Storm Pia causing trouble across the UK
Trains cancelled, roads closed, power cuts. A weather warning remains in place
A train operator has "strongly" urged its customers not to travel on services to and from Edinburgh before mid-afternoon, as Storm Pia is expected to cause significant disruption.
Issuing "do not travel" advice, TransPennine Express (TPE) asked customers to delay their journeys in and out of the Scottish capital until after 3pm, as parts of the UK brace for high winds.
A yellow weather warning for wind came into effect at midnight and will last until 9pm, with forecasted gusts of 70mph to 80mph in northern Scotland - 65mph to 70mph on high ground - and 45mph to 55mph elsewhere in the country.
The warning also covers Belfast, Newcastle upon Tyne and Manchester.
The Police Service of Northern Ireland warned people on the roads to be aware of the potential for falling trees and debris.
A statement said:
"Road users are advised of potential traffic disruption this morning, Thursday 21st December, caused by fallen trees and debris in some areas across Northern Ireland.
"Officers have been assisting with traffic control whilst local roads are being cleared of any obstructions, and we thank you for your patience as we continue to do so."
Schools in Shetland will be closed on Thursday and more electricity network engineers are being brought in to deal with any power cuts.
Ferry services across the west coast of Scotland are expected to be disrupted, CalMac said.
TPE said there will be speed restrictions in place from the early hours for trains running to and from Edinburgh and that it will not run services between the city and north-west England until Thursday afternoon.
Kathryn O'Brien, customer experience and operations director for TPE, said: "Our number one priority is to keep our customers and colleagues safe, and we will be doing all we can to keep people moving in difficult conditions.
"We are urging anyone travelling across the affected routes to plan ahead, allow extra time, check their journey up until the last minute, and follow the guidance provided."
Elsewhere on the trains, Network Rail said many services will only run once safety inspections have taken place, leading to some cancellations.
The West Highland line, Kyle of Lochalsh line, and the Far North line, along with Inverness-Inverurie services, will all be subject to inspections before trains can run, and speed restrictions will also be in place in the central belt and the south of Scotland.
Travellers have been warned of "short notice changes to journeys" on ScotRail services and are advised to check ahead, while additional engineers will be deployed to deal with any incidents.
Stephen Dixon, a Met Office spokesman, said:
"It is quite a wide wind warning area. Gusts are forecast quite widely to be 45mph to 55mph, possibly 65mph to 70mph to the east of high ground in Scotland.
"The strongest winds are likely to be found in the north and north-east of Scotland, including the Northern Isles, with 70mph to 80mph in the morning."
The Met Office also forecasts showers, with more rain expected on Friday.
Storm Pia has been named by the Danish met office.