Which places are most likely to see #uksnow next week?
As I mentioned in my blog a few days ago, next week will see the first decent cold blast of the season, with Arctic air plunging over us.
There’ll be a notable drop in temperature with snow in places, but it’ll be nothing unusual for the second half of November.
This is in stark contrast to the stories that have appeared in the Daily Express newspaper in recent days, claiming that: “Britain faces months of freezing winds and heavy snow.”
Unfortunately, such headlines are a regular occurrence and not credible, given that long-range weather computer models are nowhere near good enough to back up such claims.
However, some parts of the UK will see snow next week, with coastal areas and hills having the greatest chance – for the following reasons.
Coastal parts of the UK
At this time of year, the waters around the UK are still relatively warm. As the cold Arctic air travels over this warmer water, it is heated from below, causing the air to become unstable.
This results in parcels of relatively warm, moist air shooting quickly up into the sky, which eventually cools and condenses, forming cumulonimbus clouds over the sea.
These cumulonimbus clouds then give heavy showers which, due to the presence of cold air, fall as sleet, snow and hail – sometimes with thunder.
The wind then blows these showers from over the sea on to wind-facing coastal areas, travelling as far as 30-40 miles inland. They then tend to fade away having lost the supply of moisture and warmth from the sea.
Hills and mountains
Elevation has much more of an influence on the likelihood of snow falling than you probably think. A 20 per cent chance of snow at sea level becomes a 50 per cent chance at 150 metres up and an even greater 70 per cent chance at 300 metres.
Hills and mountains also have the effect of forcing air upwards even further than would be the case over low ground, which squeezes more moisture out of the clouds – making the showers heavier and more frequent.
Troughs – the wild card
However, despite the most likely places to see snow having already been mentioned, there is a chance of something called troughs forming.
These are more organised bands or rain, sleet or snow, which are driven by slight falls in pressure and are a wild card in these situations.
When troughs occur, they can bring snow to places that, given the weather set-up, wouldn’t normally expect to see snowfall – including inland areas right down to sea-level.
So, while coastal areas and hills and mountains look most likely to see snowfall next week, I’ll be keeping an eye out for troughs which may provide a few surprises.