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  1. 121 points
    An ode to the model output thread... "In days of old, when Thatcher was bold and Kettley was a weatherman, Tales are told of winters cold, and snow lay everywhere, man. The World Wide Web and ECM were yet to be invented And weather forecasts at the time were often quite demented! But there's no doubt, the records show, that winters then were colder And five foot drifts were commonplace - they came up to your shoulder! For years and years all we've had is windy wet and mild And although it's not all been bad we crave a winter wild.... Now... The models hint that Scandinavia could maintain a block To curb Atlantics bad behaviour - that would really rock! But... The GEM can't be trusted; the GFS is dire The ECM has often busted; the CFS? - a liar! So on UKMO we must rely but wait - is it cursed? More runs needed, standing by.... let's get the cold in first! Hope you all have a great weekend of model watching!
  2. 114 points
    Early guidance forewarning of next weeks weather was issued earlier on, and this has been further enhanced with extended outlooks in bulletins. AFAIK (comms not being my area) public agencies and major private infrastructure will begin a daily briefing cycle as of tomorrow. To revisit previous post, latest MR output (MOG) resolving to further mute ‘breakdown’ scenario; with continental blocking signal reinforcing through well into March. Atlantic incursions are expected with southerly deflection; considerable potential for extensive and disruptive snowfall as these air masses interact. Short term, ECM:UKMO evolution favoured and considered likeliest; corresponds well with other products and illustrates fair consistency. Small ramp. Next week = mega. SB
  3. 114 points
    Evening All Ice Cold hope your still with us .... So the much touted SSW is coming into view & here’s my thoughts + timelines of when / where to expect it... We have seen lots of posts & comments on it - but whats the reality likely to be -??? The Omni present warming in the GFS charts is usually due to the model & its poorer vertical resolution V the ECM, as a result there is an over reaction / over estimation of how much a warming is going to impact the zonal wind @10MB - so because of this 'bias' when viewing the mid / long term outputs churned out by the GFS we have to be a little on the sceptical side as these are normally moderated & scaled down even wiped out ! However we have now seen the evidence in the Berlin site that a downwelling SSW event will make it to the 10MB level & indeed go on to challenge the date record for the time lf year- ( this is NOT the same as the usual deceleration of the zonal wind we see at this time of year as that is more of a gentle reduction all the way to mid april when the vortex breaks its annual westerly influence ) So as highlighted we have passed the point of no return in the stratospheric modelling where a SSW is now just 5 days away for the 12th Feb *** Take note of this date -- The plots below show steep downward curve of a signature warming Note the main black line being Climo - but the ensemble mean from the GFS running out at mid -20 to -30 M/S... The clustering is quite close - further backed up by the another illustration of the ensembles from the hannah attard site With the mean bottoming out at -32M/S *The date record for this time is ~ -17 M/S & the all time record low ( using Merra data ) is -35 M/S The ECM berlin forecast below is not as bullish as the GFS coming out around -17 M/S @10MB but none the less still classed as significant event... So what we have in modelling terms of a SSW due is * The first one in 9 years ( I dont think last year was classed without checking ) * Possible record breaking reversal of tge zonal wind... If your thinking whats best in terms of impacting the UK its simple- The lower the negative number the better... - record breaker ? yeah I will take that please... Why?... The bigger the negative number the stronger the easterly flow is across the mid lattitudes. !! ( think feb 63 / jan 85 & so on ) Whats the models churning out then? The SSWs are classed as 2 types - Wave 1 displaced vortex or - Wave 2 Split Vortex .. This is whats expected - A classic wave 2 Split vortex- with 2 clear areas of poleward flux - over the far East & canada- Now luckily for me the historic SSWs have already been classified -we are looking for la nina years / W2 / split vortex- 6 years appear as matches - 28 Jan 1963 - 7 Jan 1968 - 18 Jan 1971 - 1 Jan 1985 - 21 Feb 1989 - 24 Jan 2009 Below are the 10MB increase in temps at the time when the zonal wind hits 0M/S Obviously they all have 1 thing in common- The huge rise in temps across the pole - Now the Date of the zonal Mean hitting 0M/S isnt the day of peak blocking - Looking at the dates above peak blocking appeared 7 - 11 days post Reversal - see below day 11 charts from the above warmings ( 500 MB anomaly ) Whats apparent is HLB is quite prevelent & most are centered ( for us ) around greenland & Western Scandi - Also all 6 Splits have varying levels of troughing to the south - but all have an anomaly- So that really leaves with a level of expectation that should at least give us some confidence for Feb over the following dates- 12 Febuary : is 'R' Day- as in the reversal of the 10MB zonal wind where the eastward progessional component is replaced by a westward one 13/14 Febuary : is peak 'R' days where we will know the magnitude of the warming & just how much westward ( reversal ) component there is - Sub -20 M/S is the date records & anything below is the jackpot - 16-18 Febuary - Mid to high lattitude transitioning - This is where depending on how lucky we are for our area we will see MLBs start migrating North to the pole as zonal wind lag filters through the lower layers of the atmosphere & support builds for HLB - look for the 3 key wave patterns ( atlantic / Scandi & pacific (-EPO) The UK can get very cold in this period if the migrating highs are favourably positioned from the outset.... 20-24 Feb - Peak HLB blocking across the NH - peak -AO signature & peak cold overall for the mid lattitudes ... *** IF the GFS lands with the depth of negativity then Late Feb early march will be on a par with 2013 for AO negativity & possible / probable UK cold / snow.... if the negativity is watered down then the cold signature will be watered down & less dominent in western Europe... Best S
  4. 113 points
    Come on those looking for the breadown before the major cold and snow has begun You will be very lucky if that is the correct word to see this in ANY winter in the rest of your lives I would suggest, let alone the end of official winter into the first week of spring. I worked through 1962-63 and was 8 years old in 1947, so having looked at GFS output over the last several days and UK Met along with ECMWF I am close to being gobsmacked at how the deep cold has been correctly forecast on the models from 2 weeks out. Equally congratulations to those of you who understanding the SSW and other connections far more than me were predicting cold even further back. Looking at the 12z GFS, not too different to other runs over the past -3 days for my small area, and it predicts 2 ice days, snow on 3 or 4 days with possible depths greater than anything here since 30 November into 1 December 2010. As a long since dead football commentator was fond of saying, 'quite remarkable'. I am now going to see if I can discover, during the 1962-63 coldest spells if the history is available to show what 850 mb temperatures were. I know what the surface temperature were, and have several times posted that when folk reminisce about past winters. Enjoy but please do remember to try and support anyone living near you that may need this, this is a going to be a pretty severe test for a lot of folk, even if their heating is up to it and they can afford it.
