A fresh weather warning for snow and ice has been issued for many parts of Scotland.

Drivers in the affected areas have been asked to avoid all unnecessary travel, with workers urged to go home early if possible.

Snow showers earlier in the week caused disruption in many parts of the country, with motorists becoming stranded on the M74 for hours on Tuesday night.

Friday morning's amber warning affects mostly western parts of the country, though other parts of the central belt and the Lothians may also be hit by the snow showers.

Police Scotland upgraded their travel advice from stage two to stage three on Friday morning.

The force said anyone driving after 3pm could face significant delays, and employers were asked to consider letting staff finish early.

HGV drivers have been told they should travel with "extreme caution."

The force's warning covers areas including Glasgow, East Renfrewshire, North and South Lanarkshire, East Dunbartonshire, Ayrshire, West Lothian, Dumfries and Galloway, Falkirk and the Scottish Borders.

Heavy snow showers are expected on the M74 and M77 shortly after midday.

Scotland Transerv, the firm which maintains roads in the south west, said snowfall had been heavy overnight on the M74 and the A76.

There have also been wintry showers all morning on the M80, with motorists advised to slow down and drive to the conditions.

Amey, which maintains roads in the south east, said the snow would work its way east throughout the morning.

The firm said it had 41 vehicles ready to react and blizzard-like conditions are expected.

A live map which tracks gritters is available via Traffic Scotland.

CalMac Ferries said their sailing between Iona and Fionnphort may be disrupted due to wind and swell conditions.

McGill's Buses said a number of their services would be affected by the severe weather conditions, including the 202, 212, 217, 232 and 247 routes.

ScotRail said there was disruption on the West Highland line at Crianlarich due to the weather and a signal fault.

There is not thought to be any disruption to flights from Glasgow or Edinburgh Airports.

Local authorities in North and South Lanarkshire said all schools would be closed to pupils from lunchtime due to the deteriorating weather.

Four schools and four nurseries in Fife were closed after midday on Friday, and East Ayrshire Council also said all schools would be closing early.

Scottish Borders Council shut 12 schools in the morning.

Highlands Council said 23 schools and nurseries would be closed or partially closed due to the bad weather.