lorenzo

Glosea on-board, properly.

It is.

There are wave breaks - then there are wave breaks. Stunning synoptics, it's as good as it gets for poetry in this image. The vortex clinging to it's climatological home with that furious filament, the inevitability of the Greenland break combined with the Ural Torque and the Aleutian Low. Vortex is toast.

That vortex looks pretty toasted :)

Oh we will still get the BS around random energy or shortwaves blah blah or that run has nudged this 42.1km east /west etc. That's par for the course for the GFS being available 4 times a day. Simply put, if you don't look at tonight's ECM day 10 chart in awe and wonder and enjoy the evolution - then why are you actually here looking at charts? Hope the UKMO verifies for Xmas Eve - like that for a lovely seasonal feel leading into Xmas Day.

The dynamic tropopause breaks on the EC 12z tonight are things of beauty, especially across the Greenland plateau. Appreciate this evolution is 10 days out and it's never a given with the nuances of these breaks. However that being said it is great to see this dream wave break uppercut evolution and cross model support to varying degrees dependent on how the residual energy in the vortex seeps into the CWB elements. The Greenland 'nudge' or 'uppercut' is something that over the years we have seen the PV really responsive too, and following on from the EP assault it is positive to see again. It's probably the one most of us want to see live again. Fingers crossed we get that to verification, to witness the aftermath in what will be HD or UHD /4K vs 2009 Cathode Ray Tube view !

I don't see any toys needing to be thrown out of any prams for maybe some time..

SSWs predictability is longer than one may expect... am thinking it's more about when in January vs not if in January... especially if we get anything like the amplification programmed on today's NWP output in terms of that Atlantic Ridging. Beyond that we can call in the Asian cavalry too...

Who ordered the 1070mb block then - own up !

Lets call 144 from the 12z at the limits of the envelope for the GFS 12 z There is the wave break and the resultant distribution of energy as the filament whips across NE US... let's see what the 18z does... EC had several clusters, hazard that it will take a couple of days for models to settle on resolution here.

Not teasing I promise, am enjoying this winter as it's severely random.. No SSW is a definite route to cold i.e. no one can say - Yay, SSW - Guaranteed we will benefit.. The post in the strat thread is around the upward wave activity disrupting the vortex, last year it beasted the entire winter going into absolute steroid mode leaving us at the mercy of endless crap synoptics. This season the Troposphere and Stratosphere are disconnected, we are not subject to facing down the barrel of doom. The chart attached shows Wave Activity Flux - EP Flux impacting the vortex, it's great to see a vortex which is already unsettled, be subject to more wave - driving. Simply put arrows pointing right mean that energy can impact the polar vortex as we see here at 50 / 30 hpa - Left graphic. Then arrows that are equatorward do not. In this plot we see clear signs of the EP Flux disrupting the vortex as the arrows are pointed poleward vs equatorward. Why this matters more than most is that the vortex has a typical cycle where it will fire up and continue to fire up across winter, this is a VI period, Vortex Intensification. It spins and connects to the troposphere and - that's all she wrote, no matter what happens in the troposphere we get over-ridden by this climatological intensification period. It lasts 30 -60 days and varies in strength, it is one of weather's givens. This year the stratosphere and troposphere are not connected at all, meaning what the Polar Vortex is doing way up high does not always translate down to the troposphere. And, we have signs ahead of continued disruption. This means we are not subject to winter is over or things going 'tits up' , quite the opposite. We can look forward to further changes, and looking at that flux chart this evening. An SSW is imo a strong possibility.

Zac's site is really cool in terms of it's moved our visibility beyond the Berlin plots. Have admittedly been obsessed with EP flux vectors for a wee while, and this looks again massively promising for TPV if not SPV disruption. Factor in EAMT in the post, MJO cycle in the post.. it's a great winter where our winter foe attempting as hard as it can to revert to climo - just isn't getting it's own way. Am a big fan of this winter in terms of the variation happening.. it's pretty much the opposite of last seasons uniform - none shall pass.. into - proper chaos. Yes, Jan you may say is another 'climo' pick statistically for a SSW to happen, however beyond the 'bookies shout' there is plenty of evidence that backs up that call, just a matter of when not if IMO.

Sorry @Hairy Celt a good two hours under the floor boards, then read again it will all make sense !

Only way is up !!!

Not any that anyone would enjoy reading Mr Frost... The vortex is uber cold this year, and there is a severe lack of any kind of Heat Flux transport at 100 hPa to disrupt it. Last year and year before during Novembers we had big wave breaking events that caused heat flux to disrupt the vortex during ( basically winter teases), and at least give us something to hope for, or chase. This season sees a really consistent Pacific pattern, which is only progressing minimally i.e. La Nina background, and really slow impacts of the MJO wave. Then, we know about the Vortex intensification period, a classic period where the vortex goes off on one and has tendency to return to home ( parked at Greenland where we want blocking to happen), results in a westerly regime and where blocks collapse quickly ( topplers as they are called here). For Vortex Intensification - think of where you crank up a spinning top, and with each turn it gets faster and faster. You stop and some latent acceleration, then slowly the original force eases off. Think of the MJO or Heat Flux created by blocking or wave breaks as being things that slow the spinning top down a little. This season it appears to be thus far unimpeded. We do have some flux in the Jetstream up coming, however we really need that perfect wave break to disrupt proceedings. There is nothing I can stick a pin on right now and say - yes this might disrupt that usual canonical intensification period. This means we are staring down the barrel of a vortex doing it's thing, impinging on tropospheric patterns for a period of time until we get a trigger that will create some disruption, for this you then look at the next MJO transfer across the Pacific and what can it do to reshuffle the deck. All that being said for now, it is certainly not the same vortex profile as last yr, which was truly exceptional, which gives us some small degree of hope. And, finally, the 'perfect' set ups may be ruled out by this period i.e. the big blocking and 'classic' set ups. Some of our strongest impact events have been from cold AM westerlies over recent yrs.

