SIX inches of more snow are expected in parts of Scotland tomorrow, after wintry showers swept across the country last night.
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The latest blast of icy weather comes as the start of a slow thaw caused flooding and burst pipes, prompting thousands of calls to Scottish Water and emergency services.
The Met Office said a band of heavy snow would spread north-east tomorrow morning, reaching southern Scotland.
It said up to 4in of snow would build up, with up to 6in, mainly over higher ground, and transport could be disrupted.
Last night, rain and snow falling on frozen ground over a swathe of central Scotland was expected to cause a black ice danger this morning.
Transport minister Keith Brown reinforced police warnings to motorists about "unpredictable road conditions", with an advisory 30mph speed limit on motorways because of the risk of black ice forming despite gritting.
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Mr Brown urged drivers to "keep a sharp look out" for the danger, and to also take care of pedestrians walking in the road to avoid icy pavements.
Temperatures are expected to rise to 6C in Glasgow by Wednesday and remain above freezing at night, although it will remain colder in Edinburgh at 2C and just below freezing overnight.
Scottish Water said it took 2,500 calls by mid-afternoon yesterday, after receiving 2,650 on Christmas Day - more than five times as many as usual - and 3,700 on Christmas Eve.
A spokeswoman said many of the calls were about frozen pipes inside homes. Extra staff were drafted into its contact centre, and another centre in Belfast, to help deal with calls. Advice is available at www.scottishwater.co.uk/warmpipes.
The spokeswoman said: "We are very busy, and our teams are working flat out. We apologise if someone has to wait or we do not attend as fast as they would like, but we will get to everyone as soon as we can."
Lothian and Borders Fire and Rescue Service said it had taken dozens of calls yesterday about burst pipes, while crews helped pump out a flooded building in Selkirk.
A spokeswoman said: "Flooding is definitely going to be a problem as the thaw sets in."
Mr Brown said power firms were gearing up for potential problems from snow and ice building up on overhead power lines.He said Scottish & Southern Energy, which is responsible for most lines north of the Central Belt, had 180 staff on standby along with some 60 4x4 vehicles and four helicopters.
The minister added: "Though everyone will welcome the news that temperatures may creep back over zero, the change will bring new challenges.
"We need to look out for the three Bs - burst pipes, blocked drains and black ice - and keep away from ice on lochs, ponds and canals as the thaw comes."
Strathclyde Fire and Rescue warned that the thaw would increase the danger from frozen rivers and lochs as the ice became thinner, and urged people to keep their dogs and children safe. The service said it would not risk human life to rescue animals.
Heavy snow on the east coast of the United States is expected to disrupt Scottish transatlantic flights, but Edinburgh airport said it anticipated normal operations otherwise today.
Heathrow was yesterday still returning to normal after the snow disruption forced several hundred passengers to spend Christmas in nearby hotels.
An airport spokesman said: "After any period of disruption, hundreds of planes and their crews are out of position, which has been compounded by weather problems at European airports."
ScotRail said its use of polytunnels - normally employed for protecting fruit and vegetables - to help defrost trains had resulted in a third more being available than at the start of the big freeze in early December.