lorenzo
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Posts posted by lorenzo
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Eyes down for another Winter ( extended Autumn for 120 days !)
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We are at the mercy of where any wave breaking leaves us at present... some ugly harbingers in the hunt for cold this year...
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18z is never sobre - looks like a bunch of fun to me !
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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..
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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...
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14 minutes ago, Catacol said:
As ever with GP a good read. Quite close to a few other punters. He doesn’t appear to see a split vortex scenario as likely...but otherwise I like what I read. And if actually we get that Siberian vortex split with a continued tendency for heights over Greenland then all kinds of fun and games might develop.
And another who is showing little faith in long range seasonals. Either these seasonals are about to be properly ridiculed or some of us are going to have to retire....
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..
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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.COMIt’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...-
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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.
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Proof that disconnect delivers... great contrast during that February and a really unusual alignment of HP anomalies vs a bullseye Polar Vortex, nice rewind there!
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In 2018 NAO tightened ahead of SSW, this is something I thought was linked as an artefact of all vortex events ahead of an SSW, given strong anecdotal model watching. No one was wrong, we were possibly observing other things simultaneously, trough disruption, MJO/AAM Imprints
Dr Butler confirmed it is not analogous, ergo cannot be a confirmed regime watch out on NWP... More stuff to observe lays ahead and - no comfort from NAO heralding an SSW..
Although it did last year
From Dr Amy Butler
https://twitter.com/DrAHButler
Lady is the boss folks - privilege to get insight like this
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SSW in Dec as a whole I think could be considered rare given that is the canonical Vortex Intensification period, happy to be challenged on that view however..
I think without pulling out any papers that statistically January is your go to month for SSW with December being very much the exception, still gobsmacked by the EC Seasonal update to be honest - the plot for December shows an SSW with the Ensembles posted earlier showing the cluster heading that way. Then, January plot is also a torched vortex, if that came to pass then we are in for a ride this winter.
What is also interesting is that this November feels like a throw back to when Novembers featured Canadian Warmings back at the start of the 80s, given last November saw considered action also, just a few years ago we were wondering about whether Canadian warmings were actually worthy of classification, or a nuance of the early satellite era capturing more detail and then requiring classification of a kind. Rambling now... onwards and upwards with the wave breaking !
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Given the EC Seasonal ramping up some excitement, and not without support, given the CFS also cottoning onto what would be a rare December event. Here are the precursor height anomalies for each of the previous December events. I have left out 'December 01' as this event took place on 31 December.
Each plot is annotated with the year, QBO regime and strength of reversal by way of how decelerated the u at 10hPa went to, dates also annotated so this is not a November anomaly, but the 30 days prior for each event.
One to reflect upon of we do have an SSW next month whereby we can look at what is happening tropospherically now and maybe draw some inferences, equally as November progresses and the anomaly picture builds out we can perhaps map what we can expect to see if it looks like the EC seasonal etc will eventually deliver a December event.
I know I said November was fast becoming the most interesting of winter months, didn't expect it frankly to be as exciting as this..!
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CFS plot again of interest...
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Have a look at the ensemble members dropping below the 0 line for December..
Here is a box and whisker plot Simon posted representing the shift from the EC Model from Nov > Dec..
The thing that caught me out was this box forecast time 2020-01-01 - which anyone in their right mind would load in and say cool - this is January, however due to the way the data is encoded this is reflective of the month prior, in this case December.
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Okay so the plots from last night looking at January >>> scrub that... these are for next month
Thanks to Simon Lee for messaging to highlight as the way the dataset presents on Copernicus caught him out too!
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Nice one @Recretos, that EC Jan plot is a beauty.... you beat me to it rendering the data. I had a confusing Grib error that I had to dig into notes from @Interitus to resolve.
It's certainly not messing around for
January...Correction - DECEMBER
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While this is happening - ye olde vortex aint a happy chappy
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one element of carnage
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That's a great chart knocker - Matt sent it earlier... it's a squeeze but we also have an Atlantic wall of warming for it to squeeze against.
For that view the 50hPa run is incredible, complete carnage.
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Trop Vortex pretty much getting savaged wherever u look...
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It's great to see all the gang back on the strat thread - I did nag @chionomaniac to join in the fun.
@Recretosgreat blog on Severe EU and always love seeing what data crunching . RAM abusing graphics are up next.
@zdlawrence prettty much a privilege to have you here Zac, your website is a real benchmark for Strat monitoring after years of peering at the Berlin charts. I think the testament is that even a year on the 3D work is catching the attention of esteemed pros such as Mike Ventrice. I loved the fact that #stratpants appeared this season when last year we had saw the same split troosers ( Scottish for Jeans / Trousers / etc).
Best contribute with some commentary too other than say what a great season ahead, am personally loving Novembers now - it's the chase of the what happens next as much as the will it won't it herald negative AO/NAO or a decent winter.. By that I mean the down-welling question and the concentration of minds on this. Stop and reflect for a moment on how we were only 5 years ago working out precursors or Displacement / Split Dynamics..
Loving this ! Gnarly old vortex aint enjoying the Anticyclonic stuff happening right now.. can't do what it wants...
Get your crayons out...
Not a forecast there are two other years in the mix for Solar QBO similarity...however 95 worth a look..
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Another link with a few slides...
http://www.inscc.utah.edu/~steenburgh/classes/5110/lecture_notes/PV_thinking.pdf
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ECM at 240 ends on a beauty of a chart... The Atlantic Wave Breaking during this run is continuous, it then drops this at day 10... going to be good fun if this is in the post...
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Scotland/Alba weather discussion - Autumn 2020 onwards
in Regional
Posted
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.