Police have warned that the docks area close to Belfast city centre could flood in a tidal surge later today, but have expressed hope that serious flooding in the east of the city may now be prevented.
Officers released the latest update on the flood threat as ministers from the Stormont Executive convened an emergency meeting to discuss the multi-agency response.
Much of the effort to reinforce water defences in Belfast is being focused in the docks area, with a number of roads set to be closed to traffic as temporary sandbag walls are built.
A Police Service of Northern Ireland (PSNI) spokesman said: "For Belfast city centre, we expect there could be some flooding in the Clarendon Dock, Corporation Street and Sailortown area at 12 noon. We would encourage people who live in this area to begin taking steps to protect their property.
"Police will be in contact with the residents over the morning to provide advice and guidance. We would ask people who work in this area to try and avoid travelling to work if possible. We would also encourage people not to park in this area."
Last night residents of Sydenham in east Belfast were told to pack a bag and prepare for potential evacuation. Sandbags were distributed to the public through the night while the authorities built up river defences.
But this morning the PSNI said the densely-packed neighbourhood may avoid "serious flooding".
The police spokesman said: "On a more encouraging note, the most recent meteorological report gives us a greater degree of confidence that the extensive planning and preparation work undertaken yesterday may help to prevent any serious flooding in the Sydenham area."
He said the risk of flooding had also been downgraded for the waterside Victoria Square shopping centre.
"The Victoria underground car park is being closed as a precaution and we would encourage people to not park in any other underground car parks in the area," he said.
"Whilst the risk for this area is reduced, we would encourage people to exercise caution and listen to media updates."
Police said assessments for Londonderry, Killough, Newcastle, Newry, Larne and Strangford areas also showed a slightly reduced flood risk from what had previously been expected.
The PSNI is co-ordinating a major planning operation involving many public services.
The Office of First Minister and Deputy First Minister, Belfast City Council, Northern Ireland Fire and Rescue Service, the Rivers Agency, Belfast Health Trust, Road Service, Northern Ireland Water, Northern Ireland Electricity, British Telecom and travel operator Translink are co-operating.