All change with first taste of winter possible next week

Forty-eight hours can be a long time in weather forecasting, and since I wrote my blog on Monday there’s been a growing trend for colder air to start influencing our weather from the near continent next week.


The award for the biggest flip-flop goes to the American GFS model which has performed an impressive volte-face in the last forty-eight hours.


As I’ve explained before, each model is run many times, with slightly different initial atmospheric conditions.


This allows forecasters to judge how likely a particular scenario is; in other words it gives us a level of confidence.


Currently, around sixty percent of the solutions from the European (ECMWF) model suggest that cold air from the east will win the battle against the milder Atlantic air that has been with us for virtually the whole of winter so far.


For other models the percentage of cold solutions is around fifty percent.


So at this stage although colder weather next week is more likely than not,  it’s by no means a done deal and caution is required – particularly in light of the big jump from the GFS model since Monday.


In my twenty years as a forecaster I have seen many a cold easterly scenario turn into a figment of the computer’s imagination, with a flip-flop the other way to a milder scenario always a possibility.


That said, the European model is often the most reliable, and there has been a definite trend towards this colder scenario in the last few runs of computer models.


Whatever the final outcome, next week is likely to cause real headaches for forecasters, trying to determine just which air-mass will win, and where the battle between cold and mild air takes place.


Where that battle takes place, there will be a risk of some snow.


And let’s not forget, there will also be a risk of heavy rain, which could further exacerbate the flooding situation affecting parts of the UK.


So changes are afoot, but there’s still much uncertainty which could last for a few days yet.


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