lorenzo

Keep posting them !! Tracking a wee one out East currently but colours nowhere near as vivid as your image Quinach!

EC and GFS are classicly poles apart - no pun intended - on amplification aspects.. Looks like things are shaping up for a good model viewing series of EC vs GFS - nice when this happens to create divergence.

Another drookit day in Costa del Central Belt, and the fitbaw got rained off grrrr so that meant having to do actual stuff vs lazing about... ! Things perhaps brewing / stirring on the 12z though.. January ought to be more fun that December

I reckon you have your own vintages of fuel Mr Skier...

@snowidea Good link here which explains. Polar stratospheric clouds – Australian Antarctic Program WWW.ANTARCTICA.GOV.AU Polar stratospheric clouds play a central role in the formation of the ozone hole in the Antarctic and Arctic. From the 12z earlier - you can see the temperatures currently above the UK at 10hPa. EC ensemble temps and also the record lows at 50hPa from MERRA2. Pretty to look at, yet devastating for Ozone with the column right where we are seeing PSC degraded.

TRAMPOLINE ... TRAMPOLINE... TRAMPOLINE

PSC from sunset this evening Few from this morning - 2nd and 3rd here from a FB page - Scotland's Scenery - Borders then Edi. Short vid from this evening WhatsApp Video 2023-12-21 at 16.14.06_82807158.mp4

Polar stratospheric clouds (PSCs) play a central role in the formation of the ozone hole in the Antarctic and Arctic. PSCs provide surfaces upon which heterogeneous chemical reactions take place. These reactions lead to the production of free radicals of chlorine in the stratosphere which directly destroy ozone molecules. PSCs form poleward of about 60°S latitude in the altitude range 10 km to 25 km during the winter and early spring. The clouds are classified into Types I and II according to their particle size and formation temperature. Type II clouds, also known as nacreous or mother-of-pearl clouds, are composed of ice crystals and form when temperatures are below the ice frost point (typically below −83°C). The Type I PSCs are optically much thinner than the Type II clouds, and have a formation threshold temperature 5 to 8°C above the frost point. These clouds consist mainly of hydrated droplets of nitric acid and sulphuric acid. Polar stratospheric clouds – Australian Antarctic Program WWW.ANTARCTICA.GOV.AU Polar stratospheric clouds play a central role in the formation of the ozone hole in the Antarctic and Arctic. Not seen any r correlation to SSW - if anything my gut says opposite, this speaks to a very cold vortex in our locale which is the wrong locale for known trop pre-cursors.

Now then... stunning EC progression and a 'Sudden' jump in and of itself. Am completely intrigued by this one as looking at 'LOTS' of different charts it feels nearly there in terms of the warmings moving from a 1 perhaps technical SSW with u reversal but main vortex remains robust and just a minor visit to negative u, to, 2 full SSW with the warmings over-whelming the vortex and full blows SSW... Still right now for me the vortex looks concentric, yes tilted via the W1 but core is stable and heat flux is flying around the surf zone, so much so filaments are echoing off to create a PV incursion for North America c end of first week Jan. Yet, you cannot ignore such a consolidated forecast from our best wx model.. 1 Last night's runs at 70hPa saw infiltration of this pulse into core of vortex, tonight it has eased off a little, the SSW solution is firmly in the mix though. 2 10hPa from GEOS at the edge of the modelling out to the 30th shows the next pulse - right on a cliffhanger - will the vortex swallow the red pill? 3 From CPC the much maligned CFS - which happens to have a nose for technical SSWs into the left side of it's legend after 1st week in Jan. It's going to be a close run thing. Technical reversal perhaps for now is maybe 65 / 35 on that EC U - but the caveat is the mean and how quickly it recovers, could be a function of a really strong displacement. It still feels to me like a robust vortex based on image 2..

Any split chat is bs, this will be lucky to get to 0, watch the u10 ens on EC retract from here..

Well...

An easier way perhaps of viewing the ensembles courtesy of some excellent additions to Tomer Burg's site. Also has a rather long lead heat flux plot which will be good to keep an eye on too. The cluster around Boxing day within the u10 plot caught my attention with a group displaying a notable peak before crashing. The clusters which were around Boxing day, now moving toward New year, within the u10 plot caught my attention with a couple of groups displaying peaks before deceleration. Timelines moving outward for this over the last 24-48 hrs. Also below the CFS 45 day view with 0 > -8 creeping in on the edges of model reality c19th Jan, way to far out to be in anyway reliable but have seen the CFS catch an early glimpse of SSW previously so always worth having a look in on. GFS view / GEFS view - both with clear split in Ensembles and routes ahead beyond Xmas..

