Unpredictable winter weather lies ahead
2nd October, 2014
If research from scientists at the University of East Anglia (UEA), University of Sheffield and the Met Office is to be believed, British winters could become far more unpredictable in the years ahead; fluctuating between very cold, snowy years and mild, stormy ones. Having studied weather patterns over the last 115 years they found that five of the ten most extreme North Atlantic winter weather patterns since 1899 have occurred in the last ten years.
At this stage the scientists remain uncertain over whether global warming is causing the increasing extremes, but believe that the variation reflects the increasingly wild swings in barometric pressure over the Atlantic Ocean - known as the North Atlantic Oscillation (NAO).
“When we look at the month of December in particular, our data shows that over the last 115 years, three out of five all-time record high NAO values and two out of five record lows took place in the last decade” - Professor Phil Jones , University of East Anglia Climatic Research Unit
What is the NAO?
There are two permanent pressure systems located over the North Atlantic:
- A low atmospheric pressure system, known as the Icelandic Low, which is positioned across Iceland, southern Greenland and, during the winter months, the Barents Sea.
- A high pressure system, known as the Azores High, typically found south of The Azores.
Each year the position and strength of these two systems alters, and this variation is known as the NAO:
- High index years are denoted by NAO+ and occur when the pressure from the Azores High system is greater than that of the Icelandic Low system. A high index year will result in strong westerly winds causing cooler summers and mild, wet and stormy winters.
- Low index years are denoted by NAO- and occur when the pressure from the Icelandic Low system is greater than that of the Azores High. A low index year will result in more extreme temperatures, causing heatwaves during the summer and deep freezes during the winter.
In recent years this unpredictability has been very evident:
- The winter of 2009/10 saw the UK experience its coldest winter for 30 years.
- Weaker westerly winds also brought cold weather during the winter of 2010/11.
- However 2013/14 was much more mild and stormy, resulting in the devastating floods that caused considerable disruption to areas of the West Country.
This unpredictability highlights the importance of being prepared for whatever the winters ahead may throw at us. Contact us to arrange a meeting where we can discuss how best we can protect your business from the threat of snow and ice.