Met Office Update: Climate Change or Natural Variation

Last year we had the coldest December in more than a century, with

repeated heavy snowfalls and prolonged sub-zero temperatures. This year

has been a starkly different story, with conditions so far this month

being much more normal for the time of year.

The huge difference from one year to the next is shown in the

satellite images from NERC Satellite Receiving Station, Dundee

University, Scotland. In 2010 the UK was blanketed with snow and ice,

whereas this year only areas of high ground in Scotland, the Lake

District and the Pennines show traces of white.

The main reason for the difference is down to the weather patterns seen last December compared to this year.

In

December 2010 a high pressure system was sitting over the UK, blocking

the normal westerly flow from the Atlantic and allowing easterly winds

to bring in cold air from the continent.

This year, the mild westerly has been unimpeded – allowing milder

Atlantic air and changeable, often stormy, conditions to take charge.

December

2010 was the coldest on record for the UK, with temperatures 5 °C below

the long term average, with -21.3 °C being recorded in Altnaharra in

Scotland on 2 December. There were also 23 days of frost, 13 more than

the average.

Temperatures so far this December have been notable only for being so

average. UK mean temperatures for the first half of the month were spot

on the long term average of 6.9 °C. The lowest temperature recorded so

far this December is -9.4 °C, recorded at Loch Glascarnoch in Scotland

on 18 December.

The reason for these stark differences from one year to the next is

down to natural variability in our weather – something we Brits are well

used to and why we expect to see differences in our weather from one

year to the next and even one day to another.

To keep up to date with what we're expecting for the rest 2011 and

into 2012, you can check the Met Office forecasts which look out to 30 days ahead.