Strong winds and heavy rain are forecast for parts of the country into the weekend.
Storm Erik has hit and as a result has left more than 1,000 homes and businesses in the Keady area without power this morning (Friday).
"Potentially damaging gusts may occur near Atlantic coasts towards dawn, with the threat of coastal flooding due to very high seas".
Police closed the road in both directions as they praised a quick-thinking HGV driver who blocked off the carriageway with his vehicle to stop others from crashing into the giant oak.
In fact, residents have been warned of remaining cautious as wind speed may be as fierce as possible.
"Even away from the strongest gusts we could still have gale-force winds".
The storm was named by Irish weather service Met Éireann, which has issued an orange warning for Counties Donegal, Galway, and Mayo.
She added: 'It's going to be a noticeably windy day everywhere today.
"We're expecting a widespread frost on Sunday night and into Monday, and the unsettled weather will continue into the start of next week".
It will lure widespread gales and frequent outbreaks of rain followed by heavy and blustery showers before winds ease on Sunday.
Storm Erik is set to bring high winds and heavy rain to the region.