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  1. 112 likes
    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. 89 likes
    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
  3. 75 likes
    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...
  4. 68 likes
    Leaked express headline for tomorrow. #sorrynotsorry
  5. 66 likes
    Afternoon All I guess a few of you/us are wondering whats going on with the weather this weekend & into next week... Strange, almost 'texbook' cold charts appearing in the models & actually landing with some degree of accuracy.... Well like many - you are probably wondering if its a precursor to the rest of the winter or a lucky double 6 roll in November.... Based on the information at hand I would say the nina base state forecasts of mild westerlies into december & throughout are going to be wrong & on very shaky ground - Looking at the current picture & the run up to the start of the winter season I commented on TWO about NW winters getting more extreme - The NOAA data for AO & NAO show the modes of these metrics becoming more & more diverse & when in a particular phase ( whether that be pos or Neg ) so the metrics would be topping / bottoming out at at close on record breaking levels - The whole post was in reference to the M.winter theory from IBrown To underpin this ( but without the data ) in the last 15 years we have smashed the AO record at both ends so many times - months like Dec 10 / Mar 13 spring to mind- but also the extreme mild ones as well ! However also in the post was the fact that steadily the incidence of Negative months had reduced in favour of more positive ones- so with Heinsite the M.Winter theory carries some weight but poorly communicated without all the facts- What also has become Crystal clear is the fact that the M.Winter or whatever you want to call it could be under attack by more front loaded cold winters especially when the total atmosphere favours a negative state of AO/NAO with winter 17/18 being just that- Post M.Winter ....? The fallout from the polar ice melting is creating massive impacts on the way the jet behaves in November in particular - The fuel needed to ignite the jet is simply missing in action - probably due to the self perpetuating feedback loop that develops at the same time as when the jet & vortex should be positioning over the pole ( Early Nov ) The chart below shows the current surface temp anomaly for November up until 22nd The green scaling is about 7-8c the orange & red 10-15c vice versa blue about negative 5-10 If you look close at the map the dividing line is generally alligned to 60N where the jet is usually located. We have a reducing in measured gradient by around 15-20 degrees > this essentially acts as a neutraliser on the jet- for which we are now feeling the benefits. This troposheric lead feedback is a far larger beast than El nino or La Nina - it covers the entire space North of 65N & a large part of Russia - It certainly needs a name so I am calling it this - Calido el hielo !! What we have is a troposheric feedback loop that feels lime it can run disconnected to the strat until the anomaly becomes muted but the inevitable increasing gradient as we had further into December & the strat can work its way down... So a watch out for future Novembers that Calido el Hielo may be creating more blocked extreme ( warm or cold ) Novembers.... Moving back to the hear & now we are in a rare situation, one of only 6 occasions since 1979 in winter ! of these 6 the EQBO years being just 2. 1st Jan 85 ( Front loaded EQBO ) 20 Feb 01 - So whats infront of then ? A troposheric induced stratospheric splitting event - the net being a massive deceleration of the zonal wind lagged about 10-15 days later. I would go with our splitting event to be dated 29th NOVEMBER !!!! ( This is why I kept referring to 31st Dec 84 in the model thread ) Here was the Jan 85 & feb 01 charts & the associated stratospheric response ( lag back down ~ 10-15 days ) Then importantly the following months anomaly After +10days lag * The key notes here are that the troposhere is primed for polar blocking with a core towards Greenland- Also low euro & Azores heights present... Now, Taking our event to be 29th of November we should see an immediate stratospheric collapse of the zonal wind & from about the 4th-5th & The blocking anomalies to be present from anywhere around the 8th onwards- Lets look at this mornings outputs - these are GFS based & depict a total collapse of the zonal wind - with this depiction being the daddy - showing a -35 M/S hit on the zonal wind which is a reversal at 10MB .... Jan 85 Merra data shows a reversal down to -15M/S Feb 01 shows bottoming out -3M/S So this is why the GFS / ECM are spewing out all this blocked data for first / Second week of December- Based on the science of the lagged troposperic response the 6-12th Dec will be peak for blocking & subsequent cold UK potential with Greenland being the favoured location a Below ave December / Front loaded winter is odds on favourite for me with a high probability of some very special charts appearing! fingers crossed.... Best S
  6. 65 likes
    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....
  7. 62 likes
    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.
  8. 61 likes
    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....
  9. 58 likes
    So sorry to hear that mate Dont want to clutter up this thread but im sure i speak for everyone in wishing you the very best and hope you will be ok.
  10. 56 likes
    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.
  11. 56 likes
    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.....
  12. 55 likes
    I'm here - been working and have also had to pick myself off the floor after checking the 12Z. Best ever trop response that we have been able to track following a SSW, oh those of little faith lol. I did think of buying all the snow shovels and salt in B&Q yesterday and then selling it back to them next weekend.... I have been convinced of an epic cold spell for a long time now (since before the split but my resolute belief was reinforced when I saw the residual Hudson Bay daughter vortex getting taken down). It may have taken the best part of 10 years but finally we are seeing the makings of an epic spell when you take the strat vortex out of the equation. Even @TEITS may finally have to concede that there is something in this teleconnections Malarkey!
  13. 53 likes
    So I mentioned earlier on about very high angular momentum levels, which would normally be associated with a strongish El Nino. GWO in high amplitude phase 6 orbit, expected to move towards phase 7 as the MJO component moves through the West Indian Ocean this week. There is a persistent +ve momentum signal across the tropics and sub-tropics which is holding up this unusually high angular momentum signal. Not much scope for a drastic drop in inertia although frictional torques are as expected strongly negative. When the MJO signal swings through the East Indian and Maritime Continent, angular momentum tendency will rise, driving a phase 5 projection in the GWO around 10th December. Composite: This doesn't fully capture the blocking signal over the Eastern Arctic, so some manual adjustment on this required, but the key messages - Alaskan trough, +ve height anomalies to the NE. GEFS for that time alongside the composite: Again, don't get hung upon on exact placement, the broad gist is that at that range, reasonable confidence that the GEFS mean is about right. The strong presumption from there would be for a phase 5-6-7-6 type evolution (herein the beauty of a conceptual model): There is some manual adjustment necessary to these to inflate +ve height anomalies to the NE and reduce +ve height anomalies to the west of Greenland, but some westward pull of the man trough over the North Pacific is the key thing here. That allows any blocking to our NE to manifest itself, and would consolidate a monthly expectation for +ve height anomalies across Scandinavia. Either way, a challenge to any view of returning zonality at any point during December.
  14. 52 likes
    The atmosphere is now reflecting a Nino state and has been for a while - and that chart is a change over the last 30 days chart. The actual anomaly charts look like this Still very much Nino and not Nina. What the oceans look like come March is of zero interest in any hunt for cold now, and any moderation in Nino over the next 6 weeks will not make a real impact on this winter's season. This tweet is frankly nothing more than a scare story. His twitter feed is extremely uninspiring and rather basic. Nothing to see here - move along...
  15. 52 likes
    All this fuss about downgrades - 'chill' out ! Looking at two runs 24 hrs apart so examine the same time stamp - from last night's 12z to tonight with a helpful Polar Bear diagram included. As you can see the Polar Bear still on course to arrive, just a slightly less ferocious looking bear this evening..
  16. 51 likes
    I don't think there has really been a signal for snow pre-SSW or immediately after, looking in depth at the drivers, I admire your enthusiasm to put a dampener on the outlook despite the overwhelming pointers from the likely impacts from the eventual SSW downwelliing in concert with lag of MJO moving through colder phases (7-8) plus other drivers such as anomalous East Asian Mountain Tourque and +AAM which will help amplify the flow at high latitudes. It has been stated on here by me and others that there was likely to be a few weeks after the SSW started until the impacts were felt in the trop and also the lag of the MJO now headed into 'colder' phases. I think the main reason why we have been stuck and continue to be stuck in this pattern of waxing and waning mid-latitude block with all the upper flow energy over the top, but increasingly flowing NW to SE into the deep eastern Euro trough is to do with not just a strong Pacific jet extension but also the lag effects of the slow MJO stuck in phases 4 and 5 between mid and end of December, these are ‘warmer’ phases that tend to be hostile to high latitude blocking bringing cold to the UK but favours mid-latitude blocking and cold for E/SE Europe. The reason for the slow MJO propagation down to a few likely factors, that were mentioned a while back, including equatorial Rossby waves moving westward along with –AAM which have interfered with the eastward MJO propagation. Also the wave driving into the stratosphere weakening the SPV has probably constructively interfered with the MJO propagation too. However, the MJO now looks to speed up through 7 and 8 and although GFS and EC take into the circle of death (COD) / or MJO dies off over the Pacific, the phase 8 impact on the patterns should remain once MJO has gone into COD, so shouldn’t be duly concerned with this. The downwelling of easterly winds from the strat to trop still forecast and this will be a big driver after mid-month. 9th Jan 14th Jan So although the charts look crap atm, due to the background signal explained above, we should hopefully see the models pick up on better patterns for sustained cold and snow potential for us in week or so as impacts of SSW, MJO colder phases, +AAM/EAMT work through.
