>Complexities in Forecasting British Weather

Written by on December 27, 2009 in Rest of Europe with 1 Comment

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Ever since issuing my Winter Forecast for the UK, I haven’t really relaxed much. To forecast a “Cold Winter” is really throwing yourself out there as you only have to look at recent trends to see that we have been far from cold in any way shape or form. Winters have become dominantly warm but perhaps a little burst here and there of cold. Even at that, the cold spells have been subpar compared to those of the 40s, 50s, 60s and 70s.

Since the turn from cold Atlantic Multidecadal Oscillation to warm which transitioned our winters towards a much more dominant Atlantic oriented flow of mild, wet and windy weather the warmer sea surface of the North Atlantic and North Sea warms the atmosphere above it but not only that, energizes Atlantic depressions, therefore the 1990s and 2000s displayed some of the greatest windstorms of the past 100 years across the UK and Western Europe.

Our dominant flow through winter generally comes from the mild, moist Atlantic. The prevailing southwest flow usually brings us generally mild, sub-tropical air and certainly the regime has been one of storms in about 8 out of 10 winters since 2000.

When we do actually get a decent period of winter weather, oh say for a week to 2 week period where much of the country gets snowfall and a blanket covers the country and even if we are lucky enough to see a Scandinavian or Siberian high push off the continent and across Britain, we almost always never see this pattern stay for any longer than a two week stretch.

The atmosphere usually doesn’t go against the normal flow for too long and right now after a week of cold air and regular snow showers we would be awaiting the thaw.. Yes, in the general scheme of things by now, id be watching for those numbers to start climbing and the snow to be gone in a matter of a couple of days. Recent years has been very frustrating for me as I love winter. I envy those living in Canada and many other parts of the world that despite “global warming” taking a slight edge of winter, they still get periods of severe cold and big snowfalls.
This winter is becoming different as the persistency of the cold cycle is now lasting longer and is certainly biting harder than it’s wimpy predecesors. This is holding strong to my forecast so far but in order to achieve full accuracy, this cold stretch must last for several more weeks and to be honest, forecast models and the fact that the AO is “tanking” deeper and deeper negative and the fact that this pattern is firmly establidhed, there is no reason to for this pattern to break down anytime soon.
I am calling for the snow that is now on the ground will be beefed up with either a series of small snowstorms or one big fall of between 6-14 inches across much of Scotland during the first 10 days of January and we will have an unprecidented snowcover that stays unmelted on our increasingly frozen ground for over a month. Something not seen here in my 26 years on this earth.
I did forecast that this upcoming winter had the hallmarks of an historic winter. If we remain like this through January, this will likely become one of the coldest winter’s since the late 1970s…
The return of winter to Britain appears to be happening. Last winter brought an increase in cold and more so with the longivity of the cold cycles (first 10 days of December 2008 was the coldest in 30 years) but in terms of “extreme cold”, last winter wasn’t all that bad really. This winyer is shaping up to be a more severe winter on the heels of a multidecadal period of warmth thanks to the warm Pacific Decadal Oscillation which ended in 99 and the currently warm Atlantic Multidecadal Oscillation.
So why did I forecast such a cold winter during a time of significantly mild British winters?
I believed strongly that last winter has certain characteristics of a winter fightback and that a major reversal across the hemisphere was beginning to take place. Though the AMO remains warmer but is showing signs of cooling, often the toughest, longest winters can occur during times of transition. Right now the PDO is cold, but only during the past few years has it really shown it’s cold appearence and displayed it’s effect on the North America continent. The rcent trending down in temperatures across North America and the pattern evolution with a modest El Nino which is centering itself more into the central Pacific (a big key to cold here) and what has really pulled my attention is how quiet the sun has become. A weak El Nino, the overall global pattern and the low solar cycle really forced me to forecast not only a cold winter here but one that could be far more severe than most or all may have thought.
It’s amazing when you look back and how the Met Office forecasted a warm winter…
Now, what’s very important to remember folks is that as we continue cold, we must remain cold for much more of this winter to even contend with those great winters of recent history.
I have forecasted for the “Worst winter weather” within the forst 2 weeks of January with one of the coldest New Years in many years… I believe we will become colder and with that our snow will remain on the ground until the 3rd week of January, worst case, we have have snow remain on the ground perminantly until February. I also believe many lochs and rivers will start to freeze up in persistent cold days and nights. Nights that will regularly fall into the -6C range in town and city centers and -10C in outlying rural areas…. This is exceptional to certainly recent decades but this was more the norm during the last cold era of the 50s, 60s and 70s. Thew snowiest period in Britain was around 1947 I believe. 1963 stands out as well as those brutal winters of the 1970s.
When all is said and done here, we may be waiting longer than we may think before a thaw finally arrives… Spring flooding?
This year, we will have earned a summer! Perhaps a hot and dry summer is ahead!
I shall focus tomorrow on the US pattern and how they have some extreme cold and snow ready to pound….
Thanks for reading.
-Mark

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  1. Anonymous says:

    >I'd like to pose a practical problem. If you were in charge of Scottish football, when would you schedule a winter break?

    In general?

    or for the Season 2010/2011?

    Tackle the problem however you like.

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