The Met Office has warned Northern Ireland to prepare for flooding, as it upgraded its severe weather warning to 'amber alert'.
Heavy rain pelted much of the province on Thursday morning - but the worst is still to come.
Further bands of rain will move east across Northern Ireland during Thursday and early Friday. Some of the rain will be heavy, notably during Thursday afternoon and also for the first part of Friday in the east.
The public should be prepared for the risk of localised flooding - which has already Helen's Bay, Co Down and the Castlederg to Ederney road.
A 'yellow warning' applies to the whole country - but flooding is predicted to be worst in the east of Northern Ireland, which has an 'amber alert' in place until 8am on Friday.
The Met Office's chief forecaster said: "An active frontal system will move east across Northern Ireland during Thursday and early Friday morning.
"Rainfall totals will be around 20-40 mm widely, and within the Amber area in the east, 40-60 mm with peaks in excess of 80 mm over the hills.
"This will also include some short spells of heavy rain which could produce 20 mm within a few hours at low levels too, notably later Thursday afternoon and again early Friday morning."
Bad flooding at the bridge at Helen's Bay in County Down. Photo by @ FollowAndyHill pic.twitter.com/upa5z4jfJK— Barra Best (@barrabest) November 6, 2014