SCOTLAND’S first storm of 2015 will be fiercer and come sooner than previously forecast, with winds of 100mph or more blasting the north from tomorrow night, the Met Office warned today.
It came as an additional alert for heavy rain and possible flooding across the western half of the country until 8pm today was issued by the agency.
Forecasters upgraded their severe weather warning from yellow to amber – “be prepared” – for 10pm tomorrow until noon on Friday.
It covers the Highlands and Islands north from Mull, apart from Shetland.
The rest of the country north of the southern edge remains on yellow alert – “be aware” – for that period, with wind gusts of up to 70mph.
Northern Scotland is expected to get a second battering on Saturday, with winds gusting up to 90mph.
The Met Office said its current yellow warning for midnight to 6pm on Saturday may also be upgraded to amber.
The Met Office said “significant impacts” were likely from tomorrow night’s storm.
Its spokesman said: “The public should be prepared for the potential for disruption to transport as well as power supplies and the possibility of structural damage.
“Very large waves may also lead to dangerous conditions along some coasts.”
The storm, which had been forecast to arrive at noon on Friday, is being caused by very cold air over the United States combining with 250mph jet stream winds at high altitude – compared to the usual 150mph at this time of year.
The Met Office said: “A vigorous depression is expected to run rapidly east, passing northern Scotland on Thursday night and Friday morning.
“Winds will begin to increase late on Thursday to give a period of very strong westerly winds across the Western Isles, the north and north west of the Scottish mainland and Orkney.
“Gusts of 80 to 90mph are likely quite widely, with a risk of gusts of over 100mph in places.”
The Met Office said the heaviest rain today would be in western and central Scotland, with up to 30mm (1in) falling, and 40mm (1.5in) in hilly areas.
Its spokesman said: “Outbreaks of rain will continue to be heavy at times on Wednesday afternoon and into the early evening.
“There will be a good deal of surface water and spray on roads, with the chance of localised surface water flooding in prone spots.
“The public should be aware of the risk of difficult driving conditions.
“In addition, there is the possibility of minor river flooding in parts of the western Borders.”
The Forth Road Bridge was closed to high vehicles, trailers and motorbikes because of the winds, which reached 47mph by lunchtime.
A further yellow warning – for ice – has been issued for northern Scotland between 1am and noon tomorrow.
Several centimetres of snow may fall on higher-level roads, with slight falls at lower levels.
The Met Office said: “Showers will turn increasingly wintry on high ground overnight and on Thursday morning.
“Clear spells between the showers will allow icy stretches to form.
“The public should be aware of the risk of some difficult driving conditions due to ice, and on some higher routes, local snow cover.”