SMU

This run from 06z NAVGEM is exactly where the forecast should be today--- this should be the super ensemble run- http://www.meteociel.fr/modeles/navgeme_cartes.php?ech=6&code=0&mode=0&carte=0&archive=0

Its more the actual trough disruption of the low itself look at UKMO 120 at the same time...

The GFS mean at 120 keeps the atlantic low as one entity with minimal trough disruption ( as per Euros ) Until it resolves this & moves the energy into x2 split areas - one further SE & the other further NW it will continue to create a positive tilted low at 168 & flatten the block The second it gets decent seperation the energy will go under...

Morning For the same reasons that happened yestersay from 00z across to 18z & beyond the GFS continues to take the energy off the states at 168 & move it east with a significant positive tilt - your UKMO / NAVGEM take that & move it SE - I fully expect the GFS to morph into the Euros by tomorrow- ECM 216/240 still continues to look like 2013 March with a slightly more northern extent - Wait for the 12s... S

00z GFS @ 144 further upgrades...

I always new the 18z NAVGEM was the best model !

So from nothing today - a comparison of March 13 in the afternoon 4pm post- now we have the JMA- march 13 first - very very similar with plenty of wiggle room!!

In the current position which is a possible transitional one in the mid term- pointless looking past day 7 TBH let alone forecasting 14c after day 10.. Also in just 2 runs the GFS ENS ( now 12z) have totally changed the atlantic profile at 120 from a positive tilted NE jet flow to a blocked neg tilt... S

Afternoon All- So November 26th - 4 days to the start of Winter & for once we have started the run in on a 'seasonal' note, certainly a below average November about to land & generally the AO has been negative although perhaps not as negative as one would have expected V the strength of the vortex - So we have already gone over why the NH height fields have been disrupted towards a more Postive height picture - The total breakdown & non recovery of the vortex this April - The Ice loss & subsequent reloss in October as the Cold seeped out to (mainly) Russia - The record breaking SAI for 2016 - The record breaking warmth in the Arctic... & so on.. Globally I believe 2017 will be a year like no other- Anyway, the prime driver of the optimism has come from that zonal wind weakness - The November average is Westerly @ 30 M/S & today we are running at exactly 8 M/S challenging the minimum record in 3/4 days of around 5 M/S- So with this in mind I have disputed all along that the opportunity for deep cold could come before mid December & that opportunity peaked around 30th Nov in conjunction with a brief Easterly phase of the zonal wind - IE the chance 'globally' of there being a buckled jet around 60N - Its been a rollercoaster journey in the last 4 weeks with no significant cold present, however enough flirtations with polar air to see early snow for the North- The peak weakness period of the jet circa Nov 30/Dec 1 should have been modelled as a blocky period however till today the models had produced elements of mid lattitude blocking - but nothing to sustainable- Today however we do have something different in the mix. First & foremost I'n not saying this will happen - however from experience this is where 'some' if not most of our decent snowy cold spells have come from. What we see at 120 is an opportunity to further reduce the atlantic push east as height rises try to head N/NE towards Greenland- Remember the Criteria for a decent Greenland block- * Azores High Ridging North * Scandi High ridging West or both - The key location as EVER is whether the 552 Line can get North of the west coast of Greenland- This is usually the cut off point where the jet & low pressure has been deviated so much off track that its past the point of return- any lack of upper blocking that doesnt get into that locale usually means that we have enough positive tilt in the jet to over ride the high & the subsequent block wont be far enough NW to get the deep cold in ( usually it skirts the NE coast ) as it drifts past. What I have seen this morning is exactly the same as how 7th March 2013 blocking started with a wedge of high pressure forcing its way North west & the cold plume getting forced west underneath- At that time the models especially the GFS struggled with the magnitude of the high & blocking till about 144 where all of a sudden the energy went underneath & the 554 line made is past greenland - looking at the ECM today were not quite there - Should we get just a bit more amplitude in the wave & a higher lattitude block the Ensembles will crash towards -10c.... So lets look at the date for Dec 3 ( transition period 30-2nd) in the Ensembles for 2 locations & monitor the 'means' movement Aberdeen & London Aberdeen -3 London 0 - Areas to look at 120-144 for more negative tilt bit also more amplitude in the wave... Cheers S

Will do around 3 ~

NAVGEM 06z 138 nearly reaches the point of no return...

Will do a post @ 3pm today however dont under estimate the potential of what could happen at short notice this afternoon BIG BIG DEVELOPMENTS.. Remember I mentioned the split energy scenario earlier in ECM at 120 & that was one of the important things to look for in todays models especially the GFS trending.. Heres the updated 120 06z Mean V the old 120 00z mean.. MORE AT 3 Then 162 v 168

06z 120 shows the atlantic low having no positive tilt unlike the 00z which was about 15 degrees pos 06z is neutral so thats an improved profile...

