Sepa is bracing for a “potentially significant event” as rivers continue to rise in southern Scotland.
Flooding has caused travel disruption across Scotland after heavy rain in many parts of the country.
Several rail services have been cancelled and sections of the M9 and the M74 motorways are closed.
The Scottish Environment Protection Agency (Sepa) has issued flood warnings in central and southern areas.
There are fears that flooding could hit communities in southern Scotland as river levels rise, leading to a “potentially significant” event.
A Met Office amber alert, covering Dumfries and Galloway and the Borders, had been in place, forecasting 40-50mm of rain on Friday.
That warning has ended, but river levels are not expected to peak until Friday evening.
With 27 flood warnings and 10 flood alerts in place, Sepa’s flood duty manager Vincent Fitzsimons told BBC Scotland that specific areas were giving cause for concern.
“We are already seeing impacts to transport and to agricultural land, but the rivers are rising rapidly in response to that intense rain and should be peaking any time from now into the early evening,” he said.
“Those peaks could be significant in the southern part of the country.
“We are keeping a particular close eye on communities in Dumfries and Galloway and the Borders area – communities like Dumfries, Hawick, Peebles and Newton Stewart – but we are also monitoring further north into the Clyde Valley and Kelvin Valley and the Water of Leith.”
He said that a wide swathe of southern and central Scotland was at risk of flooding and that as river levels continued to rise, community-scale flooding could emerge – affecting properties and riverside towns.
Mr Fitzsimons said: “This is potentially a significant event. What we are worried about is the intensity of the rainfall in a short period of time.”
Supt John Cairns said that police and the local resilience partnership were monitoring incidents of flooding and concerns over properties.
He said that people should not travel unless absolutely necessary.
“The multi-agency response will be focused on additional flooding from water courses and rivers making their way to areas such as Whitesands, Newton Stewart and Langholm,” he said.
“We are aware of concerns in towns and villages across the region. No properties have been flooded but mitigation measures have been taken.”
The Dumfries and Galloway Virtual Operations Support Team (DGVOST) website has been activated, signifying a major incident in the region.
People in the area are urged to check the page, which will be kept updated with real-time accurate information from local authorities.
Dumfries and Galloway Council had closed The Whitesands in Dumfries to traffic from 10:00 due to fears that the River Nith would flood the road. The river burst its banks during the afternoon, causing flooding in the area.
Multiple roads around the village of Glenlee between New Galloway and St John’s Town of Dalry were closed including the A762 at Waterside and Lochside Point, the A712 at Ken Bridge, B7000 at High Bridge of Ken and the A713 at Parton Mill.
Motorists were urged to drive to the conditions and follow updates on the Traffic Scotland website and Twitter feed.
Elswehere, the M74 is closed northbound at junction 13 near Abingdon due to flooding, with Traffic Scotland reporting delays of about 80 minutes in both directions.
The M9 had been closed in both directions between junctions 9 and 10, near Stirling. The southbound carriageway is still shut, although traffic is now passing northbound on the hard shoulder.
On the roads:
- The A77 is closed both ways at Bellfield interchange
- The A78 is shut in both directions at the Bankfoot Roundabout, Inverkip
- In North Ayrshire, the A78 between Hunterston and Portencross was closed for several hours
- The M8 westbound between junctions 2 and 3 in West Lothian is affected. Lane two is passable but the inside lane is submerged
- In Edinburgh, the A720 was closed at Dreghorn but has now reopened
Rail travel has been severely affected across Scotland.
The line at Bowling in West Dunbartonshire was completely under water, with Network Rail posting images of floodwater pouring down onto the railway line.
However, crews had managed to clear the floodwater and reopen the railway by 12:30.
Network Rail said services would remain disrupted while ScotRail worked to get its trains and crews back into position.
Severe flooding also closed the line near Bishopton for a time while engineers inspected the track for possible damage.
The railway was also flooded at Lochwinnoch, leading to the suspension of services between Ayr, Ardrossan, Largs and Glasgow.
The East Coast line was closed at Markinch due to reports of a landslip, meaning services between Edinburgh, Perth and Dundee via Fife were suspended. However, passengers can still travel between Edinburgh, Perth and Dundee via Stirling.
The West Coast Main Line was closed between Lockerbie and Carstairs due to flooding at Beattock, Dumfries and Galloway, following “extreme overnight rainfall”.
Network Rail Scotland said it had been dealing with more than 20 flooding issues across Scotland’s railway, causing “severe disruption”.
By 14:00, ScotRail said it had managed to get trains running again on all lines north of Perth and Dundee, as well as several services to and from Edinburgh and Glasgow.
McGill’s Buses suspended services and sections of routes throughout Inverclyde and Renfrewshire due to heavy rainfall and flooding.
Two yellow warnings remain in place heading into Hogmanay.
A wind warning has been issued for Grampian, Highlands, Western Isles, Orkney and Shetland from 18:00 on Friday until 03:00 on Saturday.
An alert for ice runs from 21:00 on Friday until 11:00 on Saturday, covering Grampian, Central, Tayside, Fife, HIghlands, Western Isles and Orkney and Shetland.
The Met Office said the deadly bomb cyclone that sent temperatures plunging in the US over Christmas was causing the unsettled weather in the UK.
Meteorologist Simon Patridge said the impact on Scotland would be “nowhere near as dramatic”.
Morning! A very wet start to the day with weather warnings in force for many. Gillian has the details. pic.twitter.com/T0yjcvraI8— BBC Scotland Weather (@BBCScotWeather)