Britons could experience a rare and potentially hazardous weather event on Christmas Day, according to the latest long-range forecast from the Met Office. While temperatures are not predicted to be exceptionally low, forecasters have highlighted the increasing risk of widespread freezing fog developing across parts of the country.
Unsettled Christmas Forecast Takes Shape
The Met Office expects the festive period to be dominated by unsettled weather conditions. Their forecast for December 21 to 30 indicates that low pressure is likely to be centred to the southwest of the UK, with high pressure building from the east across northern areas. This setup is expected to establish a broadly easterly flow of air.
As Christmas approaches, the influence of high pressure is predicted to grow, leading to more dry and settled weather. However, this shift also means temperatures will fall, dropping closer to or even a little below the seasonal average for some regions. Rain is expected to become increasingly confined to southern and southwestern parts of Britain.
What is Freezing Fog and Why is it Dangerous?
While the Met Office states that particularly cold conditions look unlikely at this stage, the calm, clear conditions associated with high pressure create the perfect environment for freezing fog to form. This rare phenomenon occurs when fog develops in sub-zero temperatures, leading to supercooled water droplets that remain liquid in the air.
The Met Office explains: "When droplets from freezing fog freeze onto surfaces, a white deposit of feathery ice crystals is formed. This is referred to as rime." While rime is more common on mountain tops, the forecast suggests it could develop at lower levels this Christmas.
This weather poses significant dangers, primarily through the formation of black ice on roadways, which is extremely difficult to see. America's National Weather Service, cited for its clear warnings, advises that extreme caution is necessary if travel is required. Freezing fog can also lead to a thin layer of ice forming on aircraft, creating hazardous flying conditions without proper de-icing.
Staying Safe During the Festive Period
With the potential for freezing fog on December 25th, drivers are urged to prepare for potentially treacherous conditions. Key safety advice includes:
- Driving much more slowly if icy conditions are suspected.
- Allowing extra time for any essential journeys.
- Being aware that black ice is most common on bridges, overpasses, and shaded areas of the road.
The Met Office's long-range forecast, issued on December 16th, will be updated as more data becomes available, but the current guidance points to a chilly, foggy, and frosty Christmas for many.