  17. 50 likes
    Well the models are having fun with everyone, up down, roller coaster covers it. But in the quieter world up aloft what has been happening? Obviously it is the 500 mb anomaly charts. They are means so do tend to be less up/down compared to the synoptic 6 or 12 hourly outputs. Indeed I would suggest it might be a better idea to simply look at the synoptic 500 mb chart run to run or better still to compare like runs, you may have heard that somewhere else before! Anyway The ECMWF-GFS this morning Not surprisingly they are not that different to what they have predicted over the past 4 or 5 days, see below Atlantic ridging towards Greenland and EC still with GFS now showing a building of ridging over Scandinavia with an extension west towards Greenland. Something that the occasional run on the 6 hours outputs has suggested. Marked troughing on both remains into Europe. The configuration on these two shows lower contour heights on EC compared to GFS. However on both the upper flow shows the cold will persist over the next 6-10 days. Okay it may wax and wane but no signal showing for any mild air for the UK. So what about NOAA and it has a chart that covers 8-14 days out. The 6-10 last evening, largely between the UK and Scandinavia well north with the flow dropping into the European trough. About a week ago the contour flow had the slightest hint of this. The actual +ve height anomaly is show away from any of this, just off the American coast. With such a meridional flow obviously the contour heights over the UK area are higher than the other two. This has little effect ob surface temperatures, indeed if there is any surface ridging in between weather systems might create lower values at the surface. To me the strong flow out of America does leave a question mark for day to day. Will any deepening systems move NE or SE once into the eastern Atlantic? With the deep trough east of the UK one would expect them to steer SE or ESE, which may provide some excitement if they get close to the UK. Looking at their 8-14 day chart and perhaps the most interesting change from the 6-10 is the increase in –ve heights over NW Europe. Again little signal for any mild air. That is unless we get a flow not easterly but SE/or worse SSE with air originating from the Med. Nothing to be concerned about in the next 6-10 days but a possibility beyond that. So, overall the cold will continue, the synoptic models will come and go so to speak on its depth and ideas on where/when any ppn will occur. Up to 24 hours out forget what the models may predict, they are right a few times at longer time scales but not often. Just think back to summer set ups and how often they get the rainfall correct? In winter there are another 8 or so additional variables to get right. Hope this summary helps calm the nerves a little. http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html
  18. 50 likes
    yet more output upgrades.....*yawn* change the record, it's boring now....what a boring climate we have, all it seems to want to do is snow all of the time and blow hoolies from the east.....I've heard about this mythical beast called a 'Pest from the West' influenced by a body of water called the 'Atlantic' (no, I've never heard of it either)....Perhaps one day we'll get out of this boring rut of incoming weather and get to see one of these mythical beasts again?
  19. 50 likes
    If I may clarify a point here. I have absolutely no idea who are members of the so called "mildness" gang but I am certainly not one of them. It is no secret that I detest cold weather and I do so mainly for two reasons. Firstly, the imprint of 62-63 will forever remain with me and secondly, and far more importantly, as a vulnerable, elderly pensioner, and of course I'm not alone here, cold weather very much affects my health. But none of that is relevant as to how I approach the model output, which in my very simplistic manner, is based purely and simply on a meteorological analysis. Preferences and deliberate bias are no go areas.
  20. 49 likes
    Would normally not put a one liner on without charts - however given the paywall status of the EC Ens and clusters, all I can say is think - weeklies. Today will be a good day The roller coaster is firmly back on the tracks and heading for the winter theme park.
  21. 49 likes
    Very very interesting situation. I'm at work and away from my links, but I had a quick scan this morning before jumping out the door, and left with these thoughts: 1. Modelling of the azores high is going to be problematic. The record spiking of the current mjo is creating anomalously high westerly additions which currently sit nearly 2 standard deviations above the climatological norm for this time of year. We know this is working against our Nina background and as every day passes confidence grows that this nino style imprint is substantially gaining the upper hand. For the azores high this is very bad news: the sub tropical easterlies are falling and will continue to fall, and support for the azores ridge will begin to collapse. The spike is so great I wonder whether the modelling will nail it precisely, and the GFS in particular has a known bias against these setups. Long and short of it - I expect the azores high to be overmodelled over next week and more reduction south and west to occur. 2. Knock on effects of this are a greater chance of some milder air creeping into the mix BUT also a greater chance of precipitation. Cant have it both ways. 3. The modelling of stratospheric wave 2 impacts is also growing in substance. Some fabulous graphics out on twitter yesterday showing wave breaking against the Scandy/Russian block slicing straight through the vortex and giving us the almost perfect split... with high pressure in control to the north and a vortex shard skimming southwards to be placed over Europe. This is a medium term impact - GP nailed the timeline in a post not long ago on the strat thread as week after next, with impacts to be felt between 1 and 3 weeks afterwards. This means right through the month and possibly into March. The fact that CFS has now called a cold Euro continent for March suggests one model at least sees the vortex damage to be long term - though never take that as gospel. However its good to see. 4. Chio commented recently also that the vortex split looks to be trop led rather than the more conventional downwelling event. I have to tread carefully when talking about the strat cos my knowledge lags a long way behind others... but a trop led event, to my eye, adds longevity to the setup particularly given the climatological tendency for the vortex to wane the closer we get to March. It also allows the effects of the split to be felt much more quickly. Strat experts - please jump in and correct me on this if it is a wayward view.... Bottom line? Double whammy (perhaps linked double whammy?) of major MJO event and strat split (with possible reversal but that would be jumping the gun a bit...) gives is a chance of a sustained spell of that "perfect" scenario for western areas: entrenched continental cold sparked off initially by falling AAM in northern latitudes allowing a block to build combined with decline of azores influence followed by reinforcement of the cold as a result of the split vortex. All this then setup against a westerly flow off Canada that is already bitterly cold thanks to the season's tendency of the vortex to set up shop over the NE American continent and ongoing expectation of these fronts bumping into the block. It's potential nirvana. For eastern areas the strength of the easterly flow will dictate depth and extent of streamers (if they form) and there is always the chance of a Feb91 scenario with a front spawned from the south heading north. Can anything go wrong? Of course. That record breaking MJO could collapse in the face of strong Nina background forcing... but as said at the top: this is looking less and less likely as each day passes, and we are a lot better off already than we were in December when it collapsed previously. We could also get a sudden burst of solar activity - there is a theory that his is what did for the infamous Dec 2012 non-event. but right now the sun is extremely quiet. Long may it stay that way - enhanced solar input would pep up the jet and threaten to push the block back east. Or the forecast split vortex could fade - remembering particularly that it is at least partly dependent on the MJO creating the trop pattern to create the wave breaking in the first place. Treat the MJO with kid gloves - we need it well looked after. :-) I'm optimistic - though I tend to be optimistic in cold scenarios and that probably skews my judgement a bit. However the blocks are all in place for February to deliver... and significantly perhaps for this to be a long term event rather than a 2-3 day blast. Bring on that cold front on Tuesday, watch the azores high fade, the scandy block push west and then bumpers begin to approach and slide. Friday's ECM - a long way off admittedly - has the makings of a decent event occurring over already cold ground and entrenched cold aloft. With luck the south are about to get in on the act at last this winter.
