SMU

No scandi high - but posts the anomaly chart which shows a huge +VE anomaly close to scandi ... the question isnt whether there will be a High pressure over scandi - its whether the undercut allows the cold to allign west towards the UK - not SW to france or south to Greece.... s

Morning - Merry christmas to all & your families The run of the day goes to the UKMO this morning - at 144 the atlantic jet is developing that kink ( an 'n' shape ) rather than a 'u' shape that gives the jet some directional energy SE rather than NE we need this type of energy profile to get some undercutting .... cheers s

Impressive as the T2ms are -8c for the SE !!! another day... Nothings changed since last night..... s

Well that's about as vertical as it gets ( think 2010 west of Greenland tip ) That should be a slam dunk easterly.......

well I suppose you have a point there- I guess for clarity, all the decent cold spells that have actually landed more often than not the models have been over progressive with the atlantic jet to start with -( so as we get closer towards T0 be get a better ridge in Scandi ) & of course the always brush the scandi high aside far to quickly- so If you are coming from a position of - this modelling scenario is 100% going to end in a cold spell then the models do appear to be progressive, however maybe we could take the more realistic approach ( seeing as we fail more often that not ) & assume the models are not being progressive enough .... then wait for the inevitable failure...... depends if your glass is half full or empty ! S PS the 18z has alignment over the UK at 168 of about 5 degrees- so that fits in the box of should be successful....

yep it usually is as well- But I remember the 2010 secondary cold spell & a more recent one where the ECM 12z just went very progressive- only to revert to the right solution back on the 00z... S

Evening All So the ECM ensembles are in & paint the picture that the operational ( & Annoyingly the control ) were fairly significant outliers for Debilt ( to the tune of around 6c in the latter stages ) - The 12Z ECM has had a reputation before to be very over progressive so its certainly not over yet- Infact, being here over the last 10 years has seen this type of scenario modelled countless times - A high ridging North through the UK aligning Northwards & heading the core towards Western Norway - with a deep upper air cold pool dropping into Central / Northern Europe- & the hope it aligns westwards towards the UK- At this stage its important to point out with 100% confidence that despite all the computing power we have or the past / present climatic & stratospheric data we have - no one can forecast whats actually going to become of the prediction at day 10- will it be a scandi High or will it be a flatter Euro / Sceuro High - the background signals aren't great with a beast of a northern jet this year- but sudden change unaided by the stratosphere is virtually impossible to forecast. There of course have been some spectacular fails in the last 10 years, one day going to bed seeing the -15c isotherm over the UK at t120 to find it stuck over Germany the next evening at T96, also those Bitter Easterlies slowly morphing to dry Chilly South Easterlies has been a repeat offender over the years- However less we forget the stunning model accuracy of December 2010, to the 2 week Easterlies of 2005 & the snow wipeout for the south / East in 2009 , so mixed in with the Epic fails have been some success.... Statistically you would hope at best we would be 50/50 on verification - however its more like 80/20 fail rate - even that could be generous.... So here we go again for another battle of the models for accuracy, one tip to look for if we are going to get a High pressure in the right locale is the alignment of the first bout of Vertical advection heading North from the UK- We need 0 degrees - to really a max of 15 degrees positive , ( remember the landing zone needs to be West coast of Norway - so past 20 degrees we have missed the boat- also a bit of negative tilt is ok, up to 15/20 degrees the other way is fine....) The GEM was a peach in this stakes http://modeles.meteociel.fr/modeles/gem/runs/2015122012/gemnh-0-198.png?12 So if we are going to get this Winter off the ground this projection of a significant wave 1 profile attacking the vortex needs to deliver ( in a big way ) to start the domino effect down the line For January- If we miss the boat here & get to day 10 building another big Euro block we could be 6 weeks down of winter before think about the next possible pattern change.....- lets hope so S

