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captain jack

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Posts posted by captain jack

    Model output discussion 25th Jan - The final third of winter beckons..

    in Forecast Model Discussion

    Posted

    8 minutes ago, CreweCold said:

    Never rely solely on the interpretation of others...It sounds harder than it is to interpret NWP output, once you get the hang of it the first thing you will end up doing is looking at the models and forming your own conclusions. This forum then acts as a subsidiary to cross check the views of others and perhaps supplement your own views with the views of some of the seasoned members on here (and there are a fair few). 

    Yes, there have been a fair few trolls over the years but most members on here are well meaning, even if they only profess to possess a rudimentary handle on all things NWP!

    Fair points made, I just do not have the time to study all the outputs, hence my reliability on others for information.

    • Like 3

    Model output discussion 25th Jan - The final third of winter beckons..

    in Forecast Model Discussion

    Posted

    21 minutes ago, CreweCold said:

    Conversely you have to remember that using teleconnections also relies on using data which is a projection to some extent. I've seen plenty of instances where promising background signals have faded into obscurity along with the stellar model output. November 2016 being a case in point, just 3 months ago. 

    I don't think people aim to disappoint the majority as for one that line of thinking comes across as slightly paranoid and secondly, people cannot control weather or the atmosphere- they can merely comment on what is unfolding and how they expect it to unfold going forward. Their point is just as valid as the so called 'positive' people whom you suggest seem to have more weighting on this forum. Just because it's something that you personally don't wish to hear, it doesn't mean that they are trolling or being negative nellies. 

    Soundbites like 'this is an unusual pattern for the models' and 'blocks won't be pushed aside so easily' and 'reverting to climatological norm' are fine but add nothing to the debate nor do they embellish any of the analysis of what we actually physically see represented in the modelling in front of us. Perspective and balance is sorely lacking sometimes in this thread. Being able to analyse model trends involves taking the rough with the smooth and not shutting your mind off to the less desirable outcome just because it's not what you want to see.

    I do not profess to have the knowledge of some on here and cannot read the charts as well as many, so rely on the interpretations of others. my point is not in the least paranoid as I am not attached to the outcome. I just want to see a balanced analysis based on more factors than one operational run as that is how you learn. I think you are being disingenuous to suggest that some people on here do not 'troll' as you put it and I am certainly not using soundbites, just logical thinking.

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    Model output discussion 25th Jan - The final third of winter beckons..

    in Forecast Model Discussion

    Posted

    This is an unusual set up for the UK, hence the model variations. The bigger picture according to seriously knowledgeable people like @Tamara tends to suggest that the hemispheric factors that actually drive our weather are in our favour for upcoming 'winter weather' and I for one would trust this rather than six hourly computer predictions that will inevitably try to revert to the climatalogical norm. There are some great members like @Steve Murr, @nick sussex on here that aim to give us viable options as to what may happen based on each run but unfortunately there are others that just wish to hear their own voice and take pleasure in finding opportunities to disappoint the majority. It is going to get cold, it might snow, its still winter, enjoy!

    • Like 49
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    Model Output Discussion - The final stretch to Christmas

    in Forecast Model Discussion

    Posted

     Update from previous post and extracted references to discuss progress :)

     

    So, those attempts, especially by the old prototype GFS, to prematurely flatten the pattern are proving as wrong as they seemed

     

    As suspected in recent days, the continued drive forward in -ve tendency AAM and consistently predicted dotted progress of GWO through Phases 1 and 2 at the close of the year fully support the increased amplification signal in the Atlantic which has gained modelled ascendency over the last 48 hours - with ridging into Scandinavia, on the back of the SE tracking low next weekend..

     

    gfsgwo_1.png

     

     

    This second orbit through Phase 2 in higher amplitude proving more beneficial than the first one (signal very muted) we see for Christmas itself - although, that said, a fine crisp day and frost morning and evening is infinitely much more welcome for the day than the rain and strong gales last year

     

    Progress into Phase 3 supports, as we start the New Year, some westerly push increasing Atlantic influence thereafter as some vortex energy heads back over the pole towards Canada - but this is where it might get even more interesting as we look at undercut potential of heights by this time bedding in over Scandinavia to UK.

     

    The -ve frictional torque which precipitates the -ve mountain torgue over the US (wave 2 breaking) which in turn forces the GWO through phases 1/2 signposts the positive momentum transport indicated between 50 and 60 degrees north - but also it supports the increase in easterly trade winds indicated around 30 degrees south which increases sub tropical Jetstream flow.

     

    gfs1.png

     

    This GEFS produced prediction, is a favourably enough divvied up jet energy budget, to underpin latest ECM suggestions of split Atlantic flow in the 10 day + term and support for maintaining the blocking structures across Scandinavia into UK.  On this basis, we should view any modelled sinking of the cold high to be over progressive, (and short-lived should it occur, at the very least).

     

    It translates to an excellent holding pattern of surface cold while the stakes on that New Year polar vortex bonfire rise ever higher to get arctic upper cold towards us.

     

    Could we be cued for a cold anticyclone waiting to be sucked northwards by Arctic/Svalbard Heights as zonal winds across the polar field dive to negative reverse polarity in response to the combination of wave 2 uppercut from the troposphere (MT) and then next, a singeing head blow this time from the upper stratosphere?

     

    Its a stratosphere thread watch here in this respect - but it is not at all beyond the bounds of possibility as a longer term evolution. In the meantime plenty of interest and a little wiggle room available to keep interests up for wintry prospects on the back of the weekend low and NSSC snow potential thereafter :wink:  :D

     

    A very Happy Christmas to everyone :smiliz58:  :)

    @Sunny Kent - thanks. PM sent to you

    Hi Tamara, I wish I knew what you were talking about, but deep down for some reason I know it makes sense! Thank you for your technical input into this sometimes emotional forum, you bring a professional analysis of the 'potential' that the charts and the stratospheric signals are showing. Please keep it up and Merry Christmas to you and all the rest of you mad weather nuts. What a forum!

