An Environment Agency boss has urged people living around catchment areas of the River Irwell to ‘please, please prepare for potential flooding’.
Lee Rawlinson took to Twitter to urge residents to ‘get belongings upstairs’.
He also advised people to check on their neighbours as Storm Dennis threatens the region.
Mr Rawlinson is Area Director for Greater Manchester, Merseyside and Cheshire.
Flooding from the Irwell last weekend hit Ramsbottom, Bury and Radcliffe – with the water level rising through Salford and into Manchester city centre.
The Environment Agency confirmed an ‘incident room’ was open and officers were working round the clock.
River levels across Greater Manchester are being monitored although as of 1pm on Saturday, no official flood alerts or warnings were in force.
Mr Rawlinson said however heavy rainfall was expected in catchment areas of the Irwell.
He said on Twitter: “We are expecting heavy rainfall in the Irwell catchment in Greater Manchester.
“Please please prepare for potential flooding.
“Get belongings upstairs. Check in on vulnerable neighbours.
“Our incident room is open and we are working round the clock.”
Yellow Met Office warnings for heavy rain and strong winds are in place for the whole of Greater Manchester as the storm hits the UK.
Nationally, hundreds of flights have been cancelled and there are widespread flood warnings as well as amber and yellow Met Office weather warnings as Storm Dennis hits much of the UK.
Current weather warnings in place for Greater Manchester are a yellow warning for rain from midday today to 9pm tomorrow and a yellow warning for wind from 10am today to midday on Sunday.
An Amber warning for rain extending across Rossendale almost as far south as Bury is in place from midday today until 3pm tomorrow.
The latest map of flood alerts and warnings from the Environment Agency for the north west of England shows most of the yellow ‘alerts’ to the east of Greater Manchester are the for the Calder, and flood defence work has been going on in Mytholmroyd and Hebden Bridge since Friday.
About 150 properties in Greater Manchester are believed to have been flooded during Storm Ciara last weekend.
Bury bore the brunt of the damage, with residents in Radcliffe and Redvales evacuated and homes in Ramsbottom flooded.
In a statement, Bury council said agencies were preparing for the arrival of Storm Dennis, saying it could cause a second consecutive weekend of weather-related disruption.
Council leader David Jones said: “Storm Ciara showed just what can happen when huge amounts of rain fall in a very short time.
“While we don’t yet know what impact Storm Dennis may have in Bury, we’re closely monitoring the weather forecast and we will have an extensive emergency response team on standby throughout the weekend.
River levels last weekend were the second highest on record at Blackford Bridge and at Bury Ground, second only to those recorded in the Boxing Day floods in 2015 caused by Storm Eva.
Rainfall at some locations on the Irwell was equivalent to more than a month’s rainfall in half a day.
Storm Ciara forced a number of families to leave their homes, and more than 100 calls for support were logged with the council’s emergency control team.