  22. 47 likes
    Morning! If there is one thing that sums up the current state of model output it would be the following…. Yup it’s at a crossroads and this is particularly fascinating as I will go into some technical detail below and how this is relevant to the model output. Hopefully this can be clear to other members and it will give an idea of what I am looking out for. Background So, first some context…. The UK winter is moderated by the Gulf Stream, warm ocean currents move north from the tropics and help prevent the UK from being as cold as somewhere like Moscow. The diagram below shows a picture of the ocean currents. Warm air directed to the UK from Gulf stream Now interestingly there is evidence to suggest this is slowing down which generally should mean a negative feedback in the northern hemisphere due to a decrease in heat transport. Just one problem… the strengthening of mid latitude highs and deepening of polar lows means the Eurasian continent has warmed substantially during the winter months. Trends in SLP since the 1950s (Gillett et al 2005) So where is affected by this negative feedback?, well the below diagram clearly shows one place. The central North Atlantic. Looking at warming trends in the figure below we can see that this region has actually got cooler over time, in stark contrast to almost everywhere else. IPCC, global temperature trend from 1900-2012, spot an anomaly? This is now referred to as the North Atlantic cold blob and I believe it hurts our chances of cold winters. Look at the last 4 winters. These have been dominated by more frequent then usual westerlies and the North Atlantic SST profiles are seen below. 2013/14 2014/15 2015/16 2016/17 February 2018 - See a pattern developing here? To get a cold anomaly in this region it requires cold air from NE Canada to pour into the North Atlantic…. And how is that possible? Yup with a polar vortex camped to the west of Greenland. So with a slightly weaker AMOC and an intensification of mid-latitude highs we have a pretty poor combination of factors for UK cold whereas in the US it ain’t so bad. That is why the US still sees these big cold air outbreaks from time to time. So how can we break this sequence? Well other factors also influence our climate, extreme MJO phases, low solar activity or a dramatic slowdown of the AMOC can do it. In December 2009 this is precisely what happened. With the increased warmth nowadays, if this is directed to the arctic it can really shunt the PV for long periods of time. Just look at the anomalous arctic warmth in 2010. December 2009 - Bullseye Indeed this pattern persisted until January 2011 but a very strong La Nina signal prevailed for that winter later on. Other alternatives are extreme MJO phases (the phase 7 signal recently helped build Scandi highs to our east, though they weren’t that strong) and deep cold pooling just to our east. However the warming arctic and more intense mid latitude highs makes this more difficult. Just look at the last 4 Februaries + this January and their temperature anomalies. Continental cold can stop the Atlantic in its tracks. In 2013 we got lucky and February the arctic was actually colder then normal. This cold air spilled into Scandi and in combination with the SSW event, this was allowed to stem the Atlantic tide and as a result we got a very cold March. Battleground in the model output So where does this lead? Well its of my opinion that we are seeing a more volatile NAO because positive phases are amplified by trends in mid latitude highs. Negative phases are amplified by increased warmth heading to the arctic. Just look at the NAO values for each winter since 2006. 2006/07 + 1.81 2007/08 + 1.34 2008/09 - 0.31 2009/10 - 2.71 2010/11 - 0.84 2011/12 - 2.08 2012/13 - 0.58 2013/14 +2.05 2014/15 + 2.04 2015/16 + 1.84 2016/17 +1.12 Bear in mind any mean value over one is considered extreme So Yup we are at a crossroads, will the organised polar vortex drown out the SSW again? Will there be more cyclonic westerlies? The current SSW event is fascinating because of its location shown below. Additionally if the pendulum swings the other way then we could see the strong negative NAO months make a return with an exceptionally warm arctic/Greenland. It seems conditions are becoming increasingly favourable towards the cold air in the North Atlantic persisting in the winter months and more factors need to come together to overwhelm it. We came so close early on in the winter and if this had succeeded then the winter NAO I believe would have turned strongly negative. The critical point highlighted below. I believe the struggle to overwhelm the North Atlantic cold pool is what is leading to some of the disappointing runs from the ECM. Will we succeed this time though and cause the see-saw to swing the other way? I believe if it does, it will help next winter too. At the moment its hard to tell, the ops look poor but ensemble means are more intriguing. GFS ECM Hope you enjoyed reading my thoughts and have an insight into what to look out for in the model output! This is an educated guess but it is what I believe. Quicksilver
  23. 47 likes
    Please excuse me once again quoting my own post - but continuity shows that there is an obvious clear stand-off between the models on the way ahead from this weekend with different model interpretations of how tropical>extra tropical forcing manifests itself in the forthcoming period. Which in simple terms determines the amount of amplification available for cold air advection sustaining to any given time My suggestion of keeping powder dry and an open mind in terms of these differences looks to be relevant well beond the shorter/medium term. There are going to be plenty more NWP skirmishes to come beyond the early question marks of what follows straight after this weekend. Best not to overreact to the GFS interpretation which is indicative of upstream tropical forcing being more restrictive at face value, at this time - and as a consequence delivering a much more 'La Nina-like' solution with quickest return of Canadian vortex induced downstream cyclonic energy. I see that Catacol has provided a thorough summary of the technical background to this, and which follows a pm conversation I had with him this morning, so there is little further for me to add to that.. But the implications of forward moving momentum in the tropics mean that processes start happening which in time propagate to the extra tropics - and these become vital to how the longer term plays out. One of those starting processes that accompanies an upward shift in angular momentum tendency is a corresponding upward shift in frictional torque tendency in the tropics - and which has consequences over a considerable period of time in terms of what it can do to the longwave synoptic pattern in the extra tropics mid and higher latitudes. What is this frictional torque and what exactly is implied by it? Atmospheric angular momentum in simple terms refers to the amount of turning force in the Jetstream. The balance (or budget) of AAM is determined in very simplest terms by the net amount of both easterly and westerly wind-flows that are present at any given time in the atmospheric circulation. If there is excess easterly wind inertia in the global jetflows, at any given time (c/o La Nina trade winds propagating to the extra tropics), then this has the effect of lowering angular momentum tendency and producing a -ve frictional torque at the surface. The frictional torque refers to a pressure differential created from the point of where easterly winds are added and westerly inertia is scrubbed from the atmospheric circulation. Divergence across the tropics, where the trades are found leads to the spin-up of sub tropical anticyclones which align from west to east circum-globally. One of those sub tropical ridges relevant in our sector is obviously the Azores High. This has, as expected, been a prominent feature of this winter so far and has meant that cold air incursions have been based on mid latitude amplifications. We see this coming week how the Azores High plays it part as an amplified mid latitude feature once again in introducing another cold incursion to the UK. The longevity of this phase comes down to what happens in the tropics over the coming medium term period, and pertinent to the discussion in this post, how much frictional (ocean) surface torques and extra tropical (mountain torque) mechanisms can be altered (upwards) by increasing angular momentum tendency. The consequence of a sufficiently robust eastward moving tropical signal is that the subsequent eddies in the windflows (produced by the significant alignment of tropical thunderstorm activity on a macro scale) tend to flux poleward with time. This means that an amplification mechanism is triggered which follows the principles of a stone thrown into a pond, and the ripples spread out according to the size of the stone and also how far away from starting base the stone is thrown, So poleward motion of flux, +ve frictional torque tendency in the tropics can lead to +ve mountain torque tendency in the extra tropics according to the size of the initial 'splash'. The size of the splash of course relates to the size of the tropical forcing advancing eastwards through the tropics, and if there are differences between models as to the strength and longevity of that signal, then the consequent downstream amplification signal is going to vary from one model to another What of the implications of +ve frictional torque in the tropics and +ve EAMT in the extra tropics? The shorter term product of a good amplification signal is of course the ability of the initial amplified Atlantic ridge to extend into Scandinavia, with a split jet that enables 'appropriate' jet flow over and under the ridge to support it, and enable the 'horseshoe' configurative return of the jet back SW'wards to assist cold air advection this way. But as suggested in the stratosphere thread by chiono, an H500 pattern being one of Scandinavian heights and upstream EPO ridge is one that aligns itself suitably to externally pressurise the vortex. This has, as stated, extended term implications for potential SSW much later in the month/ early Feb. But also there is the poleward effects of +ve torque mechanisms to perturb the vortex internally as part of a tropospheric tropical>extra tropical mid/higher latitude>stratosphere disrupting mechanism. The wavelength/timeline of a programme of +ve frictional torques implies a dismantling of the sub tropical ridges through westerly winds added through the tropics by eastward moving convection to scrub the La Nina easterly trades from the atmosphere that underpin those ridges. That is in addition to lagged effects of extra tropical +ve mountain torque effects that deflect warm air advection into cold vortex segments If a programme of higher heights and a -ve AO profile is to be created by a combination of poleward fluxing +AAM anomalies as well as a wave 2 activity response from a height profile each side of the pole, then the domino to fall is the weakening of the Azores High to facilitate undercut and remove the +NAO profile. It is this that restricts us to what we see this weekend that depends upon maximum amplification of the Mid Atlantic ridge to achieve a Scandinavian High, to one where the Pacific forcing pattern, that is a-typical of La Nina, can override the base state forcing and engineer maximum downstream capital c/o split-flow with enough energy going into the southern stream to undercut heights to the N and NE. This happening in the absence of a sub tropical ridge, that is both a natural feature of a La Nina pattern, but is also counter-intuitive to developing a -NAO to assist backing cold air west c/o of a -AO profile I suspect however the on-going shorter term Atlantic ridge>Scandinavian ridge plays out vs Canadian vortex, this will be a cat and mouse theme to dominate January and we will be relying on the Azores High playing ball according to (and dependant on) the relative level of atmospheric angular momentum - and to the extent the Nina trades are mitigated to allow undercutting energy. The undercut has remained elusive this winter so far in the midst of quite an amplified mid latitude pattern Can the extra mile be achieved Very long post again, but so much to watch out for - only just ahead of the next ECM...