  5. 112 points
    So a rather long post ( Will also clip into the winter forecast thread ) However just an update on saturdays post, a large debate around models - & I took the day 6 UKMO & GFS charts to compare for verification- These were both of the 6 dayers GFS on the left. Note GFS flat with no heights in Greenland, UKMO more amplified with heights - Also a circular vortex North of Scandi. UKMO has energy seperation & a closed low - GFS just sends a 'block' of energy through - Look at todays UKMO 72- Comments: -Circular vortex just North of Scandi -Closed low traversing East towards Iceland - Residual heights over Southern Greenland - Arctic High 1040MB. Conclusion UKMO is a clear resounding winner here- every element that differentiated from the GFS is still apparent in the T72 chart, this is a big thumbs up for the UKMO, proof ( on this occasion ) that the GFS clearly has an eastward bias & why looking at developing heights over the pole ( NB UKMO 144 today ) The UKMO resolves energy better... So, onto the SSW it seems an eternity since the first warming started showing up way back in December - but now we are day +6 since the wind reversal- Much of the discussion has been about the 'slow' response in terms of downwelling in terms of creating a significant AO - This is depicted nicely on the NAM index which I have saved from the other week- The GFS bias initially showed minimal downwelling, however gradually ( like the comparison with the UKMO above ) has slowly come into line with a more 'propergating' feature. I think we have been unlucky with the QTR - sadly the NOAA composites page isnt available, however twice there has been significant mid lattitude blocking developing in the locale forecast as a QTR relating to the strat split- However the blocking has been just to far East for us to really gain any benefit - *but* as far as Europe as a whole is concerned in terms of snow this winter could challenge the record books in terms of sustained depth from mid Jan onwards- My memory ( from the old teletext days ) was that St Anton could reach 600CM on the tops by the end of Winter- By the end of this week it will be North of 400CM Also records going in Greece with snow in Athens & -23c reported North of the region- So whilst the QTR missed us that release of deep cold didnt miss everyone... The next stage of this SSW / Split will be crucial for winter as the norm here would be a gentle recovery from the PV ( not to normal strength ) - however if like me you were hoping for something that lasts longer than a few days - IE 1 MONTH then a secondary warming & further splits would be the upper cut to the PV that would knock it out for the rest of the Winter. However just before commenting on that lets see the progression of the downwelling- The charts at the top are from around NYear- now look at the NAM index from the GFS today ( remember its still not the best model for coupling the Strat > Trop ) Here is the NY 100HPA profile V todays Lots more clustering below 5M/S- some below zero. This is why we are seeing the GEFS respond post 192 - Note the AO Ensembles - Starting to gain momentum towards -4. Moving through day 9 on the ECM strat from yesterday we see that the Uwind is still negative but importantly the allignment of the vortex lobes are significantly different to this week - encouraging blocking- Red is the left lobe allignment Blue is the right lobe allignment Yellow is the blocking potential- Its quite apparent that despite a split the current shape of the lobes means that the U wind off the states doesnt support blocking, but day 9 ( alligned to the trop response ) allows for a different pattern that is complimentary towards the jet being sheared up the western side of Greenland & also residual flow alligned SE in the atlantic - We should also see the vortex 'throwing' Scandi Deep cold SW across Europe - This is the jet flow -( yellow ) & associated areas of deep cold. This is a solid -AO / + PNA / -NAO pattern. This is why the models have suddenly flipped to that sharp NW > SE allignment If you are looking for sustained cold then a SSW split + follow up warmings & continual negative zonal winds are the hallmarks of LONG cold spells, * with the usual caveat that we are the SW point of the cold & could always see some milder air pushing back west * This could be a crippling final quarter of Winter for Europe & the Balkans- Best S
  6. 103 points
    Evening Guys Officially signing off for the winter from my window - still all but 5 inches on the ground - have a great year ! Current favourite See you next year S
  7. 102 points
    I assume the overnight ECM has (temporarily at least) put an end to the glass half empty stuff from some posters yesterday. I'm sure the next variation in op run will bring them back out - but if you are on here to learn and are hunting snow/cold (sad to see that thread go....) then here's a bit of learning for you. The overnight chart from ECM at the later stages of medium range reliability is fabulous. What you are looking for here is the source of the air in situ over the UK - and the angle of approach from the system in coming...and where it will pull its air from. Note here at 216 you have a generally slack E/SE flow over the UK established from the back end of the week to come, with air being drawn to us broadly from Scandy and Northern Europe - already both snowbound and across a north sea that is not especially warm. Meanwhile the incoming low has purples in it in terms of pressure - meaning it has been drawn directly from the deep vortex low over Canada. As it approaches and disrupts against the higher pressure ahead of it - it "slides" southwards and the winds from that system turn to the SE, pulling dry continental air up from France. The final image shows how the moist, atlantic air (still pretty damned cold because of its Canadian origins) has dropped into France. Eastern UK has a feed straight from central Europe - western parts of the UK from a slightly milder France - but the combination is such (especially in January) that snow is likely countrywide. This is a "slider" low - precisely because the atlantic system has come from the NW and literally slid down the face of higher pressure ahead of it. Are there historical parallels? 3 from my memory that show a variety of similar events. The most similar to the one progged here would be Feb 1996 where we had a very similar setup a couple of weeks later in the season. Note again the deep origins of the sliding system (purples) and the cold air in situ from a SE feed. 1996 brought huge snowfalls to some parts - myself fortunately included this time around while in Dorset. Slightly different, but no less impactive in terms of snow, would be 1985 and 1979. 1979 first. Note here that the incoming system is a lot flatter - it's approaching from due west and meeting the trough in place over scandy. On this occcasion the deeper cold was in the resident scandy lobe and less in the approaching system. Note the isobars ahead of the atlantic system turn, once again, to that SE flow and as the higher pressure ot the south drew away plenty of snow fell. Feb 1979 was full of such events - they kept repeating over and over giving blizzards to all parts. This image below, again not a million miles away from where we are heading but with a very convenient wedge of higher pressure just to the north of the UK - brought some of the heaviest snow falls in the last few decades, especially a few days later around Valentine's Day. And last of all 1985. A bit different this one - but if you are wanting to learn about snow giving conditions good to dig out. This time the system approaching from the west runs up against a block that is much more entrenched to our NE - but the effect really is the same. Moist air from the west disrupts against the colder, denser air in a block ahead of it and slides underneath. Because of the angle of trajectory these are sometimes described as channel lows because the atlantic system's slide angle takes it through northern France as it pulls continental air up ahead of it into its moist lead edge, turning all that moisture to snow. Bottom line is - we are approaching a pattern which could replicate any or all of these situations because of the forcings which are in operation. However - and it is a big however - for every one of these big snow makers there are plenty of historical near misses......either because too much warm air gets wrapped into the system or because pressure to the south remains too high and continues to feed warmth up from the south. Putting my own neck on the block here - I don't think these are going to be a factor this time around because of the forcings I described last night at some length....but they MIGHT be. Dont shoot the messenger if it all goes wrong - but if I'm honest I'm feeling pretty good about the alignment of things at present and in particular about the longevity of what may occur. Bear in mind that week beginning 21st January is likely NOT to be the peak of the process. If you prefer computer driven analysis then just look at the oft shown EC images for end of Jan into Feb for evidence....but the downwelling impacts of the SSW and the next phases on pacific forcing say to me that the peak will be somewhere in the last few days of Jan and on into the first couple of weeks of Feb. Historically probably the UK's sweet spot in terms of snow fall. Watch and enjoy the ride.
  8. 98 points
    It's all good folks - we are about to get slammed Think March 2013 imprinted on the middle of winter - what's not to love ! The slider solutions are dialled in as the wave guide changes, NW SE sliders will be the key feature of the next 6 weeks as the canadian vortex drains itself via downwelling. No it's not 62 or 47 or 2010 But what it actually is an SSW which we all now respect and have learned from, and have the nuance to watch in real time, spilling its arctic cold guts all over the mid latitudes. I am sorry for those of you who think , nope this is not a driver, nope AAM isnt a driver, MJO isnt a driver, Nino - isnt a driver - you get me? Simply put - they are - and always will be and GWO and AAM possibly the most reliable of the lot! Do not discourage in weather that which you have yet to understand - this science is difficult, no one is ever right, no one is ever perfect, no one on here alludes to that What I want to say is- for us afficiandos of cold, us dedicated individuals, hunting, searching, wanting looking and dissecting everything. We are all good Its near solar min, monster SSW, monster Split. NWP - Bring IT !
  9. 94 points
    Last one from me for 6 weeks before I leave in the morning for Canada . Our experts we use in resort have told me that todays upper air soundings over the Russian Arctic are showing Easterlies now established at 10mb level. They expect this flow direction to run down to the troposphere in the coming days ( the start of the reversing the westerly flow for much of Northern Europe including the British Isles ). This will impact on the models in the next 48 hours. So hopefully some good looking winter charts for you lot just around the corner. Will be watching from far a field with great interest. Bye for now and a happy New Year to all our forum members, young and old ! C
  10. 94 points
    Good afternoon gang ,its nice to be back reading all the posts again ,although i have been lurking .(Thanks to all friends on here for my much appreciated messages over the loss of my wife recently ,THANK YOU ALL ) .Its great to see that the charts are showing some Winter weather , really warms the cockles of my heart .And its the charts which keep us interested not always showing us what we want ,and i,m certain that over the coming winter there will be Prozack moments and of course STella times ,so with the Meteorological Winter looming we can look forward to 364 roughly Runs of the good old GFS ,182 of the ECM , AND HUNDREDS OF OTHERS .Looking around the Internet back last year i looked at many weather forums etc ,and found that ours is by far the best and most interesting around .In my next post i will stay on Topic ,just wanted to start with a light Hearted post today .Let the hunt for Winter Synoptics commence ,Curtain twitching ,hiding behind the settee etc ,cheers gang ,.
