HEAVY snow has started to cause disruption for commuters across Scotland, with potential for warnings to be upgraded to the highest level over the coming days.

Transport Minister Humza Yousaf said amber alerts for snow and freezing winds from the early hours of today could be changed to red for extreme weather in certain areas.

Forecasters said the entire east coast, central belt and as far west as Greenock will be hit – while the worst affected areas could see up to 40cm of snow and a wind chill of -10C.

Yousaf said: “There is a possibility that the amber warning could be in some areas upgraded to a red.

“That is a warning for snow that we have never seen since the modern system has come into place in Scotland. That’s what the Met Office tell me.

“We are right on the cusp, we are at the strongest possible amber warning, and right on the cusp of potentially becoming a red.

“That means a high likelihood of a high impact so that could be not just treacherous but frankly dangerous if you travel.”

Met Office guidance for red warnings states: “Widespread damage, travel and power disruption and risk to life is likely.

“You must avoid dangerous areas and follow the advice of the emergency services and local authorities.”

The worst of the weather so far has been south of the Border where four people have died in car crashes amid heavy snow.

Three were killed in a crash in Lincolnshire and another man died after a collision in Cambridgeshire yesterday morning.

In Scotland yesterday, rush hour saw increased congestion due to poor visibility and some crashes on the M90 and A92 causing further disruption.

Motorists have been warned to take extra care on the roads and drive accordingly for the snowy conditions.

Giving a forecast for today and tomorrow in Scotland, Met Office meteorologist Aidan McGivern said: “With the snow coming increasingly aligned into bands accompanied by strong winds there is the risk of blizzards and the risk of really significant snow accumulations building up to 5cm to 10cm widely (in the amber area) with 15cm to 25cm locally and the potential for the hills to see 40cm of snowfall building up by the end of Thursday.

“Maximum temperatures on Wednesday will be barely above freezing and adding in that keen easterly wind it will feel more like -10C.”

The transport minister said businesses have been urged to allow as much flexible working as possible for staff.

“We’re preparing but clearly we can’t stop the snow from falling or lower the intensity of those showers so it’s going to be extremely treacherous,” he said.

“That’s why the message is very, very simple – avoid travel if you’re in the amber affected area.”