After Arctic conditions gripped the country in 2009-10, on the back of a washout “barbecue summer” the Met Office came in for so much criticism that it announced it was to stop its long-range predictions.
It may indeed be an imprecise science but forecasters at the Exeter-based agency now say that new technology means they can better predict “big freezes” and help local councils prepare for the worst.
In the past, forecasters have been left red-faced after predictions of a mild winter were later dashed as freakishly harsh conditions swept in.
The winter of 2009-10 is perhaps one of the most memorable predictions of gentle conditions that failed after Arctic weather gripped the West Country.
However, Met Office chiefs now believe they can foresee similar freak winter conditions months in advance following an update in computer software.
Three years ago snow, ice and temperatures of -22°C were impossible to foresee but now an upgraded forecasting system should predict what’s on around the corner.
Since technology was upgraded two years ago, forecasters have accurately predicted the cold start to December 2010 and the mild winter of 2011.
And running the software on the data with which they failed to predict the severity of the previous winter, it predicted the conditions which saw councils across the country run out of grit for roads, motorists become stranded and parts of the country become innaccessible through huge drifts of snow.
A new study by the Met Office found the unexpected nature of the “deep freeze” lay in the inability of its seasonal forecasting equipment to simulate phenomena known as sudden stratospheric warmings (SSWs).
These happen when the usual westerly winds in the stratosphere of 10km to 50km above the ground stop or reverse, causing a knock-on effect at surface level.
Westerly winds blowing warm air from the North Atlantic across Northern Europe are blocked, causing extended periods of very low temperatures.
The new model can produce a more accurate forecast of the cold winter, especially the bitter conditions that took hold towards the end of the season.
A Met Office spokesman said: “It’s too early to predict what sort of a winter we’re in for yet. But any very cold snaps caused by the same conditions seen during the winter of 2009/10 can now be anticipated as early as November.
“This sort of information is particularly helpful for local councils who have to decide how much grit to buy for the winter.”