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  1. 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
  2. 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.
  3. 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 !
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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.
  9. 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 .
  10. 83 points
    New EC weeks 3 and 4 as you were. High pressure in all the right places.
  11. 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?
  12. 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
  13. 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.
  14. 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.
  15. 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!
  16. 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
  17. 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......
  18. 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
  19. 68 points
    Leaked express headline for tomorrow. #sorrynotsorry
  20. 68 points
    UKMO amazing - snow event followed by more snow events + longivity of cold What more could we be asking for...
  21. 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
  22. 66 points
    Well forgive this old fella asking what all the fuss is about over the 12Z, but just what re the 12 V 06 out to 144h please? I’ve looked at the overall pattern of the 558 DM line and the isobars for the 500-1000 chart. Also the same times for the 850-1000. Slight differences but why the posts that have phrases like’game over’ and such? These do not help new folk understand what is happening. I honestly cannot see that, in the time scale I mention, there is much that is markedly different on the two runs. If you are commenting beyond T+120-144, and in this fairly volatile state of the northern atmosphere perhaps even near T+00 then you MUST compare like with like. It is way too far ahead to use the argument that the run has the most up to date data and therefore must be more accurate. It does not hold, believe me, sorry to be a bit dogmatic but 20+ years of forecasting makes me feel you may just bear with me over that. Come on I posted this morning about the overall upper air signals, yes the run to run of the models may well vary but the cold is here for 2 weeks possibly longer. To be sure of what values in each of our back gardens or even more so will it snow/when/how much then be realistic. Models 2x or 4x daily will NOT be accurate for temperature before about T+72 and for ppn of whatever type before T+48 and sometimes not even T+12. If you can accept these restrictions life on here can be enjoyable and useful for learning for us all with no loss of enjoyment. Shall we try this for 24 hours or so.
  23. 66 points
    I've just read through the last 10 pages or so. Some of you seriously need to think about taking a break from watching the models and taking every run as gospel. It's gone from euphoria to throwing toys out the pram in the space of a few hours! Walk away from the computer, life is too short!
  24. 66 points
    Awful Lot of folks on here this morning with an opinion about how silly looking at day 10 models are. Interestingly not many of them had much to say on any output analysis at all until now. Amazing how we have a slew of new experts when the models don’t behave as expected if you’re in that camp of ‘day 10 model watching is pointless’ then might I suggest you stick to watching the televised weather forecasts and basking in the knowledge that you will probably always be right, and then you can leave those who like to make a stab at a forecast based on output analysis alone to pursue a hobby they enjoy. nobody gets a prize for being right or wrong and it’s frankly just a bit poor if you enjoy being the person who takes pleasure in saying ‘I told you so’. there’s lots of other places on the internet for your badly articulated ‘realism’. Thanks.
  25. 66 points
    We still believe, we still believe… We still believe, we still believe… It's coming home, it's coming home It's coming, summers coming home It's coming home, it's coming home It's coming, summers coming home Tears for netweather Skies are grey No plans to go out today Barbecue summer drifting away… There could have been storms Lightning that couldn’t be beat Waiting was nearly complete GFS FI was so sweet And now I’m singing… Three models as they were ECM still gleaming No more years of hurt No more need for dreaming Talk about Summer coming home And then we all thought it won’t But high pressure was strong It had grown And now I see UKMO’s showing more GFS is good as before NAVGEMs certain to score And Summer suns screaming Three models as they were... ECM still gleaming No more years of hurt No more need for dreaming This is our chance A better summer then France It's coming home, it's coming home It's coming, summers coming home It's coming home, it's coming home It's coming, summers coming home It's coming home, it's coming home It's coming, summers coming home
  26. 65 points
    I think it's "hold your breath" time.... I've just spent some time scanning the better minds out there on the twittersphere. and checking the recent model runs - and I'm not sure I can ever remember reading/seeing such a collection of differing views and mostly open acceptance that we have an evolving situation that is so hugely complex that we don't really know how it will pan out...and I'm damn sure NWP doesn't really have a scooby either in terms of anything past short range. 2 salient factors for me. Firstly background (strong?) pacific forcing that is going to want to throw up a high lat ridge. Secondly the very difficult predictors of the extent to which downwelling can successfully impact on the troposphere under a wQBO regime where splits such as we are (probably) about to have are so rare. And where into all this does declining solar impact sit.....and the sharp see sawing of mountain torques over the last 2/3 cycles? GLAAM operating at particularly high levels this winter season. I'm still sitting on the cold side of the fence, even if timing is being skewed later. But the uncertainty is there for sure. If we end up with a +NAO signature by mid Jan after all the build up and cumulative signals for blocking - and the sustained MetO long range calls via Glosea for cold continental feeds then a good many people are going to end up with eggy faces. Some people seem to dislike forums where hyperbole becomes the norm. Don't really get that myself....particularly when the interest is so intense. Enthusiasm is always a good thing. The weather outside our windows may appear very dull right now - but up top and out in the pacific as another significant east Asian surge is underway it is anything but ordinary. Long live hyperbolic enthusiasm....and bring on the cold.
