lorenzo

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!

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

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 !

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..!

CFS plot again of interest...

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.

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!

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

While this is happening - ye olde vortex aint a happy chappy

one element of carnage

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.

Trop Vortex pretty much getting savaged wherever u look...

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..

Another link with a few slides... http://www.inscc.utah.edu/~steenburgh/classes/5110/lecture_notes/PV_thinking.pdf

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...

Some stratospheric pornography now, courtesy of a rogue Ensemble member...

I concur, sadly no coal fire, but a proper MINGER of a day !

November certainly seems to be the most exciting Winter month these days given our further knowledge of the vortex influence. Vis a vis above post around Vortex Intensification phases, a good illustration of things we just couldn't see with any clarity with the material available vs. the amazing data on offer now. Robust cold vortex on the T Plot first off, then the zonal wind profile showing the disconnect advertised previously and expressed in AO outlooks. Following this the vT Heat Flux plot, some crude annotation on there on possible route forward. The 100hPa layer also show from stratobserve, note the GFS progressive here vs. ENS so one to watch in terms of how this may write into other data. Much wave breaking ongoing right now, the MJO kicking up - and watch the JMA NWP output here for some tasty charts, as it is definitely more progressive than GFS / ECM. An ECM which pivots to P8 on today's update. Also we have an AAM boost going on. Loads of mechanics to unfold in next 7-10 days. Been here before though in the last couple of Novembers is the caveat though, all that glitters / torches , aint gold as we know... Solar and eQBO could still prove interesting wildcards here..

Ye olde eQBO looking meaningful... No signs of stalling, or blips... Always a welcome driver to chuck in the mix. Strat Trop interaction clearly the key variable now Vs will it or won't it SSW .. good to read the conversation evolving again. Last year downwelling hit a brick wall, would be nice if that brick wall was still in place and that rampant vortex decided to remain locked at altitude.. November taking on early significance in terms of direction of travel further into winter.

Here's hoping the disruption plays out as you see it Steve... even at 100hPa we see scatter in the top medians. Lower down the strat the CFS longer view shows a healthy spin up of the vortex..

I seem to be causing forecasting problems.

Bewildering evening ahead.. the SPC advisory and replies are sobering. Radar link here http://catalog.eol.ucar.edu/torus_2019/radar

Thread title is Cold hunt - models and banter Not... Cold hunt - models and bickering It's easy to hide the poor additions to the thread , so don't waste your time adding them.

Well actually it isn't, and that's kinda the point. But metaphorically speaking - I hear you.

http://brunnur.vedur.is/kort/ec-ens/2019/