Shortly before midnight on 18th December I happened to glance at my weather station’s console. Its comforting green glow informed me that it was 11.1C outside. I did a double take, and then I had to step outside to check it wasn’t an error. Sure enough, it was insanely mild in the darkness, and the warm wind felt like a hairdryer on my face. It felt weird. It felt…..wrong.
I checked my weather data from the last five years and, true enough, that night time temperature of 11.1C was higher than ANY temperature I’d recorded in any of the previous five Decembers. Not that I or indeed anyone else needs a weather station or five years of data to tell them what they already know. That the weather so far this winter has been ‘peculiar’.
On Boxing Day as I drove home from Warwickshire the temperature on the car dashboard read 16C. 16C!! The small mound of Christmas cards I’d been given, festooned with snowmen, snow-capped thatched cottages and cold-looking robins seemed as incongruous to me as they would to anyone enjoying Christmas in Australia.
Severe flooding in Perthshire
But surprisingly it was highland Scotland that recorded the highest UK temperature in December – Plockton and Glen Shiel sizzling at 17.2C on the 16th. With just one air frost recorded here in the Lomond Hills, it’s felt more like May than December.
Tropical air
The mildness has been caused by warm air drawing up from the southwest, from the Azores and the tropics beyond. Nothing too unusual about that, to be honest. Though we like to imagine our coldest season as a winter wonderland, it’s usually dominated by milder winds from the Atlantic. For that reason, the record December temperature for the UK still stands at an impressively balmy 18.3C. And again, surprisingly, that was recorded in highland Scotland way back on 2nd December 1948, in Achnashellach of all places.
17.2C in Plockton is certainly rare, but the real weirdness isn’t so much the high temperatures we’ve experienced, rather their stubborn persistence. We haven’t just had the odd day of mildness here and there, we’ve had weeks of it. Little wonder, therefore, that the UK Met Office declared last month the warmest December since records began in 1910.
The long term UK average for December is 3.9C, but this year it was a staggering 8C. Scotland experienced cooler interludes mid month so it only came in as the 5th warmest here. But down in Central England, where the longest instrumental record of temperature in the world stretches back all the way to 1659, December 2015 was the warmest in 356 years!
Wettest month ever
I dare say many of us quite like the sound of tropical air surging up from the Azores, but be careful what you wish for. Warm air holds much more moisture than cold air and, as there’s an awful lot of water for it to cross between the Azores and here, a great deal of moisture is taken up from the sea and this is then unceremoniously dumped on Scotland.
So, while Winter 2015/16 will certainly be notable for its mildness it’s the rainfall that will be remembered longest. Both in terms of measured rainfall but also in the bonkers number of days on which it has rained.
At home in Fife, my rain gauge has so far measured rainfall on every day between 26th November and 10th January….with the exception of two gloriously cold, frosty days when nothing whatsoever fell from the sky. Two dry days out of 46!? That’s enough to push even the most diehard of scotiaphiles into considering emigration.
I measured a hefty 136mm of rain in December which, in any normal year, would be well above the average for eastern Scotland and could be considered rather extreme. But it pales to the totals seen elsewhere in Scotland, so I’m well aware that Fife got off lightly.
A high volume of rain falling in one day, such as the 50mm that fell in the northwest on the first day of the month certainly isn’t unusual in a normal Scottish winter, or summer for that matter! But again it has been the persistence of the pattern that has sent the records tumbling. We use the word ‘unprecedented’ a lot these days but this has been on a whole other level.
December 2015 was the wettest calendar month recorded in Scotland since records began, with more than twice the average rainfall. And sadly, January has carried on where December left off. I thought I’d misheard when, driving to work on 5th January, just five days into the new year, BBC Radio Scotland said that Aboyne had already recorded its second wettest January on record. Three days later it had paddled its way into first place.
Sun and snow in short supply
The impacts of this weather have been felt far and wide, to the joy of some and the despair of others. Some people I’ve spoken to have been thankful for the money they’ve saved on heating bills. Others worry about the impact all this mild weather might have on the midge and tick populations.
Glenalmond on New Year’s Day. Snow early this winter has been little more than a dusting.
For me, the most tangible impact has been the lack of sunshine. Across the UK, this November was the dullest on record. December wasn’t much better, not least in Eskdalemuir where its inhabitants were kissed by just 9.8 hours of sunshine in the whole of that month!
Today is 10th January and I’ve not seen the sun since 27th December! Even on that memorable day it was quickly obscured by high level cloud. Before that, the last blazing sunshine I saw was on the 16th December. Simply knowing the intervals between any sunny moments is surely telling in itself, as I can’t recall such persistence of dullness. I’m pale at the best of times but I’m practically translucent just now. In a typical winter my ginger visage is bronzed by the glow of sun on snow, but coupled with a lack of sunshine has been a general lack of the white stuff on the hills.
It’s not been a complete bust winter-wise, however. Unlike down south, Scotland did experience SOME brief cold with some decent snowfall in the middle and the end of December. But while the hills looked the part for a few days, the covering was mostly cosmetic. The first mild spell washed it all away and none of the five ski resorts (six, including the Lowther Hills) had fully opened by the 2nd week of January.
