Just a few months ago, the nation was gripped by extreme cold. Now, we’re overheating and some are running out of water. John looks at why our weather this year is behaving so oddly.
Love it or hate it?
Enjoying the sunshine? For a weather-beaten nation used to blustery winds and drizzle, this extraordinary spell of hot and dry weather is bringing smiles to our faces and barbecues to our back gardens. Even England are winning!
As our green and pleasant land gets just a little less green every day, thankfully the lawn doesn’t need mowing as often as usual. And for those charged with the laundry, there’s not much call for the tumble drier either. Within minutes of being hung on the line, the washing is ready to be stacked away – thanks to the desiccating hot breeze that nature is laying on for free!
…we seem to have gone straight from ‘midwinter’ to ‘midsummer’
But you can have too much of a good thing, can’t you? And for many, the novelty of this remarkable ‘Mediterranean’ period is beginning to wear very thin. With the mercury repeatedly soaring towards 30 degrees, it’s no surprise that some are suffering from the heatwave. Recently issued Heat Health Alerts confirm the risk of the high temperatures to the frail and elderly. For perspiring commuters, warped rails, melting tarmac and overheated underground trains provide a tiresome perennial reminder of our infrastructure’s inability to cope with summer heat. And now the moors are on fire!
In much smaller ways, the heat can cause discomfort too. As one friend of mine described to me, each night a game of ‘musical beds’ is played out in her household. Her tired and over-heated children try in vain to find a cool corner of the house. Meanwhile by day, for parents of small children in particular, there’s the constant vigil of sun protection and hydration to add to the daily parental responsibilities. Then there’s the watering to do (assuming you’re still allowed to water the garden, that is). After one of the driest Junes on record, restrictions are already in place in parts of the UK.
From one extreme to another
With no prospect of a sudden change in the weather through early July, some are already reaching for comparisons with the long hot summers of the past; even the ‘Daddy’ of them all – 1976. Well, we’re not there yet. Here’s just one stat to make the point: In 1976, London saw 17 consecutive days of temperatures over 27C. So far this year, we’ve managed a measly 5. So far, that is…
But as July starts off where June ended, this is the latest in a line of warm months that began back in April, with May delivering record daytime temperatures too. What’s so remarkable about this year is how we seem to have gone straight from ‘midwinter’ to ‘midsummer’, with very little ‘spring’ in-between.
The nation was grinding to a halt less then four months ago too. But for very different reasons. Back then, extreme cold and historic blizzards paralysed the country. Children rejoiced as schools were closed on the coldest March day on record. How cold? A ‘high’ of -4C in some places! This was a video I took near my house that day!
The answer is blowing in the wind
The record low temperatures and unprecedented snowfalls of early March also brought real hardship and concern for vulnerable friends and relatives. Some remote communities were isolated for several days while, more widely, tens of thousands lost their water supplies through burst pipes.
We have, it seems, lurched between opposite extremes of weather impacts in the space of just a few weeks, with very little ‘normal stuff’ in between. Hot and cold, 2018 has brought into sharp focus how vulnerable our complex and interwoven lifestyles are to extreme weather.
Where’s our normal weather gone?
Well, there’s a good reason why our ‘normal stuff’ – you know, the mild, mixed and often mundane concoction that is so typical of our climate – has been conspicuously absent. The answer is blowing in the wind, (and who am I to argue with Bob Dylan?)§
It can take six times less energy to heat or cool a kg of soil than it does to do the same to water. So continents heat up much more quickly in summer and cool more dramatically in winter than do oceans. Our prevailing westerly winds normally propel a succession of weather systems across the Atlantic in our direction, bringing a mixture of rain and shine. The elements chop and change from day-to-day, even from hour to hour. But these maritime westerly winds are seldom too hot or cold. This year, however, our mild westerlies have gone ‘AWOL’.
It’s all down to the peculiar behaviour of the jet stream – the high velocity wind several miles high that steers our weather systems around the globe. Instead of powering across the Atlantic towards us, as it normally does, the jet stream has been deflected far away. As a result, easterlies have been more commonplace since late winter; and, unlike westerlies, easterlies are seldom ‘mild’.
It started with ‘The Beast’
Odd things started happening way back in February. Ironically, it was a sudden warming way up in the stratosphere that sent winds across the whole northern hemisphere spinning into reverse – from the top to the bottom of the atmosphere. The ‘Beast from the East’ was the bone-chilling result for the UK, flagged up by Sara and me, weeks before it arrived:
The ‘Beast from the East’ was swiftly followed a couple of weeks later by the sequel: ‘Beast from the East 2’, bringing another bout of severe cold and snow – even as we headed into mid-March.
The atmospheric aftershocks of this Sudden Stratospheric Warming lingered on through Spring, meaning that our normal circulation of mild westerly winds has never really recovered into rude health. But, with lengthening days and strengthening sun, so the Continental landmass has heated up through April and May. The same winds that brought such bitter cold weather began to deliver blowtorch heat.
And now the main culprit for the continuation of our ‘Continental’ weather comes from below rather than far above our heads. The dome of hot and dry air building up from the parched ground can act as a self-sustaining ‘force-field’, deflecting the jet stream away and foiling any attempt by rain clouds to make an impact. ‘Hot and dry’ leads to more ‘hot and dry’.
What happens next?
Such a schizophrenic lurch from extreme winter cold to blistering heat is not without precedent. The severe winter of 1947 was followed by a scorcher of a summer. So will the easterlies keep the jet stream at bay through the rest of this summer too? If so, the implications could be quite serious.
“Drought” is a word that is beginning to rear its head. Certainly, the lack of rainfall so far this summer is comparable with 1976. However, back then we were coming off the back of a whole year of low rainfall. As a result, unprecedented drought brought serious water rationing as the hot summer took hold. I remember it well (yes I know – it’s hard to believe but I really am that old).
I wouldn’t be at all surprised if we lurch into yet another extreme weather pattern later in the year
In contrast, this summer has emerged out of a relatively wet spring. So reservoir and groundwater levels are not worryingly low… yet. Several more weeks of hot and dry weather could eventually take their toll, though.
As I suggest in John Hammond’s Month Ahead, there are signs that the jet stream will briefly reawaken in mid-July, perhaps bringing some welcome rain. But long-range forecast models indicate that warm and dry weather may again take over as August approaches.
We’ll see. I wouldn’t be at all surprised if we lurch into yet another extreme weather pattern later in the year. Come what may, the last few months have demonstrated our vulnerability to a shift in the winds.
Just imagine how different our great British climate could be if the our trusty Atlantic jet stream was to desert us more permanently, and easterlies became the norm. Mild, mizzly and middle-of-the-road it wouldn’t be!
Time to get the barbecue ready before the next game. Come on England!
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