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I am going to trial a prediction for the next month in order to see how possible it is to predict stratospheric events. Here it is: I am going to suggest strong wave activity will lead to a Canadian Warming(CW) middle to last third of November. This will follow the snow cover growth in October leading to the stratospheric feedback. The analogue years when this has happened previously are good, and this October's Eurasian snow cover will be promising and tropical ozone levels will have recovered somewhat. I suspect any warming will follow on from MT activity prior to the waves entering the stratosphere in around 2 weeks time. We haven't seen a CW for over 10 years.

Chio thanks for the update. I suppose you mean this one? http://mls.jpl.nasa....ng_GRL_2001.pdf Here you can find the peak of november 2000. http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/archive/30mb9065_2000.gif

Great paper that I have found here which helps explains. http://www.reading.a...on_Driscoll.pdf Firstly torque definition: 2.2 Torque A Torque, deï¬ned as T, is given by T = r × F (2.5) If a torque, or a ‘turning force’, is applied to a rotating object it will slow down or speed up the object’s rate of rotation about the origin, or even change its direction of rotation. Through friction and pressure the atmosphere applies these rotational forces to the solid Earth which cause the rotation rate of the solid earth to either speed up or slow down, and in doing so the atmosphere’s angular momentum decreases or increases as it imparts or receives angular momentum to or from the earth, thus torques represent the flux of angular momentum across the surface of the earth. Mountain torques: Mountain Torque is a function of pressure and orography and is the ‘turning force’ exerted due to a difference in pressure across any raised surface on the earth, but most signiï¬cantly, mountains or mountain massifs. Consider a mountain with a high pressure on the west side of a mountain and low pressure on the east. The pressure system will exert an eastward torque that causes the earth to increase it’s rate of rotation, imparting angular momentum from the atmosphere to the solid earth. The opposite case, where there is higher pressure on the east side of the mountain, will slow the earth’s rotation down, reducing the solid earth’s angular momentum, and imparting it to the atmosphere. The first above is a positive MT as I understand it.

Settling snow now getting down into some parts of western and southern Finland. http://en.ilmatieteenlaitos.fi/rain-and-cloudiness/southern-finland http://www2.liikennevirasto.fi/alk/english/kelikamerat/kamera-C0251902.html http://www2.liikennevirasto.fi/alk/english/kelikamerat/kamera-C0250601.html Also another small area of snow in N.Lappland. http://en.ilmatieteenlaitos.fi/rain-and-cloudiness/northern-finland http://www2.liikennevirasto.fi/alk/english/kelikamerat/kamera-C1454102.html So the snowfall situation picking up nicely now over parts of Scandinavia. Regards, Tom.

There truly has been a good step forward over the last few days as illustrated by the following link. The last update does however, appear to show a loss of ice to our North during the last 24 hours. In spite of this, the bigger picture is most encouraging. From a brief glance of the GFS 06z (12z running now) ensembles, it suggests my previously highlighted locations under this post are looking as follows. Helsinki (to our NE) to me, looks favourable for wintry precipitation (some snow at first then perhaps rain) but looks a generally disturbed cool pattern. Moscow (to our E) to me, looks similar but is basically a warmer pattern, after some snow at first. Reyjavic (to our NW) to me, is a very cold run although it is suggestive of a drier pattern. Hoepfully, I will be able to undertake a full analysis another time but for now, I feel the good news regarding snowcover could be getting undermined by overriding Stratospheric signals. As always, time will tell but the UK is entering a cooler phase and I have my eyes fixed on an interesting midweek event, having looked at the 12z run.

Nice prediction and if it were to actually happen would most certainly aid in producing a far different December this year than was evident last year, but obviously it's got to happen. At the present time it's all pretty 'quiet' really, not a great deal to discuss, the forecast and analysis charts look very similar almost daily and the lack of ozone is still a concern, for now. Good luck with the prediction, always worth having a go and from a "coldies" perspective I hope you're right. It'll be interesting to see what happens in the next 4 weeks as we really begin to firm up on potential 'events' which may affect tropospheric meteorological conditions and patterns for December. Cheers, Matt.

Hi VL, Yes you are right - a SSW is different to a Canadian Warming. Whereas a lot has been written about SSW's, there is less information in the literature about Canadian warmings. To recap a SSW is characterised by a reversal of mean zonal mean winds in the stratosphere at a level of 10 hpa at 60ºN. This requires a rather pronounced warming. A Canadian warming is a less pronounced warming seen over the Canadian sector in November or December. There is no reversal of the mean zonal winds. The stratospheric polar vortex is displaced towards Siberia and weakened somewhat. I suspect that this is a result of increased wavenumber 1 activity. Still no significant warming in the mid stratosphere forecast.

I appear to be missing the like button on my topic reply. Any ideas? (Except for the obvious one of course!)