Scotland's transport network is braced for "another major challenge" as torrential downpours are forecast over the next 72 hours.
Drivers are being urged to take extra care as heavy rain is expected to lash the country, with an increased risk of flooding in some parts.
On Wednesday, the Met Office upgraded its existing "yellow" (Be Aware) alert to "amber" (Be Prepared) for Friday in the north east of Scotland and parts of the Aberdeen, Aberdeenshire and Moray areas.
Forecasters said there could be almost a month's average rainfall in these areas over a 24 to 48-hour period, with about 80mm possible locally.
The rain will affect most of the country and is likely to be heaviest across Dumfries & Galloway, Argyll and Bute, Stirling, Perthshire and the southern Highlands, with the potential for localised flooding and travel disruption.
Transport Scotland's multi-agency response team is on stand-by and will be activated if needed.
Transport minister Keith Brown said: "Just weeks after the first major storm of the autumn, the transport network is braced for another major challenge. Our operating companies are closely monitoring the situation and are ready to deal with any weather-related issues that arise.
"A wide range of agencies and organisations are poised to react quickly to the alerts and activate their response plans for the potential impact of heavy rain.
"The travelling public also have a key role to play. The Traffic Scotland website, variable message signs and traffic internet radio are being used to provide up-to-date information, allowing them to plan and amend their journeys accordingly."
A "yellow" alert is in place for Friday for Orkney, the eastern Highlands, Tayside, Fife, Strathclyde, Edinburgh and parts of the Lothians.