  27. 65 points
    I came back on here tonight hoping to see some positivity. (I shouldn't really, I've been here long enough to know how it works), yet we are in the midst of a December SSW, a very rare beast. It could and should, give us the winter we've been waiting for, for years. It might not... however, we are in the best position we've been in for years. The models are struggling with an outcome and it's a fact that an SSW will play havoc with numerical weather prediction. We (My family) are losing our home on the 7th January. We will be ok somehow. One of our Netweather members has just been given the all clear from cancer. Is it really worth any animosity over the weather? Something which is out of our control? It's Christmas eve tomorrow, real winter weather is coming (allegedly at some point...) Just enjoy the hunt for cold and have a merry Christmas....
  28. 64 points
    Beginners guide to the psyche of a model watcher in Winter..... 1) A cold spell is shown in FI - "it will never verify it will all go pear shaped" 2) A cold spell moves into the reliable timeframe - "that run looks very dry hardly any snow showing there" 3) The snow arrives after the commencement of said cold spell - "it maybe snowing outside but this cold spell looks like it will be finished next week" We are at Stage 2 at the moment! A very decent start to the day today model wise. I would be very happy in the event the ECM verified and it would seem that all roads lead to cold this morning. Indeed the GEM is a cracker following the durge it produced last night! But will it snow IMBY?
  29. 63 points
    EC Ens up to 6 on the clusters, but the key stand out is the blocking platform across them, atlantic is primed, AAM has spiked precisely when the downwelling advertised on the paint drip connects - Genuinely cannot see a road back to the flatter solutions from here. I think 'That ECM' will get usurped in the not too distant future.
  30. 63 points
    No charts tonight - on a train and on my phone which is tedious... But did want to post some text. My eyes are moving beyond the trough now - I was pretty confident in it at the weekend and am now certain. How much snow will we get? David's post highlighting the arrival of the expected next pacific spike is very timely. While we were wading through the tedious first half of the month the pot at the end of the rainbow was always the potential for a downwell that synchronised with a powerful pacific spike. It's taken the third time of asking to arrive - but it's here. This is going to mean reinforcement of the Euro trough at the same time as a push for stronger heights to the north, and this at a time when the ssw has already begun to affect the pattern. And this in turn I think is going to mean quite a steep pressure gradient and some really quite cyclonic continental weather as the trough beds down. I'm still thinking that the block has to setup over greeny rather than scandy in the medium term, though at the start of the season I did admit to being frustrated at an inability to get ridge positions exactly right and I want to get better at this - modelling appears to be favouring more of a scandy block at the moment - but in the end ridge position when the Euro trough is deep is probably not so important overall as the feed will be cyclonic and bitterly cold at this time of year either way. And all this adds up to some considerable snowfalls I think. Someone next to me on the train just said "it's supposed to rain on Tuesday..." and I was close to grinning at him and offering an alternative view....but let's just watch it unravel. I suspect the next few weeks won't be especially dry or especially wet. Something else.