  24. 46 likes
    If we take the ECM at +168 two days ago And compare it with the ECM +120 from tonight You can clearly see that as we’ve got closer to reality, the model has; 1) Underestimated heights around Iceland area 2) Has started to disrupt the trough to our west more, it is more negatively tilted and a little more elongated. 3) heights in Europe lower than previously modelled If that trend continues in the next two days and the same for the subsequent frames after this, perhaps Day 10 will look a lot different come T+0 than it does now. This is the same for GFS too, not just ECM. Uncertain outlook but certainly upgrades in the mid term from the models. UKMO pretty solid. Going to wait a couple of days at least yet.
  25. 45 likes
    Its only an island if you look at it from the water A textbook example of where an amplitude MJO wave lead the atmosphere on a surging poleward +AAM rally and which in turn created a bitterly cold high latitude blocked pattern from the first week of February and which lasted well into the month was in 1978 January 1978 closed out having featured a lot of the cold zonal pattern which has featured through quite extensive parts of this winter, and which favoured northern parts of the UK mostly. The very distinct difference back in early 1978 being that the global atmospheric circulation was pre-disposed to a Nino-like forcing which was setting in place a tropospheric>stratospheric pathway that was conducive to supporting poleward +AAM anomaly wave breaking. A reflection of how close we have actually come to achieving a properly cold winter in 17/18 - if the a-typical La Nina east based Pacific tropical forcing had prevailed and kept angular momentum in the elevated state it began the season. GLAAM: globally averaged angular momentum: Jan Feb Mar Apr May June Jul Aug Sept Oct Nov Dec 1978 1.75 1.75 1.54 0.81 0.17 -0.07 -0.27 -0.26 -0.22 -0.20 0.20 0.93 For info http://www.esrl.noaa.gov/psd/data/climateindices/list In a year as a whole that was to all intents and purposes of a neutral ENSO persuasion overall, I bolded and underlined the +ve GLAAM figures for all the winter months, and note how they are all book-ended early and late in the year. A further clue there how the classic finale in Dec 1978 evolved through further tanking angular momentum set against the base state, and renewed -AO and -NAO But back to what evolved in Feb 1978. Soaring +AAM induced the Global Wind Oscillation into the El Nino attractor Phases 5 and 6. The synoptic pattern moved into the sort of classic Nino pattern that can occur when the stratospheric field is weak and unstable (December 2009 is another very good example). Heavy convective snow showers for many, widespread severe frosts and culminating in those spectacular 'battleground' blizzards in the SW as the Nino feedbacks from dateline MJO forcing induced the southern stream and classic undercutting -NAO. Anyway, the point of all that nostalgic snow-fix is to illustrate the importance of having an co-operative tropical>extra tropical>stratospheric poleward loop in place to buoy the troposphere and to complete the task in terms of a stratospheric vortex which is vulnerable to such +AAM forcing. The skeleton troposphere/stratosphere pattern this winter at face value has been vulnerable to such forcing, but has so far achieved what would be considered a get out of jail card. Clearly, with the overriding La Nina forcing proving too strong, we have been lacking that missing link in the middle and why any high amplitude MJO wave, that becomes possible with the warmer waters in the western Equatorial Pacific, needs extra tropical co-operation to enable the troposphere>stratosphere pathway to be completed. In synoptic terms, effectively mimicking a wave train that is more akin to an El Nino and induce jet flow away from the polar northern branch, with weakened sub tropical ridges (that have been strangle-holding the on-going pattern), and instead energy flow into the southern stream assisting an -NAO. The coming month still holds a lot of interest - and one eyebrow at least is now being slowly raised. There is no denying the suggested strength of this MJO wave, which has actually been upgrading in prospects with time - and with signs emerging that this Nina maybe has been having its last proper 'hurrah' as sub surface waters in the Equatorial Pacific return closer to normal, then its not impossible on the back of the latest still increasing tropical momentum, that a significant +AAM surge might not evolve to lead the trend. In order to support that hypothesis however, some conclusive evidence from the extra tropics is required, and would be highly satisfying to see over coming days to prove that the undoubted momentum in the tropics is set to start putting in place the decline of this La Nina. To put that decline in its perspective, that means that the expectation is to weaken towards neutral heading into the Spring. But in that sense its not the base actual state that matters - its the direction of travel that would unquestionably make tropical/extra tropical co-operation more possible than it has been proving, and complete what has been the missing link. Lets hope its not too little too late - however if the direction of travel firmly becomes one of poleward +AAM that transfers on a sustained pathway out of the MJO tropics, then the chances of turning a frustrating pattern into something more interesting definitely increases.