  11. 90 points
    Microscale detail absorbing an awful lot of attention on here, when in reality it is a waste of emotion. The macroscale pattern is now fixed - it will not change significantly now for the start of next week, and while we can hopecast for a front/kink/trough to appear in exactly the right place for every IMBY desire it is frankly impossible at 7 days' range. We wouldnt even try to get that right on a standard westerly atlantic pattern - how can we hope to get close to specifics 5 - 10 days out from the main event when we are seeing dramatic events unfold in the strat? Remember - we are still in reversal for several days yet, and the models will have larger than usual error bars on microscale events. We couldnt hope for a better anomaly chart to see in the new month and this is a belter from GEFS to kick off the week on Monday And the strat? By day 10 it has reformed over the pole as the reversal ends, but the shattered remains at 10hpa are weak, and a large eurasian block is still in place while zonal wind profiles recover to weak levels over the pole, but see a very muddled profile at 55/65N suggesting anything but a recovery. Sustained chance for high lat blocks to survive in situ though the storm track will gently slide back north. Battleground snow? Down at 150hpa blocking clearly still in place over Greenland So - 10 days of almost zero chance of a substantial change to the pattern, and decent confidence in any recovery from this point being slow and painful for the vortex. Next week will be very cold as we know...and the week after will also be cold, quite possibly for all parts throughout the week. Confidence then less sure by week 3 - need to see how pacific forcing may impact at that point, and just how quickly (if at all) the vortex recovers. If it is too late for a recovery then kiss goodbye any early spring as cold will continue to spill out at times right through the month in all probability. And what about snow next week? Well - I think all this hand wringing over each individual model is a waste of energy.... but maybe history can help. 3 days before we were hit by substantial snow in 1991 the charts looked like this 3 days before the snow hit in 1987 We are forecast currently to look like this in 72 hours BUT we know we have an SSW in the bag and a signal for sustained blocking and a retrograde pattern Which would you rather have?? Both 1991 and 1987 delivered plenty of snow. What do you think is likely from here if they are analogues to go by in terms of snow fall... - and what about the signals for longevity listed at the top of this rather long post?? The only thing going against us this time is the calendar date. All very very good. People criticising this setup really and truly need to get their history goggles on and then wander off to a quiet corner, tail between legs.
  12. 89 points
    For those who think the SSW was a bust take a look at this at T+3 Then look at the NW/SE jet axis over us, then look at the fact that the downwelling has been delayed but is just underway, and winter is not over by a long way. Then go and read up a bit about SSW's so next time you make a sweeping statement you are doing so from a position of greater knowledge. Thank You
  13. 89 points
    C'mon guys lets give @Paul and the mods a break with the bickering and personal digs type of posts after all it is a WEATHER forum and this thread is for WEATHER MODEL discussion I can only imagine how hard it is for newbies to try and decipher what is going on among all those types of posts so if anybody has any issues with posts / members perhaps it would be better to use the report post button / ignore member button or try and settle it like adults through PM's and also remember the couple of banter threads that exist Now onto the models I will refer back to my post from 8th Jan some statements / thoughts that I made in the post on 8th Jan "I still believe that any low pressures that do develop will begin to take an ever increasing NW - SE track (with the majority perhaps struggling to get much past the UK) resulting in some northerlies / North westerlies bringing the first hints at something cooler / colder to the UK " "My key period for this would be 17th Jan - 21st Jan " starting on this point, I am fairly happy with this still as we move towards those dates as it looks like around the 17th will be the first (of what I think could be quite a few within the next few weeks) at a sliding low attempt dont take the position / strength of the low too seriously as this is still changing from run to run but the NW > SE movement is there and a run showing possible north westerly / northerly / north easterly air by around the 21st onward for a few days onto my next statement / thought from 8th Jan "So what could happen after that?" "Well IMO it looks like being the last week of Jan from around 24th Jan - 31st Jan that the possibility of some fun and games with blocking and colder charts will reach its maximum potential so far this winter." Again I remain pretty confident with this, why? IMO there is still a signal for the last week of Jan for blocking to start to develop / take hold there are some more ensembles showing this but I think this demonstrates my point clearly enough AO still set to nosedive first hints that the NAO might head the same way And with the MJO looking like possibly heading back toward / through phase 6 / 7 by then that could also help aid blocking (again I am only going off my limited knowledge on the MJO and also might need to factor in some lag time) (some of the other MJO forecasts look a bit more uncertain / slower to go toward those phases ATM) Also still worth factoring in effects from the strat warming event(s) that have took place during late December / Early Jan. some more thoughts / statements that I made on 8th Jan "A word of warning / potential spoiler would be a west based - NAO which remains a possibility http://theweathercentre.blogspot.com/2012/10/east-based-v-west-based-negative-nao.html Key Points keep an eye on these beginning to nosedive once the blocking gets nearer https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.shtml be wary of the west based -NAO" All of the above are still true / possible IMO but with regards to the west based - NAO perhaps the chances of this wont be know until nearer the last week of Jan and where the models are seeing the potential blocking setting up / developing keep an eye on the ensembles for more and more BOOM type charts appearing in the run up to the last week of Jan I think the first area to focus on ATM would be the potential for slider lows and the possible snowy conditions that they may bring but I still believe the amount of BOOM charts will be on the rise the nearer we get to the last week of Jan. A few extra points I would like to make 1. I wouldn't worry too much about differences in each GEFS suite on the graphs (rises in 850 hPa temps) as slight changes in positions of possible slider lows and later on blocking highs can shift those 850's heavily in one direction or the other and I think we are seeing the usual ebb / flow of the models trying to grasp exactly where each low / high is likely to set up (possibly whilst trying to factor in ongoing effects from start event(s) and MJO etc) 2. How quickly have we seen in the past that things can change and head down a colder / much colder route a la Nov / Dec 2010 & Feb / March 2018 etc (yes there have also been occasions where charts such as "that ECM" where the cold looked like it was on route to the UK and suddenly diverted but I much prefer to look at things with a glass half full rather than immediately thinking that we have no hope / chance of the cold / snow reaching our shores / back gardens) using the 2 years mentioned above as examples and again I am not saying that anything of that severity is heading our way I am just highlighting how much can change within the space of a few weeks (using today's date 14th Jan and 2 weeks from now would have us in the last week of Jan , 28th Jan) taking the 25th November as the end date as that was when the colder air was spreading right across the UK then 2 weeks before was the 11th November 11th November 2010 > 2 weeks later 25th November 2010 11th November 2010 25th November 2010 an example of how quickly things can change / blocking can develop February 2018 - again I will use the 26th February as the end point as this was when the colder air was spreading across the UK so 2 weeks before was the 12th February 2018 > 2 weeks later 26th February 2018 12th February 2018 yes there was some snow around for some but I am highlighting how quickly more blocked conditions can develop 26th February 2018 Keep calm everyone and try and enjoy how the rest of January and beyond plays out, I still think we are in for some fascinating model watching. And I just want to remind people I am certainly no weather expert, I am just having a go at trying to predict where we are heading and seeing how close or far away I am (and if I am miles off the mark I will own up and try and examine the charts to see what happened and how we ended up with scenario A or scenario B etc) ensembles GEM 0z ensembles FNMOC/NOGAPS 0z
  14. 89 points
    After a health scare I have had the best news ever and been given the all clear. What a year it has been weather wise.Just like to take the opportunity to wish Paul,all The moderating team and all the members a very Happy Christmas,Have a break from The forum and enjoy the day with your Family's. Let hope for all us coldies January is a cold and snowy one. All the very best to you all C.S
  15. 86 points
    We have waited a long time to see this. Since the beginning of the internet age. We have all wanted to see these synoptics reel in and in and there is a bit of disbelief now it is happening, Phenomenal is all I can say. And to think that there was some that said that we would struggle to ever see these synoptics again. Well I guess that will be put to rest next week. Big time. Normally to just get the -10ºC 850 isotherm over the country for a day is an achievement so to see multiple days forecast is amazing. Look after any vulnerable neighbours whilst enjoying the freeze - but do enjoy what could be a once in a generation cold spell. I'm sure that it is just a co-incidence that this follows a SSW lol!
