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uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged. |
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Will Hand wrote:
"Bogdan Iqbal" wrote in message ... Good morning friends. Take a look at Kasim Awan's thoughts on this winter. It holds a lot of promise for snowfall I am sure you will agree. http://kasimsweatherwatcher.com/uk-winter-2014-15/ I wish Kasim all the very best in his endeavours. It is very refreshing to see younger folk so enthusiastic about our topic. There are a lot of old scrotes on here, some grumpy, some less so. But there is also a lot of experience and many of us are professionals or retired professionals. So expect some scepticism (hopefully constructive). My take on LRFs is this. We will never be able to give what the public wants, i.e. accurate daily forecasts out for a whole season. The atmosphere is inherently chaotic and always will be. The solutions to the Navier Stokes equations are not analytical and computational solutions will eventually develop magnifying errors. What we may well be able to do is predict the character of a season. Essentially will it be blocked or zonal or a mixture and when. If it is blocked where will the block be - that matters a lot. If it is zonal, how zonal? Will the zonality be progressive or pseudo blocked. Where will the jet be, north, over or south of UK. If one could get the above right then the general weather type will follow. No good trying to predict daily or even weekly detail. I issue a forecast at the end of November on my website on the above lines. Last winter I went for wet with a southerly latitude strong jet. I got the wet correct!!! But over-played lowland snow and cold over Scotland. Upland snow though in Scotland was indeed exceptional. Here is the forecast as issued: " As usual I have been looking at sea surface temperature anomalies, how Russia and Canada have cooled relative to each other, location of jet stream, local statistics and predictions from other centres to try to come to a consensus view for the weather this coming winter. The Arctic appears to have cooled faster than normal this autumn and now Arctic Canada is cooling rapidly. This would tend to encourage a strong westerly flow. Sea surface temperature anomalies provide an uncertain signal and nothing really to latch onto. The polar front jet stream continues at a lower latitude than normal after a few migrations north earlier in the year. I cannot see this pattern changing and fully expect the mean position of the jet stream to continue to be further south than normal at around 49N in the Atlantic. Probably stronger this year though than last. Last winter we had a major stratospheric warming leading to some very cold easterly spells. It is rare for these to occur in successive years, so I expect fewer easterlies this winter. Finally, there is a good correlation between cold and wet Novembers and cold winters in the UK. This November certainly looks like being wet but may not be particularly cold, so another mixed signal. Putting all of the above together I have come up with a forecast given with LOW confidence as follows. Winter 2013/14 is going to be a winter of rapid changes and a "rough ride" for many. Overall I expect it to be neither a cold one nor a mild one but temperatures may end up below average. However, I am expecting a wet winter with fewer frosty, dry and cold spells than last winter. But given the southerly located jet stream, incursions of deep very cold air from the north could give some transient exceptionally heavy snowfalls, especially in northern areas where snowfall could be above average. Further south, and especially on low ground, snowfall will be more marginal, but here, flooding may become a major issue. So the headline summary is wet and changeable with the threat of substantial snowfall at times in northern Britain. " It's always good to look back and learn from mistakes. I am looking forward immensely to see what Kasim comes up with next month. Cheers, Will ------------------------------------- ...... and we all enjoy reading them ;-) The problem I have with most seasonal forecasts is that they are always half right as with yours! My random guess will probably be half right for a whole season. If I say this winter will be more snowy than last winter, generally a mild one with about average rainfall but with some short colder spells I bet it will be at least half right. Last year the critical things were RECORD rainfall and not a SINGLE snow flake in large areas of the Country. Nobody got that and I doubt any ever will. But as you say they are still of great interest (or hope!) and there is still a lot that can be learned about climate and the weather from the rationale that attempts to predict. So roll on November for this winter's one! Dave |
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