont alter the direction of travel.
  2. Cross posting this from the cold thread, in case it is worth placing here too... I don’t think the old model thread covered itself in glory today. Disappointing runs for sure - but if you remove the op run hype of the previous day solid predictions from technical posters of the pattern for the end of the week were conspicuous by their absence, and the reason was simple: nothing from Wednesday onwards ever looked nailed on. I’m not sure why people hang on individual runs so much and lose sight of forcings and hemispheric pattern....but it has been the case all along that the forcings of the SSW and Pacific have been clear to see, but equally clearly timings have been an issue. Can interested amateurs hope to get timings right when even the Met, with their supercomputer and dedicated professional staff, have also struggled this season....with the approach of colder conditions consistently put back? I think not. The droppng of the trough into Europe midweek was the only feature of the pattern change that was “easy” (comparatively) to spot at around the 192 range but the specific direction of travel after that has been hazy. However let’s be clear. Firstly, as I tried to show last night, models all have their frailties and ECM is not king all of the time. On that basis take the full suite we have available and never right any off entirely. Taking next week as the focus there remains a huge amount of uncertainty as to what happens once heights over Europe have lowered, and while a raging easterly now looks unlikely for Thurs/Friday this doesn’t mean an easterly is out the question soon after. Secondly - and related to this - ensembles are still good, and if you cycle back to the wise words of John H earlier today the prognosis remains good. Thirdly the drivers that a few people today have tried to knock (and if we’d think we can’t improve our weather understanding then why are we here....hence such posts seem extremely odd to me) are still here and approaching peak impact. If an easterly is lost for Thurs/Fri then we move on to the next opportunity, somewhat disappointed but still optimistic given those drivers. And lastly - some people may get a good snow event on Tues/Weds....an event we were able to signpost at around a week and should have people pleased!!! Sitting in the SW I’m a bit envious of those in the midlands and north who may cash in....good luck to you all. Finally - good points have been made today about probability. Has to be true. We are never dealing in certainties when looking at forecasting beyond 72 hours ( and often at considerably less....) and it is worth reflecting on this. Probability means that outside chances can happen. And huge favourites don’t always come out on top. Reflect on that. As one fellow Scottish Rugby fan said earlier - bloody good job too. If the outlier and the underdog was automatically doomed the world would be an extremely dull place. So as we are all weather enthusiasts in here, perhaps we should cling to the understanding that hunting snow is a long odds game in the UK and be comfortable with that, or go find another hobby.
  3. I think I agree with that. Given that patterns tend to ebb and flow a bit (I’m sure a physicist somewhere could explain the process through waves...but for a numptly like me I just observe...) it seems highly likely that the long wave pattern we are moving into will prompt another attempt at the NW block very soon. I don’t think the old model thread covered itself in glory today. Disappointing runs for sure - but if you remove the op run hype of the previous day solid predictions from technical posters of the pattern for the end of the week were conspicuous by their absence, and the reason was simple: nothing from Wednesday onwards ever looked nailed on. I’m not sure why people hang on individual runs so much and lose sight of forcings and hemispheric pattern....but it has been the case all along that the forcings of the SSW and Pacific have been clear to see, but equally clearly timings have been an issue. Can interested amateurs hope to get timings right when even the Met, with their supercomputer and dedicated professional staff, have also struggled this season....with the approach of colder conditions consistently put back? I think not. The droppng of the trough into Europe midweek was the only feature of the pattern change that was “easy” (comparatively) to spot at around the 192 range but the specific direction of travel after that has been hazy. However let’s be clear. Firstly, as I tried to show last night, models all have their frailties and ECM is not king all of the time. On that basis take the full suite we have available and never right any off entirely. Taking next week as the focus there remains a huge amount of uncertainty as to what happens once heights over Europe have lowered, and while a raging easterly now looks unlikely for Thurs/Friday this doesn’t mean an easterly is out the question soon after. Secondly - and related to this - ensembles are still good, and if you cycle back to the wise words of John H earlier today the prognosis remains good. Thirdly the drivers that a few people today have tried to knock (and if we’d think we can’t improve our weather understanding then why are we here....hence such posts seem extremely odd to me) are still here and approaching peak impact. If an easterly is lost for Thurs/Fri then we move on to the next opportunity, somewhat disappointed but still optimistic given those drivers. And lastly - some people may get a good snow event on Tues/Weds....an event we were able to signpost at around a week and should have people pleased!!! Sitting in the SW I’m a bit envious of those in the midlands and north who may cash in....good luck to you all. Finally - good points have been made today about probability. Has to be true. We are never dealing in certainties when looking at forecasting beyond 72 hours ( and often at considerably less....) and it is worth reflecting on this. Probability means that outside chances can happen. And huge favourites don’t always come out on top. Reflect on that. As one fellow Scottish Rugby fan said earlier - bloody good job too. If the outlier and the underdog was automatically doomed the world would be an extremely dull place. So as we are all weather enthusiasts in here, perhaps we should cling to the understanding that hunting snow is a long odds game in the UK and be comfortable with that, or go find another hobby.
