by The Met Office has suggested that parts of the UK could be set for a cold snap next week, with many areas also told to prepare for the possibility of waking up to a dusting of snow.
But although the official long-range forecast warns of “winter showers” – including snow – British weather is rarely predicted with a simple affair.
Here, Yahoo News UK tries to make sense of things.
How accurately can the Met Office predict snow?
Forecasting snow for anyone, even the Met Office, can be tricky – just one degree warmer or colder can be the difference between a nightout and a great winter.
Location can also make a difference. The same type of weather front could result in snow somewhere at higher elevations, but rain in low-lying areas.
The Met Office says the UK’s specific location makes it extremely difficult to accurately predict snow too far ahead, especially compared to some other countries where snow can be reliably predicted “days or weeks in advance”. Part of this is due to the fact that the UK is surrounded by water.
Several media reports predicting snow weeks or months ahead will often be based on a single predictive model. However, official forecasters will compare many models before making a judgment – and this will even be stated in terms that refer to the relative likelihood of a particular weather event occurring.
“It only takes very small temperature changes to determine whether it’s falling snow reaching the ground or just brushing the tops of the mountains,” says Met Office spokesman Stephen Dixon.
“What meteorologists look for includes where the air is coming from – is it from a colder region where there might be a chance of snow?
“Where warm air meets colder air in the winter months – the coming together of these dimensions can bring in moisture, allowing snow to fall. But it’s often a fine line between who can see snow and who can see rain more than a few days ahead.”
Can the ‘exact date’ of snow be predicted?
There’s a reason the Met Office presents its long-range forecasts for the UK as a whole – there’s little point in trying to be more accurate.
Even short-term daily forecasts for the next five days can change at short notice due to small fluctuations in air pressure, temperature or wind direction.
“Forecasting is quite difficult in the UK, where we have competing air masses,” says Dixon.
“What those exciting headlines don’t capture are the forecasts of uncertainty ahead. When you are looking a week or two ahead, a date for a certain set of conditions is not really how it works.
“Meteorologists will talk about the degree of certainty they have in competing scenarios that may – or may not – occur.”
How should I prepare for the British weather?
Probably pack a big coat (just in case).
What about ‘Arctic blasts’, ‘snow bombs’ and ‘Beasts from the East’?
The Met Office is becoming less shy about criticizing some of the more “exciting” weather headlines appearing in some media.
In September, he went so far as to label one story claiming the UK was to be “pummeled by rain” as “absolute rubbish”.
While he is not opposed to some of his favorite media labels, the forecaster says his priority is to accurately reflect the expected conditions.
So, while ‘Beast from the East’ or ‘Arctic blast’ might reasonably refer to a particular weather front coming from a particular region, terms like ‘snow bomb’ should probably be avoided (unless they have explosive characteristics he really has).
Dixon says: “It’s not for me to dictate how some of those headlines are written, but what’s important to us as an organization is that the language matches the forecast.
“‘Beast from the East’ could refer to the conditions, but not reflect the current attitude [it should be avoided] and that is true in other terms.
“It’s important that people understand the forecast they’re getting and we need to show the uncertainty they’re getting – especially when snow is forecast at longer ranges. It can be a communication challenge.”
What is long range forecasting and how reliable is it?
The Met Office’s long-range forecast is divided into two parts, covering successive 10-day and 15-day periods.
While the shorter five-day forecast can offer breakdowns by area and even an indication of how much time households in a given area should expect wind, rain, sunshine or snow, the forecasts cannot long range offer the same level of detail.
Instead, they provide a general view for the whole of the UK.
The forecaster makes the reason for this clear on its own website, pointing out that “small events across the Atlantic at the moment could have a significant impact on our UK weather in a few days time”.
“Since we’ve got this colder air, it means there’s a continued chance of more of these weather hazards and icy conditions as well,” says Dixon, reflecting on the current long-range forecast .
“But at this point it’s too difficult to put that into any detail as to how that might look next week.”