  31. 63 points
    We're going to run a competition this afternoon with the winners getting special pre-Xmas thread bans, woohoo!! To win, those who keep posting solely about Met Office forecasts and the like with scary regularity, despite various requests to stop and the big notice at the top of every page in here, just have to keep doing it. Good luck to all those taking part
  32. 62 points
    The problem is, we have many spending hours on this forum, explaining why things may and may not happen. The pros, the cons with a certain setup. The background signals, from Pacific forcings to Solar to the Enso state.Going to great lengths to point out the mechanisms, the caveats, the opportunities. I understand why some feel, why do I bother? 95% are here to do exactly what the forum title says, 'HUNT FOR COLD'. Whether that is looking for a glimmer of hope in a flat zonal profile with poor background signals or in more interesting times, aka right now, it is the whole point of being here on this forum surely? Clearly this forum would be redundant if we all lived in Antartica, but we don't, we live in an area that is usually beyond the reach of any easterly train from the east and with a continuous warm belt of water being pumped up from the Gulf of Mexico to our west. The odds are stacked against us right from the off. The dice are heavily loaded and they are not in our favour. And that is the thing, the crux, the whole point is the chase itself. I won't go as far as to say the cold actually landing is secondary, but before it does, the chase, the hunt, the hope, the despair, the rollercoaster, that is why we torture ourselves on here every winter. I am a die hard lifelong Spurs fan, so that probably makes me a masochist! But the fact remains that for the 95%, just seeing those cold charts appear gives us the buzz we all crave at the time. That may make me look like a total fruit loop in 'real life' but I know full well most of you know exactly where I am coming from!! It is a shame then that we will always get one or two miserable posters who take a few op charts as gospel and on complete face value. Bad enough but to then, through no skill but their own negativity, extend that op chart out to several weeks / months beyond is what really gets people's backs up on here.
  33. 62 points
    Output is beginning to recognise the significance of the timing of +MT, MJO progression, background Nino and impact of heat transfer onto the vortex. Height rises out west to drive the trough further south, followed by invigoration of that trough via falling momentum phase - and meanwhile Greeny and Scandy height rises begin to link up. It's a near perfect sequence - and once again for all those moaning last night about how we cant predict anything and its all random blah blah - nonsense. There are spanners that regularly get thrown into the works and mess things up...but broadscale prediction is getting ever more possible with better and better tools. And this is one instance where we havent had a sudden uptick in solar activity, or a tropic storm in the wrong place....and the cold pattern will be completed on schedule. You have done well Lord Teleconnect....and now I sense that you wish to continue the search for the split vortex.... Hehe. Such fun. But to anchor my mid afternoon drivel into something with a graphical solidity about it - how about a GFS image. Usually ECM gets the bigger coverage, but I think GFS has been handling the extended picture rather better in recent days. By the end of next week we have a very good signal for a cold trough with signs of continental cold being able to back west ....and then within a few more days the heights back further west to Greenland and begin to pull in an ever more frigid flow from the E/NE Being brutally honest cold rain for many will have to be endured as we progress through this phase - but the end result looks like an increasingly cold and wintry one. Patience my friend. In time the Beast will seek you out, and when he does, you must bring him to me. He has grown strong. Only together with the additional benefit of a downwelling split vortex can we turn him to the Dark Side of The Force.......
