The predicted snowfall duly arrived over many western and southern parts of the UK overnight. From a forecaster's point of view it was a classic setup for widespread snow in southern England.

We had had a cold easterly air-stream for some days. This air had originated well to the east of the UK, somewhere over Russia in fact, and was itself cold enough to give some showers of snow. These mainly affected eastern parts of England. This is because the showers develop over the sea, and then fizzle out as they move westwards inland.

The other weather ingredient needed for the snow situation to develop is for milder Atlantic air to be pushing in from the southwest. This warmer air is less dense and lighter than the cold air it is trying to displace. This causes it to ride up over the cold air. This not only helps to make the weather system more active, but also allows the cold air to linger at the bottom of the atmosphere, near to the ground. The snow is therefore more likely to penetrate right down to low levels without melting.

Places on and near the coast, however, benefit from being near to the sea, in having temperatures 3 or 4 Celsius higher than further inland. This is because the temperature of the English Channel, even at this time of the year when it is at its coldest, is still around 7 Celsius (46F).

There were some bursts of really heavy snow on Friday morning right the way from central southern England across to Wales and up into the Midlands. This brought some treacherous driving conditions since snow will settle even on very wet and well-gritted and salted roads when it gets heavy enough. Many areas had several centimetres of snow (2 to 4 inches) and some of the higher-up towns and villages in Wales and the West Country up to 13cm (5 inches).

Other notable impact from the snow besides numerous accidents was that Bristol Airport was closed for three hours whilst the runways were cleared and 350 schools in Wales alone were closed for the day.

Weather News from the last five days:
11/03/2004
10/03/2004
09/03/2004
08/03/2004
07/03/2004

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