Its that time of the year again when the nights are really drawing in fast, and the leaves fade from brown and fall from the trees. Last year I made some weather predictions for winter 2008 – 2009, and it was pretty good! Some parts of the UK had their heaviest snowfall in years and here in Glasgow we had frequent snow falls and quite a long run of days where the frost never shifted, it was so thick after a few days it felt like snow!
As always there is a lot of time and effort and money being spent on the topic of Global Warming, now the Earth’s temperature has been increasing in recent decades but I’m in the group of people that think mankind has little or nothing to do with the increase in Global Temperatures. Here’s a fact which many of you may not know… What’s the hottest year in recent history? 2008? 2007? nope, in fact the Earth hasn’t been as hot as it was in 1998, which is the current peak in the recent global temperature. The trend since then over all has been one of cooling, with some years cooling more than others, which is reasonable to expect in the natural climate cycle.
So what are we to expect in winter 2009 – 2010?
No one really knows, forecasting is not a precise science yet, but I will try and have a look at some factors which affect our climate in the UK and see what that suggests for the winter ahead.
The Oceans are the World’s biggest storage heater, so it’s obvious that they can drive weather patterns when they heat up or cool down, the two major ocean related phenomenon which affect our climate is the North Atlantic Oscillation and the El Nino (warming in the Pacific) or La Nina (where the waters in the Pacific cool). Looking back at UK winters and correlating them to the NAO then it does seem that there is a pattern, its not a definite pattern, but years where the NAO has been Negative (ie the pressure difference between the Azore’s High and Icelandic Low has been lower than normal) there has been average or above average snowy winters. Look at the winter of 1963 and 1969 as examples. During these years the NAO Index ranged between -1 and nearly -3, 1963 was classed as a very snowy winter, and 1969 winter was classed as having more snow than average. So far the NAO index for 2009 has been more negative which would suggest a snowier than average UK winter
There are however more things to consider what about the El Nino? At the moment there is an El Nino beginning to appear in the Pacific, were 1963 and 69 during one of the El Nino cycles? Lets find out! It appears that during the warming cycle there is a reduced chance of cool snowy winter in the UK. Couple this with a positive NAO such as in 1993, the winter was a fairly mild wet one. If, however the cooling of the Pacific coincides with a negative NAO, the winters are far cooler and much snowier, as happened in 1955 and 1963. Currently there is an El nino starting in the Pacific, which would tend to suggest a milder winter if it was coupled with a neutral or positive NAO.
On a side note, last winter (2008-2009) saw a return of Arctic Sea Ice to 1979 levels, when records began… Global Ocean Temperatures increased during 1993 to 2003, but between 2003 and 2005 the Oceans cooled by up to 5 times as much as they warmed in the previous decade, so far no one has been able to explain why this is happening for sure. Since the Oceans Temperatures lag behind surface temperatures I will say that the cooling trend will continue. Cooler waters should surely mean cooler winters?
What else affects our weather? Perhaps the Sun;s activity can affect our weather, its certainly powerful enough! However, recently there has been a vast reduction in the number of sun spots seen, which indicate how active it is. Recently the Sun has been breaking records, not for how active its been but for how inactive its been, with numerous days without any sun spots. This is another indicator which would lead me to predict the winter weather for 2009 / 2010 to be around average (due to the El nino) or cooler than average, with a good few hefty snow falls and cold spells, mixed in between some warmer spells.
I am by no means an expert, but I try to take an interest and do some research before writing posts, If you spot any major, or minor, flaws, then please respond to this post with your thoughts.
Thanks you for taking the time to read this, and I hope you enjoy the winter months ahead no matter what the weather brings!