  34. 61 points
  35. 61 points
    My take on the upcoming cold spell using the usual 500 mb anomaly charts Looking at the latest upper air, 6-15 days from now. The usual 500 mb anomaly charts. Not that they have been either consistent or a good guide at times but the three I use have been slowly converging over the past week into a more coherent and agreed pattern. One item that has been consistent is the gradual lowering on all 3 of the contour heights. A week or so ago the heights just south of the UK with above 558 DM now they are predicted to be closer to 546DM or lower, ECMWF-GFS Today it is the turn of GFS to show the most meridional and cold pattern. Previously it had not had much in the way of this ridging over the western Atlantic into the Greenland area but now it does. Not sure if this will stay although judging by the EC and NOAA this is where it should be. NOAA Their 6-10 still shows a more Atlantic type of PM pattern with some ridging into Greenland, similar to how it has dealt with the pattern for about a week. +ve heights are shown off Newfoundland and these have also steadily increased over the last week on its daily output. Likewise the actual contour heights (just south of the UK) are showing at 546 DM some 10-12 DM down on earlier predictions. The 8-14 is a pretty similar chart in the pattern and positions of any ridging/troughing. Perhaps most of us might be more relaxed about this upcoming cold spell if these two charts from NOAA showed similar meridionality to EC/GFS. However, to me, the consistency of NOAA gives some confidence in the cold spell being something that is going to be there two weeks from now. How marked the cold will be, where any snow falls, is of course not for this type of chart but from the operational ones closer to T+00. My own punt would be for a cold, sometimes very cold period of at least 2 weeks for most areas. Only temporary breaks in it for parts of the west and SW, unless a very active system breaks NE from the Atlantic. Then the usual problem of show or rain ahead and/or behind it. All full of interest for all those cold fans and for anyone with a weather interest. http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php
  36. 61 points
    Reading this thread tonight has been a real rollercoaster....have to wonder why those who believe the weather is nothing but chaos with no discernible pattern bother to spend time on a forum where the main thrust is to try and make sense of complex signals and decipher a path forward - but there you go. Takes all sorts I guess.... ...and on the subject of signal deciphering all still looking pretty good, isn't it? I have a slightly warm and fuzzy feeling at the sight of this EPS chart for the 18th Good to know that GSDM theory has a basis that produces the goods. Signal for isolation of the trough underneath a growing band of high lat blocking is growing, and on schedule. To reinforce the fundamental reasons for this - time to post the MT chart that David has already put out there tonight...just for double emphasis It's a really very impressive spike at 30N - and to summarise David's detailed argument into a brief sentence - it very much increases the chances of our strat warming becoming a major one. This sharp increase in momentum will do all kinds of nasty to the vortex - but it also creates a signal for increased atlantic blocking as eddies downstream of the spiked pacific jet form. NWP has been slow to pick up on this - but that EPS chart suggests we have increased clarity now. From here? EPS at 10 days suggests again that the expected pathway may be accurate. The trough will sink south, and with it will come increasingly cold air and wintriness to high ground. This is the start of our winter proper (at least in my eyes) but don't expect widespread snow at low levels quite yet. However - this period will signal the start of the real cooldown. And from there? Time to return to GSDM forcing because strat reinforcement of the pattern will be a little way off yet. Tendency of AAM will begin its next downward cycle soon. This will signal in effect a reduced momentum signature at 30N and opportunity for enhanced momentum further north. However the difference this time is that our next MJO cycle has kicked off, with moderate wave activity emanating once again from the pacific. This will aid in preventing the pattern from becoming too flat, and I would suggest we will see a reinvigoration of the atlantic as we head into Xmas week (despite the higher than average pressure anomalies out west on that EPS chart) but with the trajectory to the south rather than through the heart of the UK (as is happening this week) as heights to our NW serve to deflect the jet on a NW/SE axis. Shamelessly cherry picking a GFS extended image from the 18z rolling out now this chart for Xmas eve would be about what I would expect though perhaps with a greater maintenance of heights over Scandy Systems tracking beneath the block heading towards mainland Europe. Polar maritime airmass mixing with a trough that is beginning to pull in air from the NE. In essence becoming progressively colder on average. So - when does all this give us snowfall at low levels in the south? Don't know yet - don't want to guess. Depends on how quickly cold air can be absorbed from the NE and just how entrenched the block becomes. But chances certainly exist prior to New Year if the flow is right. If not it wont be long after NY before we see 850s in the right kind of zone with a flow that will be evermore easterly on average. And all this being forecast on 13th December rather than 13th February. Warm and fuzzy all over again....
  37. 60 points
    The warmer air creeping east today with the font And to digress for a moment. I was in a taxi just now and the driver started wittering on about how he loved cold weather. I thought, 'the bloody nutters are every where', as i deleted the taxi firm from my contacts.
