Storm Dennis is expected to bring further heavy rain for a time on Sunday morning, increasing the likelihood of high impacts.
The Met Office has issued guidance of what to expect:
Danger to life from fast flowing or deep floodwater
Extensive flooding to homes and businesses is likely
Collapsed or damaged buildings or bridges
Road closures and bus and train service delays and cancellations
Dangerous driving conditions because of spray and flooded roads
Loss of power and other essential services, such as gas, water, mobile phone service
Communities could be completely cut off by floodwater, perhaps for several days
Whilst the worst of the rainfall is likely to be over the South Wales Valleys, high levels are also expected over Snowdonia, the Cambrian Mountains, and the Brecon Beacons.
NRW staff are working around the clock to help communities be prepared – monitoring river levels, issuing warnings, checking and erecting defences, and making sure drainage grids and screens are clear.
NRW is also working very closely with local authorities, the Police, community flood wardens and many others to help keep everyone safe.
Jeremy Parr, Head of Flood and Incident Risk Management for NRW, said:“The forecast is for very significant levels of rain, especially in the eastern valleys of South Wales. Impacts could be severe overnight, and everyone should take the warnings extremely seriously.
“We are working hard to make sure communities are as prepared as possible and urge people to take care and make arrangements to be safe.
“People are advised to take great care if you need to travel. If you are out, take extreme caution and never drive or walk through flood waters.
“Keep an eye on the forecast and visit our website for the latest information on flood warnings. You can find practical advice on flooding on our website too.”
Regions and local authorities affected:
Neath Port Talbot
Rhondda Cynon Taf