Britain faces being battered by torrential rain and gale-force winds over the Christmas period, the Met Office has warned.
Forecasters have predicted winds of up to 90mph will gust through northern and western parts of Scotland, including Inverness and Fort William, on Friday and have issued an amber "be prepared" weather warning.
A Met Office spokesman said: "Travel disruptions will affect people travelling within the yellow and amber warning area as major disruption to bridges and travel networks is expected."
The unsettled weather is expected to hit travel networks including rail, road and air services.
Chris Tubbs, deputy chief meteorologist at the Met Office, said: "Storm Barbara is forecast to form in the west Atlantic on Wednesday and will pass close to the north-west of the UK during Friday, bringing very strong winds and heavy rain.
"This brings the potential for some structural damage, disruption to power supplies and travel, with restrictions on bridges and disruption to ferries likely."
The Met Office has warned that winds will reach high speeds from noon on Friday to 6am on Saturday morning in northern Scotland.
Heavy rain and blustery weather is also expected in the southern and eastern part of the UK over Friday - but conditions are set to improve on Saturday and Sunday.
The Christmas Day storm is forecast to be the biggest to hit the UK for more than a year, as it threatens to top winds from Storm Angus in November.
The Met Office also said it could not rule out a white Christmas - but added that it was unlikely.