The 12z GFS continues to chase after the ECMs evolution from yesterday - i cant post images however at 144 the GFS ( same as 12z ECM yest) develops a ridge to the NW yesterday This ridge is going to be crucial in allowing the WAA to set up over the UK promoting the development of the scandi ridge It also allows the altantic low to be negative tilted - supporting some undercutting .... little acorns.... S

Morning - Day 10 ECM is probably the most significant chart of the winter so far - Seeing a large cold pool cut off over Eastern Europe If the UK is going to get anything significant from this developing High then at least the ECM gives us a chance - based on the day 10 you would be looking day 12-14... so a LONG way away at the moment - but at least a chance..... S

Well the GFS 18z looks a carbon copy of the UKMO 144 which was more amplified than the 12z GFS- A more positive day which has seen a larger amplitude develop in the waves, with the ECM looking very wave 1 like at t240- with the 18z more amplified - hopefully the festive period will become even more colder- belfast & glasgow a worthwhile punt on a white Christmas .... s

Could be a pub run special tonight - maybe the GFS has been at the mulled wine... note the more vertical allignment of the low in the atlantic - on the 12z it was strongly positive tilted...

Afternoon - A dreadful past 72 hours of weather modelling signalling yet more mild weather - & sadly the much anticipated pattern change is just a mere distant memory - as mentioned above by some - the immediate focus again turns to a band of significant rainfall setting up at the weekend - sods law could be that if it jogs a little further north than planned then the same areas that were recently pounded could get the same again... rough & barron times if your a snow lover ....

Eve all Just a quick one as xmas party beckens- i disagree with comments regarding the concept that there is no pattern change ahead- whether whats being touted is sustainable & leads to very cold weather down the line can be questioned- but there is a pattern change on the way take T0 ECM then follow it up with the 9 day ECM at 216 shows a distinct pattern change over the pole from a concentrate fast vortex to a weaker more broken profile allowing high pressure to start making inroads into 70N... pattern change - YES sustainable pattern change - MAYBE....

Eve all - another positive step this eve - especially from the ECM sees a fat blocking high build up into Eastern canada - it really does put the buffers on the subtropical jet & also supports the shift of the vortex towards siberia - its not perfect for the UK - but this mini wave 1 attack on the strat may allow for the pattern to develop into a wave 2 assault bringing ever colder solutions to NW & Northern Europe in the run up to xmas S

John i would suggest the signal is to muted at the moment - especially in the ENS MEAN to suggest otherwise - changes are just appearing at day 10 so thats the next landmark- S

Indeed the GFS & ECM seem to be fairly well matched at day 10 tonight - although we need these positive height predictions to filter through to the earlier timeframes...

Lovely afternoon out there - Time for a little garage cleaning time !!

CS Interestingly that ECM ens mean looks like the GFS op as it builds heights into NE Canada & beyond-

Morning - Just browsing the 15 day ECM & the spread is huge - Operational is in the top quartile, but notably there is MORE clustering towards a colder solution than mild - All to play for....

GFS control at 180 I tell thee the GFS is onto something... S

We could be seeing a GFS coup tonight .... T192 on the pub run looks a dead ringer for a scandi high- Almost good consistency from run to run from the GFS S

5 words describe the ECM tonight - Flatter than a witches T*T

Again the 18z pub run comes up trumps if its cold your looking for - 2 key ingredients - * an arctic high - supporting SOME cross polar flow * a weak signal for a 2 wave pattern trying to develop - 1 from the atlantic ridging NE & another in the far east of russia .... The 18z is almost identical to the 12z control, there are also a handful of ECM solutions with a similar evolution.. Also the good news is that its a fairly cold high to start with ( around 192 ) Best S

That is what you call a slam dunk easterly a la feb 1991... S

Nothing to get to excited about at the moment- the early promise from the models supporting the reload has faded - We now find ourselves in a mobile pattern alternating between mild & cold so pretty standard fair with some snow for the scottish hills - Next shot for cold ( proper cold ) would be away into day 12-14 with the possible development of the arctic high... So ive earmarked around the 3rd -5th dec.... A waiting game..