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ECM looking great this morning, whilst this is at day 9 it has done well so far this season, had dialled into the last Northerly Blast from a similar range. This looks a little more complicated as a deeper and much colder low filters in. Beats watching a mid latitude high ! Mon' the Snaw !!

Just spotted this gallery image on the homepage. It is from an article written by John Hammond on the bbc pages. Well written article on how complex medium - Long range forecasting actually is. http://www.bbc.co.uk/weather/features/25108639

Wave 1 and Wave 2 activity from the troposphere impacts the stratosphere. If strong enough / sustained enough, this activity can impact the polar vortex leading to either a Minor Warming or a SSW Sudden Stratospheric Warming. Wave 1 activity generally leads to 'displacement' events where the vortex is shifted off it's home, Wave 2 activity can carve up the vortex and lead to 'split' events. Once the vortex is cooked there is an immediate tropospheric response, followed by a lagged tropospheric response where easterly winds burrow down through the stratosphere. These easterly anomalies bring the cold, however there are never any guarantees on how a displaced or split vortex will play out i.e where the core of the cold will spill to lower latitudes. Last winter is a strong example of how effective a SSW can be at changing the pattern as we really were stuck in a rut which flipped when the SSW kicked in. This is why we look at what the wave activity is doing on the Stratosphere monitoring thread.

Very interesting update, some further information on the mysterious October Pattern Index (OPI) from a co-author Alessandro, this explains a little more around the science and method they are using to calculate the OPI. Hello guys. First of all, forgive me the language .. I do not speak well English. My name is Alessandro and I am the co-author of the research OPI together with Riccardo. want to compliment you for the wonderful topic and specify only a concept about the difference between OPI and SAI . OPI essentially measure the position and degree of intrusiveness of the planetary waves in the month of October by two parameters:1) degree of ellitticizzazione / elongation2) axis of polar vortex When we have a very tilted axis ( iceland -east Siberia / Aleutine ) and a pv stretched in October, like 2005/2006.a part of the rate of snow cover can not be measured as the snowfall occurring in the sea under the 60th parallel. In these cases the SAI approximates very well unless the AO . For this reason it is important to measure the position and the intrusiveness of the planetary waves rather than the snow which is nothing other than a consequence of the pattern of October.Soon we'll end the English translation and will submit to the competent authorities in the USA . Best regards ;Alessandro

Not seen it Buried, was just going by information Matt had placed on Twitter, ECM32 is 'under the counter' weather chartage. That last post is a belter, a man with a hat punching himself in the face. Genius. I am Jacks raging vortex.

Let me know if I have got this one wrong, certainly don't want to annoy the regulars, nor lose the banter on the thread. Just thought that SS thread may be better for more in depth discussion. Happy to be corrected, anyone else got any thoughts / ideas / suggestions..?

Another cold control run on the GEFS Ensemble, seems to be very reliable for the colder solutions so far this season. Still, nice to look at some very cold 850hPa temps here..

The strat has got his hat on.. hip hip hip hooray... I get some of this Buried, the punches being Wave 1 and Wave 2 Activity on the vortex. As Catch said, a real classic ! Folks, Would like to point you towards the excellent thread in the Serious Discussion forum started by Scottish Skier for all the political debate/discussion. I am sure that reading through that thread in itself will leave you more informed than the paper published today ! Am not for moderating heavily so would love it if you could continue over there. Thanks, http://forum.netweather.tv/topic/69584-scottish-politics-2011-2016/

MJO starting to feature a little more as it has left the Circle of Doom ( origin). GEFS into phase 2 and ECM into Phase 3 UKMO nearer the ECM side of things. Couple of composites similar to previous, taking account of Westerly QBO and Neutral MEI. Also filtered for the GWO moving through lower AAM phases 1-4. Low AAM Matt just tweeted that EC32 goes for the anti-cyclonic outlook and these 'background' states would support this. Now to figure out the rest of the month !!

If only....All good things.. EC32 going for HP again.

good to see they temps as low as that and hopefully it comes of atleast we will start winter with a feel of it. see the anomalies chart LS with the more blocked around Greenland and if you look at the op model run it is looking to try sink lows over us do u think if the anomalies chart is right with the more blocked greenland would this promote the heights to move into Greenland and the low heights to then slide into Europe. or could this not happen with the PV where it is. hard trying to explain bit tired. Quote function has gone weird again ! Good to see your wrestling away with the questions Buried, anomaly charts can be deceptive, you can get predicted high latitude blocking across GEFS or ECM ens, only for nearer verification for the heights to not be as strong as forecast. The anomaly is based against the climate norm. so can get skewed, based upon what is the background state in the anomaly plot. A good way to look at this presently is to follow the ENS against the operational on the Aleutian High, whilst it is ever present on the output, there is still inter run variability on how far it extends towards the pole. Re: Dr Maue posts, Weatherbell had a lead of 10 days on the US snow storm and Arctic cold shot, I think the tweets are to back up this prediction. Joe B'Staardi has been video blogging about it for the last week or so. One of the occasions where the ECM has verified quite well from day 10, similarly it did well at day 10 for our 'Arctic Blast'.

Good link plotting the path of the comet as ssen by STEREO and LASCOs http://stereo-ssc.nascom.nasa.gov/comet_ison/

Fizzled or not fizzled - that is the question. This image from a few hours ago..

Gotta love the GFS 06z, if weather models were animals it really would be a daft auld dug. It must know we are suffering from anti-cyclonic model blindness. Throws in a trademark Uber Low Anyone seen the 06z verify from 11.5 days out ?? Wouldn't trust it at 11.5 hrs 486dam air approaching the NWest of the Country. LOL !!

