Snow warning as Forth Road Bridge remains closed overnight
The Met Office has issued severe weather warnings after HGV blown over on Forth Road Bridge.
Weather warnings have been issued with thundersnow and 70mph winds expected to batter parts of Scotland.
A large area of the country is forecast to be hit with the extreme weather on Wednesday and into Thursday.
Motorists have been warned of further delays on Wednesday evening and Thursday morning following the closure of the Forth Road Bridge overnight after a HGV was blown over.
The Arctic blast is forecast to blow into the north west of Scotland from Canada before spreading across the country, bringing gale-force winds and snow.
There were also problems on the rail network, with severe disruption on the Glasgow - Paisley Canal line leading to ScotRail arranging for passengers to be taken to their destination in taxis.
The Met Office has issued Yellow weather warnings for the north of Scotland, the islands, Strathclyde, Tayside and Fife.
Temperatures are expected to plummet to as low as -10C and by Thursday around ten to 15cm of snow is forecast to fall in parts.
STV weather presenter Sean Batty said: "Over the next few days some of the showers may turn thundery, which could lead to a phenomenon known as thundersnow.
"This is where snow falls instead of rain during a thunderstorm. It's quite rare in most parts of Scotland but a bit more common across the Northern Isles.
"At the moment very cold air is travelling out of Arctic Canada and crossing the much warmer Atlantic."
He added: "This allows warmer air over the ocean to bubble up into the much colder air above and creates cumulonimbus clouds, which are also known as thunder clouds.
"These will spread in during Wednesday and Thursday and could lead to reports of thundersnow across the country."
A major operation is ongoing on the Forth Road Bridge to remove a lorry after it toppled in high winds of Wednesday morning.
However, the bridge will be closed during the evening peak due to high winds affecting work to remove the lorry.
Southbound traffic is currently being diverted from the M90 at the Admiralty junction onto the A985 to Kincardine for onward travel.
Northbound traffic on approach to the bridge is being diverted off the A90 at Echline and can travel along the A904 to join the M9 at Junction 2 or be turned around to travel to M9 J1A.
Traffic was very busy in the surrounding area in the morning, especially on approach to Edinburgh on the M9 at Newbridge, the A985 on approach to the Kincardine Bridge and at Kilbagie Roundabout.
Motorists are urged to avoid the bridge and surrounding area or allow extra time during this evening's peak as, even if the bridge does reopen, restrictions will be in place to allow repairs to be carried out.
On Wednesday evening, snow gates were closed on the A939 Cock Bridge - Tomintoul road.
Transport minister Humza Yousaf said: "Once again the engineers and Forth Road Bridge team find themselves in the spotlight.
"They are carrying out very challenging repairs in difficult conditions and the damage to the central reservation is significant.
"We should therefore be prepared for delays and disruption over the next few days as engineers assess the damage."
He added: "Even if the bridge does reopen it is likely to be under traffic management with restrictions in place in both directions.
"More widely, there are a number of severe weather warnings still in place for much of the country. The conditions will inevitably lead to some difficult driving conditions.
"Gritting teams will be out across the period to help keep the trunk roads moving. Gritters will also be patrolling at strategic locations on the network to make sure that they can respond to any emerging issues.
Sean Batty said the wintry weather is not unusual for the time of year.
He said: "The upcoming cold spell is nothing out of the ordinary for January, however, it will come as a bit of a shock to the system after weeks of mild winter weather.
"This week temperatures started around 8C to 10C but by the end of the week highs will be 3C to 5C.
"Overnight temperatures could drop below -10C in parts of the Highlands where there is lying snow."
"The showers will start as rain but as the colder air comes in these will turn increasingly to sleet and snow by the evening."
He added: "There will also be a very strong and gusty wind, with gusts up to 70mph possible in the north and north west.
"The wind will give a significant wind chill. By Thursday morning some low lying areas away from the coast will have a few cm of lying snow, while 10-15cm may have accumulated over the hills.
"It will remain very windy on Thursday with frequent showers again affecting the north and west. The showers will be of snow in many western areas, although across the far north and north east some of the showers may turn more to rain as slightly less cold air feeds in for a time. The showers here will turn back to snow later.