Severe Siberian icy blast

So many frantic posts , I understand given the short wave drama I suppose ! One thing that strikes me today is the significant shift west with the what was scandi high , it's now Iceland , toward Greenland , but we know for long lasting trough disruption it's best to see a classic murr sausage !

Yes course . It's the jet stream

Good afternoon my fellow weather enthusiasts Iv been so busy over the Xmas period I really haven't time to give my views. Just a few things to say, firstly and slightly off topic Iv spent the last 5 days in krakow Poland , I went in the hope of freezing cold but was greeted by a very unusually mild Poland , with temps ranging from -3(min) and upto 10c (max) , I found it very depressing and typical of having to suffer upper air temps at 850hpa of around +5 all the way from Africa !!! I was earnestly following the model thread however , to wife's disgust , I litterely can't leave netweather alone ! On to the models , I was absolutely delighted today with the outlook , although not completely surprised , there has been rumblings of a potential cold spell for sometime now , but one model Iv been completely proud of , is the gem , this has been barking up the tree now for ages , and slowly but surely we have saw the models coming into line it . At the same time , certain members in hear have blown me away with the analysis of models , Steve M , you have been amazing and never seize to amaze me with your knowledge of the way the individual models handles particular situations , and Nick Sussex has also been fantastic with his brilliance on short waves , and taking his time to educate us all with his diagrams , it really does feel like I'm attending a university course at times! And a massive shout out to two other individuals , Corinthian , for the insight he gave regarding what he and his team expected , with excellent timings aswell , and Tamara , for her very informative (at times not pleasant to read at times!) words of wisdom , and it certainly kept my feet well and truly on the ground, I know many others have realty stepped upto the mark this year since the department of our beloved GP , and in general the model output thread has come on leaps and bounds this year . One thing Iv done these last few years is became engrossed in the strat thread , and please make no doupt about it , absolutely everything in the winter pattern is driven by the polar vortex and the stratosphere , and with this cold spell up coming , it really wouldn't be on the horizon if it wasn't for the wave 1/2 activity , we don't need a SSW to destroy the vortex , given the strength of it this year it has taken ones by surprise that this recent activity has managed to the damage it has , but it certainly bodes well for February , and as we finally know from last year , march aswell if things go right. So all in all a very positive outlook . Behold ourselves for another night of ectacy or depression !!

Their appears to be a lot of warming putting a lot of pressure on the vortex from both sides as we go through jan , The one over our side is of interest , if we can get a split from this we may have high pressure build directly to our north , which would bring northeasterly winds . Along with a very interesting northern hemisphere pattern from quite early on Split vortex hear , "potential" is the word going forward .

Each to there own purga.But there's also a clear trend for lower precipitation toward the end of the run thank goodness , whether you see it or not , there is a change on the horizon , the jet sinking south , low pressure into Southern Europe is always a good sign , usually promotes high pressure to the north . A good 7-10 days of wet weather followed by a much colder second half of jan , into feb , and march of course . Which is normally when our cold weather comes anyway, this will be winter of two very different half's I feel

Hi chiono , so is there any particular reason why the heat flux is going away from the pole? Does the strength of the vortex have a say on diverting the heat flux away from the pole? Or is just coincidence ?im guessing there's a driving mechanism that determines which way it will go?

What a shame, your in our thoughts mate, stay safe , take no risks , safety before possessions at all times

Who are you man in disguise???!!

The irony of it is , if these forecasts go as planned we may actually have a fantastic jan , considering how poor things looked until recently , my first snow fall last year was 19th jan , so still plenty of time to have a good winter . . . Good to see such strong wave activity in the pipe line .

Iv been watching this , surprised know one's mentioned it, a kink In the isobars moves across southern areas , I heard it mentioned some days ago , but it's even dropped since. Not sure why ?