Grey, overcast, not a glimmer of sunshine, tipping it down with some decent rainfall. TLDR: Pish.

Aboyne about to get a pasting !

Finally, a sleety blob eventually made its way inland.

EC doing it's king model thing vs an adventurous 12z GFS, the NATL Ec Anom plot at D10 pretty much as expected via other drivers. Enjoy this cold spell, look ahead to 13th Dec progressions coming around.

Absolutely love that road..

Time to layer up and prepare for the frozen bin lids!

Yet another thing I cannot recall readily seeing

Also found this by accident this week re: later season action.. Just a moment... AGUPUBS.ONLINELIBRARY.WILEY.COM Meteofrance you dark horses is point 1 And 2003 - needs some retrospective. CW table referenced above is here North Pole temperatures • Atmospheric Dynamics • Department of Earth Sciences WWW.GEO.FU-BERLIN.DE

Dropped a post into Strat thread around other stuff in case of interest which develops some of the stuff above..

Briefly the conundrum, base state has crashed... AAM would normally put is in the side of things which are not blocking, the MJO phase ( really curious as to what is the truth here, Cyclones, ERWs, KWs, noise vs true MJO, the yellow blob at the foot of the chart is arguably the one to watch. And, finally the best site for the strat which shows real time movies of Vortex behaviour at diff. levels, we can see 100hPA on that still which provides credence for EC 12z tonight.. 192 would be as far as I go here though as these blocks are delicate and you can see on the vorticity plot below a classic tail which may erode the 500hPa lock out of the Atlantic. On CWs - it is a shame Berlin table did not continue to update, these were 'a thing' in the 80s when identified by Labitzke, however almost ghosted for a long time and were not classified. Nov CWs are more prevalent, Dec CWs - very rare -21 and 43 yrs ago - so literally no analog, composite or anything which would inform with any skill progression here. 1981 being 2 years into nascent strat sat monitoring then one season where classified. We have seen over the last few years though decent pulses of wave activity akin to CW ahead of the classic Vortex Intensification period, which i am unsure about how to gauge (i) these events were always likely prior to VI period and not monitored closely enough until the new sites to see the strat came on-line since 2018 > to date, or, these are genuine CWs akin to 80s view, would suspect the former. All told, CW does it's thing, vortex impinged distended, serendipty in the wave breaks does it's thing to build the Scandi break, breaks the routine regime, modelling hints at both weakeness in the lower vortex and also mechanics over North America greenland which are supportive ( currently / tentatively ) of some notable blocking. If not, then next MJO passage may be more telling on the vortex mechanics this year and how impactful the impact of wave breaks will be on vortex and our regimes here.

This should get everyone up to date. The importance of the polar vortex at 100 hPa – Simon H. Lee SIMONLEEWX.COM The most commonly-used diagnostic of the strength of the stratospheric polar vortex is the zonal-mean zonal wind at 10 hPa (~30 km) and 60°N (U10-60), which is westerly during winter. It is an easy diagnostic to...

Very lucky to live near some beautiful woodland and the low light at this time of year makes going for walks amazing.. especially in this first blast of the proper cold stuff. Really interesting modelling right now, and a proper puzzle really - the blocking currently showing is counterintuitive to what other drivers are doing such as GWO / AAM, very unexpected and tonight's EC 12z is either a case of it doing it's rogue amplification thing - or - pointing to a proper wildcard. Puzzling through it all just now ! The chart below sums up something we don't tend to see, the behaviour of lows exiting North America, retrograding North up the West coast of Greenland via some stalling, default would be they jump on the zonal train. Considerable cool down in continental Europe, Scandi already frozen, a tropospheric vortex pretty much bashed around and a strong Canadian Warming in the upper strat. Lots in play currently, still it 'feels' like another factor as yet quantified is at play, AGW artefacts possibly of NATL SSTA anoms, not sure. Still we have not had charts heralding an Atlantic lock out like this for a time. Caveat being it's the EC and it does have a historic tendency to amplify based on how it sees the pacific play out - it gets over zealous on fixtures for ridges. I would err on the block on the Atlantic here being over-run - but time will tell..

Given Space Karen has runined X / Twitter - trying to find some new spaces to find good science. Mr M leading the way - and some v cool obs, look at these changes in VERY recent years vs analogs.. gonna be a fun winter this season.. Whatsaoo ( my blah thoughts)