The Republic of Ireland has deployed military troops in preparation for the worst flooding in 20 years.
Thousands of home and business owners along the River Shannon are bracing themselves for the river to peak within the next 48 hours.
Aerial footage from the Irish Air Corps taken over the catchment area shows the extent of the steady build up of flood waters in the wake of Storm Desmond.
Thousands of acres of farmland and several homes are pictured surrounded and submerged in water.
From Athlone and the surrounding areas to Limerick city, the entire catchment is on high alert with waters expected to rise half a metre in total at some point in the next 24 to 48 hours.
The Army have been supporting efforts to contain the floods in many areas with sandbags on the streets of towns and villages like Ballinasloe, Athleague, Corofin, Craughwell and many parts of Clare.
Irish Defence Forces troops and vehicles are on standby in barracks in Donegal, Galway, Limerick and Cork.
Fresh drinking water distribution points have also been set up in many areas including by the Red Cross in Athlone, Portumna and Montpelier.
And compounding the fears of local people and emergency services, more rain is forecast.
Up to 35mm - nearly a third of what is normally recorded in December - is expected to fall on parts of Connacht, Donegal, Clare and Kerry over the course of the day, deepening the crisis for hundreds of homes.
Councils in Clare, Limerick and Ballinasloe called in the Army to help with flood defences.
In neighbouring Limerick seven pumps were in operation shifting water away from the villages of Castleconnell and Montpelier while an inflatable flood boom, which acts like movable defence wall, was being used in Castleconnell to channel the floods.
The ESB also took steps to reduce pressure on the swollen Shannon system by increasing the rate of flow at the Parteen weir to 375,000 litres a second, up from the normal 40,000 litres a second at this time of year.
It also increased flows through Inniscarra dam on the Lee in Cork.
Thousands of acres of farmland are under water with the Government putting a 5 million euro emergency response fund available to those worst affected.
Iarnrod Eireann said the Sligo line from Carrick-on-Shannon to Longford would remain closed until the weekend at the earliest due to flooding with the water about a foot over the track.
In Co Galway dozens of stretches of road have been closed.
Meanwhile, the Met Office has issued a severe weather warning for rain in Northern Ireland.
The total rainfall is only expected to be around 10-20mm, much lower than previous days, but could cause surface water flooding because the grounds are already saturated from Storm Desmond.
The heavy rainfall is expected to cross from the west on Wednesday afternoon, moving quickly.
The chief forecaster said: "The combination of rain and strong or gale-force winds will also give difficult driving conditions."