Considering what we have been forced to watch for the entire month of December these charts are so much better than what we'v had , granted we have lost the trough disruption , but the polar profile is about to undergo a pattern change , we can expect the period of transition to polar blocking to be period where the models play with different possible solutions , a transitional period brings even more chaos to the models than normal , so expect to see lots of different runs , but considering how mighty strong the vortex has been , I welcome these charts with my arms wide open .It's what Iv been searching the models for since November ! With polar blocking and the vortex shredded we have a much better chance of cold and snowy weather , so let's hope these charts move closer to the reliable timeframe because once they do we can realistically start looking for deep cold to effect our shores. On a separate note I'm off to Poland on the 3rd for 4 nights , and I really hope things the weather becomes more seasonal over their rather than been 6c , that would be Sod's law !

Tonight I feel as we have made a significant step to northern blocking , not only do we have the artic high well in place , we also have a split vortex , which given the strength of the vortex is remarkable , what we also have hear is ridging into Scandinavia , which is very close to a undercutting scenario , no doubt in my eyes that we are close to wintry set up going by the gfs fi this evening , surprised by the negativity recently , but i think we will begin to see changes as we going to the new year. This is a very good chart . If we can get the energy going under the block then we have a scandi high in place, a split vortex , high lat blocking , and lots of energy coming off the Atlantic going under . Which spells a very snowy picture .

Yes that's actually looking a good chart, high pressure towards Russia , deep low pressure toward Italy , southerly tracking jet , this could get interesting.

So judging by the image there do we think there may be further developments as the evening goes on? Because if not then I would say that looks way off tbh !? Hope you don't mind me gate crashing your thread lol!

That really is astonishing , a lot of negativity because of the polar profile but I'm looking forward to cold zonality , it's bought surprises before and im sure it will this time. Johns post as always was top. With a real possibility of something wintry next week

Yes if your focusing on the northern hemisphere with the PV looking strong it doesn't look good. But taking the 06 litterely it shows cold zonality with a much more north westerly element to the weather after Xmas , so in this instance I tend to agree with frosty. Yes it shows the euro high in deep fi but I really don't care what it's showing after 240hrs because it never happens anyway . I have seen hints of a pressure drop over Europe towards Italy recently, it happened yesterday , forget what run now . With the jet way south , and the MJO on the move (see technical thread) , that points toward a major pattern change into the new year . But cold zonality can be fun for some , and tomorrow's snow chances is very reall , and could well happen again with the jet way south .

Very interesting Ian , are we looking at organised trough's or just shower activity ?!Thurs definitely has potential to deliver a few surprises !Edit: just read your last post , thanks .

For what it's worth the gfs again moves the jet south as we head toward Xmas , surely this is a trend now? It also gives a notable snow event Xmas eve Marginal but heavy . Again showing the AO going negative with high pressure taking control over the polar regions . The last 2/3 days we finally have signs to look toward a change , all fi at the minute but consistently modelled . With wave 2 activity picking up over the next 7 days . As for the ECM 32 dayer , it's always nice to have it showing a wintry outlook but going from my experience last year, if it was right about the Greenland high pressure taking hold just 50% of the time then we would of had a very severe winter but it constantly failed in its attempts . Only to have a completely different outlook 2 weeks later .I have noticed even this year so far it's been way out . 2 weeks ago we was looking at the potential of a record breaking dry spell. Now we have the Atlantic taking control with what looks to be a very stormy spell. So can we trust any long range models? In my eyes the only long range trends that's worth looking at is the stratosphere developments , it absolutely never fails . All of our weather is controlled by what going on up there , if the vortex is vigorous , expect low pressure above us . High pressure south of us . If it gets disrupted/blown to shreds for what ever reason (ie SSW , wave activity etc , ) then the chances of cold and snowy weather are improved , but not guaranteed . The major player in our winter time is the vortex /stratosphere . Look to that for guidelines , if there is rumblings of strong -/+ mountain torques / strong wave 1/2 activity events / and if we're really lucky , a Sudden Stratosphere Warming event then chances are as this propagates down the lower levels of the strat , we will see a tropospheric response , which will show its hand in the models , first in fi , then more in the reliable time frames. So for me , we have the first signs of a major pattern change into the new year , but as ever , time will tell.