  16. 86 points
    I think too many have already become desensitised to what constitutes a 'fantastic chart' and the seasonal ailment of this thread (which is irrationally mood driven anyway by the more average synoptic charts that are customarily on offer) has taken on a latest variant of becoming superimposed and twisted on the absurd semantic that 'merely' only UK Tundra conditions are being shown and not the Canadian variety. Truly, if you cannot exercise self control in front of your lap-top by the smorgasbord of dessicating cold solutions evident on NWP, especially as we are heading right into meteorological Spring, then its maybe best that a different form of self torture is considered to spare those who take a more considered perspective. This has nothing to do with any regional bias (coming from a part of the country that relies on these increasingly rare sort of synoptic to get a snow fix) its to do with the usual fascination I have for sitting back and marvelling at watching a pattern like this unfold in the greater macro scale. If/when it snows at home, I will be less inclined to spend spare time waiting for when it is next going to snow, or when its going to end - but instead getting out, having fresh air, exercise and enjoying it. And then, when the snow and ice is over, it will be a case of seeing how the patterns evolve through Spring and into Summer - looking for the best that can be on offer for this Island, whose micro climate is fickle, elusive and overly too mobile to the sort of sustained blocked patterns that can be the deeply cold derivative as upcoming next week, or depictive of deep Azure blue skies, sunshine and warmth of the summer. Get used to this reality - it will always be thus
  17. 85 points
    All roads lead to Rome - or in this case a cold spell. There have been some odd comments on here today, given we are on the cuspy of only our second significant cold spell since 2013, and so I'm going back on my last post - and instead of looking only at short range charts from here it might be good to make some connections and map out the road ahead. Strat first of all. We have seen a slow downwell - no doubt about that - and a fairly chaotic displacement/split event that was uncertain for a while. But the mists have cleared, and the downwelling is finally going to impact more substantially on the trop pattern in the coming days. The atlantic profile for midweek is still fairly flat but the split has worked in our favour, with the Canadian lobe remaining in situ but the more substantial Siberian shard pushing back east towards the pacific. The 150hpa forecast 5 days later quite clearly shows this and you can see the push of energy at 30hpa moving away from Europe over the eastern Siberia with the Canadian shard sitting in place The signal for a resurgent midatlantic ridge up to the N/NW is quite clear. Picture those EC46 images showing more robust northern blocking by month's end - part of downwelling strat forcing. But we have a pacific signal that looks to be marrying up. Our current high has been resilient, but at too low a latitude for our liking. No getting away from that - forecasts a month ago saw the blocking, but saw it further north. The slow speed of strat impacts probably wrecked this possibility. Now torque effectis, apart from in the tropics, have been on their way down....but before long the bounce back up will begin again, and lag effects will time perfectly with maximum impact of strat downwell So we have the beginning of strat impacts to come in 7 - 10 days followed by GLAAM support 7 - 10 days after that. All good. But the story does not end there - the MJO, which on its own was not enough in early Jan to override other factors, is heading swiftly back around to phase 6 - 8 in time for February....so that just as the atmosphere needs a bit more of a bump to keep blocking in place - it gets it. Note also that the MJO is remaining generally active, and poleward wave activity is therefore going to remain a factor in preventing any flat pattern from getting a hold once again. Ventrice filtered plots remain quite impressive So - this takes a pattern of parallel forcings supporting a meridional signal and anything but a westerly atlantic pattern well into February. But let's finish on the strat…..because of all the factors that drive our weather it is becoming increasingly clear that impacts on the vortex that downwell to the trop are dramatic and forceful. The warming that started well over a week ago is just past its peak, but winds at 10hpa are set to remain easterly until the back end of the month, give or take At the same time westerly winds will return at the top. Bad news? Not at all. A return of westerly winds at the top will form part of the ongoing downwelling process - and just as we had a flushing process of westerlies pushed down into the trop round about now, helping neutralise attempts at mid atlantic to greeny height rises, so this flushing out of easterlies will serve to force them onto the trop pattern. Given that the 10hpa pattern will have been reversed for the best part of 4 weeks, we are facing a long process in this regard...and so the gradual recovery of the vortex will actually sustain a reduction in tropospheric westerlies for a long time also - I'd suggest most of February. And then in March the vortex is fading anyway. Will we get anything like enough westerly momentum to change the pattern out of the entrenched cold cycle? I'm not sure we will.....but that is a bit far off to be discussing in detail now. So - forget op runs in 8 or 9 days time that are making it look as though a resurgent trop vortex driven from Canada is about to fire through the atlantic. It isn't. a Canadian trough will remain in place as the strat image is imposed upon it - but the door in the atlantic is going to be slammed shut, and cyclonic energy will have to circulate around the edges. Cold northerlies or undercut scenarios. And if we can get slices of that cold Canadian vortex firing moisture down into Europe over the top, or later on potentially underneath, the block then we get the precipitation we want in a cold phase. This on top of the impacts of deep European snow cover that will help provide a very cold feed off the continent at times when the winds turn E/SE. Long post - apologies - but everything is in place for something a bit special. Stop worrying about NWP. It doesn't get a handle on all these processes well....and while there is no way I would want to call the microscale specifics at anything more than 72/96 hours (and always from UKMO and ECM) - we can sleep easy knowing that the macroscale factors are lining up in favour of snowy goodness for the second half of winter.
  18. 85 points
    Meant to post this last night but some forecasters saying mild Christmas. At this range ,about any thing could turn up ,strange year weather wise so far ,snow in the forecast tomorrow , STORMY with it ,plenty of rain next week and signs now of cold cyclonic next weekend . Our local squirrel s took BEDDING to their winter homes last week , yesterday they threw it out to the local polecats and like ,Today they are collecting it all back .went up woodshed just before sunset today and local vermin were BUSY storing winter food .some very interesting weather ahead I feel ,Stellas all round gang ,I'm usually lurking about as weather is always on my mind ,miss my dear late wife . It's great having this great forum , cheers all .
  19. 83 points
    New EC weeks 3 and 4 as you were. High pressure in all the right places.
  20. 83 points
    So post about it then, people aren't here to service your requirements for model info. If you're interested in what's happening in a particular part of the country, take a look at the models and comment on it yourself, rather than just moaning. Alternatively there are also many people talking more generally and not just about the low who's posts you can read. This North Vs south thing needs to stop now, before those persisting with it end up not being able to post in here, it's tedious.
  21. 82 points
    I'm starting think that for some in here following the models is a form of self-flagellation. I mean, you have lots of expert views giving lots of details on the overall signals and direction of travel at the moment and you have that same general theme showing on virtually all of the models a lot of the time. And still on every single run, there are the same people over analysing them to the nth degree either getting caught up in will it won't it snow / how much in various localities at 10 days or so out (always a pointless exercise), or on milder runs it's like that particular model just shot bambi and is responsible for the end of any cold weather ever. Things are happening in the atmosphere right now, the most likely direction of travel is a cold one. The models are a bit up and down due to all that's going on, and so therefore, surely, unless you just want to create drama the answer is to accept that fact and not get hung up on every single run of every single model?
