Expert comment: Why snow is difficult to predict

It’s freezing cold today after snow blanketed many parts of the UK. 

But were we prepared for this latest bout of wintry weather? 

Snow is difficult to forecast, as Dr Rob Thompson, from the University of Reading, explains. 

He says: “Exactly how cold the temperature is determines whether we get rain, sleet, snow and whether any snow settles.

“If we are wrong by one or two degrees in predicting that temperature, we get the wrong answer. We need to be so precise. If the temperature was five or six degrees warmer, it would be relatively simple. There would be rain. If it was five or six degrees colder. It's still really simple. There would be a snow. 

“The problem is just exactly where we are on that temperature threshold. And that's a regular problem in the UK, we are often right on that threshold when we get these events. Is it going to be snow or rain? It is very difficult to predict because one degree temperature difference will make a massive difference to what our forecast outcome is.”