Agreed. The jet coming south , along with the polar vortex itself !! We actually are in quite a wintry set up toward the end of the run . Cold northwesterly winds with sleet and snow at times. Unsettled and wintry fi tonight is how I would sum up the 18z

O I agree.I can count many of times when a cold spell looked likely only to be taken away from us inside t120 , which is why without stratosphere backing cold spells are very unlikely . If we are after really wintry weather , we all need to look at the stratosphere forecasts , this time wave 2 activity does look the strongest it's looked so far , but it's only a forecast so it needs to watching . But IF it comes in to fruition then that can wobble the vortex , and open the door to a more realistically cold pattern . But even then many things depend on things falling into place ,take last year for example the winter was loaded with potential , but even with the vortex destroyed we had a segment sitting over Greenland which in turn fed the Atlantic . We don't need things to be as favourable as last winter . But we do need the vortex to disrupt and wobble , then hopefully it can spill energy down to mid latitudes and give areas further north a chance for high pressure to form !!

Yes very very fi I know , but with what's going on in the stratosphere in 9/10 days time could this be the beginning of the vortex been shaken to the point of falling apart ? If we can get the vortex to drain away from the polar regions then northerly blocking will take hold , but we have a very disturbed week next wk to come , and maybe longer . But the are just tentative signs now of a major pattern change after Xmas . Which in reality is when the uk's snow and cold normally comes.

The trend continues from yesterday , with rather more cold zonality that was forecast . With a segment of the vortex dropping down from Greenland into the east Atlantic you can see by looking at the northern hemi charts it's hinting as the energy draws away from the north it MAY allow hight rises in the gaps appearing, that's normal really given the look of the forecasts , so as head toward Xmas and behond things should begin to look much better , excellent post by Old Met Man last night which again it's like he wrote the script this morning ,(granted in its very early stages) and over the next 4 days I think we will begin to see some eye candy.Also in the stratosphere forecast this morning we have the strongest wave 2 activity of the season at day 10 , some really potent wave activity . http://forum.netweather.tv/topic/78161-stratosphere-temperature-watch-20132014/page-26Along with some really excellent posts by chiono and recretos .

The 18z in fi shows signs the jet is moving south with southerly tracking low pressure systems, cold zonality over the Xmas period will be a good bet I think. Which can be very interesting , ie heavy squally wintry showers. I remember dec 2011 cold zonality spell well. We had lots of sleet an hail in the morning and when I came home later about half 3 that afternoon it snowed really heavy for 1.5 hrs giving two inches of wet snow , only to be washed away by heavy sleet showers that night, a small patch of sub 528dam air moved over England during the day , hence the snow. Exciting model watching it can be ) Good to see very tentative signs of things moving toward a colder set up toward new year , any news from the OMM is well received in my book , with wave 2 activity on the increase in about 9/10 days time things will begin to look brighter as the jet moves south .

Although the vortex is looking very strong at min am I right in remembering as others have said it could actually work in our favour come a SSW ? Meaning it normally means a big bang with the vortex blown to shreds ? I understand the wave 2 activity dosent mean a SSW but if persistently strong enough it contributes doesnt it? Also if we can get some pressure on the vortex via wave activity in say 10 days from now and if persistent then can we look toward the 5-10th jan for a POSSIBLE SSW ? Hope you dont mind me asking im still learning . . Thanks

All the signals are pointing to a scandi high dominated second half of winter , so really don't know where you get that from , Ian and any other forecaster will only ever say with confidence the next 5 days at most, maybe giving hints to the longer 10-15 day trends , but anything after that is nothing more than computer modeling , and we know how much they change , it's easy to get frustrated when things look bleak but putting dec 10 aside we very rarely have snow and cold in December , it's normally dominated by zonal weather as the vortex reaches its strongest point later this month. Last winter when we had everything going for us on the face of it , especially December with an 80% chance of a Greenland high according to Stewarts winter forecast , we all know what happened , it was a flop ,with too much energy left toward Greenland which actually remained in situ all winter even in jan , giving us a slightly +NAO all winter , so trends really can be meaningless for our tiny island .So just sit tight and our time will come, my first snowfall last winter came on the 18th jan , but because we had a snowy second half of winter everybody forgets the first half .