There is increasing confidence that the recent Sudden Stratospheric Warming above the North Pole could lead to prolonged cold conditions over the UK, increasing the risk of easterly wind and significant snow.
Prof Adam Scaife, of the Met Office Hadley Centre, said: “Signs of this event appeared in forecasts from late January and in the last few days we have seen a dramatic rise in air temperature, known as a Sudden Stratospheric Warming, at around 30km above the North Pole. This warming results from a breakdown of the usual high-altitude westerly winds and it often leads to a switch in our weather: with cold easterly conditions more likely to dominate subsequent UK weather.”
These events are well reproduced and can be predicted in our computer models and although there is still uncertainty around the outcome of this particular event, there is an increased risk of cold conditions in the latter part of February, including the possibility of heavy snowfall.
Frank Saunders is a Met Office Chief Operational Meteorologist. He said: “A Sudden Stratospheric Warming implies around a 70 per cent chance of cold conditions across the UK. There tends to be a lag of about 10 days before we see the downstream effects on the UK’s weather, as it takes time for the influence in the upper atmosphere to feed down to those levels where our weather happens.
“The outcome for the UK’s weather is still uncertain, but forecasts from computer models at the Met Office and at other centres are beginning to coalesce around a greater likelihood of cold conditions in the days and weeks to come.”
The Met Office will continue to monitor events in the upper atmosphere and their potential to impact on the UK long-range outlook.