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Couple of charts from the Berlin site this morning. Vorticity shows the vortex heading into two distinct vortices The Wave 2 reinforcement continues The spilt at 30hpa inside 120 hrs then out to 240 hours where the warming wave can be seen clearly as has been trailed on the GFS charts. Vortex certainly getting a beating from all angles. The flux graphs also show zonal winds running lighter again and the last 3 days EP Flux are strongly directly North or Poleward.

Today there is no Matt Hugo update about EC32? At the belgium website weerwoord (weather word) http://weerwoord.be/...325&tid=1707325 KMI meteorologist Gert has put a text about EC32. Ben ik nu de eerste, of is Matt Hugo mij toch voor? Voor wat het waard is: volgens de jongste uitdraai van EC32 blijft ook de periode 10 tot 16 december duidelijk te koud (1 tot 3 graden ten opzichte van de norm) in zowat heel West-Europa. Het gemiddelde voor de luchtdruk op zeeniveau ligt in Zuid-Europa iets lager dan de norm, ten noorden van ons is er weinig afwijking. Voor de neerslag is er geen signaal voor onze omgeving in deze week. I suppose nobody reads Dutch, so I translate it in headlines. The latest EC32 keeps Western Europe cold till 16th of december. 1-3 degrees colder than average. Low pressure in south of Europe lower than average. In the north there is no clear signal. Around normal. I introduced EC32 at weerwoord, with the tweets of Matt Huto, so he wonders where Matt Hugo is Very nice to see all the international weather/winter lovers together.

And Lorenzo that is some split modelled at 10 hPa. http://wekuw.met.fu-...ast=all&lng=eng Really high up and lasts until the end of the run. So significant for achieving cold synoptics.

It's great to have someone else with great insight to the stratosphere, you really no your stuff, so between yourself , chio , and gp we really are in a amazing position.

Hello. This year I decided to make a seasonal "outlook" of my own. I guess its a statistical forecast, because it is based on reanalysis. This is basically just a composite or a blend of the winters in the past. I used certain winters and blended them together. I have chosen the years and months, based on the overall global setup and similarities in the oceanic and atmospheric features. The graphics were made on October 29, when I finished my analysis process and first published on November 1st on a weather forum in my country. So lets say I have 1 month "lead time" before the start of the forecasted period. This is my first attempt of "statistical" forecasting, so I don't really expect much success to be honest, but I need to test it, so i decided to make a "public test", by posting it on different weather forums. Some interpretation is required. This is basically an average picture, like an ensemble mean, so it has its respected deviation and variance. But just the average or "middle" picture will suffice for my first attempt. I posted this on a forum in my country, so the text on the graphic is in my language (Slovenian). But some words, like the names of the months are similar, so I think you will understand what period is represented on the graphic. I am only aiming at the DJF 500mb geopotential height anomaly for the verification in March, when the forecasted period is over. Now the graphics. Keep in mind that this is unaltered in any way. And it was made in the end of October, when none of these features were present in the seasonal models. At least not in this magnitude. Corresponding precipitation anomaly: And temperature anomaly: And I will also add the December 500mb height anomaly, made on the same date with the same system. And this was CFSv2 when I made these graphics. I first posted these images on a weather forum in my country, on November 1st. And all the graphics were made before that. Here is the link to that topic to prove it. Basically so no one can say that I "cheated", by looking at current models (which differ anyway) and intentionally making a similar picture. Best regards.

Quite a significant (FI) warming up at the top at 1hPa tonight

This from La Bise on facebook Superb!

Hi Recretos this should answer your question. Isentropic Surfaces and the Motion of Stratospheric Air -- If we choose a particular potential temperature, all of the air with this particular potential temperature will form a surface called an isentropic surface. In fact, potential temperature divided by 25 is about equal to the altitude in kilometers (i.e., 400 K = 400/25 = ~16 km and 500 K =500/25= 20 km). Because potential temperature becomes so large at higher altitudes in the stratosphere, it is difficult to move air upward or downward. Stratospheric air tends to remain on an isentropic surface for many days. Vertical motions are consequently very small.

Looks like there will be a decent amount of WAA into the polar circle, on the west side of the Azores High expanding into Greenland. And also from the south flow on the west side of the Aleutian blocking. Also a positive factor is most defiantly the warm AMO. As a result of the overall activity, AO and NAO currently forecasted to "plummet", as one would expect from movements and pattern changes of this magnitude. Things really shaping up. Best regards. P.S.: Would someone please be kind enough, to explain the theta levels in mb height? I understand all the charts and graphs on the FU Berlin site, but I just can get the right idea of the height of the theta levels, on which vorticity is presented. I have the idea of Higher theta-lower heights, but cant get the idea of the actual height. Google wasn't of much help either.

Someone needs to tell them there are numbers other than '100' to use. It's getting a bit silly now.