  4. Last post tonight - interesting to see the ensemble spread for mean see level pressure from the ECM for 7/8 days' time. Note the greater spread to the north as the model struggles to get to grips with heights in that area. Has a big bearing on strength of the easterly and specific direction. Much still to be resolved which is why none of the more technical posters on here today have done much in the way of predicting specifics. Good fun to be heading into a cold week where the exact pattern is still a lottery! Better than Game of Thrones.
  5. It's a good GFS after a below par ECM. A lot of stuff gets said on here about ECM and GFS. Verification stats definitely favour ECM, but if you run the stats for the various models there are some interesting realities. First would be that month by month there is volatility - and while ECM tend to remain on top the other models get close. Very interestingly KMA 12z would appear to be every bit as good, if not better at times, than ECM - but we don't seem to have access to it (or does anyone know where we can get it?) Second - and maybe not so good after today!! - ECM 12z verifies much better than ECM 00z for the European area in the medium range (72 - 168) pretty much always....and often by quite a lot. But finally - and here is a twist. Which model performed best at 240h in Feb 2018, the last time we had a SSW impacted pattern? (and was only just behind ECM in March)? JMA. If you don't believe me - here's the graph. JMA by a whisker, over ECM 12z. The other model which recently has been very close to ECM verification is CMC (GEM). At 192 no difference through December compared to ECM. So - if there is a moral to this story it is that we probably shouldn't ever discount any run. For me ECM blew GFS away with the trough forecast BUT once GFS got a handle on the trough it appears to have got a handle on the trajectory more quickly than ECM, guilty perhaps again of over amplification. Weight of evidence is now saying snow for north and east on Tuesday, but definitely not so good for us SW folk... Later in the week? Bit tired tonight after a long day - and I'm going to hold fire on details still. To me the ECM evolution after 168 looks all wrong from a hemispheric angle with a quashing of the arctic high and very little extension of the Alaskan ridge - and the other models appear much cleaner and well formed with more heights over the pole. Prepared to disregard it a bit, assuming things improve tomorrow, though let's not forget the 12z verifies better. So - finish on something optimistic. If the JMA verified best in Feb 2018 at 240h what does it see for now? Pretty good.
  6. Yes - I think this is right. UKMO in the reliable time frame tends to trump the others often I think.
  7. That has to be a pretty rare sight. Back in March I was left feeling we had experienced a spell of very late season snow and cold that would be unlikely to happen again in a good long while. There is a chance - a chance - it might be topped if the depth of cold modelled now digs in for the long term. I was certain that we would see some good blocking this season conducive to cold and snow chances but I did not see such a deep trough and an SSW long delayed but high impact downwell like this that might paint northern Europe white for weeks. Maybe we can get somehing to happen that will take Brexit off our screens for a bit. Might be just what we need as a country...something cold and snowy to bring everyone back together!
  8. Ho hum dee dum. Interview done and back to the phone to see the most awesome GFS output of the season. Being blunt - pity it's GFS...but maybe something in the data has changed and we'll see ECM latch onto the same later. I hope brethren in the SW have woken up, because we'd have people drowning in the drifts again....... Usually a run like that would be written off...and in all probability it is overly extreme BUT worth pointing out at this stage that the evolution is not out of kilter with the forcings that are being applied to the north Atlantic circulation. Recent EC strat charts have shown a signal for a block to the W/NW and a jet driven further south, and so a split flow like that is entirely within the envelope of the possible, as impacts of the SSW increase. I'm sorry I can't access all my charts etc on my phone, but once home I'm going to have a really good look at the evolution of the pattern and see what may be what. Meanwhile don't forget that Tuesday is approaching and can still deliver for many. Just needs a westerly tweak as a product of underestimation of high pressure strength....something we have seen several times before. Jan 18 today. Can anyone remember the gloom and frustration of 10-14 days ago? Neither can I. Shows things can move very quickly in weather terms at times, and gloom should always be tempered with optimism when the signals are good.
  9. Yes - exactly. In the medium term we might appear to run the risk of marginal situations via inroads from the atlantic....but these are the patterns that bring the most snowfall and models will tend to underestimate resistance of residual wedges of higher pressure embedded in the cold. It’s a very good setup for snow rather than cold/dry. Offline for a bit now. Job interview.....
  10. No problem having a feeling - we are all interpreting the data for ourselves....but actually there is no model evidence for this interpretation at the moment. All ensemble data indicating the main height anomaly to the north and trough to the south. In this scenario, even if the high did drop a bit further south, we would still be very much in the general European freezer. Given the trend for arctic heights and ongoing impacts of downwelling ssw it also isn’t an interpretation that runs alongside strat teleconnections....and if you go and read David’s post from yesterday that very accurately sets out the next Pacific spike in momentum it would also fly against that forcing. Most bets I think would remain attached to the UK being more under the influence of the trough than the block....though obviously north/south location will be relevant. This isn’t a pattern that suggests a sinking block. (For once....!)
