By Steff Gaulter
The weather over Europe has been very strange over the past few weeks. Normally by April, spring would be well on the way across the continent.
Bare trees would have suddenly burst into life, green shoots would have appeared in the barren soil and lambs would be skipping happily across fields. This year, however, spring hasn’t so much as sprung as vanished.
In the northern parts of Europe, any unsuspecting buds that did manage to push their heads above the soil before 5 April, often found themselves covered in a liberal coating of snow. March 2013 was the coldest in the UK since 1962. In Germany it was arguably worse; it was the coldest March since their records began in the 1880s.
This has caused misery to all of those living there. As you might know, in Europe a lot of people walk or take public transport to the office every day. I can assure you that trudging to work in temperatures below freezing is not fun. For farmers, however, the cold weather has been more than just an annoyance.
Grass doesn’t grow unless the temperature is above 6oC (43oF). Lambs were simply starving to death.
Southern parts of Europe have also been cooler than usual, but here it wasn’t the temperature which caused most of the problems. The cooler weather was accompanied by a serious amount of rain. A series of weather systems filtered into the Mediterranean, before running up into the northeastern parts of Europe.
Heavy rain doused Spain and Portugal throughout the month of March, bringing some regions record amounts of rainfall. A number of rivers burst their banks, and a travel advisory issued on April 1 warned that flooding could affect almost all of Spain’s river basins.
The weather systems then generally ploughed across the Mediterranean, across Italy and into the southeast of Europe. The heavy rain in the Balkans fell on deep snow. As you might expect, the snow quickly melted, and the extra water from the melted snow made matters worse. Here too, rivers burst their banks and inundated homes and farmland.
As the systems continued to track northwards into the eastern parts of Europe, they slammed into the cold air in the north. The rain turned wintry and blanketed many parts with heavy snow.
Poland was hit particularly badly on Easter Sunday when 30cm (12 inches) of snow fell across the country, dragging down power lines and leaving many roads impassable. More than 100,000 people were forced to spend the Easter weekend without electricity.
The snow also fell in Russia. The extra flakes brought the depth of snow on the ground in Moscow to 65cm (25.5 inches), setting an all-time record for April. The previous record of 61cm (24 inches) was set in April 1994.
The track of weather systems in Europe is dictated by the jet stream. This is a thin ribbon of fast flowing air encircling the globe several kilometres above the earth. There are several of these jets hurtling around in the air, but by and large we are oblivious to them as they hurtle around the earth. There are only a few times that they would ever really become evident, one is when you notice that flying from the USA to Europe is far quicker than flying from Europe to the USA.
That’s because pilots often ‘hitch a ride’ on the jet stream, which flows from west to east, using it to push the plane along. Another time you might notice the jet stream is when it ‘gets stuck’.
Normally a jet stream will meander north and south, taking the weather systems with it. However, if it gets stuck in one place, then the area below the jet stream will end up far wetter than usual, but another region to the north or south will remain far drier.
Recently the jet stream has been flowing over the southern parts of Europe, further south than it would normally be at this time of year. This has pushed the weather systems southwards, over the Mediterranean, causing Spain and Portugal to suffer their endless rain. With the jet stream so far south, the southwesterly winds that often affect the northwestern parts of Europe at this time of year have been absent and cold weather has prevailed instead.
The question of why the jet stream has moved is an interesting one. Sometimes jet streams do just move and it’s merely an anomaly; however, it’s been happening quite a lot recently. I grew up on the south coast of England and snow was rare.
On the few occasions that it did snow, we would have to huddle around a little radio to see if our school was going to be closed for the day. I remember this vividly, but it can only have happened on about two or three occasions in my entire school life. However, over the last six years, it seems to have done nothing but snow.
This isn’t just a perception; the weather really has changed across the northern parts of Europe in recent years. The reason for this is unclear, but don’t howl with delight, thinking that climate change has been disproved once and for all, just yet. It looks as if climate change might actually be the cause of this cold weather.
The latest theory is that the lack of Arctic Sea ice has changed the weather patterns in the north of the globe. This has allowed the cold weather, which had previously been confined to the extreme north of the globe, to flow southwards, escaping as if someone had left the freezer door open.
Over the past few days, it does appear that winter is finally releasing its grip on Europe and the weather is slowly becoming milder. However, if the theory of the change of climate is correct, it won’t be too long before the snow returns!
(The author is Senior Weather Presenter at Al Jazeera English channel. She can be contacted on [email protected]
or on Twitter at @WeatherSteff)