  22. 80 points
    Afternoon so 2 hours on the train should be plenty of time for a post- The last 2 weeks the projected SSW has gradually worked through the models & is now 'imminent' ~ 30hours away is when we go negative on the zonal wind @10HPA/ 60N. But I guess many onlookers will be wondering why the distain for the GFS V the Euros, is it really that bad. Well sadly yes it is. The failure of the GFS is going to be 2 fold here. 1) Identity of type of SSW - Split or displacement. 2) Non propergating ENSEMBLES. So going by the first point, this refers to a models ability to 'see' what that Stratospheric energy & warming looks like at the height of the strat, you have 'high top' models - highest being Glosea then ECM, you also have non High top - GFS which IIRC is 64km V Glosea ~80KM. IIRC ECM vertical resolution is closer to the Glosea. The GFS being poor resolution & the ENS being even lower resolution means that the ability to resolve / locate & then split energy is much inferior to the Euro model, as a result the model will see a 'blob' of warming however wont be able to see the warming plus energy splitting, thats above its means. So the GFS can be scored reasonable for the 'identification' of a warmer- even taking into consideration the errors in actual timings - however its score rapidly decreases if you want resolution to a Split V Displacement- NB here is the GFS elipses about 10 days ago- You will see the GFS ENS green & operational orange not being able to pinpoint a split - ( which the sparked masses of debate on twitter from people who should know better than to use the GFS ) If we compare this to the high top ECM, whilst similar to the GFS in timing errors the actual resolution of the SSW was pretty much bang on. Why is this important - What we are currently seeing is a QTR to the split as the Troposhere mirrors the stratosphere split, however why did it take days for the GFS to see the first ridge & cutting trough over Scandi- Why was it always East!???? Simple- The 'Eastward' (E) energy from the zonal wind was incorrectly modelled - NB GFS model 'E' v ECM (E) * remember take the Eastward component * The poor modelling of the (E) component for about 5 days up until about Fri Eve / Sat AM drove a fairly uniform Eastward motion around our part of the globe, hence with the scandi tough there was a fairly amplitude inflection point meaning its bend & southerly element was low -GFS catapulting it Eastward- Then slowly as the warming proergated down from 1HPA to lower 5HPA & into the GFS comfort zone so the GFS picks up the split- We now look at todays elipses - for day 4/5 Its finally caught up 96/120 & hey presto its on the same page as the Euros now.... ( At least for the time being ) So onto point 2 - GFS propergation issues. The modelling of the strat is generally difficult especially the coupling of a downward propergating SSW to the troposhere, so again only the highest resolved models will pick it up- it appears the GFS has coupling issues as the its ENS suites for the past 5 days have stopped it fully propergating ( again creating much speculation on here & twitter ) all again annoyingly GFS based- Here is the NAM index which shows how the SSW is progressing with negative vales indicating propergation NB GFS ENS 3 - 7 days ago = Non propergation. 100HPA is where we want it to reach ! Notice it stops short - So the ensemble suite from maybe Weds onwards up to around Yesterday wasnt seeing that wave come down - hence a lot of people were looking 10/12/14 days out in the ENS for high lattitude blocking when infact it was never going to appear- Whilst the ECM had already picked up the deceleration at 100HPA for day 10 ( 26/12 ) day 1 & day 10 char So again, ECM was already factoring in a decelerating jet - hence the operational model runs showing a maintained blocked response out to day 10 with higher & higher potential. The GFS has cottoned on now though- Todays ENS @100HPA show the GFS dropping nicely ( NB how poor the operational is though in orange ) Pic 1 ENS from 5 days ago flatlining the 100HPA wind V todays dropping it from 10 to around 4 M/S The main dip comes down around the 8-10th & guess what thats why we are seeing High lattitude blocking now appearing in the GFS ENS - its not a coincidence !!!! Now that the split is in range & the GFS is picking up on the correct outcome in terms of deceleration so the gulf between the GFS v the EUROs should reduce this week as they are working on the same stratospheric & zonal wind speed data now -But never forget how bias the GFS is in terms of powering up that jet.... Propergation is alligned to the 10th Jan - ( which is about 2-3 days later than initially progged ) Dates for propensity of lowest -AO values 10-20th Jan.... Cheers S
  23. 80 points
    Well it's probably fair to say that I've been rather quiet on these forums for the last few years really, especially since 2013. After 15 years of internet weather watching, and more importantly, having witnessed the incredible run of winters we had from 2009-2013 (vs the more Ian Brown style winter in the preceding 10 years), it really takes something now to get me to show more than a fleeting interest in what's on offer. Now it's safe to say, regardless of geographical bias (bearing in mind I now work in Central London and live on the SE'ern edges of our ever-warmer capital, so I am pretty neutral when I say this) this winter has, thus far, been the most productive for watchers of a colder persuasion since March 2013, with many parts of the country seeing at least a covering and some lucky folks through Central England seeing 3 pretty decent, if temporary, snow events (of course those further North and more vertical than the rest of us have seen far in excess of this, but those lucky b******s get to see this most years). But what we stand on the cusp of, what is being modelled within a pretty reliable timeframe, is reminiscent of those days back at the beginning of this decade where the sun went to sleep and cold chaos ensued. It is far to say that, beyond just the pure pornographic synoptics, the likes of which we had not seen for many years previous, 2010 ruined the laws of model watching in so many ways. Forecast models are not supposed to pick out the correct pattern at +360 and run with them pretty much right through to +0. They're supposed to tease us with big greeny highs, fallible dreams of the biggest snowstorms of the last 100 years (circa December 2012) and then leave us distraught, crying in the corner of the shower, attacking the 'mildies' on here with our not-quite-waterproof smartphones (what a long way we have come...) at even the merest hint of an 'I told you so'. And I genuinely think the 2010 episode of near flawless modelling has left a lot of people on here far too expectant of the capabilities of predicting the friggin future with a lot of electronic circuitry and fans. This is why, more so than at any time in the past 5 or so years, this current phase of modelling really has my interest. We are on the cusp of something which, pre the 2009-2013 phase, would have had me online from 8am-10pm (which, if memory serves, is when the old BBC slowwatch forums used to shut for the night) in a far too nerdy way (nobody ever understands our snow obsession right?). Some members on here can be accused of being just that little bit too optimistic when it comes to cold and snow chances, but those same people are very much correct in these sort of short-range cold shock scenarios - whilst the models might not yet show anything significant snowfall wise, they never do until much closer to the time. In fact, if we think of events such as Jan 2003, Jan 2004, Feb 2005, Feb 2009, Jan 2010 and even in to Feb 2012, Jan & March 2013, all of them had modelling which at face value painted a cold and dry scenario....which continued until a few days before unexpected features popped up in an increasingly unstable flow given a significantly lower than usual upper temperature profile. When you combine that with the anomalously warm seas surrounding the UK right now, there is an inevitability about unexpected short range snow events. Beyond just next week, we also have a pretty consistently modelled significant warming into the stratosphere, which should yield an interesting second half of February, combined (or perhaps even coupled?) with one of the most significant MJO episodes we have seen to leave us on the cusp of a pretty memorable February overall...now when have we seen that before, with a declining solar profile...memories of 2009. Enjoy the next few weeks everyone, I will certainly be more active on here as we stand on the edge of what, from 15 years of experience, feels like a pretty significant period of wintry weather for our humble little island.
  24. 79 points
    I wish you guys could see the precip charts on the EC. Serious disruption Tues and Wed on this run across swathes of the country.
  25. 78 points
    I'm sorry for being off topic but I'm sure mods will forgive me for this one. Very sorry to hear you're missing your wife, this time of year can be especially hard and you can't just switch off that sort of emotion. That said, I always smile when I read your posts and I'm sure many others feel the same. All the best. It's always a pleasure having you around.
  26. 78 points
    Just had to talk to the wife for an entire hour!! Please don’t let that happen again ECM mean looked very good, here’s the graph, op on the cold side from D7 -10 Anyone got the UKMO D7?
  27. 78 points
    In days of old, When nights were cold, And models weren't invented, We might have hoped, we might have prayed, But we didn't drive ourselves demented. The MJO the QBO, No wonders such as these, All we had back then my dears, Was Uncle Bert's dodgy knees. He'd hobble along with back bent low, Telling all who passed 'it's goin ta snow' 'They're aching bad' he'd say, 'eee I wish I were fitter', 'You mark me words ma lass, tis goin to be bitter'. More often than not he was right, A deep white carpet fell through the night, We'd wake up to an eerie glow, First words of the day...'Yippee, SNOW!' Those days are gone, but not forgotten, Few snowy days now, seems so rotten, What will it take to make dreams come true? A long fetch beast, a bolt from the blue? A slumbering Sun? A boiling hot strat? A volcanic eruption? Dear God please, give us all that. When I was little, I'd be told, 'Yer won't like it so much when you're old' Mummy dear, I'm afraid it fell on deaf ears, I'm as bad as I was, so I'm here with the seers, I look at the charts with their purple and blue, It's all double dutch, I'm reliant on you, I've read and I've studied, I've tried and I've tried, Still makes no sense, my brain must be fried I understand there's lows and there's highs And a beast from the east makes white stuff fall from the skies But down here in the soggy south west I fear it will mean just slush at best I'm not giving up on those dreams from before, When I lived further North, instead of south of the M4, It must still be possible to get a battleground, Hopes of it happening are still around Down here we must settle for the dribs and the drabs, Seems snow is still out there, it's up for grabs, What must we do to get it to come here? Or do we just get to drown our sorrows with beer? The easterly beast that all winter's been bumbling, Will it get it together or carry on rumbling? How hard can it be to waft this way? All together now, let us pray. There'd be whoops of delight and cries full of cheer If we wake up one morning and find that it's here Open the curtains, let out a shout, 'See, I told you that's what the models were on about' Oh how I hope those dreams come true, But as I said, I'm reliant on you, Please be honest, please don't bicker, It makes reading these pages so much quicker. So finally before I go, To dream of the day we do get snow, To Paul and the Mods, be kind, please, Just lightening the mood of the FI tease.