  11. Hotel on phone...so no charts. A last word about Tuesdays trough and marginality. ECM shows -4 850s across much of the country with a filament of -8 following in behind at 120. However these are temperature bands. The -4 could very easily be -6 plus or minus...and this - in very very broad terms without considering DPs and other factors, makes the Tuesday forecast a nightmare for the pros....and a nightmare up until the very last minute. The further west that trough tracks the greater the chance of snow. But even on a track further east there is a snow to rain back to snow potential almost anywhere. 72 hours also reveals just how complex a picture the models have to resolve for Tuesday. The system jamming into the mid Atlantic block is very deep - big clash of 2 distinct pressure differences and so margin for error increases. Data on the low is likely to change - data on deep lows usually does. So genuinely Tuesday into Wednesday is likely to be a now cast situation and the models will be struggling. I usually like to nail my colours to the mast a bit, and risk getting things wrong in the process! - but right now I’m holding fire on saying anything more than has been said all along. Tuesday is the first chance of a major snow event in this forthcoming spell but it’s a chance and not a certainty.
  12. Very true. Bigger picture is excellent. Being a little bit picky this morning we could do with Tuesday’s trough just adjusting back a bit further west. The modelling of 850s may now be getting a handle on the depth of cold within the trough and the lack of ocean moderation due to the speed and angle of the evolution, but there is a marginality for much of the country that would be removed if the high to the west would surge ever so slightly more to the NW allowing the trough further west. 50miles would make a massive difference. In this regard ECM gets thumbs up for the longer term but a slight frown at 96hours. Hoping to see that slight change in the next run as the evolution coming won’t be easy for models to get accurate in microscale modelling until 24/48 so there is definitely time for adjustments. But this is me being a little bit picky. Overall the bigger picture remains just what snow hunters would want, and later in the week and beyond expect surprises as precipitation appears out of nowhere once deeper cold begins to feed in. With such a solid trough in position the overall pattern doesn’t look likely to stay dry - though local variation on a day by day basis is an obvious reality. It isn’t going to snow everywhere all of the time!
  13. No charts tonight - on a train and on my phone which is tedious... But did want to post some text. My eyes are moving beyond the trough now - I was pretty confident in it at the weekend and am now certain. How much snow will we get? David's post highlighting the arrival of the expected next pacific spike is very timely. While we were wading through the tedious first half of the month the pot at the end of the rainbow was always the potential for a downwell that synchronised with a powerful pacific spike. It's taken the third time of asking to arrive - but it's here. This is going to mean reinforcement of the Euro trough at the same time as a push for stronger heights to the north, and this at a time when the ssw has already begun to affect the pattern. And this in turn I think is going to mean quite a steep pressure gradient and some really quite cyclonic continental weather as the trough beds down. I'm still thinking that the block has to setup over greeny rather than scandy in the medium term, though at the start of the season I did admit to being frustrated at an inability to get ridge positions exactly right and I want to get better at this - modelling appears to be favouring more of a scandy block at the moment - but in the end ridge position when the Euro trough is deep is probably not so important overall as the feed will be cyclonic and bitterly cold at this time of year either way. And all this adds up to some considerable snowfalls I think. Someone next to me on the train just said "it's supposed to rain on Tuesday..." and I was close to grinning at him and offering an alternative view....but let's just watch it unravel. I suspect the next few weeks won't be especially dry or especially wet. Something else.
  14. I'm in Somerset so no imby bias here! Trough to the south makes it very difficult to have either a westerly or southerly element to the feed so marginality then works in favour of wintry precipitation. Big trough big block would be the ideal but we too often focus only on the block perhaps. Anyway all good and I'm expecting ECM to be good again too.
  15. Haven't seen the upcoming cold described as a Beast yet...but I can't stay quiet on the idea that a single run means the whole scene changes. That just isn't the way to see the data. Look at the ensembles, track the weight of evidence in the context of expectations that teleconnections suggest, and hunt the trend. One poor ECM tonight, if it happens, means very little in the far wider context of a substantial and growing mass of evidence pointing towards a wintry event that does not happen every year. This is not your good old fashioned spell of PM as one poster interpreted yesterday and there is little to no evidence supporting a pattern that is going to return to mobility. Exactly how cold it gets we will have to see, though I've twice posted the much below average 850s forecast for eastern Europe and scandy next week...but please let's not have a return to thread meltdowns over a single run, whether it be op or ensemble. I don't believe a really poor run will emerge now, but even if it did we would need to see other evidence and other runs follow suit before even beginning to react.
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