Eyes down for another Winter ( extended Autumn for 120 days !)

We are at the mercy of where any wave breaking leaves us at present... some ugly harbingers in the hunt for cold this year...

18z is never sobre - looks like a bunch of fun to me !

Some composites based on recent torque action.. Based on individual dates between 20th -30th November > then rolled forward in time. Clearly the Aleutian ridge is a big watch out and then perhaps on a secondary basis the Scandi Block and Jet angle. All of these manifesting in various mid term modelling now so let's see how well the AAM does for predictability... given the core vorticity vacating the Scandi locale as the vortex centroid position pivots back to Pacific I think the scandi high solution would be a interesting catch for this build, given it's not something you would have rightly called out lookng in NWP / ENS etc..

Picked a good evening to get to Cairnpapple for a nice view of the sunset.. Got to love low winter sun and High Pressure. Perfect.

It's laid out beautifully A Monday's page updated overnight on Tuesday to include the Vimeo Link and PDF - hopefully this will continue this week and the archive remains for a bit.. KW is right they are all on Vimeo - this link lays out the vids with the presentations. Workshop: Stratospheric predictability and impact on the troposphere (18-21 November 2019): Programme · ECMWF Events (Indico) EVENTS.ECMWF.INT #StratosphericWS This workshop will bring together experts to discuss and propose ways forward in representing the stratosphere in current and future numerical weather prediction models...

I got to the point last weekend Catacol where I just couldn't reconcile the seasonal output with that the statistical evidence was pointing toward... hence the tweet confirming as such. It really feels like it's an 'Us vs. Them' thing at the moment - not in a bad way - but either way it is a bit of an all or nothing situation where either the seasonal leads are defective, or, the reliability of looking back to look forward is flawed to a major degree. Have chewed it over plenty around the fact that the seasonals, perhaps to my naivety in understanding their input matrix, to my mind I thought they must have this stuff we amateurs / speculators look at built in to the ensembles. Or, perhaps the game here is not the 'perfect evolution' but a slow build to improved skill, more improved skill, what creates better skill and improves the correlation. Certainly having watched the symposium this week it is clear that there are hardcore questions on offer around what to 'go after' - 1 The processes and understanding of interactions vis a vis - we have enough resolution with the models 2 Increasing either the Vertical or Horizontal capacity within the modelling -which will generate enhancements in skill. 3 Hot Topic - impacts of GWD - Gravity Wave Drag and the contest between Direct Inputs vs parametrization. Am a Layman but if I was consulting I think I would ask the audience to Action Plan on 1 - which process the community should address, pick Horizontal to capture internal vortex vacillation and liase with MERRA for part 3, in particular their 132 level model. So these are there real challenges in resolving predictability, then impacts and it's been a good watch to review them.. I just hope we get a strong answer either way and not a halfway house solution where the answer fits elements of seasonal and elements of statistical..

I hope Stewart @Glacier Point won't mind me dropping this into the thread. Hugely respected poster on here who is currently not active. Some thoughts on this blog which I happened on this evening for folks to add into the Seasonal forecast mix. Solving the winter conundrum – Centaurea Weather CENTAUREAWEATHER.COM It’s that time of year again when the energy sector, hedge funds and weather enthusiasts are deluged with long range weather forecasts, the key question – what will the winter hold ? I’ve been...

Rendered this on gif from Zacs page earlier, pretty much sums up the current carnage... Lower vortex - shredding and shearing with filaments slicing off here there and everywhere. Core of Vortex - W1 doing it's thing and chomping into what appears to be a neat cylindrical funnel at points. End of run - we see the distended upper realms of the vortex where the real heat flux is in play and also some tilt to the vertical structure. Would be nice if MERRA ran out to further timeframes - but we cannot be too greedy I guess! If we think on that monster W1 and the physics in play I think on reflection it is little surprise that we will see some 'chaos theory' in the u deceleration ensembles, they just won't have it crystallized as of yet, hence the small cluster of members dipping below 0 and then a couple a few days later. Yes, it would be great to have something more positive to lock down from a GloSea perspective, but we still have the -NAO in it's infancy, a primed vortex via the W1 and lots to play through the column at all angles.. Anyone predicting where this goes is in the wrong place - esp. given the symposium this week where a room full of experts were divided on 3 > Colder conditions , 5/6 > Seasonals and essentially the rest were IDK... Am torn between the W1 resolving like a 'classic / old school CW' then retracting and the Intensification period continuing until the next MJO cycle comes round, this time aided and abetted by perhaps a more suggestive eQBO profile and another few weeks into deep zero solar. Vs. this W1 having been so anomalous that one of these consistent CWB /ACWB over the Atlantic region is the proverbial 'butterfly flapping it's wings' and the vortex internal resonance suffers some internal vacillation collapse into split mechanics. Would happily take version 2 of those events! Esp if an MJO rolls through at pace 8/1/2 mid/late December and layers the Greenland HLB over the QBO and Solar background states. Oaft.