People are being urged to consider postponing travel plans as a yellow weather warning of heavy rain was issued for part of Scotland on Friday.
The Met Office alert, covering Dumfries and Galloway and the Scottish Borders, warns that 40-50mm of rain is fairly widespread and fast flowing or deep flooding is likely and causing danger to life.
The warning applies from 3 a.m. to Friday noon and also warns of possible difficult driving conditions and delays or cancellations of train and bus services.
Police Scotland said there was a high risk of disruption and urged people to plan ahead and drive on conditions if they need to travel.
The Scottish Government said the Multi-Agency Response Team would monitor conditions during the yellow alert period.
Superintendent Stewart Mackie, of Police Scotland’s Road Policing Division, said: “A yellow weather warning has been issued for heavy rain and flooding in southern Scotland and people should consider postponing travel plans until conditions improve.
“If your trip is absolutely essential, please plan ahead by making sure you have ample fuel and supplies in your vehicle, have a charged mobile phone and always drive as conditions permit.
“Note that road closures and travel delays are likely, with possible disruption to public transport services.
The Met Office said the deadly bomb cyclone that brought down temperatures in the US is now causing wet and windy weather in the UK.
The forecaster updated its amber weather warning for heavy rain in Scotland on Friday, which now runs at midnight on Thursday instead of 3am on Friday, and expires at 2pm on December 30 instead of 6pm.
The warning applies to Central Scotland, Tayside and Fife, South West Scotland, Lothian and Borders and Strathclyde.
A yellow warning for snow and ice will cover northern Scotland except for Orkney and Shetland from midnight on Thursday to 9pm on Friday.
The Scottish Government said the Transport Scotland Resilience Room would be activated at the National Control Center to monitor the impact.
Scottish Transport Secretary Jenny Gilruth said: “The Met Office is warning us to expect a difficult spell of weather across parts of southern Scotland on Friday, with heavy rain likely to affect travel in the yellow warning area.
“Conditions could potentially cause disruption to the transport network, so it’s important that people plan their trips before they set off – particularly if they intend to use highways or travel by rail.”
Met Office meteorologist Simon Partridge said: “UK weather will remain unsettled due to strengthening jet streams due to US weather with further spells of wet and windy weather.
“The impact on the UK isn’t nearly as dramatic because this system has brought up a lot of cold air farther south, across the US.
“In fact, the cyclone is only impacting the UK due to its impact on the North Atlantic jet stream.
“What[the bomb cyclone]did is increase the jet stream because the jet stream is essentially driven by temperature differences.
“Thus, the greater the temperature difference between the North Rim and the South Rim, the stronger the jet stream becomes.”
He said the knock-on effect for Britain is wet and windy weather over the next seven to 10 days.