Severe weather warnings have been issued for the north of Scotland, with "storm-force" winds expected to hit the area throughout the weekend.
The Met Office has Orkney and Shetland on a "be aware" alert from Friday, with the Highlands issued with a warning from Saturday. Winds of 60mph may hit the Western Isles and Shetland on Thursday night and the Highlands and Islands on Saturday.
Chris Burton, a forecaster with MeteoGroup, the weather division of the Press Association, said: "Storm-force winds will be caused by a strong depression to the north of Scotland. These winds are not too unusual for this time of year but are more commonly found further out at sea."
Police and Western Isles Council are urging the public to be careful because the gales can cause rising tides and flooding from ocean spray.
A spokesman said: "Caution should be taken on causeways in the southern isles as well as at the Braighe area, near Stornoway.
"There is a risk of flooding from spray and wave overtopping during high tide on Thursday night and the early hours of Friday morning in the Western Isles. Public travelling across causeways, including the Braighe, should base their travel plans to avoid the high-tide period."
The tide will peak between 5pm and 6pm on Thursday and between 5.30am and 6.30am on Friday. Police said crossings in Braighe may be shut during these times.
Twelve Caledonian MacBrayne ferries serving the islands have been cancelled so far, with more services disrupted.
A company spokesman said: "Due to severe weather on the west coast, CalMac have experienced a number of disruptions and cancellations. CalMac regret this but hope people will understand that these are circumstances outwith our control."