  26. 44 likes
    This next 'evolution' is all about the speed & deceleration of the pacific jet & how far east the Low at 168 gets & how the 'tilt' of the low supports the cold Not sure where this cold for +10 days or 12/15 days is coming from. Its day 7!!!!!! The UKMO ( as already highlighted ) has been performing much better than the GFS in terms of non bias Eastwards, & as we stand tonight would be poised for the greatest advection of cold @168- Ive annotated the 144 charts to show the differences showing why they may or may not 'project east' hint hint.... In Order -UKMO/ ECM/ GFS The UKMO is the slowest & most amplified with a negative tilted low & support for a greater blocking wedge ahead of the low pressure, this run would project the coldest outcome @168 >192 with the most amplified trough axis & a high likleyhood of the mild 'bump' of warmth hitting the UK 192/216 - or at least seeing more of a glancing 'slider' impact across Ireland / SW. GFS is positive in the tilt indicating more forward speed & less block, which to a certain extent is supported by ECM with its neutral position, ( Glancing at the ECM 12z mean - looks more UKMO ish ) Expect ECM op to be mild outlier day 8/9/10 So tonights summary would be similar to the forecast from 3-4 days ago where we say the UKMO day 6 chart almost spot on- Which is..... UKMO / ECM blend with the low, maybe UKMO to negative, ECM to neutral so the middle ground- GFS to far east with its 'positive tilt' look for that to correct... The upshot of all this will mean the -8c line is further south & west 168-192 & also atlantic inroads into the UK less progressive. At the moment the model theme ( from 120 ) is more indicitive of cold zonality with the treasure at the end of the rainbow day 9/10 however UKMO indicates that the day 8> 9 blip could actually be a slider snow scenario... Have a good one S
  27. 44 likes
    The above summer forecast verified reasonably well in most cases, the prediction implied a top ten outcome and in fact the summer was around 3rd to 5th warmest on record depending on which data you used. The CET predictions of 16, 18 and 17 compare with 16.1, 19.1 and 16.6 for an average error of 0.53 C deg, and it has to be kept in mind that August was running close to 17 until around the 23rd with a very cool finish. The overall prediction was closer, with an average error of only 0.27 C (17.0 vs actual of 17.27). It was a dry summer in many parts of southern Britain and southeast Ireland. The magnitude of this drought was probably underplayed in the forecast. As for North America, it certainly did turn into a scorcher of a summer in the west with widespread fires in western Canada in particular. We were dealing with noxious smoke on an epic scale for much of August (although I was away on holiday in clearer skies down south) and the first week of September before the activity finally subsided. The tropical season has not been keeping pace with the forecast although it could still work out fairly close, and Michael alone is worth several ordinary hurricanes I suppose. ... well, I won't make a big deal about this forecast because basically I think almost everyone expected this sort of summer after the spring blocking, so it is now on to the winter of 2018-19 for the next instalment ... Long-Range Outlook for Winter 2018-19 As always, my forecast is based on a blend of traditional concepts and exclusive research into "index values" on the assumption that at least some variability in the climate can be linked to variations in the solar system magnetic field (a complex response to relatively small changes in solar wind output and effects on the earth's linked atmosphere and magnetosphere). It is looking quite cold compared to normal for Britain and Ireland, in particular later December and parts of January. However, this appears to be dependent on a strong jet stream either shifting far enough south or relaxing for periods of 1-2 weeks, and the intervals between the cold spells could be quite stormy at times when the jet stream is roaring at full capacity. The research index values in particular go far colder than I have seen them for the past several winters, indicating many analogue cases that were very cold winters. Looking through the analogues, I find that periods around late December into early January, and mid to late January, were favoured for the coldest weather. This is also favoured by assumptions made about lunar modulation of the pattern, which is how I have come to see the lunar influence, not as a driver so much as a shaper of larger signals from the other players at work. Another consideration is that we are well into a prolonged solar downturn and so there's nothing in the larger solar-weather paradigm to contradict the notion of this being a colder than average winter. We are in a similar position to the period 1819 to 1823 which had numerous cold winters but it's not a guarantee by itself to be in this sort of regime. I've seen some discussion saying that perhaps this won't be the widely expected "big one" and perhaps we'll need to wait another winter or two, but I have no way of choosing which one is the big one from the coarse assumptions that one is forced to make using only a solar-weather paradigm. The past summer season in the central Canadian arctic was exceptionally cold. Resolute for example had no month warmer than the 1.9 average in July, and that is the lowest such statistic on record in recent times (the record began in 1948). This has been followed up by a large-scale southward movement of a cold anomaly over central Canada that has people commenting that winter already began in the prairies in early September, with snow often on the ground. This anomaly is almost bound to be followed up by a persistent trough around 90 to 100 W longitude. That in turn would favour west Atlantic blocking and a downstream trough between 10 and 30 W. Although that's a little west of the "sweet spot" for a cold winter in Britain and Ireland, I feel that it may be a high amplitude pattern that will induce Scandinavian blocking highs, and cold outflow from those despite fairly high 500-mb heights in western Europe at times. And the pattern could oscillate east-west enough to place the trough over Britain and Ireland at times. So I am predicting a notably cold winter but with high variability possible leading to alternating spells of wintry cold and stormy fast flow situations. Another factor that may prove significant is that energy levels will be highly concentrated near the full and new moons this winter, perhaps more so than has been the case in most recent winters. I expect this to translate into alternating periods of very unsettled, stormy weather around those lunar dates, and relatively long settled intervals between them. The settled intervals are likely to be the times when blocking will deliver the colder air masses from an easterly or northeasterly source. But there may be some tendency for the disturbed intervals to remain cold and turn more northerly. This could add up to considerably more snowfall in the heart of winter than we've seen for quite a few seasons, in contrast to last winter's concentration of snowfall near the very end of the winter season (27 Feb to 2 March was very snowy in some regions). I am aware that this represents a high risk forecast, especially given the tendency of recent winters to resist opportunities to establish potent blocking. So it won't absolutely surprise me if the result is some kind of weaker compromise where some cold and some snowfall develop but longer intervals remain relatively mild. I don't foresee a really mild winter being likely given these background conditions, and I do have concerns that the volatility may produce some exceptionally stormy intervals. This pattern may persist well into late winter and March may not see a lot of change from it, except that by then the energy level considerations will be more evenly distributed into four peaks rather than two per lunation. That separation during February may lead to a peak in snowfall since the peaks will be somewhat less supported and that could be reflected in a more persistent blocking pattern. As to the dates of the stormy episodes, those appear most likely to fall around 19-22 December, 3-6 January, and 16-20 January, and there could be heavy rainfalls in the south during some of those intervals as colder regimes are pushed back to the north at least temporarily, but as time goes on the chances for snowstorms likely increases with each of these windows, then towards the end of January it may be more of a sea-effect snowfall opportunity with the storm track pushed much further south into Iberia and the Mediterranean. During the anticyclonic intervals that are likely to peak between those stormy intervals, we could see some unusually low temperatures especially if snow cover has been established towards the transition from stormy to settled weather. In the run up to the winter, I would expect quite frequent mild and unsettled patterns with the colder synoptics taking their time to appear, possibly in muted form around mid to late November so that perhaps Scotland will get the first round of this predicted wintry regime. In North America, I am expecting a winter dominated by intense cold over central regions, often extending out to both coasts, and a generally depressed jet stream but with weak El Nino tendencies likely to lead to frequent and heavy snowfall inland from the west coast over the Rockies about as far south as northern New Mexico. Parts of eastern Canada may be unusually mild with the storm track tending to run north from near Cape Cod into eastern Quebec province. I feel like this may be a very rough sketch of a winter that may contain some really unusual synoptics and bring conditions that are rarely seen at some times, and those are difficult to anticipate so would just caution that various extremes may be tested at times. I don't think it will be a dull or boring weather pattern for most of the winter, in any case. For verification, I expect the average temperatures to run as much as 1.5 to 2 degrees below recent normals and for this winter to be one of the colder ones in the past thirty or even fifty, and colder even than the longer-term averages which run almost a degree below modern 30-year averages. I somehow doubt that it could be an all-time cold contender to match the summer because that seems to be very difficult to achieve with the ice margins being as far north as they have set up in the North Atlantic in modern times. But as we saw in December 2010, anything is still possible and there could be some intervals of record breaking cold.
  28. 44 likes
    A good post based on reasoning of which You couldn’t argue based on the information that you present. There is however the small matter of ‘human intervention & forecasting’ involved here as well as experience. That’s the difference between someone who chooses to solely rely on what a model says V someone who blends what’s a model says with ‘experience’ of said models & when they perform poorly, so whilst the data you have forms your opionion - all it does is reinforce mine which is model output + blend of experience. So let’s be clear from Day 1 I think both me ( & TEITS - when he joined the party ) have forecast a ‘decent’ continental Easterly to reach the UK -circa -6 850 or below - The timeline which as with most cold spells has slightly elongated due to model progression ( haven’t got time to explain now ) is still due Thurs / Fri. Let’s not forget all the ‘teleconnection’ crew decided it wasn’t going to happen - based on reduced angular momentum etc leaving just one or 2 going against the whole model suite. we now find just 2 days later the same model suites following just 1 model - The UKMO- which has forecast pretty much the scenario suggested from day 1 just spread over 1/2 more days. People seem to forget how bad the GFS & ECM have been in the last 2 days - here a typical incidence ECM last 3 00z 168>144 & today’s 120 Its Crystal clear the model has moved to the forecast scenario - Now examine the Debilt ENs same vein - No cold - some cold then hang in a minute - lots of cold. No point in posting the GFS as it’s still a day behind. So great argument - but your data is flawed & changing in favour of cold. My current thoughts hold Easterly / Southeasterly in situ at day 6-7 with a high potential of undercut not currently shown in the models. Best s PS ***everyone*** ask yourself 1 question * Why the Met office with every MOGREPs / ECM run / ENS suite available decide not to modify the T84 Fax chart away from the UKMO 12z raw data- answer: because they have confidence it will be correct—
  29. 43 likes
    Another thing to consider is that dry snow puts down more than wet snow for the same liquid equivalent. With wet snow it's typically 10:1, dry snow can be around 30:1.