  38. 60 points
    You have been repeating this for as long as I can remember. And yet again I feel that a response is required. If we go back 10 years to when I first started the strat threads, you weren’t alone in your thoughts that this teleconnection did not influence the trop and made repeated attempts to knock this extra knowledge as a forecasting tool. Yet, in that first year we observed a record split in the SPV and were able to demonstrate quite easily how that split brought about an almost immediate trop response with the Feb 2009 easterly. Then we have the early winter splits of the next couple of years. We have also demonstrated in futher years how cold strat temps led to periods of vortex intensifications and a resultant strong trop +NAO. I am sure that if you put it to the floor on Netweather then the vast majority would agree that analysis of the strat will assist in longer range trop forecasts. And we know that every SSW is different and there is still a lot to learn. But our ignorance should not put us off that quest for extra knowledge, nor should it deny us acknowledging that the link exists even for our small island. So, the same can be said for the links between the MJO and GWO. The phases of each have been shown many times to be linked to a certain planetary wave pattern. I do not understand every little nuance of these factors but I know that they do have a bearing on our small island and in years to come I hope that the acceptance of these interactions will be as mainstream as the strat is now. In fact I feel particularly proud when I see nw members warning that not every SSW leads to a trop response. I feel that those years weren’t wasted. Back to today now, and after a little wobble yesterday the strat charts still look conducive to providing a downwelled trop response. The only difference being is that we are 3 days closer so I would be expecting changes in the output from days 12-17 now.
  39. 60 points
    Atmospheric Customer Services. If you are concerned by the lack of Winter Weather at the minute then please call this number: 0000 -1 -2 -3 -4 Option 1: ICE Option 2: Snow Showers Option 3: Heavy Snow Option 4: Blizzards Option 5: 1963 Option 6: 1947 Please press 0 to hear these options again or alternatively Nick Sussex is on line 7 to take orders for Prozac. We apologize for the lack of Winter Weather and our engineers are fixing the problem..... PLEASE HOLD... ESTIMATED FIX TIME: 10 - 15 jAN...
  40. 59 points
  41. 59 points
    GFS pretty much a carbon copy of the 18z UKMO goes from a 5/10 to a 8.5/10 which is the best positive GEM goes from zero to hero with a stella run & ICON drops in as well... A superb start to the day beast confidence ~ 75%
  42. 59 points
    Although relative angular momentum is very high right now, that is partly a reflection of a persistent +AAM signal in both hemispheres. The greatest +AMM signal in the Northern Hemisphere is that westerly inertia signal deposited 30N. That is essentially past peak and likely to decay over time. However, with the tropical VP signal migrating a tropical wave eastward during week 2: We're likely to see jet extension and +AAM signal renewed week 2. That takes GWO signal back to phase 5 (Scandinavian ridge signal). Because of the slow speed of this tropical wave, suspect that the GWO signal will remain more in phase 5 than would normally be expected. Hence ridge to our NE likely to be more durable and models likely to be too progressive with this feature. Looking beyond this, the GWO suggests a phase 6-7 evolution on the cards as the decaying +AAM signal and maturing momentum signal from the tropical wave take effect. Ridge signal to shift further west and NW. Disregard any model output that does not follow these broad lines. The final third of December into early January is stacked with cold potential. Think a decaying +AAM signal and MJO returning back to the Indian Ocean. High chance that the GWO will be heading into high amplitude phases 7 and 8 and overlaid by a collapsing polar vortex and very weak polar westerly flow. This I think is where we are heading into January.
