Scotland weather: Drivers stranded and ambulance crashes in snow
Drivers have become stuck on the A9 in Caithness, while an ambulance crashed in Aberdeenshire as heavy snowfall hit parts of Scotland.
No-one was injured when the ambulance overturned on the A98 at Boyndlie.
The A9 has been shut between Helmsdale and Dunbeath and police said some drivers had been stranded.
Police Scotland said the snow gates at Helmsdale would remain shut overnight, but added that access would be available to emergency services.
Three gritters and a tractor snow plough have been working to keep the route clear.
Police said the road had been cleared of most of the vehicles that were stuck in snow.
Hundreds of schools were closed for a fourth day as Arctic conditions continue to cause low temperatures across Scotland.
An amber weather alert for snow in place for Orkney, Shetland and northern Scotland ended at 18:00 on Thursday but a yellow warning continues until Friday afternoon.
The Orkney Local Emergency Co-ordination Group (OLECG) warned that almost all roads were "impassable" and urged drivers to stay at home.
Those with friends and family arriving by Northlink Ferries on Thursday evening were encouraged not to travel in to Hatston to meet them from the ferry - and instead to contact them with a view to finding alternative accommodation in Kirkwall.
OLECG chairman, chief inspector Scott Robertson, said: "The situation on Orkney's roads is extremely serious.
"I cannot stress this more strongly - do not travel tonight. If you are already away from home find alternative accommodation.
"If people are unable to find accommodation please reach out to the Orkney Islands Council Facebook page, who will gather details of those who are stuck."
The Scottish Ambulance Service confirmed no-one was hurt in the Aberdeenshire ambulance crash.
A spokesperson said: "The ambulance, which was on its way to an emergency call, was not transporting any patients and the crew are uninjured.
"An alternative ambulance was sent to the original call."
The Scottish Fire and Rescue Service said a lorry and two cars had been involved in a collision a few miles south of Urquhart Castle, on the shores of Loch Ness. No-one was thought to have been badly hurt.
All schools in the Northern Isles as well as the Western Isles stayed closed on Thursday.
Almost all schools in Aberdeenshire were closed. Others opened late. Some Aberdeenshire gritting teams were said to be unable to get to work due to the snow.
More than 15,000 pupils in the Highland Council area have been caught up in weather disruption. Almost 190 schools are either shut, partially closed or have had to open late due to snow and ice.
Much of the UK endured temperatures below freezing overnight, with preliminary data from the Met Office indicating the mercury fell to a low of -13.6C at Tulloch Bridge in the Highlands.
That came after the UK had its coldest night of the winter so far on Tuesday into Wednesday, when Dalwhinnie experienced a temperature of -14C.
The Met Office has said parts of Scotland could see up to 40cm (16in) of snow before the weekend.
Meanwhile, ScotRail confirmed its Dundee to Arbroath, Montrose to Inverurie and Inverness to Elgin trains will not run on Thursday.
The operator also said services between Inverness and Edinburgh/Glasgow would take 30 minutes longer.
A separate yellow warning has also been issued by the Met Office for further snow on Friday across parts of north and central Scotland.
It follows on from the existing yellow warning already in place for many parts of the country for Wednesday, where parts of Shetland saw around 24cm (9in) of snow.
The Met Office amber warning said frequent, occasionally heavy snow showers would affect the Northern Isles and northwest Scotland, creating possible blizzard conditions.
Police Scotland have warned of a high risk of disruption in affected areas.
Met Office chief meteorologist Jason Kelly said: "With deep snow already lying on the ground for many in the northern half of the UK, we're going to see a significant topping up of totals over the next couple of days, especially for those in the north of Scotland.
"Within the amber warning area, an additional 15-20cm of snow is possible in a few locations.
"Strengthening north westerly winds will also cause some lying snow to drift, potentially bringing some additional hazards, such as temporary blizzard conditions."
Scotland's Transport Minister Fiona Hyslop said winter resilience plans have been "in full effect" across the country.
Neil Hutchison, the executive manager for roads for Shetland Islands Council earlier warned drivers not to travel unless it was absolutely necessary, given the "deteriorating" conditions in the area.
ScotRail earlier made a number of alterations on the Highland line, while all flights to and from Kirkwall Airport in Orkney were cancelled on Wednesday afternoon.
Bus operator Stagecoach has suspended their services across Tain, Aviemore, Caithness, Orkney and Skye due to road conditions.
The previous lowest temperature this winter had been -12.5C, in Altnaharra, which was recorded in early December.
In January 2010, -22.3C was recorded in the same Highlands village.
The sub-zero temperatures are expected to continue until the weekend.
How is the weather in Scotland impacting you? Get in touch.
- Email [email protected]
- WhatsApp: +44 7756 165803
- Tweet: @BBC_HaveYourSay
- Upload your pictures or video
- Please read our terms & conditions and privacy policy