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    Another year we could hope to emulate is 1855. The first ten days of January were mild with a flabby high over Europe, and CET values near 8 C to 7th and above 5 C to about the 12th. The second half of the month turned much colder, the end point was 2.4 C, and February was third coldest at --1.7 C with some bitterly cold easterlies showing up mid-month. There was a ten day interval that rivals any other for sustained near-record cold. Looking at the wetterzentrale archive maps it would appear that the flabby Euro high gradually weakened in place, became an extension of higher pressure near the Ukraine, and then that ridge gradually disappeared when higher pressure still developed in Siberia and extended gradually towards the Baltic. There were no sudden or dramatic changes but eventually what we might consider perfect snow-producing synoptics appeared by early to mid February. Another similarity was that the cold appeared at roughly the same time in eastern North America after a mild start to January there as well, with some record lows in the first half of February. This was a low solar year between the 1848 and 1860 sunspot peaks although not in a long-term quiet spell. Not sure if we can say whether the Pacific was in the El Nino state. Also it was just two winters after a cold late February and early March in 1853 so while that timing is different it shows that the progression from mild winter (1852) to late cold to mid-winter cold was operational. The winter of 1853-54 was fairly average after a very cold spell in mid-December. I've mentioned before that 1895 and 1917 also had these mild starts to January followed by gradual but sustained colder patterns. 1956 was not so organized but some rather mild days at first and then again before the major cold spell in early February as late as 28-29 Jan the mean was above 7.5 C. And if I asked you to guess the mean daily CET on 15-16 Jan 1947? 9.1 and 10.0 ... the subzero spell started on the 24th of January. Sometimes mild fades out, other times it has to be removed forcefully from the premises by one last gasp of the Atlantic. Given the stratospheric pattern and the evident weakness of the Pacific at present (can't even deliver El Nino warming to my house 300 miles from the ocean) I place the odds at 4:1 in favour of a sustained cold spell this winter, most likely timing 15 Jan to 25 Feb. The 1855 analogue looks closest to a perfect fit but hey, with all these major cold years showing similar signs, you have to be optimistic.
  31. 42 likes
    Well my simplistic UK forecast on the forthcoming brutal cold would be..... Cloudy with the chance of Penguins.
  32. 41 likes
    I am sure that many many on here, and I absolutely include myself in that, do indeed get a buzz from seeing cold charts in the forecasts. No matter how far away. GFS +384, ECM +240, teleconnections, ensembles etc. Us watching for trends, patterns, signals, Trying to second guess cause and effect of every minute change in the atmosphere from run to run. All in a massive 3d world from the top of the stratosphere to the pavements outside our houses. That is all part and parcel of this mad annual winter ritual of ours. Personally, I would just find it incredibly boring if all the charts only went up to 3 or 5 days Most here are plenty long enough in the tooth to know that those faraway charts eye candy charts have many hoops to jump and many hurdles to clear before making it into the more reliable time frame (and even then will most probably go wrong).. But if it ties in with the 'background signals' (no matter how tentatively sometimes ), then yes, absolutely, that's what it's all about! I see no reason why good cheer, hope and optimism should be curtailed in those instances. In the same way nor should the perennial pessimists and pragmitists amongst us, who arrive like clockwork to pour hot water on those hopes and dreams (as long as not trolling of course). Each to their own in life, but for me it's always been all about the chase...
  33. 41 likes
    SSW Down welling will over ride the MJO signal the resurgence of the upper level westerly regime will flush down the 'burrowing easterlies' referred to in Scaife Meto vids Simply put this SSW is new - its a monster displacement - so strong - its split the vortex - no long range model saw this. The physics meant it went strong into canada, then strong into siberia - it literally has been sheared QBO is irrelevant now - this is important as upper strat advertises differing regime from lower the split means the trop is influential - and the trop players arrive from the tropics - the nino base state and the mjo transition Where we are .. the dilution of the IO development for the MJO today after the coupling of the lower TSV over the pacific means the MJO can move again - its sessions stalled in COD - we can see more modes ahead... It's going to cycle with AAM into phase 5 .. EC week 5 regresses these.. and we have the winter lock
  34. 41 likes
    Or... just don’t bother coming on here at all if every single one of your fleeting visits to the forum is to moan?
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    last one before later- Each run of the GFS is edging to the UKMO- minimal mention of this run however again if you compare 00z GFS mean V 06z GFS mean @72 its gradually sharpening up the curvature of the CAA to more of a straight easterly - The UKMO @midnight 00z Monday Has moderate snow showers pushing in from the continent - The -12c Isotherm is over the midlands- So rough approximations would say the based on the UKMO the -10c line would arrive across EA by 2pm- The arrival of snow flurries ~ 6pm. Any notion that the cold spell is being pushed back is incorrect- What the models are doing now ahead of the wave that I keep referring to - are developing a very shallow feature that would have a small milder sector of around -8 to -10c @850 - however importantly this is coming into 950 MB air / surface air & dewpoints that are already mixed to a PC airmass - meaning all the indicators for snow are perfect - The TheteE chart sums this up well- So this event would be all snow ushering in more snow- The wave behind it introduces the Vmax instability you can get - ~ * -16 c air * North sea Track over ~ 6-7c * Thermal Gradien 23c * Very Low heights / steep lapse rates T192 Look at these 2 charts - If anyone draws a conclusion that it would be snowing in MOST places then thats a big misjudgement- ** Notice the -20c just in view at the top right ** Have a great day S
  36. 41 likes
    When MJO experts are quoting eastward movement in the MJO then one tends to take notice. When MJO experts are citing CFS analogs within other variables, given the credence of CFS on here then one really does take notice, lots of noise in the Wheeler and Hendon plots, this looks legit. The Matthews site shows solid progression, and many other tweets tease the 7-8-1 progression in the offing.. blocks manifest very, very quickly in this regime. We get hints from the modelling, then they are dropped, GFS has a fight with the ramplified ECM and UKMO steadies the ship. ECM to my eye is 1.5 - 2 days quicker with MJO passage than GFS and subesquent transference to NWP, think this is to do with not the GFS bias but ECM parameterization ( may be wrong) think they were using drones a couple of years back to get into the guts of the MJO and improve performance. Point being we have the vortex heading into a potentially 'vulnerable' period if the lagged MJO p2/3 manifests vs MJO now active and seeking to mix it up across the pacific = much model interest for month end. My watch is not only for the strat precursors, but the solid MJO activity circa week one Jan and it's downwelling artefact / imposition on upper echelons of the vortex. If we can be lucky and benefit from 781 then great doubles the chances of vortex perturbation, If not it may be weakened enough to see MJO manifest more readily. Time will tell, just a week or so away now to test the p2/3 MJO eventual downwelling vortex impacts theory. The Italian site with the Nina / Nada / Nino analogs favour the limpet MA block, Nino esque favours the NNE, classical for the NNW by way of blocks. Too early to tell yet, based on today and wishing some further coherence vs CFS and the slant that the US experts are telgraphing their arctic hammer set up, we need to wait a little longer and see the nuanced play out of blocking in our locale.
  37. 40 likes
  38. 40 likes
    Well since the dawn of the internet the UK snow nuts have chased the 510 Line to the UK 1987 was temporarily 496 DAM in Dover- ECM is close @144 @~ 504 DAM- It will be like a constant fan of mahoosive STELLA DENTRITES !!