  43. 58 points
    I have some sympathy for those belittling the upcoming synoptics as "feeding off scraps", but I think this is a slightly wrong way of seeing things. Firstly, though a lot of us have been talking up the cold prospects for the end of the month, none of us have been suggesting that guarantee a record breaking, historical winter event for cold. We're forecasting a cold spell with potential (as yet not completely certain) for snow for many. And if that is "bog standard winter", then fair enough. Most winters have a snow event. So nothing unusual. Many winters have an SSW event too, so an SSW is nothing special in that regard either. Yes many are getting excited, but we're not forecasting 1947 either. Not even last March, which I fear some will use as a benchmark for a decent cold spell this time round - let's not forget, March 2018 had the coldest daytime maximum in recorded UK history, colder than any March day in 1947 and 1963. No, the excitement is not for a repeat of that - it's just excitement that there might be snow. And secondly, I think this is precisely where people may be looking in the wrong place. While temperatures are not guaranteed to be historical (at this moment), the prospects for really good snowfall look very good to me. The perfect ingredients for significant snow are an active Atlantic and any amount of cold below marginal. Often we get one or the other - I think this time we have a great opportunity for both. Historic snowfall doesn't require ice days, it requires a weather front, and many of them. This pattern looks a treat for that - if it holds to the ensemble mean. If we get lucky, we could get a series of lows squeezing through the Atlantic (precisely because the Atlantic ridge is not so strong to shut them out), but just enough steering by weak heights to our north to keep us on the cold side of activity. Now that scenario naturally means risk because anything involving the Atlantic means flirting with something milder. But there's a really, really good chance of things going just right for the UK between 20th and 28th, maybe even further out, as good as one can see several days ahead, especially in the north where I think a major extended snow event looks more and more possible. Oh and of course, if snow is on the ground, the temps will plummet regardless of uppers being minus 4 or 5 (as in 2010). So big freeze? Not synoptically. But on the ground? Totally different ball game
  44. 57 points
    So here's where it feels like we're playing meteorological Russian roulette, only the bullet is a marked step change in the hemispheric circulation towards a -AO / -NAO regime. Control run 06z GEFS goes from this .. To this ... In the space of 6 days. The Control has the same data as the operational, so it's not a question of data differences, rather resolution although at that range resulting in differences between ops and control. High resolution on a broad scale change isn't necessarily a good thing. GFS Northern Annular Mode projection, in line with AO forecasts, suggesting strat downwelling now coming into view. MJO also arriving in phase 7 at the same time, which would be conducive to blocking formation.
  45. 57 points
    Thing is, they effectively are showing that. We have full house. GEFS, EPS & CGEM means all now showing glowing +ve height anomalies in the day 12-14 zone over Greenland. Notable all three back the Pacific trough west with the EC most aggressive with the consequent pull west of the Pacific ridge. This signal becoming big stronger as runs proceed, against normal climatology drift. This allows for the Canadian lobe to be pulled south and west in the gyre of the North American trough, in turn allowing space for the Greenland ridge. Suspect this is tropical forcing week 2 acting in concert with the signal high aloft
  46. 57 points
    Well we have arrived at January 8th 2019 which was my date to look out for so here is my summary of events leading up til now and moving forward I first mentioned 8th Jan on 22nd December 2018 " I still believe that things will get interesting from a cold / snow POV from the 2nd week of Jan onward (8th Jan onward) " Today's charts that ridge of above average heights look like sticking around til around 14th Jan before beginning to sink due to lower pressure developing so what could happen next ? 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 pas the UK) resulting in some northerlies / North westerlies bringing the first hints at something cooler / colder to the UK some GEFS showing this possibility there are more but I think those are enough to display this possibility. My key period for this would be 17th Jan - 21st 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. Why? Strat events Over the Christmas period and into the new year we have seen a strat warming event Christmas day New years day today Now I have very limited knowledge when it comes to strat and teleconnective goings on so there are other posters who can and do explain these things more clearly than I can @Bring Back1962-63 @lorenzo @Glacier Point @Catacol @Singularity @s4lancia @Tamara (again sorry if I missed anyone) But a brief explanation from me why would a strat warming event lead to colder conditions? I will use last year as an example (note as @Bring Back1962-63 has already said no 2 strat warming events are the same / have the exact same effects) GFS run from 1st Feb 2018 the run started with some smaller warmings taking place but the "main event" was yet to come GFS run 14th Feb with a "split" event taking place (there are different types of strat warming events displacements , spits ,mixed where a combination of both takes place) also (Canadian warmings) https://en.wikipedia.org/wiki/Sudden_stratospheric_warming see page 37 for a list of strat warming events https://commons.erau.edu/cgi/viewcontent.cgi?article=1061&context=edt or page 66 on here https://www.earth-syst-sci-data.net/9/63/2017/essd-9-63-2017.pdf again one of the more experinced posters can give better explanation of differences and the different effects caused but I believe that split events tend to be better for us benefiting from blocking / colder conditions and displacements less so, I think this winters event was a displacement first and then we have just had the split event so perhaps a mixed event. and we all know what occurred after last years warming - the beast from the east, but here are some charts GFS run 20th Feb 2018 actual charts again I am not saying this year will see such extreme conditions just highlighting possible effects after strat warming events, there are other warming events and their effects but as I am not very knowledgeable I will leave those to the more experienced posters, see @Bring Back1962-63 s posts for better info Zonal winds - see the part tiled Sudden Stratospheric Warmings for a more in depth explanation than I am able to offer https://www.sciencedirect.com/topics/earth-and-planetary-sciences/zonal-wind however my understanding is that when we see a reversal of the zonal winds this increases our chances of blocking and in turn increases our chance of colder conditions affecting the UK (again dependent on where the blocking sets up) current zonal wind charts (I believe that below 0 is a zonal wind reversal) so as you can see we are well within zonal wind reversal territory which I believe will help aid any blocking that does develop. MJO - again posters like @Bring Back1962-63 can explain MJO better than I can but I will try my best past 40 days - current charts - I do not understand COD and amplitudes etc so cannot explain those or recognize those but here is my take oh the phase portion of the MJO going by those charts we are currently in phase 8 which equates to phase 8 nino Jan nada 8 Jan (which is weak or no enso signal, el nino or la nina, I think we are in a weak el nino ATM) http://docs.wixstatic.com/ugd/31d9e0_3c062d439cb841d2eea3ea174256642b.pdf http://docs.wixstatic.com/ugd/31d9e0_45ca90be1efa56eec7563c93f3bf6448.pdf I also think I seen some posters saying tyhere was a lag currently with MJO so here is phase 7 which we have not long came out of http://docs.wixstatic.com/ugd/31d9e0_9bbcf411b167ba537e629659eacd304a.pdf my take on those is that the majority do have a signal for blocking and quite a few concentrate that blocking toward Greenland which leads me onto the potentially blocked outlook for that last week of Jan period that I mentioned. The initial area to focus on for blocking developments seems to be Greenland and the arctic ATM but still wouldn't surprise me to see more charts with a scandi block in the coming days the award for craziest blocked chart of the winter so far goes to... ensemble NAEFS signal for blocking continues to grow 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 keep an eye on the ensembles for more and more BOOM type charts appearing in the run up to the last week of Jan so referring back to the statement I made on 22nd December " I still believe that things will get interesting from a cold / snow POV from the 2nd week of Jan onward (8th Jan onward) " *no blowing my own trumpet intended* I think overall the message is still true given the blocking possibilities that are slowly but surely beginning to increase however from a here and now POV perhaps off the mark due to no immediate cold / snow risk, and I wont shy away should my thoughts on the blocking that I have mentioned in this post disappear or fail to happen but I remain confident that this will be the UK's turn this winter to join in on the cold and hopefully snowy fun by the time we are ending January, this is why I love weather and whatever happens it is certainly all fascinating with the many possibilities / outcomes on the table, (I have done my best to be as clear as I can in this post and apologies if my lack of knowledge in some departments has lead to some incorrect statements but I am sure some of the more expert posters can help if this is the case).
  47. 57 points
    The hunt for cold is hotting up..so to speak..I'm hoping the Ecm is on the right track and that all roads lead to cold..and snow during early winter!❄❄❄
  48. 56 points
    Nope - that isn't what I would ask because an answer sits already within your first sentence. If you don't know anything about the background signals that are regularly discussed then it might be as well not to risk suggesting they are a waste of time. Dark Arts - no. If it was dark arts then we wouldn't even have NWP because science wouldn't apply either. There are a lot of helpful guides on this site, and a number of places you could go to begin growing an understanding of what drives the atmosphere, and then your contributions would be more useful. Either you are genuinely interested in what is going on and are frustrated and not being able to explain/understand the processes, or you are here to act as a deliberate lightning conductor for the frustrations that some are feeling right now - and that is an approach which is unhelpful. Whichever it is it seems a huge waste of time, because non-engagement with the processes means intellectual stagnation or attempting to magnify forum frustration means marginalisation from the real debate. Neither approach will take you anywhere.
