The road between Creeslough and Carrigart is currently blocked at Lackagh Bridge due to a fallen tree.
Gardai in Milford say that the removal operation will take some time with the road expected to remain closed for a number of hours.
They are urging motorists to seek alternative routes this morning.
Meanwhile a countrywide weather warning has now ended - but there's some more bad conditions expected this weekend.
A status yellow alert was lifted at seven o'clock after heavy downpours overnight.
Up to 40 millimetres fell in some places.