  39. 40 likes
    Evening All- All change in the NH for the 8-14 days Today is a good opportunity to cast our eyes over the Ensemble mean of the AO to try to understand why blocking ( especially cold ) is so hard to pinpoint & more importantly why at day 10 in this day & age the models struggle with such steep changes of mode ( modality ) in the AO Todays 00z Ensemble suite shows near total agreement through until day 10 onwards The starting point is @+2 sigma on the chart dropping 4-5 points out to day 10- To try to articulate what that means in laymens terms is basically a total reversal in pressure field ( net ) across the polar region & mid lattitudes. High pressure replaces Low pressure over the Pole & there are larger more stationary areas of low pressure over the mid lattitudes generally locked in by 2 or a 4 wave pattern. The fallout being huge swings across the mid lattitudes from extreme warmth to extreme cold ! The reason the model accuracy deteriorates in this scenario is due to the heights changing so rapidly across such a sort space of time the models capacity can sometimes over estimate that change by going to far, when infact whilst theres a strong signal for change - when it comes to it the actual outcome isnt quite as drastic as first depicted. So whats been modelled by the GFS/ECM today typically occurs once or twice per winter where we see ensemble suites bottoming out in the -3 to -5 region however the verification for such a drastic end result is only maybe once every 3-5 years. Looking at the last decade winters like 09 & 10 had extreme -AO episodes as did March 13 which recorded a dip down to -5.68 - Since March 13 the lowest vaue occured in Jan 16 @4.5 but generally over the last 3 winters its been very positive. So from here on out until mid November if we really are to think about seeing prolonged cold conditions & indeed below ave CETs for Winter then we need a modelled sub 5 AO to actually & not get watered down like most occasions it has over the last few winters - also Jan 16 was quite short lived... FWIW this current modelled scenario from the 12z operational which lands probably sub 5 is a series of attacks on the polar field gradually building momentum from day 4 to day 13 resulting in a near full reversal of winds around the pole inc a whopper of a greenland high accompanied by strong heights over Northern russia- So sit back & watch it unfold - Firstly day 4-9 the ridging towards scandi then further atlantic pulses backed up by high pressure from Northern russia all decending on the pole- Expect for the signal to be watered down but hope for it not to be as the more extreme it becomes the more wild it looks on the NH plots & the deeper the cold sent into the mid lattitudes... S
  40. 39 likes
    I am beginning to think I might of been wrong this morning with the medium range. Compare 12Z GFS with a couple of days ago for the 4th Feb. Are we about to see a change within the reliable timeframe of a continuation of the cold? May I dare to suggest the fabled Greenland High may even develop? At the moment im clueless with regards to snowfall this week and clueless what happens afterwards.
  41. 39 likes
    Alice was told that there wasn't much Jam left in the Jam Jar, and when she wanted her Jam today was disappointed to find out this was all that was left.. Thankfully Alice was patient and found this hiding down the back of the ECM.
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    The mighty ICON slayed by the UKMO.. @The Eagle has landed
  43. 39 likes
    Also a cut off Greenland High at 216- Rare as hen Twins with teeth !
  44. 39 likes
    Can we open an IMBY 1 please.. The very annoying...we'll get snow at my house nonsense has already begun!.. C, mon- its gonna come down 2 microscale...as per on our maritime island..with the slightest tweak/adjust..having massive ramifications.... Gets my goat something bad!!!!
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    I posted this table over in banter and perhaps a lot of more serious onlookers don't go in there, so as it's not really banter I am taking the liberty of posting it here also. Basically it's a summary of all major cold spells in the daily records of the CET from 1772 on (the first one caught being 1776, and there must have been some stonkers before 1772 but we have no way of knowing the daily details of them, 1740, 1684 and 1709 for example must have produced long cold spells. The bottom line is that one fifth of all winters have produced a cold spell of at least ten days (where the mean daily temperature stayed below 0.0). A few others produced ones that failed that test but were very significant (eight or nine very cold days, or just being a bit too late into March and getting the inevitable daytime boost). Also what this table reveals is that one cluster of cold spells started on dates in late December and early January, with another cluster preferring February. There was a bit of a half-time phenomenon in late January. However, I did note that some of the major February cold spells had a good start in that period of late January and just failed to attach by one or two days getting briefly above zero. I'm sure you would experience the 1947 cold spell as starting 24th January for example. But in the table it shows up later. So here's the table, I have reduced it to quite a small size to make the seasonal profile easier to see visually, but if you want to examine the details then go to a higher magnification. The table is arranged in order of duration of these cold spells and when several are tied, the mean temperature they achieved is used to sort them. Days _ Duration of Days 0.0 or lower ______________________________ Coldest ____ Average ______[] __DECEMBER__ [] __JANUARY__ [] _FEBRUARY_ [] __MARCH______ 32 ... ... ... ... ... ... ... ... 27 Dec 1813 - 27 Jan 1814 ....................................... -- 6.7 ...... -- 3.2 26 ... ... ... ... ... ... ... ... ... ... 7 Jan - 1 Feb 1776 ..............................................-- 7.5 ...... -- 3.0 22 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... . 5 - 26 Feb 1947..................-- 6.7 .... -- 2.5 **** 20 ... ... ... ... ... ... ... ... ... ... 8 - 27 Jan 1881 .................................................. -- 8.1 ...... -- 4.6 20 ... ... ..(+12d see below) .. 7 - 26 Jan 1963 .................................................. --8.4 ...... -- 3.6 *** 18 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .. 6 - 23 Feb 1855 ................. -- 7.5 .... -- 3.7 18 ... ... ... ... ... ... ... ... ... ... ... 9 - 26 Jan 1823 ................................................. -- 8.9 ...... -- 3.0 18 ... ... ... ... ... 9 - 26 Dec 1890 ........................................................................ -- 6.8 ...... -- 2.1 17 ... (very cold 31 Dec - 7 Jan).10-26 Jan 1795 ............................................. -- 8.9 ...... -- 4.0 15 ... ... ... ... ... ... ... 21 Dec 1870 - 4 Jan 1871 ............................................... -- 6.9 ...... -- 3.6 15... ... ... ... ... ... ... ... ... ... ... 10-24 Jan 1940 ...(+11d later) ......................... .. -- 7.1 ...... -- 3.3 15 ... ... ... ... ... ... ... .. 24 Dec 1892 - 7 Jan 1893 ....................................... ..... -- 5.0 ...... -- 3.3 15 ... ... ... ... ... ... ... ... ... ... ... ... ... 18 Jan - 1 Feb 1784 ................................ . -- 3.7 ...... -- 2.1 14 ... ... ... ... ...(+10d earlier) . 8 - 21 Jan 1838 ............................................. ... -- 11.9 ...... -- 5.1 14 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 5-18 Feb 1895 .......................... -- 8.3 ...... -- 4.8** 14 ... ... ... ... ... ... ... ... ... 3-16 Jan 1820 ................................................... ....... -- 8.5 ...... -- 3.6 14 ... ... ... ... ... ... ... ... ... ... ... ... ... ... 21 Jan - 3 Feb 1780 .......................... .... -- 3.6 ...... -- 1.0 13 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 26 Jan - 7 Feb 1954 ........................... -- 5.0 ...... -- 2.5 13 ... ... ... ... ... ... ... 17 - 29 Dec 1860 ........................................................ ........ -- 3.7 ...... -- 2.1^ 13 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 6-18 Feb 1986 .......................... ... -- 4.6 ...... -- 1.6 13 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 14 - 26 Feb 1956..................... -- 3.2 .... -- 1.6 13 ... ... ... ... ... ... ... ... ... ... 29 Dec - 10 Jan 1811 ............................................. ... -- 3.6 ...... -- 1.5 12 ...... ... ... ... ... ... ... ... ... ... ... 6-17 Jan 1987 ................................................ ..... -- 7.7 ...... -- 2.6 12 ... ... ... ... ... ... ... ... ... 23 Dec 1962 - 3 Jan 1963 .(plus 20d ^^).......................... -- 3.6 ...... -- 2.2 *** 12 ... ... ... ... ... ... ... ... ... ... ... ... ... 18 - 29 Jan 1880 ......................................... ..... -- 4.3 ...... -- 2.1 12 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 3 - 14 Feb 1991 ............................. ... -- 4.7 ...... -- 1.9 12 ... ... ... ... ... ... ... ... ... .. 25 Dec 1853 - 5 Jan 1854 ........................................ ..... -- 5.0 ...... -- 1.8 12 ... ... ... 30 Nov - 11 Dec 1796 .......................................................................... ..... -- 4.7 ...... -- 1.8 12 ......... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 17 - 28 Feb 1955 .......... -- 3.3 ... -- 1.7 11 ...... ... ... ... ... ... ... .17 - 27 Dec 2010 ............................................................. ...... -- 7.0 ...... -- 3.9 11 ...... ... ... ... ... ... ... ... ... ... ... 11 - 21 Jan 1867 ................................................. .... -- 5.0 ...... -- 2.9 11 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 1 - 11 Feb 1917 ................................. ...... -- 7.2 ...... -- 2.8 * 11 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 9 - 19 Feb 1985 ........................ ... -- 4.1 ...... -- 2.7 11 ... ... ... ... ... ... ... ... ... ... ... 2-12 Jan 1879 ..................................................... ........ -- 4.8 ...... -- 2.3 11 ... ... ... ... ... ... ... ... ... ... ... ... ... 6-16 Jan 1850 .............................................. ........ -- 2.8 ...... -- 1.4 11 ... ... ... ... ... ... ... ... ... 25 Dec 1820 - 4 Jan 1821 ............................................ ........ -- 3.3 ...... -- 1.3 11 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 11 - 21 Feb 1853....................... -- 3.2 ...... -- 1.2 11 ... ... ... ... ... ... ... ... ... ... ... ... ...(+15d earlier ^^) . 9 - 19 Feb 1940 .......................... --2.5 ....... --1.1 10 ...... ... ... ... ... ... ... ... ... ... ... ... 6-15 Jan 1982 ..................................................... .... --7.6 ...... -- 4.0 10 ... ... ... ... ... ... ... ... ... ... ... ... ... 8 - 17 Jan 1826 .......................................... .............-- 6.9 ..... -- 3.7 10 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 20 - 29 Jan 1945 ............................ ........ -- 7.6 ...... -- 3.5 10 ... ... ... ... 5 - 14 Dec 1844 ................ .............................................................. ............-- 5.5 ...... -- 2.7 ... see below Mar 1845 10 ... ... ... ... ... 8 - 17 Dec 1878 ............................................................................. ......... -- 5.3 ...... -- 2.9^^ 10 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 16 - 25 Jan 1829 .................................. ....... -- 4.8 ...... -- 2.8 10 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .. 14 - 23 Jan 1809 .................................. ........ -- 5.1 ...... -- 2.4 10 ... ... ... ... ... ... ... ... 24 Dec 1836 - 2 Jan 1837 ................................................ ........... -- 3.3 ...... -- 1.3 10 ... ... ... ... ... ... ... ...23 Dec 1837 - 1 Jan 1838 ..(+14d later) ............................. .......... -- 2.7 ...... -- 1.4 10 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 21 - 30 Jan 1917 .(1-11 Feb^)................. -- 1.8 ... -- 1.1 * __________________________________________________ ^ Most of the period 1-16 Jan 1861 was also subzero, the 31-day period 17 Dec 1860 to 16 Jan 1861 averaged -1.3 C. ^^ This cold spell extended from 7 to 26 Dec, 20 days in which the mean CET was --2.4 C. The interval 20-25 Dec was --3.7 C. * Except for +0.3 on 31 Jan 1917, a 22 day spell avg --1.8 C lasting 21 Jan to 11 Feb. ** A longer spell of 24 days with +0.4 as warmest, 26 Jan - 18 Feb 1895, avg --3.7 C. *** Although there were only two spells in winter 1962-63 that qualified for this list, note that the period of 35 days that includes the two, 23 Dec to 26 Jan, averaged -2.7 C and 70 days 22 Dec to 2 March averaged -- 1.5 C. **** The 45-day period 23 Jan to 8 Mar 1947 averaged --1.9 C. <<>> RECENT NEAR MISSES & EXPANSION OF 1986 FROM LIST <<>> 25 Nov to 4 Dec 2010 averaged -- 1.7 C and 25 Nov to 8 Dec averaged -- 1.7 C but these periods failed by a slight margin to make the list (25 Nov was +0.3 and 5 Dec was +0.4). The 26-day period from 6 Feb to 3 Mar 1986 averaged -- 1.2 C. The 15-day period from 5 to 19 Jan 1985 averaged --1.7 C. (11th not subzero so it has no ten-day interval) 1 to 10 Jan 2010 averaged --1.9 C but failed to make the list because 2 Jan was +0.3 C. 16 to 25 Jan 2013 averaged --0.9 C but failed to make the list because 24 Jan was +0.7 C. 8-26 Dec 1981 averaged -- 2.3 C. ___________________________________ honourable mention should be given to 11-20 March 1845, there were two days in that 10-day interval slightly above zero but the average so late in the season was --1.7 C and contains the coldest March day (-6.5 on 13th). Also, in terms of a sustained cold anomaly, 21 March to 1st April 2013 (12 days) had a mean of +1.2 C. 1785 was even colder at the same time of year, 13 days from 22 March to 3 April had an average of +0.8 C. In terms of early winter season sustained cold, the interval 11-16 Nov 1919 averaged --0.3 C. ________________________________ ANALYSIS of starting dates for 10-day or longer cold spells Of all the 51 spells (in 47 winters, roughly 19% of the years surveyed) including the later ones in March, but excluding those that just missed during the winter season, this is the frequency count for starting dates: xx Nov to 10 Dec __ 4 11 to 20 Dec ______ 2 21 to 31 Dec ______ 9 01 to 10 Jan ______13 11 to 20 Jan ______ 6 21 to 31 Jan ______ 3 01 to 10 Feb ______ 8 11 to 20 Feb ______ 3 21 Feb or later ____ 3 For whatever reason, there is a period from 21st January to start of February when these spells are less likely to commence. A second cluster then emerges around first week of February often lasting longer than 10 days. We have now reached the point in the winter when half of these significant cold spells had begun. The three-quarters point is around 8 February. Not that length is the only important point when comparing cold spells, last winter's late bloomer lasted about five days but "did the business" for snowfall and set a daily record on the 1st of March. Not all of the above set daily records, about two-thirds did (and sometimes quite a few, for example 1776 set five in a row). You will find examples of winters with a cold spell listed and some other memorable cold or snow outside that interval, for example, in Dec 1796 a later but shorter cold spell produced the coldest December day. February's coldest day in 1816 was embedded in a seven-day subzero stretch which was about a week after an earlier five day interval at end of January. The spell listed for 1956 is not the most memorable cold of that month, that happened in the first few days of February. But that spell only ran to five days. Will this winter join the list? If so, likely to be 23 January or so before it begins. The 1947 subzero cold spell began on 24th, the interval to 2nd averaged -1.7 but fell one day short of this list (and by 0.1 C on 23rd). Two days of 0.7 separated that from the main cold spell shown in the table and it then stayed very cold to about the 10th of March.
  46. 39 likes
    so after many days the GFS & FNMOC & canadian finally now follow the Euro with 44 out 64 Members with a split at day 9- The ECM is day 8. We will call it - SSW & Split for 1st Jan. ( perfect ) Standard Propergation time is 10 - 14 days - however the QTR can arrive from onset & throughout propergation time depending on where the split is. So High lattitude blocking to develop 'possibly' from 1st Jan - 10th & high probability 10th onwards- I think the cold will hit the UK from the transitioning AO somewhere day 5-6 as the split looks condusive to a +PNA & Altlantic ridge scenario- s
  47. 39 likes
    OK, completely sick of some of the nonsense in here. TAKE A LOOK AT WHAT THE UKMO AND GFS IS SHOWING AT +72 HOURS. How long have we been waiting to see charts like these at 72 hours? Some have been waiting decades. Now how can there be any negativity when we have charts like this only 72 hours away? I am quite amazed that people are not more excited given all the failed easterlies we've had to endure over the years. Easterlies normally disappear at 120hrs and yet here we are, after all this time of chasing with nothing to show only blood sweat and tears (OK maybe not blood, depends how hard you whacked your keyboard when things normally went titus verticus) we are facing a severe cold spell with some areas looking at substantial snowfall. Ladies and gentlemen, after all these years, we can see the train.
  48. 39 likes
    You know it's a severe cold spell when the 510 dam 1000-500mb thickness line has moved over the UK! Rare for it to happen. As the deep cold advection eventually waters down later next week on the 06z GFS op, the run offers a reload of very deep cold air from Barents Sea area maybe in the offing first weekend of March, which collides with Atlantic lows trundling across France - BOOM Oh dear, think I'm losing all kind of forecaster sensibility and sound thinking looking at these GFS charts in FI!
  49. 39 likes
    Totally ruined in this thread when it’s like this. Poor mods probably have families they would like to spend a Saturday evening with rather than sorting the children out in here! ECM brings the mild sector in, but it’s gone fairly quickly by 144, and I like this chart, low heading south! heights building to the east again perhaps?
  50. 39 likes
    Just for info, I'm going to go through the thread in a minute to clear out the off topic posts - thanks to those who have been reporting them this morning. Once that's done, I'm going to check through the list of those making those posts, and anyone who has been asked about this before / warned will be stopped from posting in here for a period of time. Enough is enough.
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