FORECASTERS issued an early severe weather warning today as Britain prepared to plunge into wintry mode, with heavy snowfalls predicted.

Up to 15cm of snow - about six inches - could fall in South and Mid Wales tomorrow night and Thursday morning with up to five centimetres - about two inches - predicted for London and southern England, including Oxfordshire, early on Thursday.

Southern England could see snowfalls of up to 10cm, or almost four inches, in areas of high ground.

Paul Knightley, forecaster for MeteoGroup UK, said cold air from the north mixing with an "active" mild weather system from the Atlantic would bring the snowfalls.

There have already been small snowfalls in the South West and overnight tonight parts of eastern England will see some snow showers.

He added: "The snow will be potentially disruptive in London because it is predicted for rush hour and is going to cause some significant disruption, I think.

"It will probably be some of the heaviest snow in the last couple of years in the London area."