Cometh the flood
Experiencing the wettest calendar month since records began would be bad enough at any time of year, but the subsequent flooding was exacerbated by the previous month having been the 2nd wettest November on record. The ground was already saturated and, because it was so mild, very little of the precipitation that fell was ‘locked up’ as snow on the hills.
The River Isla says….”You shall not pass!”
From glen to summit, water surged into watercourses, sending the Met Office’s weather warnings into overdrive both north and south of the border. On the morning after Storm Frank hit I listened to an unusually long Scottish traffic report and, I assure you, it probably would have been easier to list the roads that WEREN’T closed due to flooding.
In the New Year I tried to drive from Coupar Angus to Blairgowrie, typically a 10 minute journey but one that instead took upwards of an hour as I tried to find a road over the River Isla that wasn’t underwater. The Isla is normally a small, lazy, meandering river that you barely notice as you cross any of its bridges between Glen Isla and Cargill. This past week it’s been impossible to ignore, for it has become a monster, in parts between 1km and 2km wide.
Scotland’s infrastructure has been tested as never before. After the last round of flooding there were no trains between Inverness and Aberdeen, or between Aberdeen and Dundee. Aberdeen airport was temporarily closed because a hole appeared in the runway, and rail services between Carlisle and Glasgow won’t be up and running until the end of January.
Villages, towns and cities near rivers both big and small have been overwhelmed – the scenes in Ballater after the Dee engulfed the town were apocalyptic. As a friend in Aberdeenshire put it: ‘the destruction is immense. It’s like a tornado has been through the place. Tarmac ripped up, cars through walls, caravans in pieces, people’s entire house contents out on pavements.’
People are homeless, towns are cut off, and many bridges have been damaged or destroyed. But in the face of such hardship, communities are rallying and Scotland is very much open for business. I always advise daytrippers to spend money in the places they visit, giving something back rather than just walking the paths, eating their packed lunch and then driving home. That’s even more important now, as flood-damaged communities need that level of support from the wider public.
Ballater cleaning up after the flood. Photo reproduced with kind permission.
The impact of this extreme weather on the natural world, by default relegated to a lower tier of concern below economic and social factors, is sure to be far reaching. Flooding will benefit some species and harm others, as will the freaky mildness. Vegetation tends to grow in temperatures of 6C and upwards, so with very few days when the temperature has remained below that threshold, the plant world has been carrying on as usual. I’ve seen leaves emerging on trees for goodness sake!
A prolonged subzero cold spell is sure to come sooner or later, even in a winter like this, and that will be a shock to many a species that has been lulled into a false sense of security. Not least…us!
Thanks, jet stream!
The jet stream has become a regular feature in weather forecasts in recent years, and with good reason, as it plays a huge part in determining what kind of weather we experience.
It’s a ribbon of fast moving air, 10-15km up, that blows from west to east around the northern hemisphere at anything between 100 and 200mph. It sits at the meeting point of warm air pushing northwards from the tropics, and cold air pushing south from the North Pole, and it’s that turbulent meeting of air masses that feeds it. The greater the difference in temperature between the tropics and the poles, the faster the jet.
Crucially, the jet stream doesn’t sit in a fixed position – it flexes slightly to the north or to the south as it rushes eastwards. Storms that develop along its track, out in the Atlantic, are steered along it like a conveyor belt and, if the jet comes close to or over the UK then those storms track over or close to us. If the jet stream gets ‘stuck’ in that position then we suffer a seemingly endless conveyor belt of storms that offer very little respite between them. That is what has happened this winter, and indeed in the other recent wet or stormy spells we’ve endured, such as summer 2012 or winter 2013/14.
Now, it’s by no means unusual for the jet stream to be close to or over the UK during the winter. What IS unusual, albeit worryingly usual in recent years, is for it to get stuck in that position for weeks on end.
This is because, instead of plying a forceful, only slightly waivy path around the northern hemisphere, these days the jet stream seems to be behaving more like a lazy river in a flood plain. It meanders wildly, steering around obstacles (such as high pressure systems) and throwing out huge kinks that push up to the pole or down to the tropics.
January in West Lothian. Wildlife is confused.
Areas of high pressure and low pressure can get trapped in these kinks, and when that happens the pattern is difficult to budge. So rather than getting changeable but generally benign weather, where established patterns last days or perhaps a week or two, we instead seem to be experiencing greater and more prolonged extremes.
It’s widely acknowledged that the jet stream has become weaker in recent years but there’s no great consensus as to why. Some have suggested it could be because of a reduction in solar energy reaching the Earth, while others suggest that because the Arctic is warming faster than anywhere else on the planet, the difference in temperature between the arctic and the tropics is getting smaller, hence the more sluggish, ‘kinky’ jet. The jury’s out.
Don’t despair, though. Being stuck under one of these kinks doesn’t necessarily mean mild and wet weather. One such kink was responsible for the bonkers heatwave in March 2012 when Aboyne recorded 23.6 °C and I camped atop Goat Fell in a t-shirt. Similarly, another kink was responsible for the big freeze in 2010 when Scotland recorded it’s coldest (and wonderfully sunny) December in over 100 years.
One thing’s for sure though, our famously changeable weather doesn’t seem quite as changeable as it used to be.