Catacol

Brave words Steve. Greenland high only 1%? You sure?

See a few posts up?

January looks to be a NW month on that prediction with low pressure to the south implying a lot of southerly tracking in the atlantic pattern. While Easterlies and Northerlies are sought after by all coldies (Dec and Feb look good) I must admit I have wondered for a while what a very southerly tracking jet might do to us in January. Since I have been following the weather closely on this forum and on TWO I have yet to experience or see what might happen if systems spin their way down over France/Spain dragging colder air onto the northern flank in a high precipitation type of scenario such as is painted in the Jan chart. I could see some serious snow fall for certain favoured areas in that scenario, provided the cold to our East is embedded strongly enough. What encourages me a lot on that chart is the fact that the low pressure anomaly as forecast is strong only over the southern tip of greenland and quickly fades to close to average over and to the east of the UK. That does not imply a dominant zonal express. Interesting indeed. EDIT: mind you, backtracking to their previous run their anomaly forecast for December was totally different a month ago to what it is now. Another forecast model then that, at long range, doesnt have a clue. I have a lot more faith in GP's handling of the combined state of affairs - at least in Winter time anyway. :-)

Hello Stewart Do I sense that you are going to go against the most recent Eurosip seasonal update then and might go with the prelim thoughts video and stick with a cold prediction for winter? Do you have a target date for the release of your official forecast?

I think the upcoming period is quite a good test case. If strong tropospheric signals are turned over by a strong stratosphere then it will certainly suggest that the stratosphere is close to being the no 1 player in the weather jigsaw. My head tells me, however, that this is unlikely to be the case. I think we are in danger in this thread of seeing the stratosphere as the holy grail on its own... and forgetting that many other factors are important too. There is much that is still unknown here, not least how various levels of the strat interact with each other let along the troposphere, and the very fact that ongoing wave 2 activity is forecast suggests to me anyway that the strat is going to become proportionally less significant as it begins to wobble and moves (hopefully) towards a split. This is not to say that the cold stratosphere at the moment is not important, but I just think it cant be quite as simple as 1 factor over all the rest.

So midwinter weather patterns seem to be coming early - at least to my amateur eye. What might this mean for the latter third of winter? I'm smelling a cold (very cold) February even without Roger/Blast 's methodology or GP/Chio ' s strat knowledge. Very much looking forward to Stewart's winter forecast now. Early establishment of siberian and then European cold with a split vortex (possibly), Easterly QBO, -NAO atlantic signature and a jet that loves taking a break in Spain these days has all the hallmarks of something a bit special for coldies. Will a 4 wave pattern set up shop for winter and recur again and again? I wonder if February 2013 will be one of those months that future weather fanatics will talk about lovingly.

Ha - we have a 3 way split emerging here, more exciting than watching the vortex itself broken to pieces, or following the build up to the Hatton comeback! GP (sig cold event late November on the back of building heights over Greenie and Iceland with low pressure over Europe) vs Blast (block too far west and very mild courtesy of trough to the west and pressure building over central Europe) vs Chio (oh no my head is telling me that the vortex is going to fire up and ruin everything...) Love it. Presumably if the Canadian Warming actually happens then it will be all bets off and back to square one? :-)

Not quite everywhere... Check your satellite image and look carefully down at the SW... :-(

Well - you have strayed onto my territory here, and the statement above is misleading. The big traditional A level subjects do not reward regurgitation. At GCSE it is rarely the case these days now either. It is true that marks are given away more easily these days than used to be the case, but actually in many subjects the demands of courses are above what they were. There are some exceptions, notably probably Maths, but to state that bright students who stray from the beaten path get lower marks than the rote learners is just plain wrong - unless they have been badly taught and keep trotting out irrelevant stuff. Anyway - back on topic. Let it be cold... I fancy a snow shower over half term.

Scottish snow patches were his specialist subject at university. I'll put your point to him tomorrow and see how he comes back :-)

I am told that the most permanent patch is in one of the northern gullies on the Ben itself, and not on Braeriach...

Brilliant article - thank you. I got lost in large parts in the middle, but the opening section and conclusions were very clear. From here on in I will keep a close hopeful eye in Nov/Dec for a low pressure in the central northern pacific and high pressure in Russia/Siberia, particularly in an easterly QBO phase!

With the vortex in such a weak state already, can we make a guess as to what would happen were a warming event to occur in mid November? Just how disrupted can the vortex become? Does anyone have a chart of the "most" disrupted image of the vortex on record? My concern (as a snow lover) is that the guys at Metcheck seem to have thrown their lot in with the current pattern staying locked in for much of the winter, with high pressure a little too far east to affect us greatly and a stream of cold lows coming in from the west to keep us relatively snow and ice free, but pretty damned miserable I would bet. If the vortex gets broken up is it possible for such a pattern to get locked in over an extended period of time?