This is an extract from the conclusion of the Gerber paper. Looking at the CPC charts at the high levels kept seeing random pockets of higher temps and wondered why they appeared almost in isolation and completely randomly? Not sure if this is correct explanation so please correct my thinking if am off on one here. The theoretical work of Charney and Drazin (1961) suggests that a stronger vortex will limit Rossby wave propagation into the stratosphere, thus reducing the amplitude of the Brewer– Dobson circulation. In the lower stratosphere this provides the correct intuition: the net wave forcing of the stratosphere is reduced when the vortex is colder, especially when there is no stationary wave forcing in the lower stratosphere, as explored by Kushner and Polvani (2004). At upper levels, however, wave breaking increases with a colder vortex, as potential vorticity gradients along the edge of the vortex create a wave guide higher into the stratosphere. In effect then has this downward trend to a very cold temperature at 30hpa assisted the creation of activity at 1 hpa ? The strong warming signalled on CPC charts continues

Wow! huge gains since I last checked! Here is an animation since 10/07/12 (a few days are missing )

Ha ! I see the Yanks have a Strat Thread up and running now.. imitation, flattery and all that. Tempted to go on and post this.. 1hpa warming - Sudden Sylvester Wrestling. Okay will get my coat.

One can never be how sure an upper based warming will propagate down. The knockout blow for me will be when the 10 hPa gets blown away by a warming. However, in the last few years we have seen that a tropospheric based blow through the base of the strat vortex can have a far greater effect than an over the top warming.

Snow cover stable over the NH.....that's soon to change though!!!!! Ice cover accelerating as the below chart indicates; almost caught 2007 (previous record low)

Excellent post! The key is to get the cold here first, then the snow will look after itself. The trend over recent years has been that cold has hung about longer than originally forecast (December's 2009 and 2010 in this neck of the woods for example). Anyway, going off topic, I'm off to view the NH snow cover charts!

Let it roll guys n gals. http://www.myweather...type=UPPER_TEMP The above only goes out as far as midnight Tuesday but you can clearly see the beginnings of our cold spell, enveloping us from both the North and the East. This becoming more apparent, later within the animation. Below is the latest snow and ice image, courtesy of NOAA, although it looks a bit suspect. Here are the 21st and the 23rd November 12z GEFS for Moscow, way out East. Note the mean (red line) and control (blue line) trend in T850s and associated precipitation. Here are the 21st and the 23rd November 12z GEFS for Helsinki, way out Northeast. Note the mean (red line) and control (blue line) trend in T850s and associated precipitation here too. Finally, the 21st and the 23rd November 12z GEFS for Reyjavic, due Northwest of our shores by a few hundred miles. Note the mean (red line) and control (blue line) trend in T850s and associated precipitation here as well. From the above, I hope you can ascertain as to where the GFS models might be heading, in terms of Northern Europe and Eastern Europe's snow cover. Bear in mind as ever, trends IMO are often acquired when one compares like for like runs, as shown above. Rather amazingly, I would suggest FI is within the region of t+48 to t+72 over parts of Europe, so it would be folly to deduce anything other than a general cooling down for our shores at this stage, the snow will then follow.

If Carlsberg did vortex splits....... This is from the GFS 00Z and we witness the split with a perfect lobe pointing to Scandi from the Eurasion daughter vortex. That just directs the cold our way. We have increased warming on the 30 Hpa forecast chart today: but nothing at 10 hPa yet . We may need the downwelling to achieve warming there.

last few days compared to the snow benchmark more hopeful at the minute! so come on winter 2012! we know you can do it.

Another measured output from the MO, which describes where we are going next week and into early Dec without a shread of hype and pointless ramping. Colder yes, but not cold. Some snow yes, but mainly on high ground. Thankfully becoming drier in those areas that have seen so much rain of late.

UK Outlook for Wednesday 28 Nov 2012 to Friday 7 Dec 2012: Outbreaks of rain will continue to affect the far southeast Wednesday before clearing away by Thursday. Elsewhere will see a mixture of sunshine and showers throughout the rest of next week, with the heaviest showers towards the northeast. It will also remain windy at times, with the risk of gales in the southeast at first. Temperatures slightly below normal bringing a risk of hill snow and overnight frost. From next weekend onwards, temperatures are likely to fall away further as some slightly more settled and drier weather develops, bringing an increased risk of overnight frost and fog. Eastern and southeastern areas are likely though to remain unsettled at times with further showers or longer spells of rain, and these turning wintry across the higher ground. Updated: 1105 on Fri 23 Nov 2012 http://www.metoffice.gov.uk/weather/uk/uk_forecast_weather.html

their 30 day outlook is almost exactly what I would post had I been asked! There is little sign on the upper air charts of any change in the 15-18 day period in terms of milder weather starting to appear. What happens beyond the first week in December is not clear but their summary is about as near as anyone is likely to get UNTIL something shows up to contradict it, IF it does.

First I have to say Hello! New to this forum, and found this topic while I was searching for some stratosphere info on the web. Thank you Google. Quite a debate I must say, on a real high level. I wont interfere with your debates, so I am just going to share my thoughts occasionally. My first post post might be a bit sluggish, but I promise I will try to get in the overall flow of this topic. Things seem to be on a roll (no pun intended) against the polar vortex, or at least that's how I see it. Better defined easterlies starting to appear. Not that surprising, given the High building into the polar circle. I find it quite amazing how the ensemble mean is still keeping a 300+ anomaly on a 10-day range. Talk about ensemble consensus. Looking "cool", temperature wise. Now as it was already pointed out, it looks like the P.V. will reform after this split-up that is being almost literally thrown in our faces by the models. I don't want to speculate or anything, especially because its quite far out. But am I the only one glad to see this appearing in the models? And I am sure you have all seen it already. This is a bit awkward post, but I promise I will improve with time. Best Regards.

Thanks to catch up TV I've finally seen this now and I thought it was pretty good actually!