  28. 77 points
    Pondering evolution and longevity today. It's taken it's time in coming - and I will do a longer post later tying in the thoughts of December and early January into what is happening now - but the gloom of 5 days ago seems a distant memory as the blocks begin to drop into place. In Dec 2010 we got a very swift transition to a deep scandy trough supported by a very sharp and strong greeny high - but it wasnt particularly long lived. It started to fade within a week because all the drivers were moving things back to a mobile pattern, and then the rest of the winter was unmemorable. This time around we have a much slower evolution - but the blocks are in place for a much more sustained affair. The initial cyclonic euro/scandy blast wont be quite as severe or swift as 2010 because we havent got the same strong block surging up over greeny BUT we are in the heart of winter rather than at the outer edge and with pacific signals remaining on track and a slow strat process suggesting slow but positive evolutions ahead we could find ourselves in a pattern that sustains the cold and, at this time of year, brings plenty of snow from this predominantly cyclonic signal, at least in the medium term. Might we see mention of blizzards in parts? Quite possible. Longer term more entrenched cold, maybe a bit less precipitation. The potential for a noteworthy spell of weather that can be mentioned in the same sentences as Dec 10, Jan 13, March 18 looks on the cards. I'm breathing a sigh of relief and putting the knitting needles away - for a short time doubt began to creep in as to whether synergy of pacific and strat would work out as all instincts and understanding suggested - but today all is clicking nicely. I wouldnt bother wondering or asking where it will snow for a good while yet - but with a bit of luck and a half decent roll of the synoptic dice we can get at least one solid front to cross the country to give everyone a shot, and plenty of convective action pushing inland. Window of opportunity from Friday next week - but probably midway through the following week for maximum chances. And dont expect this pattern to return anywhere close to mild (or even average) for a while. For a little bit we can afford to put the teleconnective charts away and forget macroscale pattern drivers, and instead enjoy a bit of fax chart scrutiny, weather radar updates and even some lamp post action. Lovely.
  29. 77 points
    Another great day of model output with no concerns from me with what is shown. 2 points First is that the worst model output that we have seen today and the last few days is far better than the best output that we have seen for many a year. So don't be concerned with operational variations. The second is that normally any shortwaves scuppers any cold spell, but in this case I welcome shortwaves because once that cold air is embedded ( and movement will always be west of the general pattern), then we have shortwave snow making machines on our hands. The more shortwaves the better as far as I am concerned because the large Greenland block will keep us embedded in deep cold.... Just enjoy the output and whatever it brings.
  30. 75 points
    Well - ho hum - let's have a sit rep. My eyes are hanging out on stalks. The pacific first - engine of the climate system. How is our AAM looking in the face of the current high amplitude MJO? Tendency off the chart. How is our mountain torque input responding to the parallel rise in frictional torque? Off the chart. And the MJO itself? Well - not off the scale but not far off it. What does this mean? In a nutshell - strong pacific signal for high latitude blocking as AAM in northern latitudes falls and sub tropical high pressure gets the rug pulled out from underneath. Wouldnt it be great if this could happen in tandem with positive developments in the arctic stratosphere? Ummm - ok - funny that... 100% support now from the GEFS for a reversal at 10hpa 60N as a result of this: Huge burst of flux energy being punched straight into the vortex in the next week or so resulting in all the pandemonium on twitter today from the strat brigade. Flux angle is straight upwards - smashing into the poor vortex and giving it all kinds of grief End result: Vortex split in half in about a week's time just prior to the reversal. Proper SSW in sight - even the MetO have publicly advertised this today. What does this mean on the ground? Double whammy. Pacific forcing is pumping up high lat blocks - phase 7 composite for Scandy - while up above the vortex splits, slows, gets all in a muddle and ends up dropping one shard of the vortex over Russia and perhaps European Russia. End result - even stronger signal for the Scandy high that is already in place thanks to pacific forcing.... and a reversed flow via displaced vortex shard encouraging cold continental easterlies under the block. Length of spell hard to be precise... but certainly more than a few days. A double whammy like this would leave a strong blocked signal in place for more than a week at least - maybe longer depending on just how battered the vortex is and how quickly it could reform. Eyes still out on stalks. This is definitely a one in 10 year event - and actually it might be more than that. Cohen is advertising 1985 as the last time we had a vortex split like this one... and we ended up with this around 2 weeks later Response time for our current event looks likely to be less than 2 weeks - Chio reckons pretty instantaneous. So - are charts like this on GFS for the return to school after half term likely to come off? Yes they are. Potential is there for this to be one of our big periods of weather that gets marked in the history books. 81, 85, 87, 91, 96, 10 - and maybe now 18. Can it go wrong? Of course - as fast as it went right... but who gives a stuff about that right now. The dominoes are currently aligned... so no gloom required. And the dominoes are looking steady.... Funny. 10 days ago I was gloomily expecting the final pacific cycle of the season to be as tame as the last 2 and to give us at best a mid lat block in the face of unremarkable looking conditions. Omega block... bit of frosty gloom... the best of a poor season thought I. Strat forecasts looked moderate - no sign of a reversal if we are honest... MetO forecast nowhere near mentioning "very cold." And now we are looking at something potentially special (though note this is NOT a snow forecast because getting the cold in is only half the battle... the other half is getting the precipitation and that requires some luck.) Now... where's my hat and gloves? Not needed them in Somerset for a very long while.... tropical moths probably got 'em.
  31. 75 points
    You know what - I havent seen 1 hopecast on here. People have put all their points of view across in a pretty good mannor- infact its been pretty good debate. The only post that sticks out a mile as pointless is the one im quoting...
  32. 74 points
    An ode.... The charts they have shown from long, long away That the SSW would hold immense sway Some urged caution, some said doubt They said 'la la la, we're not listening, our faith is devout'. Their ideas they have shown with chart after chart Their belief, their knowledge, it came from the heart I always reckon, credit where credit's due So take it from me, an enormous 'thank you' I can't read the charts, they're blob after blob I rely on you all doing a fantastic job So the beasterly's coming, inching closer each day The temperature's dropping, the rain's gone away What wonders await? Well no one can say But I do know one thing, I'm polishing my sleigh Pondering starts, what can it be Surely it means '91, maybe '63? With charts such as these, manna from heaven Sure can mean just one thing, another'47 The cold, it's a coming, we all know that Wrap up warm folks and remember your hat Will we get an inversion or plenty of snow? Or that mythical beast, a channel low? Our dreams they've been busted many times in the past The cold came and it went, it just didn't last This time it is different, our boffins of gold Foresaw and predicted and then we were told Look up to the sky, high over the cloud Stratosphere it said 'yes' and it said it loud So when it comes, go out to play Sure check the charts but then step away Synoptics like these, well we know that they're rare Ski, skate, slip and slide, sledge without care Dear Mods I may be a tad off topic But charts such as these, by god, they're epic Please forgive me I beg, the rule, I don't mock it But such weather porn made this lass poetic
  33. 74 points
    I have to say when I suggested at the start of the month that the Strat was setting us up for a great cold spell, I thought that the potential was good but never envisaged this good. Again enjoy!
  34. 73 points
    Cold - Yes Instability - Yes Prolonged - Yes I just wet myself - Yes!
