Seasons to remember?
Met Office meteorologist and weather presenter Aidan McGivern looks back at the seemingly unremarkable winter, asking whether it will be one that sticks in the memory.
Ask any meteorologist what inspired their interest in the weather and they often recall a childhood memory of a hot summer or snowy winter. Often, it is claimed, these memories are formed at a particularly early age; for example, “I was born during the summer of ’76 so it was inevitable I’d become a weather forecaster.”
When my daughter was born in December 2016, I wondered what kind of winter would be imprinted on her mind. When Molly McGivern follows in her father’s footsteps and becomes a meteorologist, will she put it down to being born during the infamous snowy / windy / cold / sunny winter of 2016-17?
I just hoped it wouldn’t be another wet winter. Winter 2015-16 was the second wettest on record; 2013-14 was the wettest in a series extending back to 1910. Those seasons were dominated by a powerful jet stream over the Atlantic, spawning deep depressions and hurling them towards the UK throughout winter.
There were signs suggesting this season might be different. Atlantic storms were notable for their absence during Autumn 2016. September was dry and unusually warm, October was dominated by high pressure and November was often cloud-free with sunny days and frosty nights. In fact, some places recorded their coldest temperature for several years on 30 November.
The large anticyclones that dominated the UK’s weather during autumn remained throughout much of winter. Areas of high pressure continued to block Atlantic wind and rain, often re-directing the main storm track north of Scotland. Overall, the UK had just 76% of its average rainfall. Northern Ireland saw the fifth driest winter since 1910. Finally, following a run of wet winters, this one was mostly, although not entirely, dry.
It’s only the second winter in which the Met Office and Met Éireann, the Irish national meteorological service, have named particularly disruptive depressions to highlight impacts of severe weather – the storm-naming convention has evolved slightly between the two years, but named storms can already provide a useful indicative comparison of the contrasting character of the two years. By the early February 2016, we’d been visited by Storm Imogen. Storms are named in alphabetical order, and this was the ninth of the season. By late February 2017, Storm Ewan was only the fifth named storm.
These storms were exceptions in a winter otherwise dominated by long periods of settled weather, particularly in South East England. Kent saw its joint driest December on record. Many dry winters go hand-in-hand with colder temperatures and more frequent occurrences of frost, ice and snow. When anticyclones stop moist and mild westerlies, freezing northerlies or easterlies can dominate instead.
This year, however, cold snaps were particularly snappy creating a mild winter overall. Whilst January temperatures were below average in South East England, for the rest of the country, and the rest of the time, it was mild. Temperatures throughout the UK were 1.3 °C warmer than average this winter and for Scotland it was the fourth mildest winter on record and was ninth mildest for the UK overall.
High pressure and its position this winter was crucial. Anticyclones were generally over the near continent, bringing humid winds from the southwest and occasional incidents of dense fog, mist and low cloud.
The same anticyclone that brought benign weather to northwest Europe dragged freezing easterly winds into the Mediterranean on its southern flank. The unusual sight of snow on Spanish beaches and Greek Islands was bad news for holidaymakers seeking winter sunshine. It was also unfortunate for vegetable lovers, as unseasonable weather contributed to a shortage of courgettes and lettuces in supermarkets.
Back in the UK, this year’s relatively benign season was a relief following recent more severe winters, unlikely to be remembered for storms or snow. Although this dry winter was an interesting contrast with the last few wet winters, overall it was unremarkable, and unlikely to form a lasting impression on budding meteorologists.
Or maybe it will. According to Met Office Climate Scientist Mark McCarthy, in the UK a winter that is both dry and mild is rare:
“UK winters are strongly influenced by large-scale weather patterns over the north Atlantic that affect the track of winter storms. This generally results in our winters being either mild and stormy or cold and dry. Notably mild and dry winters are less common, with 2017 joining winters of 1921, 1932, 1976 and 1992 in this regard. To understand our variable UK climate in a global context, and how our weather might be affected by climate change, it is important to understand processes resulting in the exceptions as well as the rules.”
“UK winters are strongly influenced by large-scale weather patterns over the north Atlantic that affect the track of winter storms.”
Compared to mild and stormy or cold and snowy winters, the fact that this year was relatively unremarkable is actually of particular interest to Climate Scientists like Mark. Apparently, in this changeable climate of ours, one day of dry and mild weather may be normal but a winter full of dry and mild days is less common. So perhaps, in years to come, my daughter will boast of being inspired to be a meteorologist because she was born during the great anticyclonic winter of 2016-17, one of only five notably dry and mild winters on record at the time. Or perhaps she will become a neuroscientist like her mother.
From the very young to the very old
Winter may have been interesting enough for meteorologically-minded newborns but the warm spring that followed was exceptional for the oldest temperature records on the planet. Overall, it was a dry spring with above average sunshine. It was also another warmer than average season. In fact, Northern Ireland and Wales both had their warmest springs on record and for the UK it was one of the top five warmest springs in a temperature series that extends back to 1910.
The standout spring statistic, however, is found within the Central England Temperature (CET) series. A record of temperatures covering a roughly triangular section of England from Lancashire in the north to London in the east and Bristol in the west, the CET series has monitored monthly temperatures since 1659. It’s the longest available temperature series in the world and, in more than 350 years of observations, Spring 2017 was the warmest on record.