    • Like 10

    Model Output Discussion - The final stretch to Christmas

    in Forecast Model Discussion

    Posted

    Welcome, the models tend to trade off spells of doing relatively well but this coming period is a more complex challenge than they often face, so how they've done in past week or so would be generally inconclusive. Also this zonal pattern has been easier for them and errors were much smaller than what we're likely to find looking back from the 27th. Experienced model watchers develop ideas about what models do in certain situations and what their strong or weak points might be. GFS used to be a bit notorious for over-deepening lows at 5-7 days then backing off towards actual time. GEM is often thought to be too prone to over-amplification. European is regarded as most likely to verify when there's a conflict, but not by a wide margin. This coming situation is low on analogues and high on uncertainty even today. A good guess might be made by considering which way each model has trended past three days and seeing if those trends point to a convergence point. The best forecast at any given point is probably the accumulation of least error after weighting the models by preference. At the moment, you could assume that a moderately deep low will cross northern Scotland around the 27th and head towards southern Norway or Denmark by the 28th but possibly factor in that it might head more south than southeast. What actually verifies could be different from what any model shows today. There have been situations in the past where no guidance was all that close at day 6, but this is rare nowadays.

    Thank you for your reply Roger. I respect your opinion and advice and so basically at the moment due to the current chaotic predictions the past cannot predict the future!

    Model Output Discussion - The final stretch to Christmas

    in Forecast Model Discussion

    Posted

    Valid point Cap jack

     

    As alluded to by RJBW above the GFS P seems as though it has been the most accurate assuming the low comes off on saturday close to the UK. RJBW has counted as many as 16 runs out of 20 for the GFSP which is brilliant (if it comes off).

     

    Also of interest was the fact that a few of those 16 actually went for an Easterly afterwards..We will see.

     

    The latest 3 runs of GFSP have moved the bombing low more easterly, so it appears to have lost the signal at short range. If it is correct now then it means it will have failed on 16 out of 20!!!!

     

    There again ALL models are obviously been struggling to define some new trend which wants to set up in the medium term.. Hence their variability.    

     

    The ECM however only showed it on 2 or 3 charts of the low in the North sea or UK  at the same time..

     

    Interestingly nearly all the models have switched away from this bomb around the North Sea (though still some showing impacts), but in the last 24 hours the Euros (MO and ECM) have turned on to the idea of the low coming straight down the UK.

     

    Don't know what this  means in terms of stats, but it must  be seen as a feather  in the cap of the new GFSP, with its better resolution post 180hrs if it has picked it and stayed with it.

     

    MIA

    Thank you for your reply, I missed that post from RJBW, must pay more attention! 

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    Model Output Discussion - The final stretch to Christmas

    in Forecast Model Discussion

    Posted

    Good evening, I don't post often do but follow this thread with interest and admire all who are brave enough to make predictions at the moment. This is indeed a volatile period of model watching and I for one have no idea how it is going to pan out, nor do I think most people have, although there have been some very good posts regarding the larger / longer term perspective rather than what each individual model run shows.

     

    Just a curious question. Why not look back to what a model was showing last week or 4 days ago and see if it has verified this week or 4 days hence? It just seems logical to me to try to see what was predicted (fair enough there will be various different scenarios) and what actually occurred in order to gain some idea of how accurate those various predictions were. I know there are verification stats available for each model but I rarely see anyone posting / confirming what has happened against what was predicted.

     

    I think when you have so many different models, run at numerous times, it can become extremely confusing for people trying to learn when totally contrasting posts are made regarding the outcome based on maybe just one particular run. I for one would find it easier if a more balanced perspective were taken using a consensus of all information.

     

    Shoot me if I'm talking b*****ks, but I am just trying to educate myself on what is overall a fantastic forum.

    • Like 17

    London & The South East Regional Discussion - Part 6

    in Spring Weather Discussion

    Posted

    I live in the same area as you. That photo from Titsey is in the Surrey Weather book. I always think of it when I drive over that spot. We live in a funny spot for snow but did really well Dec 10. Won't be the same this weekend but hopefully we won't do too badly

    Last year was fantastic. I always thought that moving down here from the North East would be good for business and bad for snow, but recently it has turned out good for both!

    London & The South East Regional Discussion - Part 6

    in Spring Weather Discussion

    Posted

    well im happy knowing im not the oldest here :)

    Born in the winter of '63 although I can't remember much about it! Too young for the best winter of recent times and too young to remember the glory boys of 1966 although I made up for it with the 2003 rugby world cup!

    I do remember growing up in Middlesbrough in the 70's and going to school in short trousers, making slides on the ice on the pavement and in the playground though. It seemed in those days like winter lasted for 3 months, one year there was enough snow to make an igloo in our road! Happy days!

    London & The South East Regional Discussion - Part 6

    in Spring Weather Discussion

    Posted

    Anyone remember Jan 1987? Got sent home from work early, parked the car and didn't move it for a week! Tried to walk up Titsey Hill from Oxted with the intent of poly bagging down the North Downs, but only got as far as the M25 and was in thigh deep drifts. Tatsfield, near Biggin Hill was cut off, the pub ran out of beer and a pregnant woman had to be airlifted to hospital. There was a photo of the bus stop on the ridge totally covered with only the top of the sign sticking out. Drifts must have been 8ft at least!

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