  35. 73 points
    I quite often agree with your sort of sentiment, as I'm one who opts to look at the most likely solution to fit the signals rather than the preferred one But, equally impartially and with intended objectivity (hopefully): The situation at present is a highly unusual one and the risk of some astonishing late season wintry weather is much higher than usual, certainly than often seen in these cases where deep cold pool advection flirting with the UK graces the perimeters of more 'reliable' NWP The repercussions of this SSW are going to be sustained. The clock starting ticking back in January and carried on through this month with extreme instability of the atmospheric profile with the tropics and extra tropics being subjected to opposing high amplitude states of angular momentum tendency. The impact on tropospheric global wind-flows (the Jetstream) has been significant, in addition to the detonation of some intense cold pooling over the polar field (relative to the modern day generally warmer arctic) : more especially across the Canadian arctic as multiple programmes of hot needles are probed into the polar stratosphere The result of extreme tropical momentum and stratospheric implosion implies high impact weather events on a broad-scale. Some places are going to get bitterly cold and some weirdly warm. In this day and age fewer parts of a hemisphere can get cold with less to go around than used to be the case maybe. But this programme of events strongly favours the European sector to become bitterly cold from what looks to be an impressively large breakaway cold pool for the time of year from Siberia. While its true that the envelope of this cold has boundaries that shift in intra suite modelling, the focus of the BI being impacted in inclusion, is much higher than other situations where lesser broad-scale drivers have been in evidence Ramping indeed requires a justification - I think this situation fits that criteria. Areas of land mass infrastructure most at risk aside from weather impacts (hopefully with least human welfare risk), the synoptic blocking pattern and its associated reverse polarity from one side of the Northern Hemisphere to the other - is not something seen on an every day NWP menu
  36. 73 points
    Right time to knock it on the head. I am not interested and neither are most of the posters on here interested in how climate change may or may not be influencing SSW impacts. Keep your bickering to the climate change forum and let us concentrate on whether or not we will have a productive easterly or not. Thnk you.
  37. 72 points
    Feel I have an apology to make. If people are wondering why this thread vanished for almost an hour, basically I went ahead a locked the thread first. Then, went and hid it. Was feeling fed up (partly due to the way this thread was going and for other reasons). Regardless, I shouldn’t have taken out my frustrations on here by vaporising this thread and leaving people feeling confused and worried as to what happened. It wasn’t fair and I didn’t let any members of my team know what I did. Nor anyone on here. I’m sorry for behaving that way and wouldn’t blame anyone for being annoyed. Not really a great example for a mod/host to set. While I appreciate some of the damage I likely caused (even though some will probably look back on the mysteriousness of the missing thread and laugh), I will make sure it doesn’t happen again. After all, this thread is meant to be a laid back and fun place for you guys to chat about the models, and would hate to ruin that mood. Could have chosen not to have said anything at all, but feel you guys deserved to know the truth!
  38. 72 points
    Evening Based on the pretty successful thread around the current seasons NH patterns I thought I would lay out the thoughts for Winter 2018. Headlines - Following on from Autumn > Winter 18 Globally is set to smash records- From record warmth to record cold, record rainfall & record drought... This will be driven by weak westerlies & a possible SSW in mid December- Teleconnection notables **could** be * Lowest negative AO on record ( or at least a challenger ) * Lowest & or most positive POL on record ( this metric can be good for us in either positive or negative mode, however its the extremes of pressure that support the -AO ) * Most negative 100 or 10HPA zonal wind on record in Merra2 data at any point during the Winter ( most likely earlier rather than late ) UK wise - The overall theme is a very high probability of a below average winter with the sub 3c breeched twice - ( maybe 3 times ) Winter NH patterns For a winter forecast this last 10 or so years a traditional method by most has been adopted - taking the state of the Teleconnective background signals & matching them to analogue years in the 1900s - & I still believe there is some merit in this especially when we are in very high NINO index years as this can be the overuling global driver over & above any favourable ones - The last 5 years or so have seen attempts to create a winter forecast by morphing analogue years for the stratosphere - again with some limited success- However there is one fundemental issue with using these analogues which is the assumption that should the same metrics repeat themselves then the tropospheric responses would all align & the H500 height anomalies would be at least very similar across the NH. Well now, as we get better understanding of how climate change is impacting the weather (most notably the ice & arctic heat ) then all these analogues potentially become redundant due to the troposphere becoming more & more independent in relation to not allowing the stratosphere to downwell - ( otherwise known as being 'decoupled' ) The main driver of this is the surplus warmth left over in the arctic at the end of the summer & Autumn as well as the record breaking ice loss along the peripheral ice edges - Not only this, as the mid lattitudes heat up we have grown larger more 'intense' areas of high pressure transporting yet more heat upwards into the pole- ( NB even now this week in November we see record High pressure developing towards Scandi pumping more warmth upwards ) The feedback then becomes self perpetuating- I would also like to add to this the 2018 'spin' that not only does this year have a massive heat anomaly,but perhaps ( IMHO ) a dipole of heat / cold across the areas with early ice build up V no early ice What you then allow is even more inconsistency with heat creating vast gradients across the pole allowing for yet more blocking - & because of the dipole the balance of heat then allows potential displacement of the tropospheric vortex - Its no wonder then that we see the amount of wave 1 & wave 2 blocking attacking the early vortex & the inability of the stratosphere to couple downwards as the resistence upwards is balancing it out - What you get as a net of all this is no tropospheric analogues because there isnt a teleconnection that quantifies Arctic Amplification ( AA ) & there are no stratospheric analogues because if the strat cant downwell then its overall strength is much less impactful on the troposphere - - So as mentioned then- Autumn has been one of blocking highs - even when the stratospheric jet has increased along its seasonal pathway the troposphere has refused to couple with it- ive highlighted this is due to the anomalous vertical heat flux & perpetual bombardment of upward waves thats served to offset the downward propergation of the strat leaving the polar cap sitting in equilibrium Seen here ( Source AER ) Also shown is the continual warmth in waves pushing upwards from the troposphere - & now potentially down from the strat- Remember the upper vortex is *Stronger* than average this year so while its vulnerable to attack - early displacement to russia * Isnt * the same as a SSW split - for this we need to see a reversal of the zonal wind @60N/10HPA * Classic winters like 1962 had early warming over the canadian side which took the vortex out for the entire winter then went on to allow for blocking to remain in situ for long periods of time- I believe this winters signal of a tropospheric decoupling could allow for a similar scenario especially if the SSW underpins it - QBO support - The initial concern is that a downwelling WQBO would omit us from the chances of a SSW however we are still in the transition phase where 30MB moves to positive but the 50MB lower down holds negative- The impacts of this are that the QBO will not act as a blocker early on the potential SSW this winter - Ive uploaded the image & I should have shortened the timeline but hey ho! h Possible Strat warming ~ Mid December... The strat as we know has been under attack this winter & the lower vortex especially has recently born the brunt of any deceleration - dropping to around 5M/S where as higher up the 10HPA wind has remained less impacted The day 16 disks which when the next wave of vertical flux peak starts to show a canadian warming & relocation of the vortex - So worst case scenario a dipsplaced vortex towards Russia, best case is a split & even less eastward zonal wind speed !! ** Key date proposed for major displacement / poss warming Dec 15th but remember because of the decoupling this may only serve to reinforce the blocking thats already there - ** DJF UK CET - Viewpoint & Anomaly plot The seasonal winter CET stands from Hadley @ 4.13C broken down into D 4.7 J 3.9 F 3.8 Statistically across the last 100 years sub 0c months are - 8/300 which is about 1 every 40 years ~ 2.5% chance. sub 1c months are 17/300 which is about 1 in every 18 years ~ 6% chance sub 2c months are 29/300 which is about 1 in every 10 years ~ 10% chance. So we can see the numbers are low- in terms of our chances I try to quantify this winters numbers by saying that a sub 2c is as high as 50/50at this stage ! & sub 1c maybe 25% - Sub 0c maybe 10%... Overall projected winter CET SUB 3c ~ 2-2.5c Overall pressure anomaly locations for Winter 18- These may wax & wain however general locations feel about right- Storm track is in green - Cold winter for central states as well as possibly the east depending on whether the blocking is more East based towards a +PNA or more west based -EPO ( the further west you get the -EPO you do encourage a ridge on the SE coast ) UK sits on the NW side of the low anomaly in Europe - so in that respect continental air is sent west in our direction- which will drive snow events- Europe as a whole cold & below ave - especially central & Western, however places like Greece / Turkey could benefit from warmth up from the south - It is my belief that confidence in the projected patterns for this winter are about as high as they can be in terms of potential blocking- especially in the locations we need it - what you will see from the models is perpetual ridging to the pole from every angle across the globe ( -EPO / -NAO / -POL ) If the vortex remains uncoupled then the speed of the 100HPA vortex is more crucial than the 10HPA one higher up- This will continue into December where the idea of a 'front loaded but possibly fully loaded winter comes from' - The nature of reduced westeries also impacts the UK around rainfall- Mean averages especially for the NW will be lower however what you lose over a month in terms of loss of westerly driven wind & rain events may well be offset by slow moving PPN events ( The same as Autumn ) So there you have it - 2018/19 Global extremes of weather & for the UK higher probabilities of exceptional weather which for once is more in favour of exceptional cold instead of warmth.. S
  39. 71 points
    Roll on 4 days, and if seems that we are seeing just this. I think that we have seen that the ECM has the tendency in the past to overplay amplification and blocking scenarios........but, and a big but, when we have downwelling strat events the ECM picks these up a little better because of the better strat resolution. Now we may not see a classic evolution as seen in this latest run, but my feelings are that we will see a block to our north somewhere in a similar position. No need to comment on every run, but imo we see the trend increasing as expected, and I suspect that most of us will witness a significant snow event before the end of winter and most likely before the end of the month. And with a locked in omega type block, that snow isn’t going to disappear quickly......