Well - that's interesting. They acknowledge a more southerly polar front but dont seem to think that blocking will be prevalent. That goes against a lot of what I have read and gleaned in recent weeks. Will be interesting to see how others view it all as more forecasts come out in the next few weeks.

Funnily enough I was online with a mate of mine in Sydney on Friday night and talking him about the warming event over the Antarctic that is ongoing at present. I asked him whether he thought that this might lead to greater temperature extremes in Australia with anything like a similar meridional pattern via a disrupted vortex (I hasten to add I know NOTHING about southern hemisphere weather and was only musing as to whether it behaves anything like the arctic) - and when he told me it was snowing and they had just had their worst snow event in ages I nearly fell off my chair. Seemed like someone somewhere in the weather heavens was reinforcing the concept that a warm strat = a disrupted vortex and consequent extreme weather in places.

Agreed.

Sorry TEITS - but you are not going to win this argument by cherry picking one post out of lots and lots that stops to raise a doubt over the impact of wave activity. Jan 10 was indeed cold overall, but the vortex was reforming throughout January and eventually the cold weather passed as the month progressed. This is exactly what CH begins to refer to in posts in the latter half of Dec 10 and, once again, it came true. You have simply reinforced the argument that strat effects can often be directly linked to troposheric impacts by highlighting this post. Let's remember throughout this running debate that strat experts always tell us that troposheric impacts are time lagged by about 4 weeks give or take.

Sorry - I want to post one final comment on this. A couple of pages back you wrote this: "If we look back at recent winters I can find quiet a few examples of how we need to understand the variables that dictate our climate. For example I revisited the thread after the Dec 2009 cold spell and even just 2 weeks away prior to the cold spell arriving nobody saw that cold spell coming." I have just popped back to the old strat thread myself from November 2009 and there are multiple comments from the first week in November from CH referring to a Canadian warming and a disruption to the vortex. This key post from GP then appeared on 21st Nov: "With the tropical stratosphere cooling again, this should strengthen ozone concentrations over the Arctic into late December. A couple of things are very evident looking at these comparisons: 1) The polar vortex will be weaker than any other winter this decade. 2) The position of the ozone concentration has been consistently building over the Pacific. These drift east over time. This means that the most likely place for the warming (and tropospheric impacts) look like starting over the Canadan Arctic and migrating eastwards towards Greenland with a trough over Scandinavia and western Russia." Note that last comment: a trough over Scandinavia and Western Russia. This was a product directly of the Canadian warming that was discussed for 3 weeks prior to this post. That is exactly what we got, with the segment of the vortex that so famously now dropped over us. So - I reiterate my initial point : if you are going to state something that is palpably wrong, and potentially misleading to new members of the forum, then be prepared to take the flak. SSW may not be absolutely the holy grail of forecasting, but it is a very strong indicator, and the fact that the MetO have so publically made it clear that their latest long range model now takes account of stratospheric signals would suggest that paid professionals are on the same wavelength too.

I think TEITS the point is that you put out statements there which were very close to being factually incorrect, and then drew a conclusion from them which was therefore off target. By all means be dubious about long range forecasting... but to use 2 periods of UK weather where clearly the strat situation gave early indications of what was coming, or suggested in the case of last winter what was NOT coming, was strange. I followed those 2 periods closely and know very well what was being said and suggested in the strat thread. To new readers all you have done is rubbish a newish forecast tool that everyone acknowledges has merit - and therefore in my opinion the riposte you got was hardly surprising and probably justified. If you are going to dish it out, then be prepared to take some in return.

I was just thinking exactly the same thing and was going to respond in kind. A winter's over post on 12th Oct? Farcical. BadBoy - I suggest reading some of the posts on here and checking your calendar carefully before posting such daft nonsense.

5 of the 12 Decembers that followed that november chart GP posted are in the top 20 coldest decembers in the UK since 1878. Specifically: 2010, 1961, 1968, 1976 and 1981.

Eh??? Winter over on 5th Jan? Ridiculous. Last half of Jan and 1st half of Feb is often the deepest part of our winter.

You're just getting carried away now. :-) Forget snow in October for England despite what the record books might say about unusual events. You'll just end up disappointed. Mid november onwards and things start getting interesting...

Ah - thank you. :-) I feel happier now - good not to be a total amateur. I guess you are right though - would be asking a lot to have blocking in place solidly from October to March, so would rather see October more zonal, with blocking then creeping onto the radar by late November onwards.

Every now and again I shake my head at my incompetence... but why is this "sadly"? Does blocking at this time of year reduce the chances of SSW later on?