morning All- The overnight ECM has obviously drunk some of the mulled wine & moved towards a better solution, there was a hint of this yesterday on the 12z at 168 however the atlantic trough was still to positivly tilted & voila we had the overunning pattern at 192 > onwards Today the key ( just at 120 ! ) is to get some negative tilt out of it ( if your not sure what that is look at that atlantic low & think of its momentum on an axis - if the direction of travel of the wind/advection around the base is ESE + the around the top are WNW then you would say the low is negativly tilted, the opposite is pos tilted where the base has ENE winds & the top side is WSW - The other positive about the ECM is that it seperates the atlantic energy better & quick that any other model today - so note here @ 96 The 2 systems are being forces apart by the high - this is what also supports the negativity of that atlantic low @ 120- We know historically ( well many will ) that when it comes to energy within the jet & seperating different sequential areas of low pressure or even shortwaves the ECM will outperform the GFS every time- Here a good example from storm Angus - Actual chart that verified Note the energy seperation between Angus over SE UK & another area of energy in the atlantic a good 700 miles west - in that scenario all models struggled at 144 & they combined the energy to create one super low over the UK however the ECM was faster at getting the solution correct. If indeed we are going to get the cold we desire similar to ECM then 3 things to look for * T96-120 - Further & faster energy seperation on those 2 lows allowing for the high to retrograde a tad further west * T120-144 - that atlantic low to be a tad more neg tilted * More retrogression from the High NW 144-168 to take up more of an elevated position towards iceland - The last time a similar scenario happened with NW retrogression was 2013 - where ECM was all over it like a tramp on chips ! Actual Day 6 - 6 days before ECM the clear winner Anyway.... Its a start & step in the right direction & at the timeline 120-144 enough time for corrections to go our way.... S

ECM is as dreadful as it gets tonight with the UK thrust into very very mild air post day 8- There hasnt been 1 decent cold outlook from the ECM since it landed this week & it has thus far easily pegged the GFS which has continually backtracked on any cold- The only crumb of comfort is all the mildness comes day 9 / 10 with opportunity of change to a colder blocked high still flagging at 168... very poor couple of days models....

Yes - however with the zonal mean outlook 60N you would expect less volatility from a 'means' averaged around the globe- From the ECM EPS data I have gleened the euro have been tracking negative like the GFS however only slighty negative where as the GFS went for a full reversal of winds- this difference is also portrayed as the AO ensembles & again the GFS up to around 3 days ago had deep negativity - however the last 48 hours of so has seen the whole AO signal move to the EC means of 'just slightly negative' - Really based on that form & the very recent GFS greenland blocking forecast that failed + the fact its number 2 performing model ( often 3 ) really should have indicated that unless the ECM was on board then it wasnt going to happen- Still time for reversal of trending but the reality of this afternoon hasnt been so great..

^^ TC have you swallowed the NWP model wikipedia?

All 12z suite sees a considerable move to ECM 00z solution - UKMO + GEM are pretty much all the way, GFS is hanging on however has moved to ECM- If the ECM verifies it will be the second time in 10 days the GFS has gone for some form of Greenland block ( & ENS ) & then reverted to ECM around the 144 mark- very frustrating - not least of all because the GFS strat forecasting & zonal mean outlooks were underpinning It all & if we move to the ECM solution the 60N zonal mean will upspike TOWARDS normal .. not great...

Morning- upgrades all around today - GEM /UKMO in the ballpark for the 30th now- GFS still solid ! S

Is this the new ECM ? looks like someone at ECMWF programming has hit the 'Northern heights delete' button... To be fair it beat the GFS the other day when it was ridging to Greenland - lets hope its 1-1 come tomorrow eve- At least ECM cold @ 240 trying to build a scandi High-- S

You are correct in this case... its a closed low - although you can get this sheared apart with ridging to create 2 shortwaves - 1 moving back west towards canada & 1 sliding ESE towards Ireland...

Hi mate loads of charts above posted heres the GFS mean at 168 & 192 certainly an upgrade- assuming that all verifies then its all down to the energy moving ESE at 192 & whether it can slide like the control... All in all a good 12z suite - Mean down to -3 after 192 S

A solid day so far with the date 30th still the hinge day- all afternoon models so far are similar to the earlier GFS solution - 12z GFS 7/10 12z UKMO 8/10 12z GEM up to 144 8.5/10 S

Evening All - Some surprising discussion today around the period of end of November - Ive seen posts quoting why still 'no deep cold' , GP posting about the period 12-16 day period & cross polar ridging- perhaps that torpedo might finally land -& the met office perhaps moving away from the end of November blocking forecast + Cohens update - To be frank here the forecast period for UK specific is impossible post day 6,although with a footnote that there has been a move today in the 168-192 to increase the canadian heights which are migrating steadily eastwards with time, this perhaps has tipped the balance slightly again towards UK cold however it really depends as much on the ridge as it does on the eastward progression - We could still end up on the warm eastern side of the trough in a slightly west based NAO - In terms of context 'Globally' this Oct/November so far has been unprecedented, we have record warmth in the arctic, record low ice expansion, record high SAI, record -AO oct, Record late ice loss & finally a record low ( forecast for ~27th) 60N zonal mean - The net result from this has been that all the 'deep cold' has been locked into Siberia / Russia - & with the time of year making it difficult to tap a long fetch easterly then deep cold was never likely - However as has been mentioned the cold now is beginning to back west being supported by the core of the vortex being displaced- The last 96 hours has seen the models moving from forecasting a deeply negative AO to a weak negative AO - this has reflected in the models from the Met & the strat - by seeing an uptick in westerly flow - But I still believe the dates 29/30th hold the key whether we can attenuate enough for cold - if we do the AO means will drop as will the zonal mean forecasts- So deep cold - not yet- but decent cold available from 30th still much in the frame - S