  40. 71 points
    netweather members celebrate when the long-awaited easterly finally arrives...
  41. 71 points
    Still coming slowly off a cautious fence Long term total global atmospheric angular momentum trends can tell you a lot about pattern changes due to the effects the rises and falls in global wind-flows have on jet stream patterns. Total AAM refers to the net balance of easterly and westerly flow in the atmospheric circulation and the outcome tells you which direction the atmosphere is presently headed and which has initiative forward momentum Latest levels, assisted by a second tranch of eastward moving tropical convection since October has taken total global AAM back to parity, with even a hint of peeping a head above the parapet. This is to be set as disconnect against the negative (easterly) La Nina base state. Its no surprise that the sometimes pausing, but still steady upward trend overall, began from early October and why the pattern has been increasingly amplified over this time The importance of these feedbacks keeps being stressed repeatedly I know in these posts, but they are very important in terms of recurrence patterns that can give a good insight into how future patterns may play out. On the basis of the seasonal wavelength cycles spoken of again yesterday, the start of the winter (like any other season) is one of those especially important times when trends within the layers of the atmosphere can be especially augmented by natural seasonal wavelength cycles. Behind the rises in total AAM is continued buoyant AAM tendency as a result of positive torque mechanisms which are programming swathes of amplification poleward. This begins in the tropics c/o of the MJO cycle and propagates to the extra tropics and then from the latter c/o mountain torque into the stratosphere to sustain a destabilised profile. The momentum being created is starting to assure a cold pattern persisting longer and longer through December and slowly cancelling out cautious notions that the traditional base state might interfere and de-amplify the pattern in the ways described previously. As a consequence of the atmospheric flux, the Global Wind Oscillation (a representative plot of rising or falling AAM and global windflows) has continued to stretch its Phase 4 amplitude and enlarge the disconnect with La Nina. In synoptic terms, the implications of this are for an upper flow into Europe that looks likely to continue to be somewhat flat against the Atlantic ridge and troughing to the NE(hence some of the apparent stubbornness for breakaway lows heading from upstream to deconstruct and take optimum southerly most tracks each and every time). But with the upstream +PNA pattern assisting split flow it continues to favour the angle of the jet stream to be on a NW-SE trajectory, its set well for increasing upper cold air in tandem with surface cold to become more and more in situ and increase the possibilities of surprise more widespread snowfalls popping up more and more as time goes by. This leads to the extended period. In December the NAO has a low relationship in its response behaviour to the state of the polar field (the AO) However this starts to rapidly change as New Year arrives and the relationship, as such, consolidates much more tightly in January. Hence another aspect of this crossroads theme referred to so often. The feedbacks in process are starting to suggest with a bit better confidence that lagged effects of these amplification programmes will help prime a cold pattern to sustain or recur heading into the New Year. Assuming the atmospheric circulation doesn't deviate much from the present (and in this respect its still necessary to monitor AAM as tropical convection returns to the Indian Ocean as a potential fly in the ointment), then the effects of seasonal wavelengths bring those height rises to the NE into the equation, and the implication of this is to repress the Atlantic ridge, with less mixing of milder air in trough disruption occurring and better and better chances of snowy undercuts.
  42. 70 points
    Reading this thread is far more entertaining than anything on TV. Wrong/different data, the 12Z is so different from the 00z etc. Come on some of you. You are on the edge of the most severe wintry spell since 2010 if not before then and you moan about its not this its not that. Why not enjoy what the weather brings to the country rather than worrying about the 00z being different from the 12z at a week away. For those that get snow more than a cupful enjoy, drop your photos in here or your regional threads for the rest enjoy watching the actual weather even if it is not as good as you would like. On to the models, well one version, my hobby horse the 500mb anomaly charts. NOAA this evening with their 6-10 and 8-14 outlook. As good as I have seen in a long long time, on the 6-10 it is a so called 'magic' 528 dm line over the country from northern Canada. The 8-14 keeps a cold trend to the weather. Just how far north any milder air gets we have to wait and see, I suggest Wednesday before the different models start to converge on what will actually happen. Note the Fax charts as perhaps the best guide. Anyway here with the NOAA charts http://www.cpc.noaa.gov/products/predictions/610day/500mb.php
  43. 70 points
    Dear wife, Due to the netweather code of conduct I am unable to tell you this directly now as, otherwise, this will go pear shaped and as we haven’t seen lying snow for 5 years... I can’t risk that. If today’s icon/gfs 00z (17/02/18) charts verified, we could be in for the snowiest spells of weather we have seen in our 40 years living in the south and this could pretty much be a nationwide event. I know that you hate and loathe cold, snowy weather but all I can say is........ get to Tesco’s and stock up on supplies, alcohol and logs as we’re in for the long haul!!! All things going well, I will show you this message on Tuesday/Wednesday as I may be allowed then!!! Amazing charts today, not sure the ecm 12z from yesterday could be beaten but it may have been by icon/gfs 00z runs. Great to see the ukmo onboard, need the ecm back on board later today. Enjoy the ride! Clem (suffering in silence!)
  44. 70 points
    Sorry, I just thought I’d walked into the moans threa.. oh wait. <passes around a big bag of grips> No sooner do we get a cold spell within sight it astonishes me that time and time again some people seem hell bent on being the first to find signs of it unravelling. Is there some kind of prize for this I don’t know about? We don’t live in Siberia. We are never going to have three month of bitter cold. We all know this! It’s one run. 48 hours ago some of you were dismissing the idea of an easterly entirely based on the output. Maybe when the hangovers and cruddy moods have lifted this will improve the quality of posts?
  45. 70 points
    00z EC showing interesting battleground snow event for the north and west next Tuesday, as Atlantic frontal system moves in from the west and bumps into the cold air If only my wife could understand my fascination of looking at weather charts ...
  46. 70 points
    We should rename thread the ‘miserable git’ thread - So much negativity & misery in here I’m surprised people even make it out of bed. updated 06z JMA joins the euro party to 84
  47. 69 points
    I love having the FV3 now. There used to be that dead time between the end of the GFS and the start of the ECM where I had to talk to the wife. Not any more
  48. 68 points
    Leaked express headline for tomorrow. #sorrynotsorry
  49. 68 points
    Last one from me for a few weeks. Spending Christmas in the East Sussex Weald, thats ,if I survive a drone attack at Gatwick battlefield ! Then on to British Columbia to see my new grandson during January. Going to ski for a few days in a new resort called Big White but most of my time in Vancouver. I know you cold lovers find the hunt very frustrating, having to wait for weeks on end for it to arrive and then just watch it melt away in a matter of an eye blink. Like the Japanese water drip punishment, a slow painful pulling of the teeth or waiting for Brexit to conclude ! You lot deserve better and fingers crossed for a proper cold and snowy spell to surprise all soon as the picture below shows , when it comes there is no where nicer than the British village. So no snow for my short visit to Blighty but the welcome sight of a nice pub, log fire and fine pint of Sussex Best Bitter awaits. Have a merry Christmas and good New Year and may the snow gods be with you . Cheers, C
  50. 68 points
    First rule of GFS model watching. Never trust a dartboard low....... But especially in this type of set up.
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