The location of the strongest strat. warming and attempt at splitting the vortex at 30hPa extends from SW of Iceland to the near side of Scandinavia day 10 onward, as opposed to sticking around over Greenland.

This continues a trend which began this morning but which I forgot to account for (I'm only human, and it is New Year's Eve after all), and shifts the focus for a weaker jet further east, which then opens the door for height rises to our NE.

The past two GFSP runs were too weak with the warming to have much effect within the 16 day range, but the 12z has stepped it up a gear and this seems to produce a faster, more pronounced trop. response.

This allows the Siberian High to finally emerge from it's long slumber and start smashing up the polar vortex. That would be quite a result given that this is how Cohen originally thought it would unfold in the November outlook (but delayed by two weeks).

Nice to see an entertaining bit of trop. output for a change, even if it is way outside of the reliable. The response does seem to be rather strong given that the vortex is only displaced and elongated rather than split, and the GFS 06z, which had similar intensity of warming (though a bit less than GFSP has later on), produced far less of a response, so the usual truckload of salt needs to be taken with this GFSP 12z run.

Given that ECM was showing a similar progression out to day 10 this morning, it seems we should hope for this warming, starting near or over Greenland in 6 days time (below left - note that the strongest warming is at higher levels at this point in time) and traversing the Atlantic to Scandinavia during the following 10 days (below right), to be as strong and persistent as possible. That improves the odds of reversing the zonal wind at 60*N and also seems to allow for more of the warming to propagate downward - which may explain how the 30hPa warming grows stronger during days 10-16 of the GFSP run.

Cohen stated yesterday that GFS persistently underestimates the strat. warming, so perhaps we shouldn't worry too much about what that model shows. The updates for GFSP, on the other hand, might have accounted for that bias - though it would be handy right now if they haven't!

Those reading my recent posts can probably tell that my understanding of the stratosphere and how it impacts the troposphere is still rather sketchy so it's probably best not to pay too much attention to how I think the troposphere may be impacted - I'm still learning, and I'm hoping that events this month will prove to be a useful case study. What makes it so tricky to understand is the fact that key developments happen at a range of different heights.

you need those yellows a bit further North- East,  and well I suppose anything could happen. A 5% chance ATM, and I think that is being generous. Still, something to cast my eye on in the next day or two. 

If only we could get an easterly 

http://www.meteociel.fr/modeles/ecmwf/runs/2014123112/ECH0-144.GIF?31-0

The high will get bulldozed and pummelled out of the way by the Atlantic jet bully.

very.

thats not as straight forward as you would think. 

A little interest tonight and a small hope for coldies

 Still looking cool rather than cold after an early mild spell 

Very basically, see that high over Scandinavia, with the H (= "hoch"/high, it's in German)? Now imagine that expanding, particularly westwards. The low over the UK, with the T (= "tief"/deep, i.e. low), would be forced beneath it (or "undercut" it in the jargon on here). 

Now picture that scenario and follow the resulting isobars (the lines around the T), bearing in mind the direction of wind is anti-clockwise around areas of low pressure. You'd find the consequent airflow would be coming off cool land to the east rather than mild water to the west.

The other noteworthy point is that the high over Scandinavia is coloured green and yellow, indicating warmth and consequently strength in the high. What coldies are looking for is warm air advection (WAA) northwards to promote areas of high pressure to our north (so-called northern blocking). This forces the areas of low pressure southwards and, if everything falls in the right places, a visit from colder Arctic or Continental air rather than mild sea air.

It really is that simple.

 some very great stuff above just before i start getting drunk and my girlfriend starting on me for being on the net,  I want so say HAPPY NEW YEAR TO EVERYONE here on TWO. loving this site loving the upgrades, nice to see the model charts than the old skool links that never worked when clicked on them, thanks to everyone who post to MR BRIAN and MATTY H and the MODS for doing such a good job on this forum and keeping the rampers at bay and away   looking forward to 2015, a great BUZZ update from MR BRIAN RESPECT to you all, and to my buddy gavin partridge for all his great work and time he gives us thru the year. cheers guys,   [ sorry for of topic, ]

I've only one issue with that post, the rest is fab.

I dunno, if you took the output from the big three to Mon/Tues next week and no further things may have seemed a little more interesting. Imagine if they modelled the area to our north wrong and its too progressive? That might be all the high building to the n/e and e needs.

Excellent description there.

SFB that is brilliant! Thanks very much, I have learned something today, great description.  I will study the modeland use your description. yes it is quite simple😳 I suppose!😜😀

Now that's interesting - more of a split polar vortex pattern emerging on the ECM 12z op run (above left), no word on the strat. charts from this model yet but I would not be surprised to see a better attempt at splitting the strat. vortex at 30mb than was seen on the 00z, with the Canadian vortex suppressed further - more like recent NAVGEM runs perhaps.

Edit: or perhaps similar to the 12z JMA which is really sticking to its guns, now shown above-right. There is little move to transfer a new 10mb trough over to Canada, which is GFS and GFSP have taking place really quite quickly days 7-10.

This version of events seems heavily dependent on having stronger warming over East Asia days 5-6 which seems to stand in the way of the trough transfer event. It might also be helping to get the core of the wave 2 warming all the way up to -8*C.

Shifting attention back to the 500mb charts, the ECM evolution is quite literally a different angle to the GFSP 12z in terms of where the build of high latitude blocking begins; it's quite a bit further east on this ECM op run with a strong dig of low heights down into Central Europe already well underway (GFSP shows a similar thing but it's more gradual and closer to the UK). The ridge to the Pole is being sustained by undercutting lows and is nicely placed to try and break up the Atlantic westerlies.

By contrast, there's still no suggestion of high latitude blocking from GFS, which ties in with it's weaker strat warming. GEM looks about the same, so I guess it is similar to GFS at the strat. levels, presuming it models them all.

Shifting focus to the shorter range for a moment, Snow Hoper has made an interesting point about the heights to our E and NE in 6 days time. There was a case in late November or early December when we had a similar situation, and the ridge did turn out to be a little more resilient in the end - but not quite enough to save us from the westerlies.

To be honest though, I'd rather see low heights smash through on route to Central Europe as per ECM/GFSP.

Overall, I'm just glad to have some interesting changes in the 500mb charts to think about after so many days of 'same old, same old' 

Happy New Year 

great post storm chaser just nipped on to view your post DAM this forum is like a heavy drug I cant keep away,  anyway thanks storm chaser happy new year to you buddy, back to the JD and coke.