  49. 56 points
    Ho hum dee dum. Interview done and back to the phone to see the most awesome GFS output of the season. Being blunt - pity it's GFS...but maybe something in the data has changed and we'll see ECM latch onto the same later. I hope brethren in the SW have woken up, because we'd have people drowning in the drifts again....... Usually a run like that would be written off...and in all probability it is overly extreme BUT worth pointing out at this stage that the evolution is not out of kilter with the forcings that are being applied to the north Atlantic circulation. Recent EC strat charts have shown a signal for a block to the W/NW and a jet driven further south, and so a split flow like that is entirely within the envelope of the possible, as impacts of the SSW increase. I'm sorry I can't access all my charts etc on my phone, but once home I'm going to have a really good look at the evolution of the pattern and see what may be what. Meanwhile don't forget that Tuesday is approaching and can still deliver for many. Just needs a westerly tweak as a product of underestimation of high pressure strength....something we have seen several times before. Jan 18 today. Can anyone remember the gloom and frustration of 10-14 days ago? Neither can I. Shows things can move very quickly in weather terms at times, and gloom should always be tempered with optimism when the signals are good.
  50. 56 points
    What's interesting at the moment is the consistency of the ECM op forecast for Tues/Weds. To be honest it's slightly surprisingly consistent - and the fact that both timing and angle of the slider/incoming trough have remained in the same 12 hour time bracket for the last 3 days makes me wonder whether finally we have a handle on the rate of downwell and strat imprint onto the trop pattern. The diving, sliding low remains on a trajectory that is mostly west of England and steep enough for an undercut of cold air to turn the moisture to snow for many. Confidence in this scenario is now about as high as it can be at 168 hours, and before too long we can begin to look at what may follow. So - why such confidence? Leaving aside the MetO reports/video (which if interpreted say a lot....) and GP's tongue in cheek comment about the comparative EPS / GEFS suites there are a number of reasons to be approaching the kind of confidence in product that was possible for the Beast. Ensembles first - EPS ensembles have been rock solid now for days, and the depth of the trough anomaly over NW France is the strongest low pressure anomaly in the NH for next week. Note too the strength of the high - and the expectation therefore that this trough is going to drop hard and fast down and through the UK. Snow chances increasing by that fact alone. Berlin strat slices are also revealing - at 50hpa we have a very slow westerly average now, and a main vortex lobe to our east that has shunted way over the Siberia at 240h However a residual strat trough lies across Asia and Europe....and heights to the NW are forecast to build as energy transfer across the north atlantic simply dries up. 150hpa image shows the approximate end result, also at 10 days There is less of a straight easterly component to the forcing at this point than we had back in Feb, so no scandy hieghts yet in all probability....but as the arctic high strengthens in response to the downwelling of negative anomalies from the last couple of weeks it looks likely to me that easerlies by month's end and into Feb...and maybe more scandy heights in time. And tropospheric forcings? Calculated GLAAM tendency currently is stalled - but awaiting an anticipated uptick which will produce more of a shove for high lat blocking in the 10-14 day period probably, just at the same time as the strat impacts are peaking MJO has been advertised by others to be re enteritng 6 - 7 - 8 before too long. All of this is just fuel to the stratospheric fire. So - if we are to see a fail where will it come from? Not from a rampant stratospheric vortex. Not from a flat Nina signal in the pacific. Strong trough activity off Canada as very cold air hits warmer seas? It will certainly create some sparks via a steep temperature gradient - but is there enough westerly momentum at present to send this through the blocking signal and flatten everything out (as GFS, with its less good strat model keeps playing around with)? Cant see it. Downwell timing has done for that option. Might even help by putting a bit of sparkle into what is left of the jet as it splits/dives south and feeds the trough over time. Solar uptick as per Dec 2012 when everything went t*ts up? Spaceweather currently reads "Spotless Days: Current Stretch: 8 days" - so not a spot in over a week. It's about as good as it can be. And to finish - a look again at the forecasted 850hpa anomaly out east. This has strengthened considerably - now forecast to sit at -8 to -10 from normal in parts - so once we get more of an easterly feed come month's end it is potentially going to turn extremely cold. Time to look in detail at that scenario later. For now - Tues/Weds is going to be interesting and the more cold air we can get in situ from Thurs/Mon the better things will be. 850 temps for Mon as the trough prepares to dive/slide look pretty good to me as a starter of the spell. It isn't going to be diving into warm air that's for sure. Marginal event - but someone somewhere will cash in. And with luck we all get some of the action soon after.....
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