swilliam

Definite changes in the overall pattern on this run in F1. Looking at the 00 run you can see mainly PV to the North of Scandinavia. On the 06 run this is now replaced by an Arctic high as the WAA from the US Pacific coast is much more energetic and reaches the Pole region. Will this make any difference to the length of our cold spell on this run?

Looking at the FI possible evolutions (I know JH says we should only enjoy the cold spell but model watching is also about looking at possible scenarios coming up) it is interesting to look at the Reyjavic pressure ensembles. Out to 23/12 we can see the drop corresponding to the dropping on of the Northerly low pressure system. Beyond that there is huge diversity with by the pressure varying from 1038 to 958 mb. The op run is near the top of this range. Depending on which evolution occurs gives vastly different outcomes. First for Reyjavic the HP means the op is near the top of the temperature range. Conversly for us it is at the bottom of the range. Therefore depending on whther you live in Iceland or the UK would determine whih of these solutions you might prefer. One small gripe - we were discussing this possible easterly in FI about 5 days ago and were told by SP that it was in FI and also implausible. We were also told by others that it would never verify. Well it looks like it is plausible and may well verify - not exactly as was portrayed then but correct in the overall scheme. So please if we do discuss FI do not keep telling us it is in FI (we know that) or that it won't verify - we also know that most of the time that is also true - but it does show what is possible and that is what we like to discuss. Stewart

Indeed - Steve Murr's breakfast sausage which he was discussing several days ago. Stewart

Ok thanks - that is much clearer- and yes I agree

what do you mean?

Excellent - as Stephen Prudence said earlier maybe this is implausible but with a good reason to say so this time. Do you think the Greek weather sites are discussing this evolution with a lot of enthusiasm - or do you think they are not as sad as us Brits who are always talking about the weather. Gosh - I hope this does not happen now!

For me the model thread is fine and I would not change it. It is a bit annoying reading the one liners like that is a fantastic output but it is easy to skip these. I do not think an expert thread is a good idea as it would be difficult to know which thread to read so we would end up having to read both. You also have the problem in deciding who or which comments are deemed to be expert with an obvious grey area. If something was to change then I would vote for two threads looking at different timescales, say before and after t144. This is because when discussing changes or charts in so called FI we immediately get a reply that it is FI anyway so will not verify or that the models are useless at the range. Yes we know that but we like to discuss the general situation and possibble scenarios - some people don't seem to be able to handle that. However the problem with this arises when something interesting is about to happen like we have now. Eventually this will move to the T144 time frame and it will be unclear where posts should be and we will end having to read two threads. In addition of course what happens before t144 affects what happens after. One improvement I would like to see is that the number of pages that you can one click is expanded beyond three. If you have not been on the thread for a while then more than three pages may have been added. But you either have to skip to the end or three pages at time - could we have say 6 pages shown. Also I would like to have a permanent link to this thread on the home page (maybe underneath the model output links or on the model pages) - if it is not on the selection panel you have to scroll through lots of pages to get to it. In general though I think the site and thread are excellent. Stewart

Yes probably wins in terms of (cold) intensity but I think 10 might deliver more snow. Anything remotely approaching these would be welcome though Nice bit of fun.

I think 10 is going to win and 12 is the big loser

I would also add about cold lovers dismissing runs that don't show their favoured synoptics. Often we read that one run or another is being 'binned' for some reason or other and usually as far as I can see it is because it does show them what they want to see. As far as I am concerned all runs are equally valuable in making an assessment of what is likely to happen.

I think you are correct in that the charts shown are very unlikely to be real as the chances of them occurring are pretty low ( my guess would be about (10-20% - in line with the number of very cold ensemble members)). The problem arises with the dismissive language which implies zero chance and gets people going. Cheers Stewart

Why is it not credible - it is happened before so it can happen again. As has been alluded to before this evolution is similar to Jan 87. Then we went from this To this and finished with this Fairly similar I would say with a Euro low ridging North and connecting with an Arctic high to deliver a very cold Easterly. That of course is not to say it is likely but neither is it incredible. Whoops TIETS beat me to it.

Yes and interesting to look at the Reykjavik pressure. One thing is clear we are almost certainly going to lose the low pressure in that vicinity after 11th December - so something is certainly going to change - the question is what to. I like the 18Z tonight as that is definitely a repeat of Jan 87 - it just shows that that scenario is plausible in the current set up. Cheers Stewart

Oh dear - I should haven't joked about northern blocking and Bartlett highs!!

Or the North pole moved South???? (20 +384)

It is quite entertaining flicking through the ensemble members and looking at some of the incredible charts that are appearing in FI. My favourite is the one below which is from member number 10 at + 276. It shows extensive 1050mb blocking from Scandi to Greenland + a Bartlett high???????

One thing that can be said though is that we will get the cold pooling to our East and North that we were all desperate for a few weeks ago

No one is disputing that the CO2 levels are high at the moment and that possibly this may be man-made. But in the period you mention the earth as been much warmer at times without high CO2 levels (they always follow as the gas is emitted from the oceans as they warm). Also it is clear that the warming has occurred over the very short period of the last forty years (but not the 30 before when CO2 was rapidly increasing). I think as scientist to claim a proven cause and effect is impossible - therefore for me AGW is at most speculation. Returning to the models I am off to Cornwall for the next two weeks. For me the general prognosis of LPs developing in the Atlantic (at a fairly southerly latitude) and then moving NE is fine. This should ensure that we have some fine days (I always assume it is going to rain - it is question of how much) and in addition we should have reasonable surf. What is not required at the moment is any stalling LPs and this currently looks unlikely. The LP progged for next week looks very favourable on GFS - mostly dry but generating some nice swells. Cheers Stewart

Yes I thought so to - if you look at the satellite picture movie you can see the circulation setting up. http://www.meteox.com/h.aspx?r=&jaar=-...;soort=satradar Stewart

It has gone off here in Cranfield (nr Milton Keynes). Been going darker and darker over the last 1/2 hour. NO torrential rain and the the thunder and lightning is really increasing in frequency and intensity Stewart

Excellent storm here in progress at Cranfield (nr Milton Keynes). Storm has built steadily over the last hour and significant lightning over the last 15 minutes. Very heavy rain. At yeast 3 rain cells visible and all is moving slowly East Stewart

Finally ended up with a fresh 18cm here in Northampton - so 20cm in total. - No disappoinment here! Stewart

Looking at radar and satellite image surely there is a small low forming at eastern end of the Thames estuary and moving slowly NE. This could help the front to stall and lead to more prolonged snow just North of London. Stewart

Put this in the Eats Mids thread and then realised I was the only on there! Very heavy snow here in Northampton now - 3 cm so far - 2 cm in the last 1/2 hour. Temp -2, dew -3, couple of hours of this and there will be chaos in the morning. Stewart Another 1 cm in the 20 mins since I posted

Very heavy snow here in Northampton now - 3 cm so far - 2 cm in the last 1/2 hour. Temp -2, dew -3, couple of hours of this and there will be chaos in the morning. Stewart