Wouldn't want you wondering CH, I think we can trust the paper, It's best in class current data http://www.atm.ox.ac.uk/user/mitchell/ Very strong academic pedigree and also collaborators looking at this list of publications http://www.atm.ox.ac.uk/user/mitchell/dann_pubs.html Dataset Tropospheric precursors to warming events are something that is a backbone to studies on SSW, there are historic studies pre-dating the above paper and I am sure many to follow. Yes I agree GP is a big miss, no doubt, but one thing about him not being around is that it forces the learning curve up and others can begin to work through where he left off. Safe to say that he was light years ahead of anyone else.. MJO forecast from CPC is updated on a Monday, so we will get an update on how they see it going later this afternoon / evening. http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml#discussion

Thanks for asking Misty, gives me a chance to dig this one out, one of my best Winter memories. Was at a football match with my Dad, and it got abandoned at half time, couldn't make it home, ended up staying at a friends as the roads were completely drifted out. Not identical , but for our location shows the evolution is not impossible. At present, I would say unlikely in terms of December 2013, we can only hope !!

Mentioned ISON earlier, good thread and within it a post on viewing the comet here

RE ^ Looking through the Berlin plots this morning.. This at the 30hPa, heading towards 30m/s and a temp of -80 degrees, one compact vortexy looking vortex.. Some poleward EP Flux visible on the Strat plots, however the above gives you an idea of what it is up against. SEND IN THE NUKES.

What you find BUS is that when the NWP has a less than impressive outlook, folks tend to visit the strat thread to see if there are any changes in the post that will alter things. Re Troposphere vs Stratosphere. This excellent post from Chiono is a great visual description of what happens that addresses some of your thoughts from last evening. http://forum.netweather.tv/topic/78161-stratosphere-temperature-watch-20132014/page-3#entry2809151 Beautiful clear morning, a nice crunch underfoot, hopefully more days like this to follow and we manage to get a view of ISON in the next couple of weeks should it survive Perihelion. Looks nailded on Catch Today, looking out for the latest CPC MJO update later on, will be interesting to see what this is due to be up to later in the month..

Here you go CH these are from the Mitchell paper and show the patterns prior to / and after displacement and splitting events. As for GLAAM, still working hard to unravel it.. Bloody frustrating to learn, two steps forward one back half the time. Frictional Torques lead into Mountain Torques, can be monitored here There are many good papers in the technical papers thread to have a look at also, excerpt from Baldwin 2012 a. Vortex displacements Preceding these events are often anomalously low pressure systems over North America and high pressure systems over western Europe and the Pacific. Associated with this are warm temperature anomalies over Northern America and an increase in blocking over northern Eurasia. b. Vortex splits Preceding splitting events are anomalously low temperatures over Eurasia, with a wave-2-like pattern observed in MSLP.

I agree, GFS will pick an idea and then drop it and then go with it again. To be fair this variance is visible across the models now and again. Another one to watch out for in Winter model watching is the dream cold charts 'getting stuck in FI'. Another tease the models like to roll out in lower resolution. This high is really enjoying it's UK visit, absolutely everything steered NNE. Over to TScahernaker for a Doodle Really is a holding pattern for the weather, could be worse weather I suppose !

Re Decider, see link here http://www.metoffice.gov.uk/media/pdf/l/f/decider.pdf or in the presentation linked below https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&ved=0CD0QFjAC&url=http%3A%2F%2Fwww.ecmwf.int%2Fpublications%2Fmember_states_meetings%2FForecast_products_users%2FPresentations2011%2FPDFs%2FMylne_Parker.pdf&ei=9yiSUq3_Ku7e7Aaek4DoCw&usg=AFQjCNFVmcgEv7GBfuPKhaey_KTsZKD0bQ&bvm=bv.56988011,d.d2k Looks brilliant, clusters ensembles into regimes to provide an outlook on predicted weather type, if anyone wants a run through Dec 81 click here..

Indeed, and with charts like this in FI then he has rocket fuel for a rampede. Stunning cold shot into the CONUS. Not jealous...much...at all....really. I love mid latitude limpet highs.

From the initial post in the thread, for November so far the 30hpa plot and predicted, looks like a solid result coming up for November, let's hope this continues and the Jan / Feb predictions follow the same route.

Been a bit of a week in the model thread ! Good this lazy one is here, helps to keep track of things.. Looking at December and with such variety of divergence as the models get to grips with a pattern change it is tricky to see a way ahead. So much going on to get through - The wave activity in the strat. showing on the models has been inconsistent, the Pacific SST profile is cooler, but with a warmer profile beneath the surface. The AO threatens after some massive model spread earlier in the week to set it's positive stall out, and we are seemingly at the mercy of the subtle orientation if the ridge to our west. This not withstanding the ECM upgraded this week so who knows if that requires fine tuning.. GEFS and ECM Ens quite different on the AO outlook, although the means are similar, the control runs are in complete contrast. Made some composites based on perhaps more predictable factors for the 1st - 10th December. These are based on the 50mb QBO, ENSO MEI index and AAM. QBO figure is 7 to 10 ms, ENSO is a wider filter -1 to 1. All dates from 1974 to 2009 using the daily dataset First is for QBO and ENSO Neutral, some similarities to current model output, namely the troughing into the heart of Europe, this has to be a signature pattern now surely, also the mid-Atlantic ridging. Next is QBO without the ENSO Filter Next is QBO for dates with a lower AAM Recent long range mean plots from GEFS and ECM Ensemble. GEFS days 10 and 15 ECM day 15 Variations on a theme, and perhaps a backdrop for the start of December.