Winter forecast anyone? Expect a flurry of false prophets

There’s already bold talk of a harsh winter to come. John discusses whether the hyped up headlines are backed up by the science.

The ‘game’ has begun. Amongst the winter soothsayers, promises of bitter cold and snowstorms seem always to hold more appeal than suggestions of a run-of-the-mill mild winter. But then, mundane stories struggle to sell newspapers, don’t they?

So who can we really trust amidst a blizzard of mixed messages? Some might say that long-range forecasting is no more scientific than football punditry; and in a way, I’d agree. It all depends on the quality of punditry.

Why is “Crystal Palace to win the league” a less sound prediction than “Manchester City to win the league”?

Squad size, player skill, team spirit, managerial ability, injuries – they all play a part. Whilst opposing attacks will ebb and flow, the usual suspects normally hold sway in the end.

Occasionally, several chance factors will come together and lead to a surprise goal. But for the underdog to win a match is a novelty, and to claim a cup competition is a shock. To end up as league champions is very rare indeed.

If only it was that simple…

From football matches to meteorology – the weather is also a battle between opposing sides. There’s much chopping and changing from day to day. But whilst the odd cold snap is commonplace, it’s not often sustained beyond a week or two. An entire winter of severe cold and blizzards would be truly historic.

The strongest force within the battling weather elements is the jet stream. This overarching channel of energetic winds tends to power relatively warm and damp Atlantic air across us from the west. For this reason, ‘’mild and muddy” and “wet and windy” tend to win over “deep, crisp and even” – most of the time. Only so often does the normal Atlantic dominance get pushed back by a bitter attack from the North Pole or Siberia; and usually only briefly.

So when does the unusual become more likely? What are the signs that we should prepare for a long deep freeze? There are many disparate factors: Tropical Pacific ocean temperatures; the strength and direction of winds in the stratosphere; the extent of sea ice and Eurasian snow cover; even the number of spots on the sun! They can all have a marginal influence on the strength of the jet stream, and the relative dominance of warmth or cold in the UK. And these are just the ones we know about.

Very seldom do all the known factors work together in one direction to give scientists a clear, unambiguous lead. If only it was that simple. This year the signals are, as usual, quite mixed. It’s a complicated business. which is why long-range forecasting is still so fiendishly difficult.

But limited knowledge is better than none at all. Government, industry and commerce all see benefit in long-term forecasts. They improve preparedness, resilience, profit and loss – however marginal the gain. That’s why these bodies use the projections of top scientists and some of the most powerful supercomputers in the world, rather than the fantasies of Mystic Meg.

I doubt Crystal Palace have much chance of winning the league (sorry, Palace fans). Similarly, many of the dramatic headlines about our winter weather should be taken with a pinch of road salt.

But we have no certainties, only probabilities. And the improbable can sometimes happen. Remember Leicester City a couple of years ago?

It’s a funny old game!